Lipid and fatty acid profile of Geobacillus kaustophilus in response to abiotic stress

Bioprospecting potentials of moderately halophilic bacteria and the isolation of squalene producers from Kuwait sabkha

Sabkhas in Kuwait are unique hypersaline marine environments under-explored for bacterial community composition and bioprospecting. The 16S rRNA sequence analysis of 46 isolates with distinct morphology from two Kuwait sabkhas recovered 11 genera. Phylum Firmicutes dominated these isolates, and Bacillus (32.6%) was recovered as the dominant genera, followed by Halococcus (17.4%). These isolates were moderately halophilic, and some of them showed tolerance and growth at extreme levels of salt (20%), pH (5 and/or 11), and temperature (55 °C). A higher percentage of isolates harbored protease (63.0), followed by DNase (41.3), amylase (41.3), and lipase (32.6). Selected isolates showed antimicrobial activity against E. faecalis and isolated Halomonas shengliensis, and Idiomarina piscisalsi harbored gene coding for dNDP-glucose 4,6-dehydratase (Glu 1), indicating their potential to produce biomolecules with deoxysugar moieties. Palmitic acid or oleic acid was the dominant fatty acid, and seven isolates had some polyunsaturated fatty acids (linolenic or γ-linolenic acid). Interestingly, six isolates belonging to Planococcus and Oceanobacillus genus produced squalene, a bioactive isoprenoid molecule. Their content increased 30-50% in the presence of Terbinafine. The potential bioactivities and extreme growth conditions make this untapped bacterial diversity a promising candidate for future bioprospecting studies.

Text mining tools for extracting information about microbial biodiversity in food

Information on food microbial diversity is scattered across millions of scientific papers. Researchers need tools to assist their bibliographic search in such large collections. Text mining and knowledge engineering methods are useful to automatically and efficiently find relevant information in Life Science. This work describes how the Alvis text mining platform has been applied to a large collection of PubMed abstracts of scientific papers in the food microbiology domain. The information targeted by our work is microorganisms, their habitats and phenotypes. Two knowledge resources, the NCBI taxonomy and the OntoBiotope ontology were used to detect this information in texts. The result of the text mining process was indexed and is presented through the AlvisIR Food on-line semantic search engine. In this paper, we also show through two illustrative examples the great potential of this new tool to assist in studies on ecological diversity and the origin of microbial presence in food.

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We present new text-mining tools to extract information in food microbiology.

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The results of the extraction are available in an on-line semantic search engine.

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Taxa, habitats, phenotypes and links between them can be queried in PubMed abstracts.

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Text-mining tools could assist to browse past and recent scientific literature.

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Two use-cases are presented: fruit microbiota and spore-forming bacteria in food.

A comparative study of fatty acid profile and formation of biofilm inGeobacillus gargensisexposed to variable abiotic stress

Understanding bacterial fatty acid (FA) profile has a great taxonomic significance as well as clinical importance for diagnosis issues. Both the composition and nature of membrane FAs change under different nutritional, biotic and (or) abiotic stresses, and environmental stress. Bacteria produce both odd-carbon as well as branched-chain fatty acids (BCFAs). This study was designed to examine the effect of abiotic pressure, including salinity, temperature, pH, and oxinic stress on the growth, development, and FA profile in thermophilic Geobacillus gargensis. Under these stresses, 3 parametric ratios, 2-methyl fatty acids/3-methyl fatty acids (iso-/anteiso-FAs), BCFAs/straight-chain saturated fatty acids (SCSFA), and SCSFAs/straight-chain unsaturated fatty acids (SCUFA), in addition to total lipids affected by variable stresses were measured. Our results indicate that the ratio of total iso-/anteiso-FAs increased at the acidic pH range of 4.1–5.2 and decreased with increasing pH. The reverse was true for salt stress when iso-/anteiso-FAs ratio increased with salt concentration. The BCFAs/SCSFAs and SCSFAs/SCUFAs ratios increased at neutral and alkaline pH and high salt concentration, reduced incubation time, and comparatively high temperature (55–65 °C) of the growth medium. The bacterial total lipid percentage deceased with increasing salt concentration, incubation period, but it increased with temperature. The formation of extracellular polymeric substances was observed under all stress conditions and with the addition of sodium dodecyl sulfate (2 and 5 mmol/L) to the growth medium. The membrane phospholipid composition of the bacterium was analyzed by thin-layer chromatography.