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Plants deploy both primary and species-specific, specialized metabolites to communicate with other organisms and adapt to environmental challenges, including interactions with soil-dwelling microbial communities. However, the role of specialized metabolites in modulating plant-microbiome interactions often remains elusive. In this study, we report that maize (Zea mays) diterpenoid metabolites with known antifungal bioactivities also influence rhizosphere bacterial communities. Metabolite profiling showed that dolabralexins, antibiotic diterpenoids that are highly abundant in roots of some maize varieties, can be exuded from the roots. Comparative 16S rRNA gene sequencing determined the bacterial community composition of the maize mutant Zman2 (anther ear 2), which is deficient in dolabralexins and closely related bioactive kauralexin diterpenoids. The Zman2 rhizosphere microbiome differed significantly from the wild-type sibling with the most significant changes observed for Alphaproteobacteria of the order Sphingomonadales. Metabolomics analyses support that these differences are attributed to the diterpenoid deficiency of the Zman2 mutant, rather than other large-scale metabolome alterations. Together, these findings support physiological functions of maize diterpenoids beyond known chemical defenses, including the assembly of the rhizosphere microbiome. [ABSTRACT FROM AUTHOR]

Background: Due to their high amount of carbohydrate and enough moisture, cereals are a good environment for the growth of toxigenic fungi. Because of the carcinogenicity and mutagenicity of mycotoxins, preventing them from entering the food chain is essential. Therefore, the present study was conducted to determine the amount and type of contaminated imported cereals and rice produced in Khuzestan province. Materials & Methods: In October and November 2015, a total of 50 random samples of rice was collected from paddy fields . Aspergillus were identified based on available diagnostic criteria and PCR. The amount and type of aflatoxin in rice samples and mycotoxins in imported cereals (winter 2015 to autumn 2016) were evaluated by HPLC. Results: Based on one sample t-test and comparing the mean of mycotoxins contaminating cereals in different seasons with national maximum standard, the amount of mycotoxins in barley and wheat were within the standard range but %8.4 of corn was higher than the permitted level (ppb5). Analysis of aflatoxins in rice also showed that 16 samples were contaminated with aflatoxin B1. Aspergillus flavus was the major pollutant (%42.1) isolated from rice. Conclusion: Aspergillus flavus is the major producer of aflatoxin B1 in domestic rice. Examination of imported cereals also showed high rates of fungal growth and production of secondary metabolites, possibly due to inadequate storage conditions, high temperature and humidity. Therefore, it is recommended to strengthen the monitoring tools in the processing and storage of rice and cereals. [ABSTRACT FROM AUTHOR]

Maize is a major staple food in sub-Sahara Africa. Maize grains are susceptible to mycotoxin contamination during production and storage. Tropical weather, poor agricultural practices, poor storage conditions and little knowledge on mycotoxins exposes sub-Sahara Africa (SSA) community at high risk of mycotoxin. Studies in SSA demonstrated that, maize grains are infested by toxigenic fungi and contaminated with mycotoxins to varying degree. Mycotoxins frequent occurring in maize include; aflatoxins, deoxynivalenol, fumonisins, ochratoxins and zearalenone. Their effect can be acute and/or chronic leading to health problems such as; liver cancer, immunosuppression, irritation, and respiratory problem among others. Local practices, maize seems to be less contaminated are used for human consumption while those unfit for human are used as feeds exposing human health at high risk of mycotoxins toxicity. It is important for sub-Sahara Africa countries to invest in infrastructures and enforce practices which leads to prevention and control of mycotoxins in maize before they become real risks. Also, interventions on public awareness on the effect of mycotoxins to human health should be promoted to guarantee safe maize and maize products. In this review, mycotoxins occurrence, incidences, prevention, control, decontamination and inactivation in maize are scrutinized and presented. [ABSTRACT FROM AUTHOR]

In most parts of Africa, the process of fermentation is not controlled and does not adhere to good manufacturing practices, therefore spoilage and pathogenic microorganisms can alter the quality of the end product and may cause foodborne illness. Traditional fermented products are mostly processed in an environment which creates a selection of microorganisms that produce the desired end product. In an attempt to find Lactobacilli which have probiotic properties and can be used in the development of starter culture for controlled fermentation of cereal products, the microbial populations of maize flour, overnight soaked dough, fermented cooked porridge, Mkarango and Busaa were enumerated and the inherent lactobacilli isolated. The microbial and biochemical profiles of the 6 days spontaneous Mkarango fermentation process were determined. The total viable count was 6.93 log cfu/g for fermented cooked porridge, 7.70 log cfu/g in Mkarango and 8.58 log cfu/g for Busaa. Lactobacilli counts were higher in maize flour with 7.43 log cfu/g while Enterobactericeae were lower in Mkarango. The highest moulds and yeasts counts were observed for Busaa, 7.25 log cfu/g. The lactobacilli isolates from fermented maize based products from western Kenya were predominantly Lactobacillus fermentum and Lactobacillus Plantarum. During fermentation time, Lactobacilli increased from 6.62 to 12.46 log cfu/g after 3 days of fermentation. From day 4, an increase in moulds and yeast count was observed, varying from 8.42 to 10.53 log cfu/g. Enterobactericeae count decreased from 5.99 log cfu/g on day 1 to less than 1 log cfu/g on day 6. Titratable acidity increased from 0.32% to 0.73% on day 5. Inversely, the pH of Mkarango decreased sharply from 6.64 to 3.64 on day 5 and slightly increased on the last day of fermentation. The microbial status of finished fermented maize based products is predominated by Lactobacilli and their isolates are predominantly Lactobacilli especially Lactobacillus fermentum and Lactobacillus Plantarum though further molecular tests are needed to confirm the species. [ABSTRACT FROM AUTHOR]

Aspergillus flavus is an opportunistic pathogen and may produce aflatoxins in maize, one of the most important crops in Argentina. A promising strategy to reduce aflatoxin accumulation is the biological control based on competitive exclusion. In order to select potential biocontrol agents among isolates from the maize growing region in Argentina, a total of 512 A. flavus strains were isolated from maize kernels and soil samples. Thirty-six per cent of the isolates from maize kernels did not produce detectable levels of aflatoxins, while 73% of the isolates from soil were characterized as non-aflatoxin producers. Forty percent and 49% of the isolates from maize kernels and soil samples, respectively, were not producers of cyclopiazonic acid (CPA). Sclerotia morphology was evaluated using Czapek Dox media. Eighty-six per cent of the isolates from maize kernels and 85% of the isolates from soil samples were L sclerotia morphotype (average diameter > 400 μm). The remaining isolates did not produce sclerotia. All isolates had MAT 1-1 idiomorph. The competitive ability of 9 non aflatoxigenic strains, 4 CPA(+) and 5 CPA(−), was evaluated in co-inoculations of maize kernels with an aflatoxigenic strain. All evaluated strains significantly ( p  < 0.05) reduced aflatoxin contamination in maize kernels. The aflatoxin B 1 (AFB 1 ) reduction ranged from 6 to 60%. The strain A. flavus ARG5/30 isolated from maize kernels would be a good candidate as a potential biocontrol agent to be used in maize, since it was characterized as neither aflatoxin nor CPA producer, morphotype L, MAT 1-1 idiomorph, and reduced AFB 1 content in maize kernels by 59%. This study showed the competitive ability of potential aflatoxin biocontrol agents to be evaluated under field trials in a maize agro-ecosystem in Argentina. [ABSTRACT FROM AUTHOR]

We investigated the potential effects of genetic modification of Bt maize on the community composition and functions of bacterial endophytes associated with transgenic maize (Bt MON 810) in comparison with its isogenic parental line at two developmental stages. Bacterial isolates were obtained from transgenic (Bt) and non-transgenic (non-Bt) maize at 50- and 90-day-old developmental stages. Isolated bacterial endophytes were screened for their capabilities in phosphate solubilisation, nitrogen fixation, production of antifungal metabolites and production of indole acetic acid. After molecular identification, 60 isolates were obtained and clustered into 19 and 18 operational taxonomic units from 50- and 90-day-old maize, respectively. The isolates belonged to the genera Bacillus, Pantoea, Serratia, Yersinia, Enterobacter, Pseudomonas, Acinetobacter and Stenotrophomonas. Functional attributes and diversity of the isolated endophytes at both developmental stages were not significantly different for both maize varieties. However, functional attributes were significantly affected by plant growth stage. Isolates from younger plants were more efficient producers of indole acetic acid, but exhibited little or no capabilities for nitrogen fixation, phosphate solubilisation and antifungal activity in both maize genotypes. Based on these outcomes, Bt modification in maize does not seem to affect the community composition or functional attributes of bacterial endophytes. Significance: • Bt modification in maize does not affect the ecological guild or functional attributes of cultivable bacterial endophytes. [ABSTRACT FROM AUTHOR]

