Use of fatty acid methyl ester profiles for discrimination of Bacillus cereus T-strain spores grown on different media

Fatty acid methyl ester (FAME) profiling for species-specific characterization and detection of fungal pathogens that cause tree and grapevine trunk diseases

Fungal trunk diseases are of major concern for tree fruit, nut, and grape growers throughout the world. These diseases include Eutypa dieback of grape, caused by Eutypa lata, band canker of almond, caused by Neofusicoccum mediterraneum and Neofusicoccum parvum, and twig and branch dieback of walnut, caused by N. mediterraneum, Botryosphaeria dieback of grape, caused by Diplodia mutila, Diplodia seriata, N. mediterraneum, and N. parvum, and esca of grape, caused by Phaeomoniella chlamydospora and Phaeoacremonium minimum. Given the common occurrence of mixed infections, and the similar wood symptoms at the macroscopic level, species-specific detection tools are needed. Fatty acid methyl ester (FAME) profiling can be an effective and inexpensive diagnostic tool. FAME analyses were conducted on pure cultures of multiple isolates per species to characterize profiles and assess whether this technique could result in consistent identification. FAME profiles were dominated by oleic acid (18:1 ω9c) and palmitic acid (16:0), with less abundant FAMEs in different ratios for each species and isolates within species. Canonical discriminant analyses revealed which minor FAMEs were most variable, with a total of 20 different FAMEs that can explain 69.01% of profile variance in the first two canonicals. Using these analyses, samples were self-tested and correctly sorted 97.18% of the time. Within species, canonical discriminant analyses were able to separate isolates further, often by original geographic location or by host plant species. These results further suggest that potential novel species, subspecies, or races may be present among the isolates analyzed, demonstrating the capacity of FAME profiling to have a role in discovering cryptic species and accurately identifying fungal pathogens in conjunction with other molecular techniques and genomic analyses.

Dual stable isotopes enhance lipidomic studies in bacterial model organism Enterococcus faecalis

Dual stable isotope probes of deuterium oxide and 13C fatty acid were demonstrated to probe the lipid biosynthesis cycle of a Gram-positive bacterium Enterococcus faecalis. As external nutrients and carbon sources often interact with metabolic processes, the use of dual-labeled isotope pools allowed for the simultaneous investigation of both exogenous nutrient incorporation or modification and de novo biosynthesis. Deuterium was utilized to trace de novo fatty acid biosynthesis through solvent-mediated proton transfer during elongation of the carbon chain while 13C-fatty acids were utilized to trace exogenous nutrient metabolism and modification through lipid synthesis. Ultra-high-performance liquid chromatography high-resolution mass spectrometry identified 30 lipid species which incorporated deuterium and/or 13C fatty acid into the membrane. Additionally, MS2 fragments of isolated lipids identified acyl tail position confirming enzymatic activity of PlsY in the incorporation of the 13C fatty acid into membrane lipids.

The Fatty Acid Methyl Ester (FAME) profile of Phytophthora agathidicida and its potential use as diagnostic tool

Phytophthora diseases cause devastation to crops and native ecosystems worldwide. In New Zealand, Phytophthora agathidicida is threatening the survival of kauri, an endemic, culturally and ecologically important tree species. The current method for detecting P. agathidicida is a soil bating assay that is time-consuming and requires high levels of expertise to assess, thus limiting the analytical sample throughput. Here, we characterized the fatty acid methyl ester (FAME) profile of P. agathidicida. We also compared it with the FAME profile of P. cinnamomi and assessed the efficacy of FAME analysis as a diagnostic tool for detecting the pathogen in soil samples. In FAME analysis, the total fatty acid content is isolated from a sample and converted to FAMEs for analysis, a process that takes less than a day. Unique fatty acid acyl chains can serve as biomarkers for specific organisms. We detected 12 fatty acids in P. agathidicida, two of which (20:4ω6 and 20:5ω3) show promise as potential Phytophthora specific biomarkers. Collectively, these findings advance our fundamental understanding of P. agathidicida biology and provide a promising technique to increase the rate of sample processing and the speed of pathogen detection for P. agathidicida in soil.

