N-161. Microbial Communities at the Metal Contaminated Lake Sediment

S. Kang¹, H. L. Gough², J. Van Nostrand^1,3, Z. He^1,3, L. Wu^1,3, D. A. Stahl^2,3, T. C. Hazen^4,3, J. Zhou^1,3;
¹Univ. of Oklahoma, Norman, OK, ²Univ. of Washington, Seattle, WA, ³Virtual Inst. for Microbial Stress and Survial, Berkeley, CA, ⁴Lawrence Berkeley Natl. Lab., Berkeley, CA.

Microbes are known for their versatility under different and even certain extreme environmental conditions. The versatility is of particular interest in many applications including bioremediation. Lake DePue has been subjected to metal contamination over the last 80 years by adjacent zinc smelting activities. Sediments were collected in triplicate from five areas of the lake. These areas were previously identified as having varied metals contamination levels, and are located along a transect from near a creek inlet to the main body of the lake. GeoChip II, with over 10,000 microbial functional genes, was used to investigate metal impact on the microbial diversity and community structure. Three microbial communities of functional subgroups, defined by genes relevant to metal contamination (S cycle, metal resistance and reduction, and C cycle genes) were analyzed. Proximity of sampling sites to the contamination source was important factor in shaping microbial communities. The two sites closest to the contamination source (Sites 1 and 2) clustered together in all three communities, as measured by NMDS, hierarchical clustering and k-means clustering. Interestingly, these two sites also showed the greatest diversity (Shannon’s H’, Simpson’s -lnD and Fisher’s α). Proximity of sampling locations alone could not explain community variability as samples from Site 4, located between Sites 3 and 5, were more similar to samples from Sites 1 and 2. Multivariate correlation analysis by both Mantel test and Procrustes test revealed very significant correlation among three functional categories of communities (P < 0.001). Spatial structures of the three microbial communities were fairly distinctive, in that smaller scale patch size in C cycle community and larger scale patch size in metal-related community were observed while virtually no patchiness was observed in S cycle community by multivariate correlogram analysis. In conclusion, three microbial communities relevant to metal contamination were rather similar in their composition and diversity while their spatial structure was quite distinctive.