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Bambara groundnut, an underutilized crop has been proved to be an indigenous crop in Africa with the potential for food security. The rhizosphere of Bambara groundnut contains Rhizobacteria, with the ability to grow, adapt, and colonize their surroundings even in unfavorable conditions and have not been explored for their plant growth-promoting properties. The aim of this research was to determine the potential of rhizobacteria from Bambara groundnut soil samples as either biofertilizers or biocontrol agents or both to help provide sustainable agriculture in Africa and globally. Bambara groundnut rhizospheric soil samples were collected and analyzed for their chemical composition. Rhizobacteria isolates were cultured from the soil samples. Plant growth-promoting, antifungal activities and phylogenetic analysis using 16S rRNA were carried out on the isolates to identify the rhizobacteria. A 2-year field study planting was carried out to determine the effect of these rhizobacteria as biofertilizers for Bambara groundnut (Vigna subterranean). The study was carried out in a complete randomized block experimental design with three replications. All the isolates were able to produce ammonia and 1-aminocyclopropane-1-carboxylate, while 4.65, 12.28, and 27.91% produced hydrogen cyanide, indole acetic acid, and solubilized phosphate, respectively, making them important targets as biocontrol and biofertilizer agents. The field results revealed that treatment with rhizobacteria had significant results compared with the control. Characterization of selected isolates reveals their identity as B. amyloliquefaciens, B. thuringiensis, and Bacillus sp. These Bacillus isolates have proved to be plant growth-promoting agents that can be used as biofertilizers to enhance the growth of crops and consequent improved yield. This is the first time the rhizobacteria from the Bambara groundnut rhizosphere are applied as biofertilizer.

Compounds present in oil sludge such as polycyclic aromatic hydrocarbons (PAHs) are known to be cytotoxic, mutagenic and potentially carcinogenic. Microorganisms including bacteria and fungi have been reported to degrade oil sludge components to innocuous compounds such as carbon dioxide, water and salts. In the present study, we isolated different bacteria with PAH-degrading capabilities from compost prepared from oil sludge and animal manures. These bacteria were isolated on a mineral base medium and mineral salt agar plates. A total of 31 morphologically distinct isolates were carefully selected from 5 different compost treatments for identification using polymerase chain reaction (PCR) of the 16S rRNA gene with specific primers (universal forward 16S-P1 PCR and reverse 16S-P2 PCR). The amplicons were sequenced and sequences were compared with the known nucleotides from the GenBank. The phylogenetic analyses of the isolates showed that they belong to 3 different clades; Firmicutes, Proteobacteria and Actinobacteria. These bacteria identified were closely related to the generaBacillus, Arthrobacter, Staphylococcus, Brevibacterium, Variovorax, Paenibacillus, Ralstonia and Geobacillus.The results showed thatBacillus species were predominant in all composts. Based on the results of the degradation of the PAHs in the composts and results of previous studies on bacterial degradation of hydrocarbons in oil, the characteristics of these bacterial isolates suggests that they may be responsible for the breakdown of PAHs of different molecular weights in the composts. Thus, they may be potentially useful for bioremediation of oil sludge during compost bioremediation.

Crop fungal infections such as those caused by Fusarium species often result in yield loss pre- and post-harvest and during storage, contaminate food and exacerbate food insecurity. Synthetic fungicides are becoming less attractive as they pose health risks to consumers and are not environmentally friendly. As an alternative to synthetic fungicides, medicinal plant species may present sustainable and affordable sources of environmentally friendly fungicides for controlling plant diseases. This study was aimed at evaluating the in vitro antifungal activity of different medicinal plant extracts individually or in combination against Fusarium proliferatum, F. solani, F. verticillioides and F. graminearum. Different solvent (water, acetone and ethyl acetate) extracts obtained from the leaves of thirteen medicinal plant species were evaluated for antifungal activity using the micro-plate dilution assay. Their combined effect was evaluated by determining their fractional inhibitory concentration index (FICI). When evaluated individually, acetone extracts obtained from Combretum erythrophyllum, Harpephyllum caffrum and Quercus acutissima were the most active extracts inhibiting the growth of all the four pathogens with minimum inhibitory concentration (MIC) values less than 0.1 mg/ml. Out of 204 extract combinations evaluated, 150 extract combinations demonstrated either synergistic or additive antifungal activity. among the best combinations, combined acetone extracts of Harpephyllum caffrum and Combretum erythrophyllum showed strong synergistic antifungal activity against F. graminearum, F. proliferatum and F. verticillioides (MIC values of 0.02 mg/ml, 0.002 mg/ml and 0.001 mg/ml, respectively), and strong additive antifungal activity against F. solani (MIC = 0.02 mg/ml). The approach of using medicinal plant extracts from renewable plant parts either individually or in combination is sustainable, affordable, environmentally friendly and may be more beneficial in the fight against crop pathogenic diseases, particularly in organic farming.

