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Co-cultivation and effective downstream processing of microalgae and oleaginous yeast are potential strategies to enhance lipid yield. The findings of this work suggest that each cultivable partner should be screened and optimized for the best mutualistic co-cultures. In this case, T. pullulans was found to be the most effective yeast culture with microalgae S. obliquus, C. sorokiniana, and C. protothecoides along with additional cell disruption techniques. Co-cultures of C.protothecoides and T.pullulans had the highest relative lipid yield (RLY) of 68.71%, 59.32%, 55.33%, 53.19%, and 47.3% with sonication, microwave, osmotic shock, freeze-drying, and autoclave, respectively. Sonication was concluded as the best disruption technique with five out of nine co-cultures showing significant lipid enhancement. Even though T. pullulans was the best yeast partner with disruption techniques, co-culture of Y. lipolytica and S.obliquus (RLY 37.11%) produced lipids which was significantly higher than that of their respective monocultures (S. obliquus RLY 23.96%, Y. lipolytica RLY 4.96%) without any disruption process. R. glutinis and Y. lipolytica produced significantly enhanced lipid yield with C.sorokiniana and S. obliquus with sonication (RLY 51.44%) and osmotic shock (RLY 57.70%), respectively. FAME analysis reported that the co-cultures produced higher percentage of total FAME nearly 100% in the case of C. sorokiniana and R. glutinis with high content of saturated fatty acids (SFAs). The presence of biofuel precursors like palmitic acid, linoleic acid, oleic acid, and heptadecanoic acid, confirms their suitability for biofuel production. [ABSTRACT FROM AUTHOR]

This study emphasises the significant role of various microalgal species in promoting environmental sustainability through their ability to treat Palm Oil Mill Effluent (POME) while enhancing biomass and biodiesel production. The microalgae strains, Nannochloropsis oculata, Chlorella vulgaris, Chlamydomonas biconvexa, Scenedesmus dimorphus, Spirulina platensis, and Tetraselmis suecica , were assessed for their POME treatment efficiency under diverse growth conditions. In flask cultures, N. oculata effectively reduced oil, grease, COD, BOD, TOC, and TN; while immobilized C. vulgaris showed significant reduction in COD, BOD, Fe(II), TN, TP, and Mn(II). S. dimorphus and S. platensis showed excellent pollutant removal in outdoor raceway ponds, whereas C. biconvexa effectively eliminated PO 4 and NH 4 +-N in photobioreactors. S. platensis and C. sorokiniana showed impressive growth rates and biomass production. Furthermore, cytochrome P450 monooxygenases in N. oculata and C. vulgaris provided a 70–90 % reduction in polyaromatic hydrocarbons (PAHs). Biodiesel potential was confirmed with Nannochloropsis sp. achieving lipid productivity of 362–600 mg/L−1d and a lipid content of 61.60 %, while Chlorella pyrenoidosa yielded 230 mg/L−1d and 68 % lipid content. FAME analysis highlighted Chaetoceros affinis with 74.6 % monounsaturated fatty acids (MUFA) and 72.3 % oleic acid (C18:1), while C. vulgaris exhibited a diverse FAME profile. These results demonstrate the dual capacity of microalgae in renewable energy production and wastewater treatment, showcasing their potential as a sustainable feedstock for biodiesel production from palm oil mills effluents. • Effective removal of contaminants from Palm Oil Mill Effluents (POME) using microalgae Nannochloropsis sp. and Chlorella sp. • Nannochloropsis sp., absorbs and enzymatically degrades PAHs from POME. • Microalgae produce cytochrome P450 monooxygenases to degrade PAHs into simpler hydroxylated molecules in treated POME. • Phycoremediation enhances Chlorella sp. biomass from POME treatment, promoting lipid accumulation for biofuel production. [ABSTRACT FROM AUTHOR]

