Differential utilization of pyrene as the sole source of carbon by Bacillus subtilis and Pseudomonas aeruginosa strains: role of biosurfactants in enhancing bioavailability
Article first published online: 31 JUL 2006
Journal of Applied Microbiology
Volume 102, Issue 1, pages 195–203, January 2007
How to Cite
Das, K. and Mukherjee, A.K. (2007), Differential utilization of pyrene as the sole source of carbon by Bacillus subtilis and Pseudomonas aeruginosa strains: role of biosurfactants in enhancing bioavailability. Journal of Applied Microbiology, 102: 195–203. doi: 10.1111/j.1365-2672.2006.03070.x
- Issue published online: 31 JUL 2006
- Article first published online: 31 JUL 2006
- 2005/1030: received 10 September 2005, revised 13 February 2006 and accepted 6 April 2006
- Bacillus subtilis;
- Pseudomonas aeruginosa;
- pyrene biodegradation
Aims: Our goal is to compare the efficiency of utilization of pyrene as the sole source of carbon for growth and energy by two nonactinomycetous groups of bacteria viz., Bacillus subtilis DM-04 and Pseudomonas aeruginosa mucoid (M) and nonmucoid (NM) strains, isolated from a petroleum-contaminated soil sample of north-east India.
Methods and Results: Bacillus subtilis DM-04 and P. aeruginosa M and NM bacterial strains were capable of secreting biosurfactant in the culture medium while growing on pyrene and their pyrene utilizing efficiency was demonstrated by correlating the bacterial growth in the presence of pyrene as the sole source of carbon along with a concomitant decrease in pyrene content from the culture medium with respect to time. The biosurfactant secreted by the respective bacterial strains enhanced the apparent solubility of pyrene by factors of 5–7 and influenced the bacterial cell surface hydrophobicity resulting in higher uptake and utilization of pyrene by bacteria. The growth of B. subtilis DM-04 and P. aeruginosa M and NM strains at the expense of pyrene after 96 h showed an assimilation of about 48·0 ± 1·1% (mean ± SD) and 32·0 ± 0·6% (mean ± SD) of pyrene carbon, respectively, showing differences in metabolism of pyrene by these bacterial strains.
Conclusions: Bacillus subtilis DM-04 strain exhibited higher utilization and cellular assimilation of pyrene compared with P. aeruginosa M and NM strains. Further, the biosurfactants produced by the bacteria under study are capable of enhancing the solubility of pyrene in aqueous media and can influence the cell surface hydrophobicity of the biosurfactant-producing strains that results in a higher uptake of pyrene.
Significance and Impact of the Study: It may be suggested that the bacteria used in this study are suitable candidates for practical field application for effective in situ bioremediation of pyrene-contaminated sites.