Assessment of biosurfactant-producing bacteria from oil contaminated soils and their hydrocarbon degradation potential

Abstract

Biosurfactants (BSs) are amphiphilic compounds produced by microorganisms and have diverse applications in various industries. This study was aimed to identify and characterize BS producing bacteria from three oil-polluted sites from Pune, Maharashtra, India. Out of the total 48 bacterial isolates, 14 BS producing isolates were detected through drop collapse method (DCM) and oil spreading method (OSM), hemolytic activity, cetyl trimethyl ammonium bromide (CTAB) test, emulsification index (E24), and surface tension (SFT) measurement. The BS producing isolates were identified by matrix-assisted laser desorption/ionization time of flight mass spectrophotometry (MALDI-TOF MS) and 16S rRNA gene sequencing. Results indicated that the isolates belonged to six genera, including Bacillus, Agrococcus, Arthrobacter, Kocuria, Dietzia, and Lysinibacillus. We are reporting BS producing Agrococcus terreus for the first time. Out of 14 BS producing bacteria, four isolates showed β hemolysis in blood agar plates, while all isolates showed negative results on CTAB agar plate. A positive correlation was observed between DCM, OSM, and SFT measurements. Bacillus sp. (isolate PR170) presented the maximum diameter of the clear zone (32 mm) in OSM. The E24 was found to be in the range of 15–57%. Four isolates including PR170, PP151, PP168, and PG138 significantly reduced the SFT of the medium by up to 26.79, 27.81, 28.83, and 30.99 mN/m, respectively. Nine isolates were able to grow in media containing various polyaromatic hydrocarbons. Results gathered in this study demonstrated that isolates belonging to four genera from the contaminated sites had an outstanding potential for further application in biotechnological processes such as large-scale BS production or bioremediation of hydrocarbon polluted sites, and will contribute towards environmental sustainability.