Biosurfactant production and diesel-fuel removal by isolated bacteria from Kalimas Estuary, Madura Strait

Abstract

This experiment was done to evaluate isolated bacteria in the production of biosurfactant and biodegradation of diesel-fuel. Diesel-fuel degrading bacteria were isolated from Kalimas Estuary, Surabaya using three-stage enrichment culture in Bushnell Haas Mineral Salts medium with 1% diesel fuel. Purified isolates were subjected to both oil-displacement and E24-emulsification tests to assess the high activity of produced biosurfactant. Selected isolates were next used in biodegradation analysis of diesel-fuel using a gravimetric total petroleum hydrocarbon test. The potential isolates were identified based on their 16S rDNA sequences. Twenty-eight purified isolates were obtained from the water samples and confirmed as gram-negative hydrocarbonoclastic bacteria. Among them, isolate K8 demonstrated the widest diameter on diesel-fuel displacement test by 3.5 cm of oil-free zone. It was also superior in emulsifying diesel-fuel with 9.4% of E24 index. Isolate K8 was capable of degrading 57% of 1 mL of diesel fuel within 14-day incubation. The isolate was potential in both producing biosurfactant and degrading diesel fuel. Isolate K8 was identified as Pseudomonas aeruginosa with 99.74% sequence similarity.