Inhibition of microbial influenced corrosion on carbon steel ST37 using biosurfactant produced by Bacillus sp.

Microbial influenced corrosion that associated with biofilm has been one of the major problem in industry. It causes damage to equipment and infrastructure because of rapid material deterioration and often resulting in pipeline failures. Pipeline failures can lead to large economic losses and environmental problems. Synthetic chemical biocides are commonly used to prevent corrosion but are not effective against preformed biofilm on pipes and toxic to the environment. Anew antimicrobial is being developed by using biosurfactant produced by indigenous oil reservoir bacteria Bacillus sp. to prevent and eradicate biofilm. This study aims to determine minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration for 50% eradication (MBEC50) of biosurfactant against biofilm forming bacteria isolated from oil resevoir, its effect on biofilm community structure and its ability to inhibit the corrosion rate of Carbon Steel ST37. MIC, MBIC, and MBEC50 were determined using broth macrodillution technique, biofilm community structure were analyzed using total plate count method, and corrosion rate of steel were determined using weight loss method. Biofilm and corroded steel surface was also visualized using SEM-EDS. From this study, it is revealed that MIC, MBIC, and MBEC50 values respectively are 62.5; 31.25; and 500 mu g ml(-1). Biosufactant is able to inhibit Pseudomonas sp. 1 and Pseudomonas sp. 2 attachment to Carbon Steel ST37 surface and also able to eradicate preformed biofilm on steel surface. This study also showed the reduction of corrosion rate in Carbon Steel ST 37 as a result of biosurfactants treatment; from 4.56 x 10(-4) mm year(-1) to 3.31 x 10(-4) mm year(-1) based on MBIC value and from 5.18 x 10(-5) mmyear -1 to 2.7 x 10(-5) mm year(-1) after biofilm eradication at MBEC value. The results showed that biosurfactant in this study could be a good candidate for a new anti-corrosion agent.