Oil presence in soil, as a stressor, reduces phytoremediation efficiency through an increase in the plant stress ethylene. Bacterial 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, as a plant stress ethylene reducer, was employed to increase oil phytoremediation efficiency. For this purpose, the ability of ACC deaminase-producing Pseudomonas strains to grow in oil-polluted culture media and withstand various concentrations of oil and also their ability to reduce plant stress ethylene and enhance some growth characteristics of maize and finally their effects on increasing phytoremediation efficiency of poly aromatic hydrocarbons (PAHs) in soil were investigated. Based on the results, of tested strains just P9 and P12 were able to perform oil degradation. Increasing oil concentration from 0 to 10% augmented these two strains population, 15.7% and 12.9%, respectively. The maximum increase in maize growth was observed in presence of P12 strain. Results of high-performance liquid chromatography (HPLC) revealed that PAHs phytoremediation efficiency was higher for inoculated seeds than uninoculated. The highest plant growth and PAHs removal percentage (74.9%) from oil-polluted soil was observed in maize inoculated with P12. These results indicate the significance of ACC deaminase producing bacteria in alleviation of plant stress ethylene in oil-polluted soils and increasing phytoremediation efficiency of such soils. [ABSTRACT FROM AUTHOR]

Microbial population dynamics associated with corn silage, with and without Lactobacillus plantarum treatment, was studied. Whole crop corn was ensiled using laboratory silos and sampled at different times, up to 3 months. The dominant bacteria, before ensiling, were Acinetobacter (38.5%) and Klebsiella (16.3%), while the dominant fungi were Meyerozyma (53.5%) and Candida (27.7%). During ensiling, the microbial population shifted considerably, and Lactobacillus (> 94%) and Candida (> 74%) became the most dominant microbial genera in both treated and untreated silages. Yet, lactic acid content was higher in the treated silage, while the microbial diversity was lower than in the untreated silage. Upon aerobic exposure, spoilage occurred more rapidly in the treated silage, possibly due to the higher abundance of lactic acid-assimilating fungi, such as Candida. Our study is the first to describe microbial population dynamics during whole-crop corn ensiling and the results indicate that microbial diversity may be an indicator of aerobic stability. [ABSTRACT FROM AUTHOR]

An attempt was made to compare between easy and inexpensive qualitative method (ammonia vapour test) and analytical methods (thin layer chromatography and enzyme-linked immunosorbent assay) for identification of aflatoxigenic isolates of Aspergillus flavus in maize. In this comparative study the toxicity level of A. flavus isolates exhibited 100% agreement among ammonia vapour test, ELISA and TLC for highly toxigenic (>2000 ppb) and toxigenic (501–2000 ppb) isolates while 88.5% agreement observed for least toxic (<20 ppb) isolates. In ammonia vapour test 51% of A. flavus isolates showed creamish or no colour change corresponding to least toxic/atoxic (<20ppb) category estimated by ELISA. Similarly 22% highly toxic isolates exhibited plum red colour, 12% moderately toxic indicated pink colour and 10% toxic isolates showed red colour. However, 11.5% isolates were found to be false positive in cream colour category (least toxic) and 28.5% false negatives in pink colour (moderately toxic) category. The isolates from different agroclimatic zones of maize in India showed high variability for aflatoxin B1 (AFB1) production potential ranging from 0.214–8116.61 ppb. Toxigenic potential of Aspergillus flavus isolates in culture was further validated by inoculating maize grain sample with four different isolates with varied toxin producing ability. With good agreement percentage between cultural and analytical methods the study concludes the ammonia vapour test to be easy, inexpensive reliable and time saving method that can be used for segregating or pre-screening of contaminated samples from bulk food/feed stock. [ABSTRACT FROM AUTHOR]

The effects of silver nanoparticles (AgNPs) on plants and soil microbial communities have been widely documented. However, the influence of AgNPs on plant growth and rhizospheric microbial communities, especially the important symbiotic microbes, such as arbuscular mycorrhizal (AM) fungi, remains under debate. In this study, a greenhouse pot experiment was established to investigate the responses of maize ( Zea mays L.) growth and rhizospheric AM fungal assemblages to different application levels (0.025, 0.25 and 2.5 mg kg −1 ) of AgNPs or bulk Ag. The results indicated that 2.5 mg kg −1 of AgNPs significantly decreased ( p < 0.05) plant biomass and dissolved organic carbon (DOC) content in rhizospheric soils compared to the control and bulk Ag conditions. Growth inhibition was associated with increased Ag accumulation in plant tissues and increased antioxidant enzyme activity. A similar toxicity for the AM fungal community was observed as a significant decrease ( p < 0.05) in their diversity and remarkable variations in their structure, which were closely correlated with plant root biomass, soil soluble Ag and DOC content. Consequently, AgNPs caused a reduction in AM fungal growth and ecological function, characterized by a significantly decreased ( p < 0.05) root mycorrhizal colonization rate, soil alkaline phosphatase activity, available phosphorus (P) content and P nutrition in plants. These results suggest that high concentrations of AgNPs can deteriorate the mutual interaction between plants and AM fungi and negatively influence the rhizospheric soil P cycling, both of which go against plant growth and soil fertility. [ABSTRACT FROM AUTHOR]

The drying status and quality aspects in terms of physical, nutritional, functional properties and microbial status of three common maize varieties (900M gold, pioneer 92 and kavri) dried in different drying complexes are presented in this paper. Total drying varied from18-20 h for drying of freshly harvested maize varieties in the complexes where sun drying method was used. The overall calculation reveled that drying cost in the mills ranged from US$11.5 to US$14.75 per ton of fresh maize (1 US$ equals 80 BDT). The dimensions of the maize varieties as length, width and thickness were found to be ranged from 12.62±0.34 to 14.54±0.32, 9.56±0.24 to 10.60±0.35, 6.38±0.28 to 7.3±0.41 mm, respectively. The 900M gold variety gave the highest bulk density of 575.84±3.8 kg m-3. The highest crude protein (8.75%±0.10%) and water solubility index (1.90±0.02 gm gm-1 of gel) were found in the dried samples of 900 M gold variety at 14% moisture content. The highest ash, fat and starch content were 2.01%±0.02%, 3.97%±0.09% and 76.33%±0.88%, respectively in pioneer 92 varieties at 14% moisture content. The highest microbial load was found at higher moisture dried grain (14%) than lower moisture dried samples. The quality of dried grain was found to be affected with the variation in final moisture content during storage. Therefore, maize should be dried at moisture content less than 14% to maintain quality and to keep free from microbial infestation for its future use as food and feed. [ABSTRACT FROM AUTHOR]

Fusarium proliferatum produces fumonisins B not only on maize but also on diverse crops including wheat. Using a wheat-based medium, the effects of abiotic factors, temperature and water activity (a W ), on growth, fumonisin biosynthesis, and expression of FUM genes were compared for three F. proliferatum strains isolated from durum wheat in Argentina. Although all isolates showed similar profiles of growth, the fumonisin production profiles were slightly different. Regarding FUM gene transcriptional control, both FUM8 and FUM19 expression showed similar behavior in all tested conditions. For both genes, expression at 25 °C correlated with fumonisin production, regardless of the a w conditions. However, at 15 °C, these two genes were as highly expressed as at 25 °C although the amounts of toxin were very weak, suggesting that the kinetics of fumonisin production was slowed at 15 °C. This study provides useful baseline data on conditions representing a low or a high risk for contamination of wheat kernels with fumonisins. [ABSTRACT FROM AUTHOR]

Phosphate fertilization is a common practice in agriculture worldwide, and several commercial products are widely used. Triple superphosphate (TSP) is an excellent soluble phosphorus (P) source. However, its high cost of production makes the long-term use of crude rock phosphate (RP) a more attractive alternative in developing countries, albeit its influence on plant-associated microbiota remains unclear. Here, we compared long-term effects of TSP and RP fertilization on the structure of maize rhizosphere microbial community using next generation sequencing. Proteobacteria were dominant in all conditions, whereas Oxalobacteraceae (mainly Massilia and Herbaspirillum) was enriched in the RP-amended soil. Klebsiella was the second most abundant taxon in the RP-treated soil. Burkholderia sp. and Bacillus sp. were enriched in the RP-amended soil when compared to the TSP-treated soil. Regarding fungi, Glomeromycota showed highest abundance in RP-amended soils, and the main genera were Scutellospora and Racocetra. These taxa are already described as important for P solubilization/acquisition in RP-fertilized soil. Maize grown on TSP and RP-treated soil presented similar productivity, and a positive correlation was detected for P content and the microbial community of the soils. The results suggest changes of the microbial community composition associated to the type of phosphate fertilization. Whilst it is not possible to establish causality relations, our data highlights a few candidate taxa that could be involved in RP solubilization and plant growth promotion. Moreover, this can represent a shorter path for further studies aiming the isolation and validation of the taxa described here concerning P release on the soil plant system and their use as bioinoculants. [ABSTRACT FROM AUTHOR]