Microalgae are the unicellular or multicellular photosynthetic microorganisms that can efficiently fix carbon dioxide (CO2) from various sources such as the environment, industrial flue gas, and some carbonate salts. In the present study, one green microalgal strain and a cyanobacterial consortium were used separately for the sequestration of CO2 at different pHs (7–11), at different initial concentrations of CO2 (5–20%), and at various inoculum sizes (5–12.5%). The maximum sequestration of CO2 was found to be 74.37 ± 0.49% and 71.12 ± 0.05% at 5% and 15% CO2 for green algae and cyanobacterial consortium. The biomass generated after sequestration of CO2 was utilized for the synthesis of biomolecules. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the diversity of cultivable nitrogen fixing, phosphate solubilising and total bacteria originated from 580 rhizospheric acidic soils samples of tea plants grown at 62 locations. Based on FAME profiles of over 1428 rhizoplane bacteria, 63 bacterial genera were identified with a similarity index > 0.3, but 56.4% of the identified isolates belonged to six genera: Bacillus (37.02%), Pseudomonas (12.67%), Stenotrophomonas (5.71%), Paenibacillus (6.58%), Arthrobacter (4.35%) and Brevibacillus (3.98%). Most of the total, N2-fixing and P-solubilizing bacteria isolated were Gram positive (59.9, 58.8 and 56.3%) and Gram negative constituted only 40.1, 41.2 and 43.7%. Among different groups, Firmicutes, Gammaproteobacteria and Actinobacteria comprised the largest groups contributing to about 50.3 and 46.6%, 30.8 and 32.5%, and 8.3 and 9.6% of the total N2-fixing and P-solubilizing isolates, respectively. B. cereus, P. fluorescens, B. megaterium, S. maltophilia, P. putida, B. licheniformis, B. pumilus, B. subtilis and P. polymyxa were the most frequent N2-fixing and P-solubilizing species in the acidic tea rhizosohere soils. In these studies were evaluated to represent the dominant culturable diversity of diazotrophs and phosphobacteria, and thus potentially beneficial to the growth and survival of tea plants in that specific acidic ecosystem of eastern Black Sea region. [ABSTRACT FROM AUTHOR]

Formulation and optimization of a media comprising rubber seed oil 1 1 RSO: Rubber seed oil, PHA: Polyhydroxyalkanoates, DCE: Dry coconut cake extract, CDW: Cell dry weight (RSO) as a low cost substrate for polyhydroxyalkanoates (PHA) biosynthesis in the bacterial strain Bacillus cereus was implemented. The formulation study using general full factorial design concluded that 1.5% (v/v) RSO in distilled water is sufficient to obtain PHA content as high as 604.77 mg/g cell dry weight and a total yield of 2.16 g/L within a growth period of 72 h at 150 rpm. Response surface methodology based design was used for the optimization of production parameters. Accordingly, PHA content of 641.14 mg/g cell dry weight and a total PHA yield 2.56 g/L were obtained in 69.2 h with RSO concentration of 1.567% (v/v) and an agitation of 130 rpm. Characterization of the polymer was performed by Fourier transform infrared spectroscopy, X-ray diffraction crystallography, scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis. Scale up studies and industrialization of this media for PHA production will result in value addition to rubber seeds that are currently commercially insignificant. [ABSTRACT FROM AUTHOR]

The eftA gene in Bacillus subtilis has been suggested to be involved in the oxidation/reduction reactions during fatty acid metabolism. Interestingly etfA deletion in B. subtilis results in impairment in CaCO3 precipitation on the biofilm. Comparisons between the wild type B. subtilis 168 and its etfA mutant during in vitro CaCO3 crystal precipitation (calcite) revealed changes in phospholipids membrane composition with accumulation of up to 10% of anteiso-C17:0 and 11% iso-C17:0 long fatty acids. Ca2+ nucleation sites such as dipicolinic acid and teichoic acids seem to contribute to the CaCO3 precipitation. etfA mutant strain showed up to 40% less dipicolinic acid accumulation compared with B. subtilis 168, while a B. subtilis mutant impaired in teichoic acids synthesis was unable to precipitate CaCO3. In addition, B. subtilis etfA mutant exhibited acidity production leading to atypical flagella formation and inducing extensive lateral growth on the biofilm when grown on 1.4% agar. From the ecological point of view, this study shows a number of physiological aspects that are involved in CaCO3 organomineralization on biofilms. [ABSTRACT FROM AUTHOR]