Bacterial association and comparison between lung and intestine in rats

The association between lung and intestine has already been reported, but the differences in community structures or functions between lung and intestine bacteria yet need to explore. To explore the differences in community structures or functions, the lung tissues and fecal contents in rats were collected and analyzed through 16S rRNA sequencing. It was found that intestine bacteria was more abundant and diverse than lung bacteria. In intestine bacteria, Firmicutes and Bacteroides were identified as major phyla while Lactobacillus was among the most abundant genus. However, in lung the major identified phylum was Proteobacteria and genus Pseudomonas was most prominent genus. On the other hand, in contrast the lung bacteria was more concentrated in cytoskeleton and function in energy production and conversion. While, intestine bacteria were enriched in RNA processing, modification chromatin structure, dynamics and amino acid metabolism. The study provides the basis for understanding the relationships between lung and intestine bacteria.

Highly accurate classification of biological spores by culture medium for forensic attribution using multiple chemical signature types and machine learning

Future proliferation of biological expertise and new technology may increasingly lower the difficulty to produce biological organisms for misuse. Rapid attribution of a biological attack is needed to quickly identify the person or lab responsible and prevent additional attacks by enabling the apprehension of suspects. Here, triplicate batches of Bacillus anthracis Sterne strain (BaSt) spores were grown in a total of seven amateur and professional media. Multiple orthogonal analytical signatures (peptides, metabolites, lipids by fatty acid methyl ester (FAME) analysis, bulk organic profile, and trace elements) were collected from the BaSt spores. The proteomics and metabolomics analyses identified promising attribution signature compounds that are unique to each of the seven production methods. In addition, while each of the signature types showed varying degrees of value individually for attributing BaSt spores to the culture medium used to prepare them, fusing results from all five signatures types to increase sourcing robustness and using a random forest sourcing algorithm yielded 100% hold-one-batch-out cross-validation classification accuracy and an average relative source probability for the correct source 5.5× higher than the most probable incorrect source. These preliminary results provide a proof-of-concept for the development of forensic examinations that can attribute biological agents to production methods for use in future investigations.

Genome Insights of the Plant-Growth Promoting Bacterium Cronobacter muytjensii JZ38 With Volatile-Mediated Antagonistic Activity Against Phytophthora infestans

Salinity stress is a major challenge to agricultural productivity and global food security in light of a dramatic increase of human population and climate change. Plant growth promoting bacteria can be used as an additional solution to traditional crop breeding and genetic engineering. In the present work, the induction of plant salt tolerance by the desert plant endophyte Cronobacter sp. JZ38 was examined on the model plant Arabidopsis thaliana using different inoculation methods. JZ38 promoted plant growth under salinity stress via contact and emission of volatile compounds. Based on the 16S rRNA and whole genome phylogenetic analysis, fatty acid analysis and phenotypic identification, JZ38 was identified as Cronobacter muytjensii and clearly separated and differentiated from the pathogenic C. sakazakii. Full genome sequencing showed that JZ38 is composed of one chromosome and two plasmids. Bioinformatic analysis and bioassays revealed that JZ38 can grow under a range of abiotic stresses. JZ38 interaction with plants is correlated with an extensive set of genes involved in chemotaxis and motility. The presence of genes for plant nutrient acquisition and phytohormone production could explain the ability of JZ38 to colonize plants and sustain plant growth under stress conditions. Gas chromatography-mass spectrometry analysis of volatiles produced by JZ38 revealed the emission of indole and different sulfur volatile compounds that may play a role in contactless plant growth promotion and antagonistic activity against pathogenic microbes. Indeed, JZ38 was able to inhibit the growth of two strains of the phytopathogenic oomycete Phytophthora infestans via volatile emission. Genetic, transcriptomic and metabolomics analyses, combined with more in vitro assays will provide a better understanding the highlighted genes' involvement in JZ38's functional potential and its interaction with plants. Nevertheless, these results provide insight into the bioactivity of C. muytjensii JZ38 as a multi-stress tolerance promoting bacterium with a potential use in agriculture.