BACKGROUND: The uncontrolled overproduction of fruit and vegetable waste causes serious environmental challenges such as emission of greenhouse gases. Anaerobic digestion (AD) is becoming a widely adopted technology for treatment of food waste with the concomitant production of biogas. This study investigated the link between microbial community structure and biogas production when using cow dung and mixed fruit and vegetable waste (MFVW) as substrates. RESULTS: Semi‐continuous stir tank reactors were used for AD of cow dung and MFVW over a period of 40 days. The highest accumulative methane yield (112.9 L) was obtained from co‐ digestion, intermediate yield (59.5 L) was obtained from cow dung and lowest yield (6.1 L) from MFVW at the end of the digestion experiment. Polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) revealed higher bacterial and archaeal diversity indices in co‐digestion in comparison to mono‐digestion of cow dung and MFVW. High‐throughput sequence analyses showed that operational taxonomic units (OTUs) belonging to the phyla Bacteroidetes, followed by Firmicutes, Actinobacteria and Proteobacteria were dominant in all treatments. CONCLUSION: The results of the study demonstrated that the enhanced methane production in co‐digestion could be attributed to the neutral pH and partial shift of archaea from Methanosaeta to Methanosarcina rich communities. © 2019 Society of Chemical Industry

Highlights • Serratia marcescens 39_H1 could enhance the hydrolysis of lignocellulosic biomass. • Serratia marcescens 39_H1 is a plant growth promoting organism. • Genome analysis showed diverse potential biotechnological application of organism. • This is an original report on the hydrolytic and acidogenic attributes ofSerratia marcescens 39_H1 for biogas production., Here, we report a high quality annotated draft genome of Serratia marcescens 39_H1, a Gram-negative facultative anaerobe that was isolated from an anaerobic digester. The strain exhibited hydrolytic/acidogenic properties by significantly improving methane production when used as a single isolate inoculum during anaerobic digestion of water hyacinth and cow dung. The total genome size of the isolate was 5,106,712 bp which corresponds to an N50 of 267,528 and G + C content of 59.7 %. Genome annotation with the NCBI Prokaryotic Genome Annotation Pipeline (PGAP) predicted a total of 4,908 genes of which 4,755 were protein coding genes; there were no plasmids detected. A number of genes associated with hydrolytic/acidogenic activities as well as other metabolic activities were identified and discussed.

Until recently, research has focused on Clostridium perfringens in clinical settings without considering environmental isolates. In this study, environmental genomes were used to investigate possible antibiotic resistance and the presence of virulence traits in C. perfringens strains from raw surface water. In silico assembly of three C. perfringens strains, DNA generated almost complete genomes setting their length ranging from 3.4 to 3.6 Mbp with GC content of 28.18%. An average of 3,175 open reading frames was identified, with the majority associated with carbohydrate and protein metabolisms. The genomes harboured several antibiotic resistance genes for glycopeptides, macrolide–lincosamide–streptogramin B, β-lactam, trimethoprim, tetracycline and aminoglycosides and also the presence of several genes encoding for polypeptides and multidrug resistance efflux pumps and 35 virulence genes. Some of these encode for haemolysins, sialidase, hyaluronidase, collagenase, perfringolysin O and phospholipase C. All three genomes contained sequences indicating phage, antibiotic resistance and pathogenic islands integration sites. A genomic comparison of these three strains confirmed high similarity and shared core genes with clinical C. perfringens strains, highlighting their health security risks. This study provides a genomic insight into the potential pathogenicity of C. perfringens present in the environment and emphasises the importance of monitoring this niche in the future.

