Production of biosurfactant from Bacillus subtilis (MF 582633) and its evaluation for antimicrobial, antioxidant, larvicidal and antitermite activities

Abstract

Present study evaluates the production and characterisation of biosurfactant for its antimicrobial, antioxidant, larvicidal and antitermite activities. A bacterium has been isolated from fatty acid contaminated soil and identified as biosurfactant producer , Gram positive Bacillus subtilis (MF582633) subspecies inaquosorum based on 16S rRNA sequencing and unique QR codes. The bacterium produced 2.03 g/L of biosurfactant using 3% glycerol as a carbon source. Among the tested five organisms K.pneumoniae revealed (20.3 mm) and E coli (10 mm) zone of inhibition as compared to standard antibiotic ampicillin (40 µg/mL ) when biosurfactant concentration is reported to be 40 µg/mL. Antioxidant activity in terms of IC₅₀ value at 0.4 mg/ mL is recorded. The 100% larvicidal activity is recorded at 50 mg/mL concentration of biosurfactant while 40 mg/mL concentration in 48 h revealed 100% antitermite activity. Biosurfactant is purified through silica gel column chromatography. Purified biosurfactant has been characterised using FTIR and ¹H NMR analysis and revealed surfactin type of lipopeptide biosurfactant. Experimental results may add its value in the development of antibiotics and biopesticides to stop the menace of UTI infections, Culex larvae and termites.