Customizable 3D printed diffusion chambers for studies of bacterial pathogen phenotypes in complex environments

Gaps in our understanding of the natural ecology and survival mechanisms of pathogenic bacteria in complex microenvironments such as soil typically occur due to the difficulty in characterizing biochemical profiles and morphological characteristics as they exist in environmental samples. Conversely, accurate simulation of the abiotic and biotic chemistries of soil habitats within the laboratory is often a significant challenge. Herein, we present the fabrication of customizable and precisely engineered 3D printed diffusion chambers that can be used to incubate bacterial cultures directly in soil matrices within a controlled laboratory experiment, and study the dynamics between bacterial cells and soil components. As part of the design process, different types of 3D printing materials were evaluated for ease of sterilization, structural integrity throughout the experiment, as well as cost/ease of production. To demonstrate potential applications for environmental studies, the diffusion chamber was used to incubate cultures of Bacillus cereus T-strain and Escherichia coli strain O157 directly in soil matrices. We show that the chamber facilitates diffusion of abiotic/biotic components of the soil with target cells without contamination from in situ microbial communities, while allowing for single cell and ensemble level phenotypic analyses of bacteria cultured with and without soil matrices.

Decoding the Fatty Acid Profile of Bacillus licheniformis I89 and Its Adaptation to Different Growth Conditions to Investigate Possible Biotechnological Applications

Bacillus licheniformis I89 is a Gram-positive bacterium, a producer of the lantibiotic lichenicidin. No information is available on its fatty acid (FA) composition. Bacillus species are rich in branched FA (BrFA), claimed to be beneficial to human health and to treat diseases. Herein, the FA profile of B. licheniformis I89 was evaluated under different growth conditions: at two growth temperatures (37 and 50 °C) and at different growth phases (lag, exponential, and stationary), using gas chromatography-mass spectrometry. The FA profile revealed predominant BrFA of the iso-series and anteiso-series (i-15:0, ai-15:0, i-16:0, i-17:0, and ai-17:0) and low amounts of saturated FA (14:0, 16:0, and 18:0). Comparing the FA profiles at different temperatures, in the lag phase, at 50 °C, there was a decrease of ai-17:0 and a decrease of i-15:0 in the exponential phase, in comparison with 37 °C. In all growth phases, there was a decrease of ai-15:0 and an increase of i-17:0. From the lag to the stationary phase, at 50 °C, there was a decrease of ai-17:0 and i-16:0, whereas i-15:0 increased, while at 37 °C, there was an increase of i-15:0 and i-16:0, and a decrease in ai-15:0 and ai-17:0. B. licheniformis I89 can adapt its FA profile, at moderate temperatures, by changing the iso-FA and anteiso-FA composition and the iso/anteiso ratio. This nonpathogenic bacterium species can be used as a source of BrFA with putative beneficial health effects for gut protection and with reported antitumor properties, foreseeing its use for producing compounds with biotechnological applications.