Pseudogymnoascus destructans is a psychrophilic fungus that infects cutaneous tissues in cave dwelling bats, and it is the causal agent for white nose syndrome (WNS) in North American (NA) bat populations. Geomyces pannorum is a related psychrotolerant keratinolytic species that is rarely a pathogen of mammals. In this study, we grew P. destructans and G. pannorum in static liquid cultures at favourable and suboptimal temperatures to: 1) determine if triacylglyceride profiles are species-specific, and 2) determine if there are differences in fatty acyl (FA) saturation levels with respect to temperature. Total lipids isolated from both fungal spp. were separated by thin-layer chromatography and determined to be primarily sterols (∼15 %), free fatty acids (FFAs) (∼45 %), and triacylglycerides (TAGs) (∼50 %), with minor amounts of mono-/diacylglycerides and sterol esters. TAG compositions were profiled by matrix-assisted laser desorption–ionization time-of-flight mass spectrometry (MALDI–TOF). Total fatty acid methyl esters (FAMEs) and acyl lipid unsaturation levels were determined by gas chromatography–mass spectrometry (GC–MS). Pseudogymnoascus destructans produced higher proportions of unsaturated 18C fatty acids and TAGs than G. pannorum . Pseudogymnoascus destructans and G. pannorum produced up to a two-fold increase in 18:3 fatty acids at 5 °C than at higher temperatures. TAG proportion for P. destructans at upper and lower temperature growth limits was greater than 50 % of total dried mycelia mass. These results indicate fungal spp. alter acyl lipid unsaturation as a strategy to adapt to cold temperatures. Differences between their glycerolipid profiles also provide evidence for a different metabolic strategy to support psychrophilic growth, which may influence P. destructans ' pathogenicity to bats. [ABSTRACT FROM AUTHOR]

Biofuels derived from non-crop sources, such as microalgae, offer their own advantages and limitations. Despite high growth rates and lipid accumulation, microalgae cultivation still requires more energy than it produces. Furthermore, invading organisms can lower efficiency of algae production. Simple environmental changes might be able to increase algae productivity while minimizing undesired organisms like competitive algae or predatory algae grazers. Microalgae are susceptible to pH changes. In many production systems, pH is kept below 8 by CO addition. Here, we uncouple the effects of pH and CO input, by using chemical pH buffers and investigate how pH influences Nannochloropsis salina growth and lipid accumulation as well as invading organisms. We used a wide range of pH levels (5, 6, 7, 8, 9, and 10). N. salina showed highest growth rates at pH 8 and 9 (0.19 ± 0.008 and 0.19 ± 0.011, respectively; mean ± SD). Maximum cell densities in these treatments were reached around 21 days into the experiment (95.6 × 10 ± 9 × 10 cells mL for pH 8 and 92.8 × 10 ± 24 × 10 cells mL for pH 9). Lipid accumulation of unbuffered controls were 21.8 ± 5.8 % fatty acid methyl esters content by mass, and we were unable to trigger additional significant lipid accumulation by manipulating pH levels at the beginning of stationary phase. Ciliates (grazing predators) occurred in significant higher densities at pH 6 (56.9 ± 39.6 × 10 organisms mL) than higher pH treatments (0.1-6.8 × 10 organisms mL). Furthermore, the addition of buffers themselves seemed to negatively impact diatoms (algal competitors). They were more abundant in an unbuffered control (12.7 ± 5.1 × 10 organisms mL) than any of the pH treatments (3.6-4.7 × 10 organisms mL). In general, pH values of 8 to 9 might be most conducive to increasing algae production and minimizing invading organisms. CO addition seems more valuable to algae as an inorganic carbon source and not as an essential mechanism to reduce pH. [ABSTRACT FROM AUTHOR]

Variability in the activity and composition of soil microbial communities may have important implications for the suite of microbially-derived ecosystem functions upon which agricultural systems rely, particularly organic agriculture. An on-farm approach was used to investigate microbial communities and soil carbon (C) and nitrogen (N) availability on 13 organically-managed fields growing Roma-type tomatoes, but differing in nutrient management, across an intensively-managed agricultural landscape in the Central Valley of California. Soil physicochemical characteristics, potential activities of nine soil enzymes involved in C, N, phosphorus (P), and sulfur (S) cycling, and fatty acid methyl esters (FAMEs) were measured during the growing season and evaluated with multivariate approaches. Soil texture and pH in the 0-15 cm surface layer were similar across the 13 fields, but there was a three-fold range of soil C and N as well as substantial variation in inorganic N and available P that reflected current and historical management practices. Redundancy analysis showed distinct profiles of enzyme activities across the fields, such that C-cycling enzyme potential activities increased with inorganic N availability while those of N-cycling enzymes increased with C availability. Although FAMEs suggested that microbial community composition was less variable across fields than enzyme activities, there were slight community differences that were related to organic amendments (manure vs. composted green waste). Overall, however, the general similarity among fields for particular taxonomic indicators, especially saprophytic fungi, likely reflects the high disturbance and low complexity in this landscape. Variation in potential enzyme activities was better accounted for with soil physicochemical characteristics than microbial community composition, suggesting high plasticity of the resident microbial community to environmental conditions. These patterns suggest that, in this landscape, differences in organic agroecosystem management have strongly influenced soil nutrients and enzyme activity, but without a major effect on soil microbial communities. The on-farm approach provided a wide range of farming practices and soil characteristics to reveal how microbially-derived ecosystem functions can be effectively manipulated to enhance nutrient cycling capacity. [ABSTRACT FROM AUTHOR]

