Biodegradation of n-hexadecane by bacterial strains B1 and B2 isolated from petroleum-contaminated soil

Abstract

Two hydrocarbon-biodegrading bacterial strains, B1 and B2, were isolated from petroleum-contaminated soil collected from Tianjin, China. The strains were identified as Pseudomonas aeruginosa (B1) and Acinetobacter junii (B2). The degradation rate of n-hexadecane by B1 and B2 reached 96% and 78% respectively after 7 days, though the strains employed different mechanisms of degradation. The results showed that B2 was not able to use glucose as carbon source. B1 could produce glycolipid surfactants using glucose as the carbon source, according to the results of blue agar plate analysis and thin layer chromatography (TLC), and the bacterial culture of B1 had a high oil discharge and emulsification activity. Both B1 and B2 could produce biosurfactants with hexadecane as the sole carbon source, but their modes of action were different. The carbon source was found to affect the cell surface hydrophobicity. Cell surface hydrophobicity was poor with glucose as the carbon source, but enhanced when hexadecane was used as the carbon source.

Single-cell genome and metatranscriptome sequencing reveal metabolic interactions of an alkane-degrading methanogenic community

“…Expression of this gene during growth with hexadecane may assist Smithella to adapt its membrane composition to the presence of the hydrophobic substrate. Transporters for long-chain fatty acids, such as palmitate, octadecanoate and tetradecanoate, were also encoded in the genome and actively expressed during growth with hexadecane only, suggesting that these genes may be assisting in the export of biosurfactants for hexadecane emulsification (Breuil and Kushner, 1980;Liu et al, 2012).…”

Biosurfactant from Pseudomonas species with waxes as carbon source – Their production, modeling and properties

“…P. aeruginosa achieves maximum CSH with n-hexadecane and n-eicosane as substrates within one day (90 and 85%, respectively) and the corresponding values for P. fluorescens are 82 and 86%. Liu et al [46] and Pereira et al [4] observed 74 and 88% CSH, respectively, with Pseudomonas species. The high hydrophobicity observed here indicates high affinity of these organisms toward the crude oil than water.…”

“…The corresponding values with P. fluorescens were 78 and 76%. Liu et al [46] and Lotfabad et al [47] observed the emulsification activity of 18 and 61% using P. aeruginosa. It can be inferred from the results that the isolates have the ability to emulsify the immiscible paraffins including n-eicosane and n-hexadecane.…”

“…Biosurfactant helps the microorganism to grow on hydrophobic (paraffin) substrate and increases their bioavailability [13]. Microorganisms with higher CSH can attach to hydrophobic surfaces with ease and hence can degrade hydrophobic organic compounds at a higher rate than those microorganisms with less CSH [46]. The presence of biosurfactant acts as a link between microorganism, and oil and hence connects it to the carbon source [49].…”

“…In addition, pipelines made up of polymers including, poly vinyl chloride, etc., are hydrophobic in nature [46]. Thus, the pipelines in general have more affinity for hydrophobic microorganisms than those that are less hydrophobic.…”