Bacterial exopolysaccharide promotes acid tolerance in Bacillus amyloliquefaciens and improves soil aggregation

In this paper we report the isolation and taxonomic characterization of exopolysaccharide (EPS) producing bacteria followed by the role of EPS in conferring acid tolerance to the soil bacteria Bacillus amyloliquefaciens p16. The role of EPS in promoting soil aggregation is also presented. A total of 75 isolates were tested for acid tolerance and biofilm production under acid stress of which, 54 isolates were further tested for EPS production. Out of the 54 isolates, 28 isolates produced EPS in the range of (67.88 and 219.96 µg/ml) with B. amyloliquefaciens p16 showing the highest production. The 28 isolates characterized for phenotypic and molecular traits mostly belonged to the members of the genera Bacillus, Brevibacillus, Brevibacterium, Paenibacillus, Serretia, Pseudomonas, Arthrobacter and Lysinibacillus. The monosaccharide components of the EPS produced by B. amyloliquefaciens p16 shifted from galactose to arabinose under acid stress as revealed through HPLC analysis. Inactivation of the epsB gene encoding putative bacterial protein tyrosine kinase (BY-kinases) in B. amyloliquefaciens p16 resulted in significantly less EPS (33.23 µg/ml) production compared to wild-type (WT) (223.87 µg/ml). The mutant (B. amyloliquefaciens 6A5) was barely able to survive in pH 4.5 unlike that of the WT. Further, inoculation of the WT and mutant B. amyloliquefaciens 6A5 in the soil resulted in formation of small sized soil aggregates (42.41 mm) with less water holding capacity (27.67%) as compared to the soil treated with WT that produced larger soil aggregates of size 80.59 mm with higher 53.90% water holding capacity. This study indicates that EPS produced by acid-tolerant B. amyloliquefaciens p16 can not only impart acid tolerance to the bacteria but also aids in promoting soil aggregation when applied to the soil.

Novel Bacillus cereus strain from electrokinetically remediated saline soil towards the remediation of crude oil

A new strain SWH-15 was successfully isolated after initial electrokinetic remediation experiment using the same saline soil sampled from Shengli Oilfield, China. Four methods (morphological and biochemical characteristics, whole-cell fatty acid methyl esters (FAMEs) analysis, 16S rRNA sequence analysis and DNA G + C content and DNA-DNA hybridization analysis) were used to identify the taxonomic status of SWH-15 and confirmed that SWH-15 was a novel species of the Bacillus (B.) cereus group. Then, we assessed the degrading ability of the novel strain SWH-15 to crude oil through a microcosm experiment with four treatments, including control (CK), bioremediation using SWH-15 (Bio), electrokinetic remediation (EK), and combined bioremediation and electrokinetic remediation (Bio + EK). The results showed that the Bio + EK combined remediation treatment was more effective than the CK, Bio, and EK treatments in degrading crude oil contaminants. Bioaugmentation, by addition of the strain SWH-15 had synergistic effect with EK in Bio + EK treatment. Bacterial community analysis showed that electrokinetic remediation alone significantly altered the bacterial community of the saline soil. The addition of the strain SWH-15 alone had a weak effect on the bacterial community. However, the strain SWH-15 boosted the growth of other bacterial species in the metabolic network and weakened the impact of electrical field on the whole bacterial community structure in the Bio + EK treatment.

Rapid differentiation of epithelial cell types in aged biological samples using autofluorescence and morphological signatures

Establishing the tissue source of epithelial cells within a biological sample is an important capability for forensic laboratories. In this study we used Imaging Flow Cytometry (IFC) to analyze individual cells recovered from buccal, epidermal, and vaginal samples that had been dried between 24 hours and more than eight weeks. Measurements capturing the size, shape, and fluorescent properties of cells were collected in an automated manner and then used to build a multivariate statistical framework for differentiating cells based on tissue type. Results showed that epidermal cells could be distinguished from vaginal and buccal cells using a discriminant function analysis of IFC measurements with an average classification accuracy of ~94%. Ultimately, cellular measurements such as these, which can be obtained non-destructively, may provide probative information for many types of biological samples and complement results from standard genetic profiling techniques.