There are a total of 30 strains including 27 strains of Aspergillus niger intended used in Chinese food industry, two strains used as control and one strain isolated from corn for fumonisin (FB) production on 3 media. It was found that FB2 production by A. niger was function-dependent and highly related to culture media, as well as incubation time. All strains studied were unable to produce FB1 and FB3. Almost all strains were found to produce FB2 on corn, rice and wheat bran. Based on their intended use in the food industry, the higher level of FB2 producers were strains used for saccharifying enzyme (n = 13) production, followed by organic acid (n = 6), tannase (n = 7) and α-galactosidase (n = 1) production, with the FB2 mean level of 3553-10,270 μg/kg, 1059-12,036 μg/kg, 3-7 μg/kg and 2-4 μg/kg on corn, 5455-9241 μg/kg, 559-2190 μg/kg, 4-9 μg/kg and 6-10 μg/kg on rice, 5959-7709 μg/kg, 9491-17,339 μg/kg, 8-14 μg/kg and 120-222 μg/kg on wheat bran, respectively. Comparatively, strains of Fusarium verticillioide were capable of producing fumonins simultaneously with broader spectrum including FB1 , FB2 and FB3 , but at a much lower level. In conclusion, it is necessary to evaluate FB2 production by A. niger before intended use in the food processing industry. [ABSTRACT FROM AUTHOR]

In this study, we designed a microcosm experiment to explore the composition of the bacterial community in the rhizosphere of maize and bulk soil by sequencing the V3-V4 region of the 16S rRNA gene on the Illumina system. 978–1239 OTUs (cut off level of 3%) were found in rhizosphere and bulk soil samples. Rhizosphere shared features with the bulk soil, such as predominance of Acidobacteria, Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Gemmatimonadetes and TM7. At genus level, many of the dominant rhizosphere genera (Chitinophaga, Nitrospira, Flavobacterium, etc.) displayed different patterns of temporal changes in the rhizosphere as opposed to the bulk soil, showing rhizosphere has more impact on soil microorganisms. Besides, we found that significant growth-related dynamic changes in bacterial community structure were mainly associated with phylum Bacteroidetes, Proteobacteria and Actinobacteria (mainly genera Burkholderia, Flavisolibacter and Pseudomonas), indicating that different growth stages affected the bacterial community composition in maize soil. Furthermore, some unique genera in especial Plant-Growth Promoting Rhizobacteria (PGPR) such as Nonomuraea, Thiobacillus and Bradyrhizobium etc., which were beneficial for the plant growth appeared to be more abundant in the rhizosphere than bulk soil, indicating that the selectivity of root to rhizosphere microbial is an important mechanism leading to the differences in the bacteria community structure between rhizosphere and bulk soil. [ABSTRACT FROM AUTHOR]

Aims The objective was to determine the effect of biochanin A ( BCA), an isoflavone produced by red clover ( Trifolium pratense L.), on corn fermentation by rumen micro-organisms. Methods and Results When bovine rumen bacterial cell suspensions ( n = 3) were incubated (24 h, 39 °C) with ground corn, amylolytic bacteria including group D Gram-positive cocci ( GPC; Streptococcus bovis; enterococci) proliferated, cellulolytic bacteria were inhibited, lactate accumulated and pH declined. Addition of BCA (30 μg ml−1) inhibited lactate production, and pH decline. BCA had no effect on total amylolytics, but increased lactobacilli and decreased GPC. The initial rate and total starch disappearance was decreased by BCA addition. BCA with added Strep. bovis HC5 supernatant (containing bacteriocins) inhibited the amylolytic bacteria tested ( Strep. bovis JB1; Strep. bovis HC5; Lactobacillus reuteri, Selenemonas ruminatium) to a greater extent than either addition alone. BCA increased cellulolytics and dry matter digestibility of hay with corn starch. Conclusions These results indicate that BCA mitigates changes associated with corn fermentation by bovine rumen bacteria ex vivo. Significance and Impact of the Study BCA could serve as an effective mitigation strategy for rumen acidosis. Future research is needed to evaluate the effect of BCA on mitigating rumen acidosis in vivo. [ABSTRACT FROM AUTHOR]

Background and Aims Maize bushy stunt phytoplasma (MBSP) is a bacterial pathogen of maize (Zea mays L.) across Latin America. MBSP belongs to the 16SrI-B sub-group within the genus 'Candidatus Phytoplasma'. MBSP and its insect vector Dalbulus maidis (Hemiptera: Cicadellidae) are restricted to maize; both are thought to have coevolved with maize during its domestication from a teosinte-like ancestor. MBSP-infected maize plants show a diversity of symptoms. and it is likely that MBSP is under strong selection for increased virulence and insect transmission on maize hybrids that are widely grown in Brazil. In this study it was investigated whether the differences in genome sequences of MBSP isolates from two maize-growing regions in South-east Brazil explain variations in symptom severity of the MBSP isolates on various maize genotypes. Methods MBSP isolates were collected from maize production fields in Guaíra and Piracicaba in South-east Brazil for infection assays. One representative isolate was chosen for de novo whole-genome assembly and for the alignment of sequence reads from the genomes of other phytoplasma isolates to detect polymorphisms. Statistical methods were applied to investigate the correlation between variations in disease symptoms of infected maize plants and MBSP sequence polymorphisms. Key Results MBSP isolates contributed consistently to organ proliferation symptoms and maize genotype to leaf necrosis, reddening and yellowing of infected maize plants. The symptom differences are associated with polymorphisms in a phase-variable lipoprotein, which is a candidate effector, and an ATP-dependent lipoprotein ABC export protein, whereas no polymorphisms were observed in other candidate effector genes. Lipoproteins and ABC export proteins activate host defence responses, regulate pathogen attachment to host cells and activate effector secretion systems in other pathogens. Conclusions Polymorphisms in two putative virulence genes among MBSP isolates from maize-growing regions in South-east Brazil are associated with variations in organ proliferation symptoms of MBSP-infected maize plants. [ABSTRACT FROM AUTHOR]

Aims The aim of this study was to evaluate the chemical and microbiological characteristics and to identify the lactic acid bacteria ( LAB) and yeasts involved in rehydrated corn kernel silage. Methods and Results Four replicates for each fermentation time: 5, 15, 30, 60, 90, 150, 210 and 280 days were prepared. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and PCR-based identification were utilized to identify LAB and yeasts. Eighteen bacteria and four yeast species were identified. The bacteria population reached maximum growth after 15 days and moulds were detected up to this time. The highest dry matter ( DM) loss was 7·6% after 280 days. The low concentration of water-soluble carbohydrates (20 g kg−1 of DM) was not limiting for fermentation, although the reduction in pH and acid production occurred slowly. Storage of the rehydrated corn kernel silage increased digestibility up to day 280. Conclusions This silage was dominated by LAB but showed a slow decrease in pH values. This technique of corn storage on farms increased the DM digestibility. Significance and Impact of the Study This study was the first to evaluate the rehydrated corn kernel silage fermentation dynamics and our findings are relevant to optimization of this silage fermentation. [ABSTRACT FROM AUTHOR]

