D-phenylalanine inhibits the corrosion of Q235 carbon steel caused by Desulfovibrio sp.

D-phenylalanine (D-Phe) was tested for its effect on the corrosion of Q235 carbon steel caused by Desulfovibrio sp. which belongs to sulfate reducing bacteria (SRB). Weight loss results indicated that the corrosion rate of Q235 coupons exposed to D-Phe was reduced. Much less pits were found on the surface of these coupons. It was found that pH and dissolved oxygen content of bacteria cultures as well as the growth of bacteria were not affected by D-Phe. However, the cell shape of D. sp. was changed to a more filamentous or spherical shape by treatment with D-Phe, and the structure of biofilms formed by bacteria with transformed shapes was looser and thinner. Moreover, the hydrogen sulfide production of D. sp. was inhibited by D-Phe. These results suggest that D-Phe may inhibit the corrosion process through two ways, i, D-Phe alters the bacteria shape, which inhibits the formation of biofilm and changes the structure of it consequently; ii, D-Phe reduces the production of hydrogen sulfide.