Protection of mild steel (UNS G 1020) against microbial induced corrosion using biofilm- producing bacterium Bacillus sp. strain TB16.

A biofilm producing bacterium , strain TB16 was isolated from the tabriz refinerys cooling towers and identified as bacillus sp.by 16SrRNA gene sequencing , shown to be able to reduce corrosion rates of mild steel by establishment of antimicrobial agent producing biofilm which inhibit the activity of sulfate -reducing bacteria SRBs. the corrosion behavior of mild steel UNS1020 was studied during exposure to SRBs in postgates E and / or luria bertani LB-Bushnel hass BH media in sterile condition in bench scale batch reactor iusing electrochemical impedance spectroscopy EIS. when a mixed SRB culture was intorduced to a non -antimicrobial producing control biofilm of paenibacilus polymyxa ATCC10401 , an increased corrosion was observed and the mild steel coupons underwent more severe corrosion than when only SRB population was present , showing 3 fold increase via EIS. however , when a gramisidin -s-producing bacillus migulans aneurinbacillus ATCC9999 or strain TB16 biofilms were pre -established on mild steel the metal coupons were protected aginst the attack of mixed SRB populations.

Keywords:

Microbial corrosion , electrochemical impedance spectroscopy EIS , biofilm , sulfate reducing bacteria SRB.