Isolation and characterization of polyhydroxyalkanoate-degrading bacteria in seawater at two different depths from Suruga Bay

Polyhydroxyalkanoate (PHA) is a highly biodegradable microbial polyester, even in marine environments. In this study, we incorporated an enrichment culture-like approach in the process of isolating marine PHA-degrading bacteria. The resulting 91 isolates were suggested to fall into five genera ( , , , , and ) based on 16S rRNA analysis, including two novel genera ( and ) as marine PHA-degrading bacteria. (DSM 20489) and (NBRC 102226), the type strains closest to the several isolates, have an extracellular poly(3-hydroxybutyrate) [P(3HB)] depolymerase homolog that does not fit a marine-type domain composition. However, exhibited no PHA degradation ability, unlike . This result demonstrates that the isolated spp. are different species from . P(3HB) depolymerase homologs in the genus should be scrutinized in the future, particularly about which ones work as the depolymerase.