Biosurfactant production by a Bacillus megaterium strain

The aim of the present study was to investigate the ability of Bacillus megaterium IBBPo17 (GenBank KX499518) cells to produce biosurfactant when the growth was done in the presence of long-chain n-alkane n-hexadecane on medium supplemented with yeast extract, proteose peptone, starch, or cellulose. B. megaterium IBBPo17 revealed a higher growth in the presence of n-hexadecane when the medium was supplemented with yeast extract, proteose peptone, or starch, compared with cellulose. Biosurfactant production was higher when B. megaterium IBBPo17 was grown in the presence of n-hexadecane on yeast extract, proteose peptone, or starch supplemented medium, compared with biosurfactant produced on cellulose supplemented medium. A direct correlation between cell growth and biosurfactant production was observed. When the growth of B. megaterium IBBPo17 cells was higher, the decrease in pH values of the medium was higher too, and more amount of CO2 was released. Changes in cell morphology, aggregation of the cells in clusters, and biofilm formation were observed when B. megaterium IBBPo17 was grown in the presence of n-hexadecane on medium supplemented with yeast extract, proteose peptone, starch, or cellulose. Due to its physiological abilities, this Gram-positive bacterium could be a promising candidate for the bioremediation of petroleum hydrocarbon polluted environments

Effect of organic solvents on solvent-tolerant <i style="">Aeromonas <strong>hydrophila</strong> </i>IBB_Po8 and <i style="">Pseudomonas aeruginosa </i>IBB_Po10

352-361Alkanes (n-hexane, n-heptane) with logarithm of partition coefficient between n-octanol and water (log POW) 3.86 to 4.39 were less toxic to Aeromonas hydrophila IBBPo8 and Pseudomonas aeruginosa IBBPo10 as compared to aromatics (toluene, styrene, xylene isomers, ethylbenzene &amp; propylbenzene) with log POW 2.64 to 3.69. The toxicity of 0.5% (v/v) second phase of organic solvents to these bacteria could be predictable on the basis of the solvents’ log POW. The tolerance, viability, adhesion and β-galactosidase activity of A. hydrophila IBBPo8 and P. aeruginosa IBBPo10 cells in the presence of 0.5% (v/v) organic solvents varied significantly. The results indicated that A. hydrophila IBBPo8 was more susceptible to organic solvents than P. aeruginosa IBBPo10, whereas both the bacterial strains harbour plasmids. A. hydrophila IBBPo8 did not posses hydrophobe/amphiphile efflux 1 (HAE1) transporter genes, while P. aeruginosa IBBPo10 did posses these genes. The adaptation mechanisms (modification of cell hydrophobicity, induction of β-galactosidase activity and changes in the membrane’s lipid and protein content) of bacterial cells, underlying solvent tolerance, in A. hydrophila IBBPo8 and P. aeruginosa IBBPo10 showed a complex response to the presence of 0.5% (v/v) organic solvents in the culture medium. Bacterial strains able to survive in the presence of organic solvents could be used in two-phase biotransformation systems with whole cells for adequate bioremediation of heavily contaminated sites and could be&nbsp; a source for new solvent-stable enzymes with different applications

Role of Indigenous Bacteria in Corrosion of Two Types of Carbon Steel

This study aimed to investigate the presence of both aerobic and anaerobic bacteria in a water sample collected from a nuclear power plant and establish if the indigenous bacteria or the products of their metabolic activities could initiate the corrosion of two different types of carbon steel (i.e., A570, 1045). The aerobic (heterotrophic, iron-oxidizing) and anaerobic (sulfate-reducing) bacteria were detected in low numbers in the water sample. Three bacterial strains were isolated by the enrichment procedure from this sample. Based on phenotypic and genotypic characteristics, the isolated bacteria were identified as Stenotrophomonas maltophilia IBBCn1 (MT893712), Stenotrophomonas maltophilia IBBCn2 (MT893713), and Bacillus thuringiensis IBBCn3 (MT893714). The bacteria existing in the water sample were able to initiate the corrosion of carbon steel A570 and 1045. The sulfate-reducing bacteria were detected in higher numbers than the heterotrophic bacteria and iron-oxidizing bacteria at the end of the biocorrosion experiments. The carbon steel coupons revealed macroscopic and microscopic changes in the surface characteristics, and these changes could be due to biofilm formation on their surfaces and the accumulation of the corrosion products. The corrosion rate varied from one type of carbon steel to another, depending on the incubation conditions and the chemical composition of the coupons

Highly Solvent Tolerance in Serratia marcescens IBBPo15

ABSTRACT The aim of this study was to investigate the solvent tolerance mechanisms in Serratia marcescens strain IBBPo15 (KT315653). Serratia marcescens IBBPo15 exhibited remarkable solvent-tolerance, being able to survive in the presence of high concentrations (above 40%) of toxic organic solvents, such as cyclohexane, n-hexane, n-decane, toluene, styrene, and ethylbenzene. S. marcescens IBBPo15 produced extracellular protease and the enzyme production decreased in cells exposed to 5% cyclohexane, n-hexane, toluene, styrene, and ethylbenzene, as compared with the control and n-decane exposed cells. S. marcescens IBBPo15 cells produced carotenoid pigments and alteration of pigments profile (i.e., phytoene, lycopene) were observed in cells exposed to 5% cyclohexane, n-hexane, n-decane, toluene, styrene, and ethylbenzene. The exposure of S. marcescens IBBPo15 cells to 5% cyclohexane, n-hexane, n-decane, toluene, styrene, ethylbenzene induced also changes in the intracellular (e.g., 50 kDa protein) and extracellular (e.g., 39, 41, 43, 53, 110 kDa proteins) proteins profile. Significant RAPD, ARDRA, rep-PCR and PCR pattern modifications were not observed in DNA extracted from S. marcescens IBBPo15 cells exposed to 5% cyclohexane, n-hexane, n-decane, toluene, styrene, and ethylbenzene. Though only HAE1 and acrAB genes were detected in the genome of S. marcescens IBBPo15 cells, the unspecific amplification of other fragments being observed also when the primers for ompF and recA genes were used