Diversity and functional properties of acid-tolerant bacteria isolated from tea plantation soil of Assam

In this study, we report on the bacterial diversity and their functional properties prevalent in tea garden soils of Assam that have low pH (3.8-5.5). Culture-dependent studies and phospholipid fatty acid analysis revealed a high abundance of Gram-positive bacteria. Further, 70 acid-tolerant bacterial isolates characterized using a polyphasic taxonomy approach could be grouped to the genus Bacillus, Lysinibacillus, Staphylococcus, Brevundimonas, Alcaligenes, Enterobacter, Klebsiella, Escherichia, and Aeromonas. Among the 70 isolates, 47 most promising isolates were tested for their plant growth promoting activity based on the production of Indole Acetic Acid (IAA), siderophore, and HCN as well as solubilization of phosphate, zinc, and potassium. Out of the 47 isolates, 10 isolates tested positive for the entire aforesaid plant growth promoting tests and further tested for quantitative analyses for production of IAA, siderophore, and phosphate solubilization at the acidic and neutral condition. Results indicated that IAA and siderophore production, as well as phosphate solubilization efficiency of the isolates decreased significantly (P ≤ 0.05) in the acidic environment. This study revealed that low soil pH influences bacterial community structure and their functional properties.

Degradation study of lindane by novel strains Kocuria sp. DAB-1Y and Staphylococcus sp. DAB-1W

BACKGROUND

This study was carried out to isolate and characterize the bacterial strains from lindane-contaminated soil and they were also assessed for their lindane-degrading potential.

METHODS

In this study the enrichment culture method was used for isolation of  lindane degrading bacterial isolates, in which the mineral salt medium (MSM) supplemented with different concentrations of lindane was used. Further, the screening for the potential lindane degrading isolates was done using the spray plate method and colorimetric dechlorinase enzyme assay. The selected isolates were also studied for their growth response under varying range of temperature, pH, and NaCl. The finally selected isolates DAB-1Y and DAB-1W showing best lindane degradation activity was further subjected to biochemical characterization, microscopy, degradation/kinetic study, and 16S rDNA sequencing. The strain identification were performed using the biochemical characterization, microscopy and the species identifies by 16S rDNA sequence of the two isolates using the standard 16S primers, the 16 S rRNA partial sequence was analyzed through BLAST analysis and phylogenetic tree was generated based on UGPMA clustering method using MEGA7 software. This shows the phylogenetic relationship with the related strains. The two isolates of this study were finally characterized as Kocuria sp. DAB-1Y and Staphylococcus sp. DAB-1W, and their 16S rRNA sequence was submitted to GenBank database with accession numbers, KJ811539 and KX986577, respectively.

RESULTS

Out of the 20 isolates, the isolates DAB-1Y and DAB-1W exhibited best lindane-degrading activity of 94 and 98%, respectively, recorded after 8 days of incubation. The optimum growth was observed at temperature 30 °C, pH 7, and 5% NaCl observed for both isolates. Of the four isomers of hexachlorocyclohexane, isomer α and γ were the fastest degrading isomers, which were degraded up to 86 and 94% by isolates DAB-1Y and up to 93 and 98% by DAB-1W, respectively, reported after 8 days incubation. Isomer β was highly recalcitrant in which maximum 35 and 32% lindane degradation was observed even after 28 days incubation by isolates, DAB-1Y and DAB-1W, respectively. At lower lindane concentrations (1-10 mg/L), specific growth rate increased with increase in lindane concentration, maximum being 0.008 and 0.006/day for DAB-1Y and DAB-1W, respectively. The 16 S rRNA partial sequence of isolate DAB-1Y showed similarity with Kocuria sp. by BLAST analysis and was named as Kocuria sp. DAB-1Y and DAB-IW with Staphylococcus sp. DAB-1W. The 16S rDNA sequence of isolate DAB-1Y and DAB-1W was submitted to online at National Centre of Biotechnology Information (NCBI) with GenBank accession numbers, KJ811539 and KX986577, respectively.

CONCLUSIONS

This study has demonstrated that Kocuria sp. DAB-1Y and Staphylococcus sp. DAB-1W were found efficient in bioremediation of gamma-HCH and can be utilized further for biodegradation of environmental contamination of lindane and can be utilized in bioremediation program.

