Survival of sulfate-reducing bacteria in oxic surface sediment of a seawater lake

Microhabitats and survival of sulfate-reducing bacteria (SRB) in an oxic surface sediment of a seawater lake were examined. The size of fractionation of the sediment suspension showed that most of SRB were associated with sediment particles larger than 10 μm. The D values (time in h required to destroy 90% of the initial viable population) for SRB in the whole sediment suspension and for SRB i n the < μ m and the < 5 μ m fractions were, respectively, 23.7, 10 and 4 when the SRB were exposed to air. Survival of the FeS-associated Desulfovibrio desulfuricans (D value, 9.3) was higher than that of the free-living ones (D value, 1.8). These results show that particle-associated SRB are more protected against oxygen than free-living ones in oxic sediments.