This study investigated 13-commercial biofertilisers for their microbial contents and potential functional capabilities using a culture-based approach. Isolates obtained were identified by sequencing the partial I6S rRNA gene and ITS 1 and 2 regions and screened for plant growth-promoting capabilities. A total of 58 bacterial and three fungal isolates were obtained from all biofertilisers, with major genera being Bacillus, Rhizobium, Pseudomonas, Candida and Aspergillus. Five of the biofertilisers had the microbes (all or some) listed in the label detected while eight products had none detected. All the products had more microbes than that declared in the labels, suggesting the presence of potential contaminants. Generally, all the identified microbes, including the potential contaminants, had different beneficial capabilities. Approximately 40% of the isolates showed potential for nitrogen-fixation, while 27% exhibited high phosphate-solubilisation ability. Additionally, 87% of the isolates produced indole acetic acid in the range of 0.1–114.4 μg/mL. High levels of siderophore production were mainly observed amongst Bacillus and Pseudomonas genera. The potential of the microbes, including those not listed in the label, to fix nitrogen and produce acid phosphatase, indole acetic acid and siderophore, was highest in four products. This suggests the products have multiple functional abilities in improving crop productivity. However, other qualities of biofertiliser, such as viable cell count and level of contamination, must always be within the acceptable standards. This will guarantee high product quality as well as efficiency when applied in the field. Overall, the results show that there is a high correlation between microbial compositions and potential capability of biofertilisers for plant-growth promotion., Agricultural sciences, Ecology, Microbiology, Environmental science, Biotechnology, Commercial biofertiliser, Efficiency; Crop productivity, Correlation, Nitrogen-fixation, Sequencing

BACKGROUND Water hyacinth (Eichhornia crassipes) is a fast growing water weed that threatens the aquatic ecosystem and human activities, hence control of the plant is essential. One such control approach is to harvest and utilize hyacinth as a substrate for anaerobic digestion (AD). Various factors influence AD performance, including substrate pre‐treatment and microbial community composition, amongst others. This study was aimed at establishing the link between method of substrate pre‐treatment, microbial diversity, inoculum addition and biogas yield during AD of hyacinth. RESULTS The addition of an inoculum resulted in microbial community stability and early biomethane production of up to 0.4 L irrespective of pre‐treatment method. However, cultures that lacked inoculum showed distinct microbial community structure variation in response to pre‐treatment method, and minimal early biomethane production (up to 0.1 L). Biogas produced by cultures lacking inoculum was initially mostly composed of carbon dioxide (up to 100% of total biogas), but as digestion proceeded, an increase in biomethane production was observed (up to 60% of total biogas), which correlated with the shift in microbial community structure and increased microbial diversity. This indicates the presence of biogas‐producing microorganisms associated with the collected hyacinth. Canonical correspondence analysis proved that dynamic changes in microbial community structure and biogas yield were strongly correlative. CONCLUSION This study proves that hyacinth pre‐treatment influences microbial community structure and concomitant biogas yield in the absence of an inoculum. The addition of an inoculum aids in stability of microbial community structure and biogas yield irrespective of method of hyacinth pre‐treatment

The study investigated microbial population dynamics and petroleum hydrocarbon degradation during 56-day landfarming bioremediation of crude oil-polluted soil at a Community in Niger Delta Nigeria. Landfarming involved the addition of fresh top soil from unpolluted soil to the polluted soil followed by periodic ploughing. Active oleophilic bacteria identified by 16S rRNA sequencing were screened with 2,6-dichlorophenol indophenol (DCPIP) redox indicator for their degradation profile. Physicochemical parameters monitored during landfarming included the extractable Total Petroleum Hydrocarbons (TPH), Polycyclic Aromatic Hydrocarbons (PAHs), pH and heavy metals. TPH was more than 9000 mg/kg which exceeded the Department of Petroleum Resources’ (DPR's) intervention value of 5000 mg/kg. Total viable counts of culturable heterotrophic and hydrocarbon utilizing bacteria in the polluted soil pre-landfarming were between 0.2 and 0.5 × 103 cfu/g. Monitoring of microbial population dynamics on days 0, 9, 18, 36 and 56 revealed an increase in hydrocarbon utilizing bacterial population from 104 up to 107 cfu/g which correlated significantly (R = 0.88; p = 0.05) with TPH reduction to below 700 mg/kg by day 56 when bioremediation experiment ended. Pseudomonas aeruginosa was the most efficient diesel degrader which showed 100% DCPIP decolourization. Acinetobacter, Myroides, Pseudomonas and Bacillus were central in the degradation of the long chain hydrocarbon fraction in the spill site. The fungal classes recovered included Eurotiomycetes, Saccharomycetes and Sordariomycetes. The findings from this study showed that the addition of virgin top soil to a compromised and chemically stressed soil is a green and eco-friendly strategy for enriching microbial degradative activities without addition of chemical fertilizers.