Role of fatty acids in Bacillus environmental adaptation

The large bacterial genus Bacillus is widely distributed in the environment and is able to colonize highly diverse niches. Some Bacillus species harbor pathogenic characteristics. The fatty acid (FA) composition is among the essential criteria used to define Bacillus species. Some elements of the FA pattern composition are common to Bacillus species, whereas others are specific and can be categorized in relation to the ecological niches of the species. Bacillus species are able to modify their FA patterns to adapt to a wide range of environmental changes, including changes in the growth medium, temperature, food processing conditions, and pH. Like many other Gram-positive bacteria, Bacillus strains display a well-defined FA synthesis II system that is equilibrated with a FA degradation pathway and regulated to efficiently respond to the needs of the cell. Like endogenous FAs, exogenous FAs may positively or negatively affect the survival of Bacillus vegetative cells and the spore germination ability in a given environment. Some of these exogenous FAs may provide a powerful strategy for preserving food against contamination by the Bacillus pathogenic strains responsible for foodborne illness.

Involvement of the CasK/R two-component system in optimal unsaturation of the Bacillus cereus fatty acids during low-temperature growth

Bacillus cereus sensu lato is composed of a set of ubiquitous strains including human pathogens that can survive a range of food processing conditions, grow in refrigerated food, and sometimes cause food poisoning. We previously identified the two-component system CasK/R that plays a key role in cold adaptation. To better understand the CasK/R-controlled mechanisms that support low-temperature adaptation, we performed a transcriptomic analysis on the ATCC 14579 strain and its isogenic ∆casK/R mutant grown at 12°C. Several genes involved in fatty acid (FA) metabolism were downregulated in the mutant, including desA and desB encoding FA acyl-lipid desaturases that catalyze the formation of a double-bond on the FA chain in positions ∆5 and ∆10, respectively. A lower proportion of FAs presumably unsaturated by DesA was observed in the ΔcasK/R strain compared to the parental strain while no difference was found for FAs presumably unsaturated by DesB. Addition of phospholipids from egg yolk lecithin rich in unsaturated FAs, to growth medium, abolished the cold-growth impairment of ΔcasK/R suggesting that exogenous unsaturated FAs can support membrane-level modifications and thus compensate for the decreased production of these FAs in the B. cereus ∆casK/R mutant during growth at low temperature. Our findings indicate that CasK/R is involved in the regulation of FA metabolism, and is necessary for cold adaptation of B. cereus unless an exogenous source of unsaturated FAs is available.

Fatty Acid Profiles for Differentiating Growth Medium Formulations Used to Culture Bacillus cereus T-strain Spores

Microbial biomarkers that indicate aspects of an organism's growth conditions are important targets of forensic research. In this study, we examined fatty acid composition as a signature for the types of complex nutrients in the culturing medium. Bacillus cereus T-strain spores were grown in medium formulations supplemented with one of the following: peptone (meat protein), tryptone (casein protein), soy protein, and brain-heart infusion. Cellular biomass was profiled with fatty acid methyl ester (FAME) analysis. Results showed peptone cultures produced spores enriched in straight-chained lipids. Tryptone cultures produced spores enriched in branched-odd lipids when compared with peptone, soy, and brain-heart formulations. The observed FAME variation was used to construct a set of discriminant functions that could help identify the nutrients in a culturing recipe for an unknown spore sample. Blinded classification tests were most successful for spores grown on media containing peptone and tryptone, showing 88% and 100% correct identification, respectively.

