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

Abstract

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.

Untargeted metabolomics of the bacterial tongue coating of intra-oral halitosis patients

“…We hypothesize that bacterial BCFAs are essential for the formation of the tongue coating in IOH. Recently, Al-Beloshei et al (2015) showed that the bacterial BCFA levels increase during biofilm formation at neutral and alkaline pHs [32]. This observation is consistent with our current findings.…”

Leishmania, microbiota and sand fly immunity

“…More specifically, Bacillus subtilis can colonize L. longipalpis larvae gut under laboratory conditions (Heerman et al , 2015 ). Curiously the Geobacillus genus, that can form biofilms on food industry surfaces (Seale et al , 2012 ; Al-Beloshei et al , 2015 ) is present in the L. longipalpis studied samples and has been rarely studied in insects. The sand fly bacterial diversity and distribution indicates that although laboratory feeding systems can interfere in the L. longipalpis natural microbial diversity, some bacteria species can persist through the adult fly feeding and environmental differences (field and laboratory conditions).…”

Cell envelope remodeling requires high concentrations of biotin during Mycobacterium abscessus model lung infection

“…Increases in environmental pH correlate with increases in branched and unsaturated fatty acid content [78][79][80] , and acidic stress leads to an altered fatty acid profile 78,79 , suggesting that extracellular pH may influence fatty acid metabolism. To address how alkaline stress might increase demand for biotin, fatty acid abundance was measured in M. abscessus grown in tissue culture medium either at pH 7.8 or pH 6.8.…”