Kunu is a traditional fermented single or mixed cereals-based beverage popularly consumed in many parts of West Africa. Presently, the bacterial community and mycotoxin contamination profiles during processing of various kunu formulations have never been comprehensively studied. This study, therefore, investigated the bacterial community and multi-mycotoxin dynamics during the processing of three kunu formulations using high-throughput sequence analysis of partial 16S rRNA gene (hypervariable V3-V4 region) and liquid chromatography tandem mass spectrometry (LC-MS/MS), respectively. A total of 2,303 operational taxonomic units (OTUs) were obtained across six processing stages in all three kunu formulations. Principal coordinate analysis biplots of the Bray-Curtis dissimilarity between bacterial communities revealed the combined influences of formulations and processing steps. Taxonomically, OTUs spanned 13 phyla and 486 genera. Firmicutes (phylum) dominated (relative abundance) most of the processing stages, while Proteobacteria dominated the rest of the stages. Lactobacillus (genus taxa level) dominated most processing stages and the final product (kunu) of two formulations, whereas Clostridium sensu stricto (cluster 1) dominated kunu of one formulation, constituting a novel observation. We further identified Acetobacter, Propionibacterium, Gluconacetobacter, and Gluconobacter previously not associated with kunu processing. Shared phylotypes between all communities were dominated by lactic acid bacteria including species of Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, and Weissella. Other shared phylotypes included notable acetic acid bacteria and potential human enteric pathogens. Ten mycotoxins [3-Nitropropionic acid, aflatoxicol, aflatoxin B 1 (AFB 1 ), AFB 2 , AFM 1 , alternariol (AOH), alternariolmethylether (AME), beauvericin (BEAU), citrinin, and moniliformin] were quantified at varying concentrations in ingredients for kunu processing. Except for AOH, AME, and BEAU that were retained at minimal levels of < 2 μg/kg in the final product, most mycotoxins in the ingredients were not detectable after processing. In particular, mycotoxin levels were substantially reduced by fermentation, although simple dilution and sieving also contributed to mycotoxin reduction. This study reinforces the perception of kunu as a rich source of bacteria with beneficial attributes to consumer health, and provides in-depth understanding of the microbiology of kunu processing, as well as information on mycotoxin contamination and reduction during this process. These findings may aid the development of starter culture technology for safe and quality kunu production.

Anthropogenic disturbances of soil environments predispose loss of soil ecosystem functions, including its habitat support function. In this study, the potential ecosystem support and habitat functions of soils from stockpiles and post-mining reclamation areas (ranging from 3 to 25 years) in two coal mining sites were assessed using Eisenia andrei bioassays. Endpoints such as avoidance response, mortality, relative growth rate and fecundity were determined. By taking into cognisance the ages of the reclamation areas, inference was drawn on the potential restoration of ecosystem support functions over the years since reclamation. Mortality and fecundity of earthworms did not suggest limited support functions of control and test soils. Net avoidance response (AR) indicated significant differences (P < 0.05) among treatments with only the net AR in a 3-year old reclaimed soil >80%. Earthworms generally preferred (P < 0.05) undisturbed (“reference”) soils to OECD and test soils. Furthermore, trends in AR suggested a negative effect (P < 0.05) of anthropogenic disturbance and a general improvement of soil habitat function in older reclaimed areas. Of all endpoints, the avoidance test was the most sensitive, which generally reflected the differences in soil physicochemical properties among test soils. Although high intra-site variations in soil properties suggest lack of strict adherence to best reclamation practices, coal mining soil environments are not ecologically derelict with regards to supporting biocoenosis

