Hydrocarbon biodegradation and surfactant production by acidophilic mycobacteria

• Published in: Microbiology (New York) Vol. 85; no. 3; pp. 317 - 324
• Main Authors: Ivanova, A. E., Sokolova, D. Sh, Kanat’eva, A. Yu
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-05-2016
• Subjects: Biomedical and Life Sciences; Experimental Articles; Life Sciences; Medical Microbiology; Microbiology; acidic environment; acidophilic mycobacteria; cell surface hydrophobicity; hydrocarbon biodegradation; biosurfactants; adhesion; surface and interfacial tension
• ISSN: 0026-2617; 1608-3237
• DOI: 10.1134/S002626171603005X

Production of biosurfactants by acidophilic mycobacteria was demonstrated in the course of aerobic degradation of hydrocarbons (
n
-tridecane,
n
-tricosane,
n
-hexacosane, model mixtures of С
14
–С
17
, С
12
‒С
19
, and С
9
–С
21
n
-alkanes, 2,2,4,4,6,8,8-heptamethylnonane, squalane, and butylcyclohexane) and their complex mixtures (hydrocarbon gas condensate, kerosene, black oil, and paraffin oil) under extremely acidic conditions (pH 2.5). When grown on hydrocarbons, the studied bacterial culture AG
S10
caused a decrease in the surface and interfacial tension of the solutions (to the lowest observed values of 26.0 and 1.3 mN/m, respectively) compared to the bacteria-free control. The rheological characteristics of the culture changed only when mycobacteria were grown on hydrocarbons. Neither the medium nor the cell-free culture liquid had the surfactant activity, which indicated formation of an endotype biosurfactant by mycobacteria. Biodegradation of
n
-alkanes was accompanied by an increase in cell numbers, surfactant production, and changes in the hydrophobicity of bacterial cell surface and in associated phenomena of adsorption and desorption to the hydrocarbon phase. Research on AGS10 culture liquids containing the raw biosurfactant demonstrated the preservation of its activity within a broad range of pH, temperature, and salinity.