Understanding molecular identification and polyphasic taxonomic approaches for genetic relatedness and phylogenetic relationships of microorganisms

The major proportion of earth's biological diversity is inhabited by microorganisms and they play a useful role in diversified environments. However, taxonomy of microorganisms is progressing at a snail's pace, thus less than 1% of the microbial population has been identified so far. The major problem associated with this is due to a lack of uniform, reliable, advanced, and common to all practices for microbial identification and systematic studies. However, recent advances have developed many useful techniques taking into account the house-keeping genes as well as targeting other gene catalogues (16S rRNA, rpoA, rpoB, gyrA, gyrB etc. in case of bacteria and 26S, 28S, β-tubulin gene in case of fungi). Some uncultivable approaches using much advanced techniques like flow cytometry and gel based techniques have also been used to decipher microbial diversity. However, all these techniques have their corresponding pros and cons. In this regard, a polyphasic taxonomic approach is advantageous because it exploits simultaneously both conventional as well as molecular identification techniques. In this review, certain aspects of the merits and limitations of different methods for molecular identification and systematics of microorganisms have been discussed. The major advantages of the polyphasic approach have also been described taking into account certain groups of bacteria as case studies to arrive at a consensus approach to microbial identification.

Simple procedure for fatty acid analysis of glycerophospholipids in Escherichia coli and Saccharomyces cerevisiae

Rapid, convenient methods have been developed for fatty acid analysis of membrane glycerophospholipids in microorganisms. Fatty acid methyl esters derived from glycerophospholipids have been prepared directly from wet pellets of Escherichia coli cells or Saccharomyces cerevisiae spheroplasts without lipid extraction and fractionation in high yields under mild temperature conditions for analysis by gas chromatography.

An evaluation of commercial DNA extraction kits for the isolation of bacterial spore DNA from soil

AIMS

To evaluate six commercial DNA extraction kits for their ability to isolate PCR-quality DNA from Bacillus spores in various soil samples.

METHODS AND RESULTS

Three soils were inoculated with various amounts of Bacillus cereus spores to simulate an outbreak or intentional release of the threat agent Bacillus anthracis. DNA was isolated from soil samples using six commercial DNA extraction kits. Extraction and purification efficiencies were assessed using a duplex real-time PCR assay that included an internal positive control. The FastDNA(®) SPIN kit for Soil showed the highest DNA extraction yield, while the E.Z.N.A.(®) Soil DNA and PowerSoil(®) DNA Isolation kits showed the highest efficiencies in removing PCR inhibitors from loam soil extracts.

CONCLUSIONS

The results of this study suggest that commercially available extraction kits can be used to extract PCR-quality DNA from bacterial spores in soil. The selection of an appropriate extraction kit should depend on the characteristics of the soil sample and the intended downstream application.

SIGNIFICANCE AND IMPACT OF THE STUDY

  The results of this study aid in the selection of an appropriate DNA extraction kit for a given soil sample. Its application could expedite sample processing for real-time PCR detection of a pathogen in soil.

The effect of growth medium on B. anthracis Sterne spore carbohydrate content

The expressed characteristics of biothreat agents may be impacted by variations in the culture environment, including growth medium formulation. The carbohydrate composition of B. anthracis spores has been well studied, particularly for the exosporium, which is the outermost spore structure. The carbohydrate composition of the exosporium has been demonstrated to be distinct from the vegetative form containing unique monosaccharides. We have investigated the carbohydrate composition of B. anthracis Sterne spores produced using four different medium types formulated with different sources of medium components. The amount of rhamnose, 3-O-methyl rhamnose and galactosamine was found to vary significantly between spores cultured using different medium formulations. The relative abundance of these monosaccharides compared to other monosaccharides such as mannosamine was also found to vary with medium type. Specific medium components were also found to impact the carbohydrate profile. Xylose has not been previously described in B. anthracis spores but was detected at low levels in two media. This may represent residual material from the brewery yeast extract used to formulate these two media. These results illustrate the utility of this method to capture the impact of growth medium on carbohydrate variation in spores. Detecting carbohydrate profiles in B. anthracis evidentiary material may provide useful forensic information on the growth medium used for sporulation.