Diversity of potential culturable humic substance- transforming bacteria in sediments from 12 stations in the western Pacific polymetallic nodule province

Abstract:

[Background] The marine environment, as the largest organic carbon store on the earth, stores a large amount of humic substances, which may harbor abundant humic substance-transforming bacteria. [Objective] To isolate potential humic substance-transforming bacteria from marine sediments, and provide bacterial resources for the biotransformation of refractory natural organic polymers. [Methods] With humic substances as the sole carbon source, the humic substance-transforming bacteria in the sediment samples from 12 stations in the western Pacific polymetallic nodule province were enriched and purified. The taxonomic status of the purified bacteria was preliminarily identified by 16S rRNA gene sequence comparison. The potential humic substance-transforming bacteria were screened out by aniline blue-containing medium. [Results] A total of 276 strains were isolated from 12 sediment samples, belonging to 56 species, 37 genera, 14 orders of Actinobacteria, Cytophagia, Flavobacteria, Alphaproteobacteria and Gammaproteobacteria, including 1 potential new genus and 2 new species. Of the 56 species, 49 species were lignin-modifying enzyme positive. [Conclusion] The medium with humic substances as the sole carbon and energy source can be used to isolate potential humic substance-transforming bacteria with high diversity.