Food security considerations have shifted in recent years, with the recognition that available food should also be nutritious and safe. There is a growing evidence base for contamination of maize and other crops by fungal toxins in the tropics and sub-tropics. As an initial snapshot of contamination by one of these toxins in Rwanda, Aflatoxin B1 (AFB1) was analyzed in 684 samples of maize flour collected in seven principal retail markets of Kigali and in 21 samples of animal feed from seven feed vendors. Two rounds of sample collections were carried out, the first in September 2014 and the second in January 2015. A questionnaire given to vendors was used to determine if gender and education level of vendors, origin of maize and awareness of aflatoxins had any significant effect on AFB1 level in collected samples. Enzyme-Linked Immunosorbent Assay (ELISA) and Immuno-affinity fluorimetery were used to analyze samples. Only markets had a significant effect on AFB1 level; for the two collections, differences were inconsistent among markets. In the first round, market means of AFB1 varied between 8.0 ± 5.57 μg/kg and 24.7 ± 23.74 μg/kg and for the second round, between 10.4 ± 8.4 μg/kg and 25.7 ± 25.85 μg/kg. In most animal feed samples AFB1 was >100 μg/kg. None of the vendors interviewed was aware of the risk of mycotoxin contamination in their maize-based flours and feed. Limits set by the United States Food and Drug Administration (20 μg/kg) for total aflatoxins and European Commission (2 μg/kg) for AFB1 for maize flour imports, were varied between 2–35% and 66–100% of samples, respectively. The implications of this study for human and animal health in Rwanda suggest that expanded surveys are needed to understand the scope of contamination, given the influence of environment and other factors on aflatoxin accumulation. Available options to mitigate and monitor aflatoxin contamination can be further deployed to reduce contamination. [ABSTRACT FROM AUTHOR]

In a natural ecosystem, the plant is in a symbiotic relationship with beneficial endophytes contributing huge impact on its host plant. Therefore, exploring beneficial endophytes and understanding its interaction is a prospective area of research. The present work aims to characterize the fungal endophytic communities associated with healthy maize and rice plants and to study the deterministic factors influencing plant growth and biocontrol properties against phytopathogens, viz, Pythium ultimum, Sclerotium oryzae, Rhizoctonia solani, and Pyricularia oryzae. A total of 123 endophytic fungi was isolated using the culture-dependent approach from different tissue parts of the plant. Most dominating fungal endophyte associated with both the crops belong to genus Fusarium, Sarocladium, Aspergillus, and Penicillium and their occurrence was not tissue specific. The isolates were screened for in vitro plant growth promotion, stress tolerance, disease suppressive mechanisms and based on the results, each culture from both the cereal crops was selected for further study. Acremonium sp. (ENF 31) and Penicillium simplicisssum (ENF22), isolated from maize and rice respectively could potentially inhibit the growth of all the tested pathogens with 46.47 ± 0.16 mm to 60.09 ± 0.04 mm range zone of inhibition for ENF31 and 35.48 ± 0.14 to 62.29 ± 0.15 mm for ENF22. Both significantly produce the defensive enzymes, ENF31 could tolerate a wide range of pH from 2 to 12, very important criteria, for studying plant growth in different soil types, especially acidic as it is widely prevalent here, making more land unsuitable for cultivation. ENF22 grows in pH range 3-12, with 10%salt tolerating ability, another factor of consideration. Study of root colonization during 7th to 30th days of growth phase reveals that ENF31 could colonize pleasantly in rice, though a maize origin, ranging from 1.02 to 1.21 log10 CFU/g root and in maize, it steadily colonizes ranging from 0.95 to 1.18 log10 CFU, while ENF22 could colonize from 0.98 to 1.24 Log10CFU/g root in rice and 1.01 to 1.24Log10CFU/g root in maize, just the reverse observed in Acremonium sp. Therefore, both the organism has the potency of a promising Bio-resource agent, that we must definitely explore to fill the gap in the agriculture industry. [ABSTRACT FROM AUTHOR]

In the present study, a total of 70 Trichoderma spp. were isolated from the rhizosphere soils of vegetable and spice crops that were grown in Andaman and Nicobar Islands, India. Initial screening of Trichoderma spp. for salt tolerant properties showed 32 isolates were able to tolerate 10% NaCl. Furthermore, these isolates were screened for their potential plant growth-promoting characteristics such as IAA production, phosphate solubilization, and siderophore production. Among 32 isolates, nine isolates were able to produce IAA, siderophore, and solubilize phosphate. Jar trial was carried out on maize under axenic conditions at 1.67, 6.25, 11.25, 17.2, and 22.9 dS m−1 salt stress using the best nine isolates. Three isolates (TRC3, NRT2, and THB3) were effective in improving germination percentage, reducing reduction percentage of germination (RPG) and also in increasing the shoot and root length under axenic conditions. These three isolates were further tested under pot trial at 52 (sea water), 27, 15, 7, and 1.67 dS m−1. TRC3 was found to be the most effective isolate compared to the other isolates and significantly increased the physiological parameters like shoot, root length, leaf area, total biomass, and stem and leaf fresh weight at all stress levels. Similarly, total chlorophyll content also increased by TRC3 over control. All three isolates, NRT2, TRC3, and THB3 showed lower accumulation of malondialdehyde (MDA) content whereas, proline and phenol content were higher than the uninoculated control plants under both normal and saline conditions. The results suggest that these isolates could be utilized for the alleviation of salinity stress in maize. [ABSTRACT FROM AUTHOR]

The chemical contamination of food is among the main public health issues in developing countries. With a view to find new natural bioactive products against fungi responsible for chemical contamination of staple food such as maize, the antifungal activity tests of scopoletin extracted from different components of the cassava root produced in Benin were carried out. The dosage of scopoletin from parts of the root (first skin, second skin, whole root, and flesh) was done by High Performance Liquid Chromatography. The scopoletin extract was used to assess the activity of 12 strains (11 strains of maize and a reference strain). The presence of scopoletin was revealed in all components of the cassava root. Scopoletin extracted from the first skin cassava root was the most active both as inhibition of sporulation (52.29 to 87.91%) and the mycelial growth (36.51–80.41%). Scopoletin extract from the cassava root skins showed significant inhibitory activity on the tested strains with fungicide concentration (MFC) between 0.0125 mg/mL and 0.1 mg/mL. The antifungal scopoletin extracted from the cassava root skins may be well beneficial for the fungal control of the storage of maize. [ABSTRACT FROM AUTHOR]

In this study, the occurrence of Fusarium mycotoxins deoxynivalenol (DON), zearalenone (ZEA) and fumonisins (FUM) was investigated in a total of 257 samples of unprocessed cereals (maize, wheat and barley), sampled annually in Bosnia and Herzegovina throughout the 2013-2015 harvesting period. The levels of mycotoxins were determined using a validated ELISA method. The results showed maize to be the most contaminated cereal among the three, with DON detected in 85%, ZEA in 73% and FUM in 67% of samples, the mean concentrations of the toxins observed during the study period thereby being 984±957 μg/kg, 326±314 μg/kg, and 1,259±1,161 μg/kg, respectively. Twenty samples (7.8%) were proven inadmissible for consumption as foodstuffs (Commission Regulation 1881/2006), and 3 samples (1.2%) were proven inadmissible even as feedstuffs (Commission Recommendation 2006/576/EC). Significantly higher (p < 0.05) mycotoxin levels determined in samples harvested in 2014 as compared to those harvested in 2013 and 2015 could be associated with heavy rainfall periods witnessed in 2014 that could favour the formation of moulds, and consequently also the increased production of Fusarium mycotoxins. [ABSTRACT FROM AUTHOR]

Maize ( Zea mays L.) is a multi-use crop, but its cultivation has a number of associated environmental and ecological impacts. Few investigations have been undertaken to understand the impact of different maize cultivation techniques on above- and below-ground arthropod communities. This study has shown that strip tillage cultivation of maize improves arthropod community structure and biodiversity though a reduction in the area disturbed by cultivation and increased non-crop. Furthermore, increasing the richness of non-crop plants within strip tillage systems further increased the numbers of above- and below-ground taxa. Although there was a significant reductions in maize yield under strip tillage cultivation systems compared to the more conventional cultivation techniques making adoption unlikely, our results do show with simple changes in maize cultivation practice there can be benefits to biodiversity. The research challenge is now not to be able to enhance biodiversity, but to develop integrated crop management practices that sustain yields. [ABSTRACT FROM AUTHOR]

Introduction: Root-mediated changes in soil organic matter (SOM) decomposition, termed rhizosphere priming effects (RPE), play crucial roles in the global carbon (C) cycle, but their mechanisms and field relevance remain ambiguous. We hypothesize that nitrogen (N) shortages may intensify SOM decomposition in the rhizosphere because of increase of fine roots and rhizodeposition. Methods: RPE and their dependence on N-fertilization were studied using a C-to-C vegetation change. N-fertilized and unfertilized soil cores, with and without maize, were incubated in the field for 50 days. Soil CO efflux was measured, partitioned for SOM- and root-derived CO, and RPE was calculated. Plant biomass, microbial biomass C (MBC) and N (MBN), and enzyme activities (β-1,4-glucosidase; N-acetylglucosaminidase; L-leucine aminopeptidase) were analyzed. Results: Roots enhanced SOM mineralization by 35 % and 126 % with and without N, respectively. This was accompanied by higher specific root-derived CO in unfertilized soils. MBC, MBN and enzyme activities increased in planted soils, indicating microbial activation, causing positive RPE. N-fertilization had minor effects on MBC and MBN, but it reduced β-1,4-glucosidase and L-leucine aminopeptidase activities under maize through lower root-exudation. In contrast, N-acetylglucosaminidase activity increased with N-fertilization in planted and unplanted soils. Conclusions: This study showed the field relevance of RPE and confirmed that, despite higher root biomass, N availability reduces RPE by lowering root and microbial activity. [ABSTRACT FROM AUTHOR]