Evaluation of biofuel production cropping systems should address not only energy yields but also the impacts on soil attributes. In this study, forage sorghum ( Sorghum bicolor L. Moench) cropping systems were initiated on a low organic matter soil (<0.9 %) with a history of intensively tilled low-input cotton production in the semiarid Southern High Plains of the U.S. Sorghum cropping systems were evaluated in a split-plot design with sorghum cultivar as the main plot and the combination of irrigation level (non-irrigated and deficit irrigated) and aboveground biomass removal rate (50 % and 100 %) as the split plot. The sorghum cultivars used varied in yield potential and lignin content, which are important features for feedstock-producing crops. Within 1 year, the transition from long-term cotton cropping systems to sorghum biofuel cropping systems resulted in increased soil microbial biomass C (16 %) and N (17 %) and shifts in the microbial community composition as indicated by differences in fatty acid methyl ester (FAME) profiles. Additionally, enzyme activities targeting C, N, P and S cycles increased 15-75 % (depending on the enzyme) after two growing seasons. Increased enzyme activities (16-19 %) and differences in FAME profiles were seen due to irrigation regardless of aboveground biomass removal rate. Biomass removal rate and the cultivar type had little effect on the soil microbial properties during the time frame of this study. Early results from this study suggest improvements in soil quality and the sustainability of sorghum biofuel cropping for low organic matter agricultural soils. [ABSTRACT FROM AUTHOR]

Abstract: Supercritical carbon dioxide (SC-CO2) was employed to extract oil from hemp (Cannabis sativa L.) seeds. For ground seeds, the supercritical extraction was carried out at temperatures of 40, 60 and 80°C and pressures of 300 and 400bar. Different solvent-ratios were applied. Supercritical CO2 extractions were compared with a conventional technique, n-hexane in Soxhlet. The extraction yields, fatty acid composition of the oil and oxidation stability were determined. The seed samples used in this work contained 81% PUFAs, of which 59.6% was linoleic acid (ω-6), 3.4% γ-linolenic (ω-3), and 18% α-linolenic (ω-6). The highest oil yield from seeds was 22%, corresponding to 72% recovery, at 300bar and 40°C and at 400bar and 80°C. The highest oxidation stability corresponding to 2.16mM Eq Vit E was obtained at 300bar and 80°C. [Copyright &y& Elsevier]

Indicators of soil quality, such as microbial biomass C and N (MBC, MBN) and enzyme activities (EAs), involved in C, P, N, and S cycling, as affected by dryland cropping systems under conventional (ct) and no tillage (nt) practices were evaluated for 5 years. The soil is sandy loam with an average of 16.4% clay, 67.6% sand, and 0.65 g kg OM at 0-10 cm. The crops evaluated were rotations of grain sorghum ( Sorghum bicolor L.) or forage sorghum (also called haygrazer), cotton ( Gossypium hirsutum), and winter rye ( Secale cereale): grain sorghum-cotton (Sr-Ct), cotton-winter rye-sorghum (Ct-Rye-Sr), and forage sorghum-winter rye (Sr-Rye). The tillage treatments did not affect soil MB and EAs of C cycling (i.e., β-glucosidase, β-glucosaminidase, α-galactosidase), P cycling (alkaline phosphatase, phosphodiesterase), and S cycling (arylsulfatase)-except for separation due to tillage for Sr-Rye and Ct-Rye-Sr observed in PCA plots when all EAs were evaluated together. After 3 years, rotations with a winter cover crop history (Ct-Rye-Sr and Sr-Rye) enhanced soil MBN (up to 63%) and EAs (21-37%) compared to Sr-Ct. After 5 years, Sr-Ct and Ct-Rye-Sr showed similar soil MBC, MBN, EAs, total carbon (TC), and organic carbon (OC). A comparison of Sr-Ct plots with nearby continuous cotton (Ct-Ct) research plots in the same soil revealed that it took 5 years to detect higher TC (12%), MBC (38%), and EAs (32-36%, depending on the enzyme) under Sr-Ct. The significant improvements in MB and EAs found, as affected by dryland cropping systems with a history of winter cover crops and/or higher biomass return crops than cotton, can represent changes in soil OM, nutrient cycling, and C sequestration for sandy soils in the semiarid Texas High Plains region. It is significant that these soil changes occurred despite summer crop failure (2003 and 2006) and lack of winter cover crops (2006) due to lack of precipitation in certain years. [ABSTRACT FROM AUTHOR]

