Glycolipid biosurfactant as an eco-friendly microbial inhibitor for the corrosion of carbon steel in vulnerable corrosive bacterial strains

In the present studies, glycolipid type of biosurfactant was used as a microbial inhibitor for corrosive bacterial strains (Bacillus subtilis Al, Streptomyces parvus B7, Pseudomonas stutzeri NA3 and Acinetobacter baumannii MN3). Biosurfactant was produced by using the bacterial strain, Pseudomonas mosselii F01 and characterized by using Fourier transform infrared spectroscopy and thin layer chromatography. Weight loss experiment and electrochemical analysis (Tafel polarization and AC-impedance) were used to confirm the corrosion reaction. X-ray diffractometer analysis was carried out to confirm the nature of the corrosion product formed during the corrosion reactions. Microdilution methods confirm that biosurfactant has higher antibacterial activity in the range of 1280-2560 mu g/mL in presence of those corrosive bacterial strains. Further, lower corrosion rate of carbon steel (0.0215 mm/y) was recorded in presence of the mixed consortia included with biosurfactant as inhibitor/biocide compared to the mixed bacterial system (0.1653 mm/y). The inhibition efficiency was found about 87% for mixed consortia included with biosurfactant system. The decreased level of corrosion current and potential was also recorded in the biosurfactant added system, similarly higher resistant capacity was found in the mixed consortia included with biosurfactant system. The XRD analysis supports other analysis that biosurfactant play a key role in the corrosion inhibition process in presence of the indigenous corrosive bacterial consortia. Anti-biofilm properties of the biosurfactant over the wide range of the bacterial strains make them as an efficient microbial corrosion inhibitor for the diverse environment. (C) 2018 Published by Elsevier B.V.