A field experiment was conducted at Main Agricultural Research Station (MARS), Agriculture College, Dharwad to study the effect of sequential application of herbicides on microbial activities and yield of maize. Six herbicides, namely, glyphosate, paraquat, glufosinate ammonium, saflufenacil, halosulfuron and imazathapyr were tried as postemergence in addition to pre-emergence application of atrazine. Totally nine treatments were tested using randomized block design having three replications with three controls [Weedy check, weed free check and standard recommended package of practices (RPP)]. Weed free check was recorded higher weed control index (WCI) than rest of the weed control methods at all the growth stages of maize. However, the treatment, pre-emergence application of atrazine @ 1 kg/ha fb post-emergence application of glyphosate @ 2.5 kg/ha recorded WCI of 92.12% next to weed free check. Weed free check recorded significantly higher grain yield (84.59 q/ha), stover yield (114.10 q/ha) and harvest index (42.57%). At different growth stages of maize, both pre- and post-emergence applications of herbicides, all the enzymatic activities in the soil were reduced as compared to untreated plots. [ABSTRACT FROM AUTHOR]

Rhizobia respond differently for improving physiology, nutrition, and yield of maize under field conditions. Therefore, in the present study, maize seeds (cv. Neelum) were inoculated with Rhizobium phaseoli (strains RS-1 and RS-3) and Mesorhizobium ciceri (strains RS-8 and RS-12) and sown in fields (sites 1 and 2) having sandy clay loam soil. Plants inoculated with RS-3 showed significant increases in plant height, fresh biomass, cob yield, grain yield, grain P, and shoot K contents, as compared to control at both sites. Whereas RS-1 inoculated plants showed increases in the photosynthetic rate, stomatal conductance, water use efficiency, mesophyll conductance, and intrinsic/photosynthetic water use efficiency compared with control. RS-8 inoculated plants showed highest 1000 grain weight, sub-stomatal conductance and relative water content compared to control. However, the highest amount of crude protein, N in shoot/grain and shoot K contents were recorded due to RS-12 inoculation as compared to un-inoculated control. The findings of the experiments clearly demonstrated higher potential of RS-1 and RS-3 species over RS-8 and RS-12 for improving growth, physiology, and yield of maize plants under field conditions which might be due to a specific compatibility of RS-1 and RS-3 with maize cultivar Neelum, as the strength of association is determined by type and species of plant/bacteria and growth conditions. [ABSTRACT FROM AUTHOR]

On October 12, 2015, a county health department notified the Wyoming Department of Health of an outbreak of gastrointestinal illness among residents and staff members at a local correctional facility. The majority of ill persons reported onset of symptoms within 1-3 hours after eating lunch served at the facility cafeteria at noon on October 11. Residents and staff members reported that tortilla chips served at the lunch tasted and smelled like chemicals. The Wyoming Department of Health and county health department personnel conducted case-control studies to identify the outbreak source. Consuming lunch at the facility on October 11 was highly associated with illness; multivariate logistic regression analysis found that tortilla chips were the only food item associated with illness. Hexanal and peroxide, markers for rancidity, were detected in tortilla chips and composite food samples from the lunch. No infectious agent was detected in human stool specimens or food samples. Extensive testing of lunch items did not identify any unusual chemical. Epidemiologic and laboratory evidence implicated rancid tortilla chips as the most likely source of illness. This outbreak serves as a reminder to consider alternative food testing methods during outbreaks of unusual gastrointestinal illness when typical foodborne pathogens are not identified. For interpretation of alternative food testing results, samples of each type of food not suspected to be contaminated are needed to serve as controls. [ABSTRACT FROM AUTHOR]

In this work, the photosynthetic process of maize plants ( Zea mays), which were grown using seeds inoculated with plant growth promoting bacteria Azospirillum brasilense and Burkholderia unamae, was monitored. Photothermal and photobaric signals obtained by a time-resolved photoacoustic measurement configuration were used for measuring the oxygen evolution rate in situ. A frequency-resolved configuration of the method was utilized to determine the oxygen diffusion coefficient and the thermal diffusivity of the maize leaves. The latter parameters, which can be used as indicators of the photosynthetic activity of maize, are found to vary according to the plant-microbe interaction. Treatment with plant growth promoting bacteria induced a decrease in the oxygen diffusion coefficient of about 20 %. [ABSTRACT FROM AUTHOR]

This short review discusses the need to manage climate-driven expansion of old toxins in new geographic areas (e.g., aflatoxin or fumonisin in corn in historically cooler areas, and ergot where rainfall and cropping patterns have changed). In addition, a renewed consideration of the toxins that can occur in feed sources used in cool-season dairy areas is needed (e.g., silage and distillers dry grains with solubles). A separate issue concerns genetic changes that are occurring in the species that cause Fusarium head blight/Gibberella ear rot. Small differences in climate appear to determine the distribution of the two dominant populations (native to the new world and from Asia). The chemotype that produces deoxynivalenol via the monoacetate at the 3 position results in the accumulation of somewhat more deoxynivalenol than the native population, which involves the monoacetate at the 15 position. There are also genetic changes occurring that have resulted in populations that produce different metabolites. Similarly, an increase in the area where Aspergillus flavus can thrive and the discovery of the sexual stage of this fungus have raised the potential of genetic change accelerated by climate. To address all these issues, new methods and increased availability of reference standards, as well as training and awareness, will be required. [ABSTRACT FROM AUTHOR]

Insecticide and fungicide seed treatments are commonly used to control pests and pathogens in conventional maize and soybean culture, but little is known about their effects on the communities of non-target microbes that inhabit the rhizospheres or leaves of these crops. Because rhizosphere bacterial and fungal communities influence carbon and nutrient turnover, nutrient transformation, nutrient uptake and disease suppression, and because leaf endophyte fungal communities influence many aspects of stress tolerance in plants, any effect of a pesticide seed treatment on these microbial communities could have unintended and possibly adverse effects on seedling performance. We conducted a three-year field experiment in which maize (2013, 2015) and soybean (2014) were grown in rotation from seeds that were either coated or not coated with common pesticide treatments, which included contact and systemic fungicides and systemic insecticides. We sampled seedling rhizosphere soil (maize in 2013, soybean in 2014) and seedling leaves (soybean in 2014, maize in 2015) and characterized their microbial communities. For maize, the rhizosphere fungal and bacterial communities were significantly affected by the seed treatment, but leaf endophytic fungal communities were not. For soybean, the rhizosphere fungal community was significantly affected, as was the leaf endophytic fungal community, but not the rhizosphere bacterial community. These results show that pesticide seed treatments may affect rhizosphere soil microbial communities and endophytic leaf fungal communities more than one month after planting and, therefore, may have significant, unintended effects on non-target organisms. Additional research must determine the consequences of these effects and the nature of their context dependency. [ABSTRACT FROM AUTHOR]

Considering the inadequacy of grain storage structures in Nigeria, which has been partly attributed to high cost and unavailability of construction materials, this study investigated the suitability of using readily available termite mound clay (TMC) for grain silo construction in comparison to conventional reinforced concrete (RC) and galvanized steel (GS) silos for maize storage in the humid tropics. The extent to which temperature and relative humidity affected the quality of stored grain during 8-month unaerated storage, covering both dry and rainy seasons, was evaluated using bacterial and fungal counts as performance parameters. The initial bacterial count of 3500 colony forming units (CFU) per gram (CFU g-1) increased to 120000, 11000, and 8800 CFU g-1 for TMC, RC, and GS silos, respectively. There was no fungal activity at the beginning of storage, but fungal activity increased to 1500, 5500, and 350 CFU g-1 in TMC, RC, and GS silos, respectively. Fungal activity was noticed in the TMC silo in the fourth month of storage, which coincided with the start of the rainy season. Fungal counts exceeded the acceptable threshold of 1000 CFU g-1 in the TMC and RC silos. Relative humidity was of greater significance than temperature in affecting all maize quality parameters considered. TMC was found suitable for constructing silos for short-term grain storage under unaerated conditions. Modification of the current TMC silo design to address permeability issues is expected to improve its performance for longer-term maize storage. [ABSTRACT FROM AUTHOR]

