MICROBIAL INDUCED CORROSION DUE TO DESULFOTOMACULUM NIGRIFICANS

摘要

Many studies on the corrosivity of SRB's sp Desulfovibrio devulgaris have been reported, however, much fewer investigations have been done on Desulfotomaculum nigrificans. Corrosion studies were, therefore, conducted on stainless steels exposed to media with SRB's sp Desulfotomaculum nigrificans. Baar's medium, both blank and inoculated, were used as media for the electrochemical and immersion corrosion tests. The extent of attack and the components inside the pits were identified by SEM/EDS. Biofilm formed on the coupons were analysed for the amount of carbohydrates and proteins. A correlation has been tried between corrosivity and the composition of the biofilm. Also extent of corrosion is influenced by the presence of heavy metals in the tested stainless steels and bacterial concentration. SRB also showed the ability to produce EPS and biodegrade the carbohydrate, a dominant component of the EPS produced by them. The study also suggests Desulfotomaculum nigrificans to be less corrosive than Desulfovibrio desulfuricans. Attempt has been made to understand this observation in terms of the biofilm composition.