Abstract: It is the first time when psychrotrophic, solvent tolerant, psychro-thermoalkaline protease producing strain of Pseudomonas putida isolated from dairy sludge was capable of growing in the presence of 30% (v/v) organic solvents. The strain exhibited resistance against heavy metals (Cr6+, As3+, Pb2+, Cs1+) and various antibiotics. The isolate was able to grow at wide range of temperature (10–40°C) with maximum growth at 25°C. In glucose gelatin yeast extract (GGY) broth (pH 9.0 and 25°C), the strain produced 514UProteaseml−1. The presence of organic solvents n-dodecane, n-decane, isooctane and n-octane, enhanced the protease production. The protease was not only stable but also its activity enhanced in the presence of 25% (v/v) solvents n-dodecane, n-decane, isooctane, n-octane, n-hexane, n-butanol, n-heptane, cyclohexane and xylene, after prolonged incubation of fourteen days. The molecular weight of purified protease was ∼53kDa as revealed by SDS-PAGE and activity gel analysis. The protease was active in broad pH and temperature range of 8.0–12.0 and 10–70°C, respectively, with maxima at pH 9.5 and 40°C. The unique property of solvent tolerance, antibiotic and heavy metal resistance proves the potential candidature of this isolate not only for peptide synthesis, but also for industrial use and bioremediation strategies involved in environmental clean up. [Copyright &y& Elsevier]

Eighty one potential phosphate solubilizing bacteria (PSB) were isolated from the rhizosphere soils of crop plants in Athirampuzha, Kottayam, Kerala and were screened for their efficiency. Burkholderia sp. (MTCC 8369) emerged as the most efficient isolate based on biochemical characteristics, FAME analysis, and 16S rDNA typing (GQ246871). The conditions for maximum P solubilisation were: pH 7, temperature 32.5°C, 18 days of incubation, glucose as a source of carbon, ammonium sulphate as N source, 0.5-1% salt, and 3% sugar. HPLC analysis of the culture filtrate identified gluconic acid as the principal organic acid released by Burkholderia sp. The isolate also exhibited antifungal activity and produced indole acetic acid (IAA), siderophore, hydrogen cyanide, and exopolysacharides. This isolate with its multidimensional plant growth promotion characteristics broadens the spectrum of phosphate solubilizers for field application. [ABSTRACT FROM AUTHOR]

Evaluation of the soil rhizosphere has been limited by the lack of robust assessments that can explore the vast complex structure and diversity of soil microbial communities. Our objective was to combine fatty acid methyl ester (FAME) and pyrosequencing techniques to evaluate soil microbial community structure and diversity. In addition, we evaluated biogeochemical functionality of the microbial communities via enzymatic activities of nutrient cycling. Samples were taken from a silt loam at 0-10 and 10-20 cm in an organic farm under lettuce (Lactuca sativa), potato (Solanum tuberosum), onion (Allium cepa L), broccoli (Brassica oleracea var. botrytis) and Tall fescue pasture grass (Festuca arundinacea). Several FAMEs (a15:0, i15:0, i15:1, i16:0, a17:0, i17:0, 10Me17:0, cy17:0, 16:1ω5c and 18:1ω9c) varied among the crop rhizospheres. FAME profiles of the soil microbial community under pasture showed a higher fungal:bacterial ratio compared to the soil under lettuce, potato, onion, and broccoli. Soil under potato showed higher sum of fungal FAME indicators compared to broccoli, onion and lettuce. Microbial biomass C and enzyme activities associated with pasture and potato were higher than the other rhizospheres. The lowest soil microbial biomass C and enzyme activities were found under onion. Pyrosequencing revealed significant differences regarding the maximum operational taxonomic units (OTU) at 3% dissimilarity level (roughly corresponding to the bacterial species level) at 0-10 cm (581.7-770.0) compared to 10-20 cm (563.3-727.7) soil depths. The lowest OTUs detected at 0-10 cm were under broccoli (581.7); whereas the lowest OTUs found at 10-20 cm were under potato (563.3). The predominant phyla (85%) in this soil at both depths were Bacteroidetes (i.e., Flavobacteria, Sphingobacteria), and Proteobacteria. Flavobacteriaceae and Xanthomonadaceae were predominant under broccoli. Rhizobiaceae, Hyphomicrobiaceae, and Acidobacteriaceae were more abundant under pasture compared to the cultivated soils under broccoli, potato, onion and lettuce. This study found significant differences in microbial community structure and diversity, and enzyme activities of nutrient cycling in this organic farming system under different rhizospheres, which can have implications in soil health and metabolic functioning, and the yield and nutritional value of each crop. [ABSTRACT FROM AUTHOR]