Aflatoxin contamination in agricultural products has been an important and long-standing problem around the world. Produced by certain fungal species of the Aspergillus genus, aflatoxins are highly toxic and carcinogenic. This study investigated the integration of fluorescence and reflectance visible near-infrared (VNIR) hyperspectral images to detect aflatoxins in whole corn kernels. Field-inoculated corn ears were harvested, and kernels having different aflatoxin contamination levels were collected. Both fluorescence hyperspectral images under ultraviolet (UV) excitation and reflectance hyperspectral images under halogen illumination were recorded on the two sides of the kernels (endosperm and germ). Subsequent chemical analysis was performed on each kernel to provide reference aflatoxin concentration. Threshold values of 20 and 100 ppb were adopted separately to group kernels as contaminated or healthy. Contaminated kernels exhibited different fluorescence and reflectance spectral features compared with healthy kernels. Spectral datasets were compressed and interpreted using principal component analysis (PCA). Least squares support vector machines (LS-SVM) and k-nearest neighbor (KNN) classifiers were used on the fluorescence PC, reflectance PC, and integrated fluorescence and reflectance PC variables for classifying both sides of kernels as contaminated or healthy. The best overall prediction accuracy was 95.33% for the LS-SVM model with the 100 ppb threshold on the germ side in the integrated analysis. Overall, the germ side performed better than the endosperm side, especially for the true positive rate (TPR). Fluorescence and reflectance image data generally achieved similar classification accuracy. The integrated analysis achieved better results than separate fluorescence or reflectance analysis on the germ side, and conspicuous improvement in the TPR of the germ side was observed after integration. The mean aflatoxin concentration in the prediction samples was reduced from 2662.01 ppb to 64.04, 87.33, and 7.59 ppb after removing samples that were classified as contaminated by fluorescence, reflectance, and integrated analysis, respectively, on the germ side. This study demonstrated the potential of the integrated technique for better screening of aflatoxin-contaminated kernels and could lead to rapid and non-destructive scanning-based detection in the corn industry. [ABSTRACT FROM AUTHOR]

We studied how the Lo5 and T250 maize lines, characterized by high and low nitrogen use efficiency (NUE), respectively, modified the microbial biomass, enzymatic activities and microbial community structure in the rhizosphere after exposure to different N forms. The two maize lines were grown for 4 weeks in rhizoboxes allowing precise sampling of rhizosphere and bulk soil with no nutrient additions, and then exposed to with nitric-, ammonium- and urea-N. After N exposure, the plants were inserted back into their original rhizoboxes to allow the root exudates diffusion into the rhizosphere. After 24 h rhizosphere soil were sampled and analyzed. Microbial biomass and soil enzymatic activities were increased after the exposure to different N forms of both maize lines. The plant exposure to different N forms also induced changes in the rhizosphere bacterial and fungal communities composition. Plant responses to the availability of different N forms was a dominant factor regulating activity and composition of the rhizosphere microbial communities, likely due to changes in the rhizodepositions. Therefore different N forms used for fertilization of agriculturally relevant plants such as maize can result in different plant mediated effects on the microbial activity and community structure in the rhizosphere. [ABSTRACT FROM AUTHOR]

The s-triazine herbicide, atrazine, has been well acknowledged as an important source causing contamination of soil, water, and sediment. Functional bacteria are one of the critical candidates for removing residual atrazine from contaminated environments. Here, seven bacterial strains showing atrazine-degrading ability were isolated from long-term atrazine-contaminated corn field and identified based on 16S rRNA gene sequencing. Among these bacterial isolates, a bacterium, later designated as Arthrobacter sp. C3, was found to be capable of completely degrading 25 mg/l atrazine. The high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis indicated that the atrazine was dechlorinated to hydroxyatrazine, a non-phytotoxic compound. The functional gene, trzN, which participates in the first step of atrazine degradation was successfully amplified and showed high similarity to the known trzN genes from different bacterial genera. Based on the HPLC-MS and the functional gene analysis, the functional bacterium C3 was speculated to degrade atrazine via dechlorination, which detoxified the herbicide. This study suggested a great potential of Arthrobacter sp. C3 to be used in indigenous bioremediation of atrazine in field. [ABSTRACT FROM AUTHOR]

The Gram-negative proteobacterium Pantoea stewartii subsp. stewartii causes wilt disease in corn plants. Wilting is primarily due to bacterial exopolysaccharide (EPS) production that blocks water transport in the xylem during the late stages of infection. EsaR, the master quorum-sensing (QS) regulator in P. stewartii, modulates EPS levels. At low cell densities EsaR represses or activates expression of a number of genes in the absence of its acyl homoserine lactone (AHL) ligand. At high cell densities, binding of AHL inactivates EsaR leading to derepression or deactivation of its direct targets. Two of these direct targets are the key transcription regulators RcsA and LrhA, which in turn control EPS production and surface motility/adhesion, respectively. In this study, RNA-Seq was used to further examine the physiological impact of deleting the genes encoding these two second-tier regulators. Quantitative reverse transcription PCR (qRT-PCR) was used to validate the regulation observed in the RNA-Seq data. A GFP transcriptional fusion reporter confirmed the existence of a regulatory feedback loop in the system between LrhA and RcsA. Plant virulence assays carried out with rcsA and lrhA deletion and complementation strains demonstrated that both transcription factors play roles during establishment of wilt disease in corn. These efforts further define the hierarchy of the QS-regulated network controlling plant virulence in P. stewartii. [ABSTRACT FROM AUTHOR]

Background: While the few studies that have looked at the association between stunting and aflatoxin exposure have found surprisingly large effects, the results remain inconclusive due to a lack of randomized controlled studies. This protocol describes a non-blinded, cluster-randomized controlled trial with the specific objective of testing the impact of reduced aflatoxin exposure on (individual) child linear growth.Methods/design: Participants were recruited from among households containing women in the last 5 months of pregnancy in 28 maize-growing villages within Meru and Tharaka-Nithi Counties in Kenya. Households in villages assigned to the intervention group are offered rapid testing of their stored maize for the presence of aflatoxin each month; any maize found to contain more than 10 ppb aflatoxin is replaced with an equal amount of maize that contains less than this concentration of the toxin. They are also offered the opportunity to buy maize that has been tested and found to contain less than 10 ppb aflatoxin at local shops. Clusters (villages) were allocated to the intervention group (28 villages containing 687 participating households) or control group (28 villages containing 536 participating households) using a random number generator. The trial, which is funded by United Kingdom (UK) aid from the UK government, the Global Food Security Portal, and the Ministry for Foreign Affairs of Finland, is currently ongoing.Discussion: This study is the first randomized controlled trial (RCT) to test for a causal impact of aflatoxin exposure on child growth. Whether or not this relationship is found, its results will have implications for the prioritization of aflatoxin control efforts by governments in affected regions, as well as international donors.Trial Registration: American Economic Association RCT Registry # 0000105 . Initial registration date: 6 November 2013, last updated 30 December 2014. [ABSTRACT FROM AUTHOR]

We studied the molecular diversity of β-glucosidase-encoding genes, microbial biomass, cellulase, N-acetyl-glucosaminidase, β-glucosidase, and β-galactosidase activities in the rhizosphere and bulk soil of two maize lines differing in nitrogen use efficiency (NUE). The maize lines had significant differences in diversity of β-glucosidase-encoding genes in their rhizosphere, and Actinobacteria and Proteobacteria were the dominating phyla in all samples, but representatives of Bacteroidetes, Chloroflexi, Deinococcus- Thermus, Firmicutes, and Cyanobacteria were also detected. Among the Proteobacteria, β-glucosidase genes from α-, β-, and γ-Proteobacteria were dominant in the rhizosphere of the high NUE maize line, whereas δ- Proteobacteria β-glucosidase genes were dominant in the rhizosphere of the low NUE maize line. The high NUE maize line also showed higher glucosidase activities in the rhizosphere than the low NUE maize line. We concluded that plants with high NUE select bacterial communities in the rhizosphere differing in the diversity of β-glucosidase-encoding genes which likely result in higher C-hydrolyzing enzyme activities. These effects on the diversity of β-glucosidase-encoding genes may influence the C dynamics in the agro-ecosystems. [ABSTRACT FROM AUTHOR]