This study offers a Nature-based Solutions (NbS) for the recovery of long-term oil-polluted soils. An NPK-type substituted organic fertilizer (SOF) was formulated using available nature-based materials, and its effect on bacterial diversity, richness and community composition investigated during the remediation of a long-term crude oil-impacted soil. Results obtained were compared to a control and a chemical fertilizer (CF) treatment. The rate of total petroleum hydrocarbons (TPH) degradation was observed to be highest in the SOF treatment (0.022 d – 1) compared to the CF (0.016 d – 1) and control treatments (0.001 d – 1). Improvement of bacterial diversity in the SOF treatment significantly correlated with pH and soil organic matter (SOM). Proteobacteria was the dominant phylum across all the treatment systems. Acidocella was dominant in both the control and CF treatments, while Brevundimonas and Alcanivorax were the most abundant genera in the SOF treatment. The bacterial community structure and composition were significantly differentiated (PERMANOVA, p ≤ 0.01) in the different treatment processes. Constrained redundancy analysis revealed that pH, SOM, calcium, TPH and potassium influences the bacterial community composition. Analysis of bacterial community interaction suggests that there was higher efficiency in information processing and chemical transmission in the SOF treatment compared to the CF treatment. PICRUSt2-based functional prediction revealed that dissimilatory/assimilatory nitrate reduction and denitrification were among biomarkers in the nutrient amended treatments, while enzymes for nitrogen fixation were differentially abundant in the control treatment. Overall, the findings of this study suggest that the formulated NbS-fertilizer might stimulate more rapid biodegradation by improving soil nutrients and the proliferation of diverse microbial species in oil-polluted soils.

Arbuscular mycorrhizal (AM) fungi contribute to the restoration of soil ecological functions and processes during ecosystem development. Here, diversity and differentiation of AM fungi in rhizosphere soils and roots of the dominant vegetation along a post-coal mining reclamation soil chronosequence of 3, 11, 15, 19 and 24 years after reclamation were investigated. High-throughput sequence analysis of partial Glomeromycotan 18S rRNA in soils and roots revealed a high number of core operational taxonomic units (OTUs) across chronosequence. Arbuscular mycorrhizal fungal (AMF) OTU richness, Shannon-Weiner index and species dominance were not significantly different across soil and root but were significantly (P < 0.05) correlated with ammonium, nitrate, silt fraction, litter, pH, foliar and/or basal covers. AMF community structure was significantly different (P < 0.05) across unmined and reclamation chronosequence soils, with differentiation between younger reclaimed areas (3 and 11 years) and older reclamation ages (19 and 24 years) in multivariate space. In contrast, structural differentiation in the AMF community colonising the single plant-host across the chronosequence was not significant (PERMANOVA, P > 0.05), although community composition and structure were heterogeneous within 3–11 years but similar within 15–24 years. Seven Glomeromycotan genera were detected in soil and roots, including the relatively dominant Glomus genus, and the differentially abundant Acaulospora, Diversispora, Paraglomus and Scutellospora in either earlier or later years since post-mining reclamation. Canonical correspondence analysis revealed that nitrates (NO3-N), clay content and bulk density significantly influenced (P < 0.05) the AMF community structure in soil, whereas, the AMF community in root was not significantly influenced (P > 0.05) by environmental variables. Overall, the study suggests that AMF community differentiation reflect ecosystem development over chronological space-time. Thus, AMF species differentiation may be included as part of a minimum dataset for monitoring ecosystem restoration following post-mining reclamation

Bacterial diversity and community structure of two maize varieties (white and yellow) during fermentation/steeping for ogi production, and the influence of spontaneous fermentation on mycotoxin reduction in the gruel were studied. A total of 142 bacterial isolates obtained at 24–96 h intervals were preliminarily identified by conventional microbiological methods while 60 selected isolates were clustered into 39 OTUs consisting of 15 species, 10 genera, and 3 phyla by 16S rRNA sequence analysis. Lactic acid bacteria constituted about 63% of all isolated bacteria and the genus Pediococcus dominated (white maize = 84.8%; yellow maize = 74.4%). Pediococcus acidilactici and Lactobacillus paraplantarum were found at all steeping intervals of white and yellow maize, respectively, while P. claussenii was present only at the climax stage of steeping white maize. In both maize varieties, P. pentosaceus was found at 24–72 h. Mycotoxin concentrations (μg/kg) in the unsteeped grains were: white maize (aflatoxin B1 = 0.60; citrinin = 85.8; cyclopiazonic acid = 23.5; fumonisins (B1/B2/B3) = 68.4–483; zearalenone = 3.3) and yellow maize (aflatoxins (B1/B2/M1) = 22.7–513; citrinin = 16,800; cyclopiazonic acid = 247; fumonisins (B1/B2/B3) = 252–1,586; zearalenone = 205). Mycotoxins in both maize varieties were significantly (p < 0.05) reduced across steeping periods. This study reports for the first time: (a) the association of L. paraplantarum, P. acidilactici, and P. claussenii with ogi production from maize, (b) citrinin occurrence in Nigerian maize and ogi, and (c) aflatoxin M1, citrinin and cyclopiazonic acid degradation/loss due to fermentation in traditional cereal-based fermented food.