DIVERSITY AND DISTRIBUTION OF SUBTERRANEAN BACTERIA IN GROUNDWATER ATOKLO IN GABON, AFRICA, AS DETERMINED BY 16S RIBOSOMAL-RNA GENE SEQUENCING

This paper describes how groundwater was sampled, DNA extracted, ampli fied and cloned and how information available in the ribosomal 16S rRN A gene was used for mapping diversity and distribution of subterranean bacteria in groundwater at the Bangombe site in the Oklo region. The results showed that this site was inhabited by a diversified populatio n of bacteria. Each borehole was dominated by species that did not dom inate in any of the other boreholes; a result that probably reflects d ocumented differences in the geochemical environment. Two of the seque nces obtained were identified at genus level to represent Acinetobacte r and Zoogloea, but most of the 44 sequences found were only distantly related to species in the DNA database. The deepest borehole, BAX01 ( 105 m), had the highest number of bacteria and also total organic carb on (TOC). This borehole harboured only Proteobacteria beta group seque nces while sequences related to Proteobacteria beta, gamma and delta g roups and Gram-positive bacteria were found in the other four borehole s. Two of the boreholes, BAX02 (34 m) and BAX04 (10 m) had many 16S rR NA gene sequences in common and they also had similar counts of bacter ia, content of TOC, pH and equal conductivity, suggesting a hydraulic connection between them.