Native soil bacterial isolate in Malaysia exhibit promising supplements on degrading organic pollutants

• Bacillus salmalaya strain 139SI produced a novel biosurfactant.
• 70% of waste crude oil was removed from polluted soil by strain 139SI.
• High correlation was found between the TPH degraded and dehydrogenase activity.
• First order kinetics model described the highest biodegradation rate (0.107 day−1).

A novel strain was isolated from an agricultural soil in Malaysia. After morphological and genetic characterization, the novel strain showed the highest similarity to Bacillus species. The ability of biostimulation (waste tealeaf) and bioaugmentation (Bacillus salmalaya 139SI) activities was investigated on soil polluted with 6% (w/w) waste crude oil for duration of 60 days. Strain 139SI was able to decrease the surface tension to 35 mN/m. Degradation of the initial petroleum hydrocarbon by 70% was achieved in the treatments involving B. salmalaya strain 139SI and tealeaf compared to the sterilized polluted soil (15%), which served as a control for this study. The aerobic utilizing bacteria counts and dehydrogenase activity were significantly increased during the period of study. Analysis of residual waste crude oil monitored by gas chromatography spectrophotometer indicated 80–95% degradation of n-C8 to C12 followed by a 40% removal ratio of C22. Kinetic model showed that treatment amended with both tealeaf and strain has indicated the highest level of biodegradation rate, with rate constant of 0.107 day−1, while the biodegradation rate was 0.08 day−1 in treatments amended with only tealeaf. The finding showed the potentiality of tealeaf and Bacillus salmalaya 139SI toward the degradation/decomposition of crude oil in contaminated soil.

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