N-160. Microbial Communities as Sensitive Indicators of Ecosystem Health and Processes in Bauxite Soils of Jamaica

D. E. Lewis, A. Chauhan, H. N. Williams;
Florida A&M Univ., Tallahassee, FL.

Jamaica is the third largest producer of Bauxite ore, which is further processed to manufacture Aluminum. These Bauxite mining companies are required by law to restore sites where mining operations are no longer economically viable. A major objective in the restoration process is to reverse the perturbation caused by mining operations such that these areas become self-sustaining ecosystems. Microbial communities are known to be sensitive indicators of ecological change, such as impacts due to changing land use patterns. Since microorganisms rapidly adapt to environmental change, miniscule shifts in microbial populations and activities can serve as a sensitive bio-indicator of ecosystem health. The aim of this study was to parameterize soil microbiota along un-mined and chronosequentially restored bauxite soils in Jamaica. Structure and function of these bauxitic microbial communities were assessed by culture-based, most probable number (MPN) and community level physiological profiling (CLPP) techniques. Further, microbial assemblages of these bauxite soils were analyzed by a culture-independent, 16S rDNA PCR-DGGE approach. MPNs and CLPP data revealed significant differences in utilization of carbon sources, including carbohydrates, carboxylic acids, amines/amides, and amino acids such that un-mined sites consisted of higher numbers and functionally more active microbial community; microbiota of chronosequentially restored sites appeared to be severely perturbed as indicated by lower MPNs and CLPP data, indicating that reclamation efforts were not enough to restore the health of these mined sites. Sequence analysis of the DGGE bands from various sites suggested dominance of a number of phylogenetically diverse bacteria with variability observed both, within individual sites and between un-mined and restored sites. Our data unequivocally shows that microbial culture-based techniques, used in tandem with molecular techniques, can facilitate significant improvements over current assessment procedures for assessment of ecosystem health and restoration efforts.