IDENTIFYING NUMERICALLY ABUNDANT CULTURABLE BACTERIA FROM COMPLEX COMMUNITIES - AN EXAMPLE FROM A LIGNIN ENRICHMENT CULTURE

Culturable bacteria that were numerically important members of a marin e enrichment community were identified and characterized phylogenetica lly, Selective and nonselective isolation methods were used to obtain 133 culturable bacterial isolates from model marine communities enrich ed with the high-molecular-weight (lignin-rich) fraction of pulp mill effluent. The culture collection was screened against community DNA fr om the lignin enrichments by whole-genome hybridization methods, and t hree marine bacterial isolates were identified as being numerically im portant in the communities, One isolate was in the or-subclass of Prot eobacteria , and the other two were in the gamma-subclass of Proteobac teria. Isolate-specific 16S rRNA oligonucleotide probes designed to pr ecisely quantify the isolates in the lignin enrichment communities ind icated contributions ranging from 2 to 32% of enrichment DNA, values n early identical to those originally obtained by the simpler whole-geno me hybridization method, Two 16S rRNA sequences closely related to tha t of one of the isolates, although not identical, were amplified via P CR from the seawater sample originally used to inoculate the enrichmen t medium, Partial sequences of 14 other isolates revealed significant phylogenetic diversity and unusual sequences among the culturable lign in enrichment bacteria, with the Proteobacteria, Cytophaga-Flavobacter ium, and gram-positive groups represented.