Abstract: The temporal and spatial dynamics of arbuscular mycorrhizal fungal (AMF) spore communities and biomass were studied in an intensively managed maize agroecosystem located in the North China Plain, one of the most important regions for cereal production in China. Maize roots and soils from three depths (0–30, 30–60 and 60–90cm) were sampled in conventional agricultural management (CAM) and recommended agricultural management (RAM) systems at V6 (six leaf collar), V12 (twelve leaf collar), R1 (silking) and R6 (physiological maturity) stage of maize. The dynamics of percent root colonization by AMF, extra-radical hyphal length density (HLD), AMF fatty acid biomarkers (C16:1w5 and C18:1w7) and spore density were analyzed. AMF spore species were identified according to their morphological characteristics. Maize roots were rapidly and heavily colonized by arbuscular mycorrhizal (AM) fungi even under intensive agricultural management. The abundance of arbuscules and hyphal coils within maize roots peaked during early reproductive growth suggesting a period of high P demand by maize. This was preceded by increased concentration of the AMF biomarker C16:1w5 in the soil at the V12 growth stage, and led to a peak in soil HLD at R1. Twenty seven AMF species belonging to five genera were isolated in total, and dominant species such as Glomus aggregatum, Glomus claroideum, Glomus etunicatum, Glomus geosporum and Glomus mosseae occurred widely across growth stage, soil depth and management system. Rare species occurred mainly at a particular growth stage or soil depth. The effects of growth stage, soil depth and management system on spore relative abundance differed among AMF species. The highest species richness and diversity occurred at the R1 stage and may stem from increased C supply to the fungus during peak arbuscular development within the roots. The AMF community and biomass were mainly affected by soil depth and growth stage rather than agroecosystem management. The abundance of AMF biomass and species found deep in the soil profile highlights the potential for P uptake by AMF from lower soil depths under intensive maize management. [Copyright &y& Elsevier]

The purpose of this study was to investigate the diversity of cultivable phosphate solubilising (PSB) and total bacteria originated from 384 rhizospheric acidic soils samples of tea plants grown at 32 locations. Over 900 rhizoplane bacteria were randomly selected from agar-solidified trypticase soy broth, and identified using fatty acid methyl ester (FAME) profiles. Based on FAME profiles, 53 bacterial genera were identified with a similarity index >0.3, but 60.3% of the identified isolates belonged to five genera: Bacillus (34.6%), Pseudomonas (8.9%), Stenotrophomonas (6.1%), Paenibacillus (5.9%) and Arthrobacter (4.8%). The bacilli group comprised many different species, with the most abundant being B. cereus, B. megaterium and B. sphaericus. The main identified Pseudomonads included P. fluorescens, P. putida, and P. alcaligenes. About 30.4% of the bacterial isolates could not be classified to genus since their similarity indices were <0.3 indicating no close matches. Most of the total and P-solubilizing bacteria isolated were Gram positive (61.3 and 52.3%), and Gram negative constituted only 38.7 and 47.7%. Out of the 214 PSB from a pool of 506 bacterial isolates recovered on the selective media from the rhizosphere of tea, 74 of them were characterized by carbon sources using BIOLOGM GN2 and GP2 plates. Bacillus, Pseudomonas, Paenibacillus and Stenotrophomonas genera were the most prominent P-solubilizing groups in the rhizosphere and soil populations analyzed. B. cereus, P. fluorescens, S. maltophilia, B. megaterium, P. putida, B. sphaericus and Paenibacillus polymyxa were the most frequent P-solubilizing species in the acidic tea rhizosohere soils. Selected Gram-positive PSB appeared to favour carbohydrates, and Gram-negative bacteria appeared to favour carboxylic acids, amino acids and carbohydrates as carbon sources. Selected phosphate solubilizing acid tolerant strains showed high variability in utilizing various carbon sources. [ABSTRACT FROM AUTHOR]

