Production and characterization of biosurfactant from Enterobacter cloacae SJ2 isolated from marine sponge Clathria sp.

In the present work, the production of biosurfactant was studied from the bacterial strains isolated from the marine sponge Clathria sp. sample collected from oil-contaminated coastal region of V.O. Chidambaranar Harbour, Thoothukudi, Tamil Nadu, India. Six morphologically distinct biosurfactant-producing bacterial strains (SJ1-SJ6) isolated on oil agar plates were further screened for biosurfactant production (BP). Based on the screening results, the isolate SJ2 showed a surface tension reduction value of 31.6 mN m(-1), oil displacement zone of 26 mm and positive results of drop collapse test with the emulsification index percentage (EI24%) of 68.14%, and the bacterial adherence to hydrocarbon percentage of 79.2% was selected as the most potential BP strain, and it was identified as Enterobacter cloacae using 16S rRNA gene sequencing. Growth and BP optimization revealed 36 h of incubation period, 150 rpm agitation, pH 7.5, 37 degrees C temperature, 1% salinity, 2% glucose as carbon source and 1% yeast extract as nitrogen source were the ideal conditions with the biosurfactant yield of 2.61 g L-1. FTIR and MALDI-TOF-MS analysis of the biosurfactant showed the presence of functional groups, and it was a rhamnolipid. This rhamnolipid biosurfactant showed antibacterial activity against tested bacterial pathogens.

Automated summary

This study isolated a bacterial strain capable of producing biosurfactant and optimized the production conditions. The biosurfactant exhibited good surface activity and antibacterial activity.