ISOLATION AND CHARACTERIZATION OF HETEROTROPHIC, AEROBIC-BACTERIA FROM OIL STORAGE CAVERNS IN NORTHERN GERMANY

Aerobic heterotrophic bacteria were enriched and isolated from three o il storage caverns of the German national oil reserve at different dis tances from the oil/brine interface. Microscopically no bacteria were found in the original samples, but colony counts showed more than 100 colony-forming units (cfu)/ml in two samples, whereas 0 to 4 cfu/ml we re found in the other samples. Enrichments using defined mineral salts medium or complex medium revealed culturable organisms in all samples . All colony types were isolated and further separation of organisms d uring isolation was completed microscopically. Enrichments in media co ntaining complex organic compounds led to higher numbers of isolates i n samples near the oil/brine interface than enrichments with oil as th e sole source of carbon. Micro-organisms that could utilize oil as the sole source of carbon were isolated from all enrichment cultures. Ide ntification of the isolates revealed Bacillus strains in all samples a nd coryneform bacteria in the samples from cavern 123.