Sugarcane Mosaic Virus (SCMV) causes one of the most severe virus diseases in maize worldwide, resulting in reduced grain and forage yield in susceptible cultivars. In this study, two association panels consisting of 94 inbred lines each, from China and the U.S., were characterized for resistance to two isolates: SCMV-Seehausen and SCMV-BJ. The population structure of both association panels was analyzed using 3072 single nucleotide polymorphism (SNP) markers. The Chinese and the U.S. panel were both subdivided into two sub-populations, the latter comprised of Stiff Stalk Synthetic (SS) lines and Non Stiff Stalk Synthetic (NSS). The relative kinships were calculated using informative 2947 SNPs with minor allele frequency ≥ 5% and missing data ≤ 20% for the Chinese panel and 2841 SNPs with the same characteristics were used for the U.S. panel. The Scmv1 region was genotyped using 7 single sequence repeat (SSR) and sequence-tagged site (STS) markers, and 12 SSR markers were used for the Scmv2 region in the U.S. panel, while 5 of them were used for the Chinese panel. For all traits, a MLM (Mix Linear Model) controlling both population structure and relative kinship (Q + K) was used for association analysis. Three markers Trx-1, STS-11, and STS-12 located in the Scmv1 region were strongly associated (P = 0.001) with SCMV resistance, and explained more than 16.0%, 10.6%, and 19.7% of phenotypic variation, respectively. 207FG003 located in the Scmv2 region was significantly associated (P = 0.001) with SCMV resistance, and explained around 18.5% of phenotypic variation. [ABSTRACT FROM AUTHOR]

Background: Contamination of corn mash by lactic acid bacteria (LAB) reduces the efficiency of the ethanol fermentation process. The industry relies heavily on antibiotics for contamination control and there is a need to develop alternative methods. The goals of this study were to determine the diversity and abundance of bacteria contaminating commercial ethanol fermentations, and to evaluate the potential of anti-LAB bacteriophages in controlling production losses. Results: Bacterial populations in 27 corn mash samples collected from nine different commercial plants were determined by pyrosequencing of 16S rRNA amplicons. The results showed that the most abundant bacteria (>50% of total population) in 24 of the 27 samples included LAB genera such as Lactobacillus, Streptococcus, Lactococcus, Weissella, Enterococcus, and Pediococcus. Lactobacillus was identified as the most prevalent genus at all fermentation stages in all plants, accounting for between 2.3 and 93.7% of each population and constituting the major genus (>50%) in nine samples from five plants and the most abundant genus in five other samples. Lactobacillus species, including L. delbrueckii, L. fermentum, L. mucosae, and L. reuteri were the most well-represented species. Two bacteriophages that target L. fermentum strains from ethanol plants, vB_LfeS_EcoSau and vB_LfeM_EcoInf (EcoSau and EcoInf), were isolated and characterized as a siphophage and a myophage, respectively. Analysis of the 31,703 bp genome of EcoSau revealed its similarity to the P335-like phage group, and the 106,701 bp genome of phage EcoInf was determined to be a novel phage type despite its distant relationship to the SPO1-like phages. Addition of phages EcoSau and EcoInf to L. fermentum-contaminated corn mash fermentation models restored the yields of ethanol and reduced levels of residual glucose, lactic acid, and acetic acid to that comparable to the infection-free control. Conclusions: This study provides detailed insight into the microbiota contaminating commercial ethanol fermentations, and highlights the abundance of LAB, especially L. delbrueckii, L. fermentum, L. mucosae, and L. reuteri, in the process. This study suggests that phages with broad coverage of major LAB species can be applied directly to corn mash for antibiotic-free control of contamination in the ethanol fermentation industry. [ABSTRACT FROM AUTHOR]

Aims To identify cultivable filamentous fungi before ensiling, after silage conservation, in farm-silos covered with two different plastic films (polyethylene (PE) vs biodegradable (MB)), as well as after aerobic exposure of whole-crop corn silage. Methods and Results Molecular techniques coupled with traditional microbial counting were utilized to identify the predominant fungal species. The cultivable fungal population changed remarkably from harvesting to silo opening. Anaerobiosis and low pH reduced mould count and the presence of Fusarium species both under PE and MB film. However, in the peripheral areas of the silo, where air penetration could not be completely prevented, the fungal population did not decrease. The predominant fungal species after aerobic exposure of silage was Aspergillus fumigatus, without differences between the two plastic films. Conclusions Maintenance of anaerobiosis and a low pH also in the upper layer of the silo reduce the risk of mould growth during corn silage feed-out. Significance and Impact of the Study Even if the new MB plastic film did not completely maintain the anaerobiosis in the upper layer of silage, the overall silage quality was not compromised and was similar to that observed under PE, indicating that the development and use of MB film to cover silage is promising, but needs some improvement. [ABSTRACT FROM AUTHOR]

Filamentous fungi produce a great variety of enzymes, and research on their biotechnological potential has recently intensified. The objective of this work was to identify, at the species level, using DNA barcoding, 46 fungal isolates obtained from maize grains with rot symptoms. We also analyzed the production of extracellular amylases, cellulases, proteases and lipases of 33 of those fungal isolates. The enzymatic activities were evaluated by the formation of a clear halo or a white precipitate around the colonies in defined substrate media. The found fungi belong to the genera Talaromyces, Stenocarpella, Penicillium, Phlebiopsis, Cladosporium, Hyphopichia, Epicoccum, Trichoderma, Aspergillus, Irpex, Fusarium, Microdochium, Mucor and Sarocladium. In the genus Fusarium, the species Fusarium verticillioides was predominant and this genus presented the highest diversity, followed by the genera Aspergillus. The best genera for lipase production were Cladosporium and Penicillium; while Cladosporium, Aspergillus and Penicillium were best for cellulase activity; Hyphopichia, Aspergillus and Irpex for amylase activity; and Cladosporium and Sarocladium for proteases activity. In conclusion, a collection of fungi from maize seeds presenting rotten symptoms were obtained, among which exist important producers of hydrolases. [ABSTRACT FROM AUTHOR]

Fumonisins are secondary metabolites produced primarily by fungi strains that belong to the genera Fusarium and Alternaria , which have been shown to be highly prevalent in maize crops. Some authors have documented the presence of hidden forms of fumonisins occurring in raw maize. This purpose of this study was to determine the occurrence of free and hidden fumonisins in raw maize. The concentrations of fumonisins in 72 naturally contaminated maize samples were analyzed using liquid chromatography coupled to mass spectrometry. The performance parameters of the method to determine free fumonisins forms (FB 1 and FB 2 ) and hydrolyzed fumonisins forms (HFB 1 and HFB 2 ) were evaluated using the standards from the Commission of the European Communities (Commission, 2002). The analytical methods employed fell within the established guidelines. The amount of total fumonisins measured based on the hydrolyzed forms (HFB 1 + HFB 2 ) was 1.5–3.8 times greater than the amount of free fumonisins (FB 1 + FB 2 ). The concentration of hidden fumonisins was calculated by subtracting the levels of free fumonisins from the total fumonisin levels. The levels of hidden fumonisins were calculated to be 0.5–2.0 times greater than the level of free fumonisins. A strong positive correlation (R = 0.97) was observed between free fumonisins (FB 1 + FB 2 ) and. total fumonisins (HFB 1 + HFB 2 ). Based on this correlation, a predictive model was generated to estimate the total fumonisin level based on the measured/reported free fumonisin concentration. These results show that the risk of exposure to fumonisins is likely underestimated if only free fumonisins are considered. However, the predictive model could be a novel approach to estimating the total amount of fumonisins in maize samples without needing to perform expensive and time-consuming analytical methods. [ABSTRACT FROM AUTHOR]

Five desiccation-tolerant rhizobacteria (Brevibacterium frigoritolerans-LPS1B, Bacillus subtilis- CHFT15, B. subtilis-CHFT12, B. subtilis-CH13, and Pseudomonas stutzeri-CHP413A) isolated from Pakistan's Cholistan desert were characterized on the basis of morphological, biochemical, and 16S rDNA ribotyping. The desiccation tolerance was checked at various relative humidity levels (5, 23, and 100%) for a period of 1-40 days. Heavy metal and antibiotic resistance, auxin, cytokine, siderophore, hydrogen cyanide production, and phosphate solubilization of select bacterial isolates was also investigated. Pot experiments with corn in sandy and pure soil were also carried out to check the plant growth-promoting potential of select strains after 90 days of growth. After harvest, various growth parameters like seed germination, root and shoot length, number of leaves, dry weight per gram fresh weight, and chlorophyll contents were determined. The inoculation of P. stutzeri-CHP413A resulted in 3, 33,12, and 37% increases in seed germination, number of leaves, shoot and root length, and dry weight·g-1 fresh weight, respectively, in sandy soil (p<0.05). [ABSTRACT FROM AUTHOR]

