Short Communication Iron reduction by psychrotrophic enrichment cultures

Psychrotrophic (6 203C) enrichment cultures from deep Pacific marine sediments and Alaskan tundra permafrost reduced ferric iron when using organic acids or H2 as electron donors. The representative culture W3-7 from the Pacific sediments grew fastest at 103C, which was 5-fold faster than at 253C and more than 40-fold faster than at 43C. Fe(III) reduction was also the fastest at 103C, which was 2-fold faster than at 253C and 12-fold faster than at 43C. Overall, about 80% of the enrichment cultures exhibited microbial Fe(III) reduction under psychrotrophic conditions. These results indicated that microbial iron reduction is likely widespread in cold natural environments and may play important roles in cycling of iron and organic matter over geological times. ß 1999 Published by Elsevier Science B.V. All rights reserved.