This study evaluated microbial communities of soil (0-10 cm) as affected by dryland cropping systems under different tillage practices after 5 years. The soil type was an Olton sandy loam with an average of 16.4% clay, 67.6% sand and 0.65 g kg-1 of organic matter (OM). The cropping systems evaluated were grain sorghum (Sorghum bicolor L.)-cotton (Gossypium hirsutum) (Srg-Ct), cotton-winter rye (Secale cereale)-grain sorghum (Ct-Rye-Srg), and a rotation of forage (f) sorghum (Sorghum bicolor L. and Sorghum sudanense) with winter rye (Srf-Rye), which were under no-tillage (nt) and conventional tillage (ct) practices. Soil microbial communities under cotton based cropping systems (Srg-Ct and Ct-Rye-Srg) showed lower fungal:bacterial ratios compared to the soil under Srf-Rye. Soil under Srf-Rye showed higher population densities of Bacteroidetes and Proteobacteria while lower Actinobacteria compared to Srg-Ct and Ct-Rye-Srg. Chloroflexi, Gemmatimonadetes and Verrucomicrobiae were higher in tilled soil compared to the no-tilled plots. Regardless the limited irrigation available to sustain agricultural production within these dryland cropping systems, this study demonstrated that differences in microbial communities are more affected by crop rotation than tillage management history. Although soil fungal diversity was not analyzed in this study, pyrosequencing suggests that tillage practices can affect bacterial phyla distribution in this sandy soil. [ABSTRACT FROM AUTHOR]

Abstract: A new methodology is presented here as an effective, preliminary technique for the identification of indigenous aerobic and facultatively anaerobic bacterial communities found within microbial fuel cells (MFCs). The dual-phased method, named Rapid Agitation Static Incubation–Microbial Identification, or RASI–MIDI, is comprised of rapidly agitating the sample within a SLYM-BART tester followed by stationary incubation which produces a biomass that is subjected to extraction of methyl ester fatty acids. These distinctive fatty acid profiles represent a bacterial community fingerprint unique to the MFC, and are stored in a library for analysis. A total of 84 samples were analyzed for bacterial community structures from seven different groups of MFCs, with each MFC group comprised of a different bacterial community. Results showed that comparisons of replicate MFCs comprising the same bacterial communities generated high similarity index (SI) numbers (SI values ranging from 0.77 to 0.97), indicating highly correlated fatty acid profiles. In contrast, comparisons of MFCs having known dissimilar community structures did not consistently generate SI values in the analysis considered to be a significant match. It was found that this protocol described herein uniquely and accurately produced MFC fatty acid profiles contained in bacterial communities and thus provides a potential method for routinely studying MFC bacterial community fingerprints. [Copyright &y& Elsevier]

Abstract: The potential for microorganisms to affect the quantity and quality of organic and condensed forms of phosphorus (P) in soils was investigated by repeated addition of different carbon sources (glucose, starch, cellulose; 2.5g Ckg−1) with or without inorganic P (50mg Pkg−1) to acid and calcareous soils which were either natural soils or clay–sand mixtures free of organic matter. Forms of P after five amendments and subsequent incubation periods of 5 weeks each were analyzed by 31P solution nuclear magnetic resonance (NMR) spectroscopy, and the microbial community composition was assessed by selective plate counts and fatty acid methyl ester (FAME) analysis. All carbon additions induced a redistribution of P from inorganic to organic and condensed forms, which was only little affected by the addition of inorganic P. Compared to non-carbon-amended controls, the greatest increase (7–38mg Pkg−1) in organic P was observed in the monoester region. In the acid clay–sand mixture, there was a large accumulation of pyrophosphate (101mg Pkg−1) after glucose addition and smaller accumulations (6–25mg Pkg−1) after addition of starch and cellulose. Carbon additions increased the microbial biomass in all cases and except in the natural calcareous soil also the proportion of fungi. Redundancy analysis with Monte Carlo permutation tests revealed that for carbon-amended soils, the microbial community composition was more strongly influenced by soil type than by carbon source. Pyrophosphate was positively related to fungi, and diester P was positively related to soil pH. A large proportion of organic and condensed forms of P may still have been in microbial cells at the time of extraction. We have shown that soil organic P consists of some discrete and simple compounds along with some more complex forms, and that organic P recently synthesized by microbes consists almost exclusively of and thus is a likely source for the simple compounds found in natural soils. [Copyright &y& Elsevier]