The effect of three pesticides used in corn protection: Targa Super 05 (chizalofop-Pethyl), Roundup 360SL (glyphosate) and Karate Zeon 050CS (lambda-cyhalothrin), on the growth of entomopathogenic fungi Hirsutella nodulosa Petch and Beauveria bassiana (Bals.) Vuill. was evaluated under laboratory conditions. Fungi isolates were cultured on Sabouraud's medium with addition of pesticides at three different concentrations. H. nodulosa was more susceptible to pesticides than B. bassiana. The most inhibitory effect on tested entomopathogenic fungi showed chizalofop-P-ethyl herbicide. Lambda-cyhalothrin at the recommended field dose showed minor toxic effect on entomopathogenic fungi, which suggests the possibility of compatible use of this insecticide with biopesticides based on the tested species. [ABSTRACT FROM AUTHOR]

Dry milling of different corn types resulted in varied proportions of germ, pericarp, grit and flour. Grit and flour produced during different reduction stages varied in particle size and chemical constituents, hence applications in food industry. In this study, recovery of different fractions and variation in physicochemical and pasting properties of grit and flour fractions obtained during 3 successive reduction dry millings of 2 normal (African tall, HQPM1) and 1 waxy corn (IC 550353) were evaluated. Waxy corn grains had the highest L*, a*, b*, ash, fat, and protein content and the lowest weight. Waxy and African tall gave the highest recovery of germ and pericarp, respectively. Waxy corn showed lower grit and flour recovery as compared to normal corn. Flour fractions showed higher L* and lower a* and b* values than grit fractions. Particle size of grit and flour fractions ranged from 840 to 982 μm and 330 to 409 μm, respectively. Fractions with larger particle size showed lower L* value. The b* value showed positive correlation with yellow pigment content. Grit and flour from the 1st reduction stage showed higher ash and fat content. Protein content was correlated positively with ash content and negatively with L* value. Grit and flour fractions with higher protein content had lower pasting viscosities. Pasting viscosities were higher for flours than their corresponding grits. Protein profiling of grit and flour fractions from different stages showed quantitative and qualitative differences in medium (22, 28, and 35 kDa) and low molecular weight (16, 17, and 19 kDa) polypeptides and were related to grit and flour yield. [ABSTRACT FROM AUTHOR]

Background and aims: Plant-growth promoting rhizobacteria (PGPR) can promote plant performance under water deficit, but the physiology and biochemistry of the promoting process induced by PGPR under different water deficits is not well known in maize ( Zea mays L). Methods: A glasshouse study was conducted to determine the effects of Burkholderia sp. LD-11 on morphophysiological traits for plant growth and homeostasis between reactive oxygen species (ROS) and antioxidant enzymes under five regimens in two maize inbred lines. Results: Soil inoculation with Burkholderia sp. LD-11 promoted biomass accumulation and improved instantaneous water-use efficiency (WUEi), regardless of the soil water availability. It also triggered production of indole-3-acetic acid (IAA), decreasing the accumulation of abscisic acid (ABA) induced by the water deficit, alleviated ROS accumulation, and resulted in a reduction in lipid peroxidation induced by the water deficits. Soil inoculation also enhanced the tolerance to water deficit through reducing stomatal aperture by increasing the sensitivity of stomatal conductance ( g) to small changes in ABA concentration in the leaves. Conclusions: Soil inoculation with Burkholderia sp. LD-11 enhanced root systems and WUEi, offering a potential avenue for improving maize tolerance to water deficit. [ABSTRACT FROM AUTHOR]

The integrated application of resistant crop varieties with biological control agents (BCAs) such as the Fusarium oxysporum [f.sp. strigae ] strain “Foxy-2” has shown to be effective in fighting off the weed Striga hermonthica which is parasitic to several cereals cultivated in Sub-Saharan Africa (Schaub et al., 2006; Venne et al., 2009). “Foxy-2” proliferates in the rhizosphere and has been mainly studied for its virulence and mode of action. Contrary, no understanding is available regarding its interactions with key rhizosphere microorganisms steering relevant nutrient cycles in soils including nitrogen (N). In this study, we tested the hypothesis that “Foxy-2” displaces indigenous prokaryotic, N cycling communities in the maize rhizosphere due to competition for organic resources. Consequently, we evaluated if the application of an N-rich organic residue (i.e., Tithonia diversifolia with C/N ratio = 13, lignin content = 8.9%, polyphenol content = 1.7%) compensates these presumed competition effects. In a rhizobox experiment, quantitative polymerase chain reaction was used to follow the response of rhizosphere ammonia-oxidizing archaea (AOA) and bacteria (AOB) as well as total bacteria and archaea following “Foxy-2” inoculation in two physico-chemically contrasting soils (sandy Ferric Alisol versus clayey Humic Nitisol). Soils were treated with or without “Foxy-2”, S. hermonthica seeds, and T. diversifolia residues. Contrary to our expectations, we observed a distinct soil texture dependent, promoting effect of “Foxy-2” on rhizosphere prokaryotes. Abundance of AOA and total prokaryotic communities increased in response to “Foxy-2” in the sandy soil, while AOB remained unaffected. This effect on AOA was accelerated when T. diversifolia residues were incorporated. Further, in the clayey soil, AOA abundance was promoted when exposed to S. hermonthica infestation of maize. This suggested their capability to adapt to this biotic stress situation. It was concluded that “Foxy-2” did not pose a negative effect on targeted indigenous microorganisms, but the underlying mechanisms for the observed promoting effect of AOA abundance by “Foxy-2” inoculation are yet to be understood. [ABSTRACT FROM AUTHOR]

Maize is highly sensitive to short term flooding and submergence. Early season flooding reduces germination, survival and growth rate of maize seedlings. We aimed to discover genetic variation for submergence tolerance in maize and elucidate the genetic basis of submergence tolerance through transcriptional profiling and linkage analysis of contrasting genotypes. A diverse set of maize nested association mapping (NAM) founder lines were screened, and two highly tolerant (Mo18W and M162W) and sensitive (B97 and B73) genotypes were identified. Tolerant lines exhibited delayed senescence and lower oxidative stress levels compared to sensitive lines. Transcriptome analysis was performed on these inbreds to provide genome level insights into the molecular responses to submergence. Tolerant lines had higher transcript abundance of several fermentation-related genes and an unannotated Pyrophosphate-Dependent Fructose-6-Phosphate 1-Phosphotransferase gene during submergence. A coexpression network enriched for CBF (C-REPEAT/DRE BINDING FACTOR: C-REPEAT/DRE BINDING FACTOR) genes, was induced by submergence in all four inbreds, but was more activated in the tolerant Mo18W. A recombinant inbred line (RIL) population derived from Mo18W and B73 was screened for submergence tolerance. A major QTL named Subtol6 was mapped to chromosome 6 that explains 22% of the phenotypic variation within the RIL population. We identified two candidate genes (HEMOGLOBIN2 and RAV1) underlying Subtol6 based on contrasting expression patterns observed in B73 and Mo18W. Sources of tolerance identified in this study (Subtol6) can be useful to increase survival rate during flooding events that are predicted to increase in frequency with climate change. [ABSTRACT FROM AUTHOR]

Laboratory-scale silos were prepared to evaluate the efficacy of two different lactic acid bacteria (LAB) on the fermentation quality and mycobiota of corn silage. Their influence onAspergillusspecies’ variability by using the q-PCR technique was studied. Silage inoculated withLactobacillus rhamnosusRC007 orL. plantarumRC009 were compared with uninoculated silage. Silos were opened after 1, 7, 45, 90 and 120 days after ensiling. At the end of the ensiling period, silos were left open for 7 days to evaluate aerobic stability. Rapid lactic acid production and decline in pH values were seen in the early stages of fermentation in silage inoculated withL. rhamnosusRC007. After aerobic exposure, a significant decline in lactic acid content was observed in untreated andL. plantarumRC009-inoculated silages. Counts for yeasted and toxigenic fungus remained lower, after aerobic exposure, inL. rhamnosusRC007-inoculated silage, in comparison withL. plantarumRC009 and uninoculated silages. Comparing the influence exerted by both BAL, it was observed thatL. rhamnosusRC007 was more efficient at inhibiting the three fungal species tested whose DNA concentrations, determined by q-PCR, oscillated near the initial value (pre-ensiling maize). The ability ofL. rhamnosusRC007 to produce lactic acid rapidly and the decline in pH values in the early stages of the fermentation along with the reduction of yeast and mycotoxicogenic fungus after aerobic exposure shows its potential as a bio-control inoculant agent in animal feed. [ABSTRACT FROM AUTHOR]