THE EFFECT OF MOLECULAR-OXYGEN ON SULFITE REDUCTION BY SHEWANELLA-PUTREFACIENS

Recently, Shewanella putrefaciens isolated from an industrial cooling water system has been shown to play a role in microbially influenced c orrosion. In this study S. putrefaciens isolated from industrial cooli ng waters was shown to produce low levels of hydrogen sulfide from sul fite at dissolved oxygen concentrations up to 1.5 mg l(-1) oxygen. Alt hough oxygen is the prefer-red electron acceptor with the highest ener gy yield, some of the electrons were diverted to sulfite. When the sta rting inoculum was from a sulfite-reducing culture, the growth rate an d oxygen depletion rate were lower compared to when the inoculum was f rom an aerobic culture that did not reduce sulfite, indicating that su lfite reduction occurred concurrently with oxygen reduction. The reduc tion of sulfite by S. putrefaciens under microaerophilic as well as an aerobic conditions points towards a more significant role of this spec ies in microbially influenced corrosion when growing as a biofilm. (C) 1998 Published by Elsevier Science B.V. All rights reserved.