Effect of iron, nickel and cobalt on bacterial activity and dynamics during anaerobic oxidation of organic matter

The present study reports on the effect of Fe2+, Ni2+ and CO2+ on anaerobic bacterial activity and dynamics during anaerobic mineralization of organic matter. Fe2+ stimulated biogas yield and methane content at 37 degrees C, but inhibited same marginally at low temperatures (10 and 20 degrees C). Ni 2+ and CO2+ inhibited methane production; the toxicity increased with decre asing temperature. Fe2+ stimulated sulfate reducing bacterial (SRB) and met hane producing bacterial (MPB) counts while Ni2+ and CO2+ inhibited the sam e. All the metals had no effect on obligate proton reducing bacterial (OPRB ) counts. Fe2+ stimulated, Ni2+ severely and CO2+ appreciably inhibited H-2 uptake and acetate/propionate utilization irrespective of presence/absence of sulfate. Thus, Ni2+ and CO2+ inhibited the overall anaerobic degradativ e process by inhibiting SRB and MPB activity.