The use of fatty acid methyl esters (FAME) as biomarkers to identify groups of microorganisms was studied. A database was constructed using previously published results that identify FAME biomarkers for aerobic, anaerobic and facultatively aerobic bacteria. FAME profiles obtained from pure cultures were utilized to confirm the predicted presence of biomarkers. Principal component analysis demonstrated that the FAME profiles can be used to determine the incidence of these bacterial groups. The presence of aerobic, anaerobic and facultatively aerobic bacteria in the communities, in four bioreactors being used to treat different wastewaters, was investigated by applying FAME biomarkers. [ABSTRACT FROM AUTHOR]

The existence of Pseudomonas aurantiaca DNA-bound fatty acids and lipids is presented in this work. The isolation of DNA was carried out by two different procedures, namely, phenol and detergent-based phenol isolation in order to prove the presence of DNA-bound lipids. The lipid content of DNA is expressed in terms of fatty acid profile. A high level of 16:0, 18:0 and 18:1 is characteristic for tightly bound DNA lipids. On the other hand, the fatty acids such as 14:1, iso14:0 and iso16:0 are found in trace amounts only in DNA lipid fraction, but these fatty acids are not found in the whole-cell lipids. Absolutely no 3-hydroxy fatty acids were found in DNA lipids. However, both C16 and C18 species represent the main fatty acids of whole-cell and DNA-bound lipids. The presence of DNA-bound lipids even under tough treatment of DNA allows to conclude that these lipids represent a special pool among cellular lipids. [ABSTRACT FROM AUTHOR]

Abstract: The Formosan subterranean termite, Coptotermes formosanus Shiraki, is an aggressive, invasive termite species that has caused billions of dollars of damage across the United States for the past 50 years. Termites depend on intestinal microorganisms for cellulose digestion. Symbiotic microorganisms in the termite gut play key physiological functions such as cellulose and hemicellulose digestion, acetogenesis, hydrogenesis, methanogenesis, sulfate reduction, and nitrogen fixation. Additionally, intestinal microbes create suitable conditions for symbiotic protozoans through the production of nutrients and the maintenance of the pH and the anaerobic conditions in the gut. Although extensive research has been done on the symbiotic relationship of these termites and the microbes found in its gut, there is little information available on the role of facultative anaerobes in the gut. We isolated four enteric bacteria from the hindgut of Formosan subterranean termite, C. formosanus. All isolates were facultative anaerobes and G−. The isolates were identified as Serratia marcescens, Enterobacter aerogens, Enterobacter cloacae, and Citrobacter farmeri by using BIOLOG assay and fatty acid methyl ester analysis (FAME). Each isolate was characterized using sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis and biochemical study. This is the first report on the presence of facultative microbes in termite gut. Results of this first study on facultative microbes in the termite gut indicate that the role of facultative organisms in the Formosan termite gut may be to scavenge oxygen and create anaerobic conditions for the anaerobic microorganisms, which are essential for digestion of cellulose consumed by the termite. [Copyright &y& Elsevier]

Increased disturbance of terrestrial ecosystems in recent years for purposes of mineral extraction has created interest in development and optimization of reclamation methodologies for these lands. Currently, criteria for judging surface mine reclamation success, or progress toward reclamation goals, predominantly rely on aboveground indicators that fail to account for the abundance and composition of soil microbiota, an essential aspect of soil health. To test the utility of fatty acid methyl ester (FAME) biomarkers as indicators of reclamation progress, FAME bacterial, fungal, and total biomass biomarkers extracted from soil of surface mine reclamation sites of different ages and an adjacent undisturbed site were compared with other indicators of reclamation progress and ecosystem stability. Our results indicate that FAME microbial biomarkers and soil organic matter (SOM) contents were greatly impacted by disturbance. Discriminant analysis of FAME bacterial, fungal and total microbial biomass biomarkers, although clearly able to discriminate between disturbed and undisturbed ecosystems, indicated a trend towards the undisturbed condition with reclamation age. The ratio of FAME bacterial to fungal biomarkers reflected changes in other indicators of soil health (SOM, inorganic N concentration), suggesting that this ratio is a useful indicator of reclamation progress. [Copyright &y& Elsevier]