Aurantivibrio plasticivorans gen. nov., sp. nov. and Aurantivibrio infirmus sp. nov., biodegradable plastic-degrading bacteria belonging to the family Cellvibrionaceae, isolated from the coast of Japan.

Two Gram-stain-negative, aerobic, non-spore-forming, rod-shaped bacterial strains, designated 4NK60-0013^T and 4NH20-0068^T, were isolated from biodegradable plastic films immersed in the coastal waters of Japan. These strains showed the ability to degrade biodegradable plastics, poly(butylene succinate-co-adipate) (PBSA) and poly(ε-caprolactone). Phylogenetic analyses based on the 16S rRNA gene sequences revealed that strains 4NK60-0013^T and 4NH20-0068^T belong to the family Cellvibrionaceae in the order Cellvibrionales and are closely related to members of the genus Gilvimarinus. The species most closely related to strains 4NK60-0013^T and 4NH20-0068^T were Gilvimarinus agarilyticus M5c^T and Gilvimarinus polysaccharolyticus YN3^T, with 16S rRNA gene sequence similarities of 94.4 and 93.3%, respectively. The sequence similarity between the two novel strains was 94.8%, indicating that they represented separate species. The genome length and G+C content of the genome sequence of strain 4NK60-0013^T were 4,354,061 bp and 46.9 mol%, respectively, whereas those of strain 4NH20-0068^T were 4,154,637 bp and 43.3 mol%, respectively. The average nucleotide identity values between the strains were <72.0%, similar to the values between the strains and type strains of species from the genera Cellvibrio, Gilvimarinus and Marinimicrobium. Based on phenotypic, cellular fatty acid and phylogenetic characteristics, the two isolates represent novel species within a new genus of the family Cellvibrionaceae, for which the names Aurantivibrio plasticivorans gen. nov., sp. nov. (type species) and Aurantivibrio infirmus sp. nov. have been proposed. Additionally, these strains and other bacteria belonging to the family Cellvibrionaceae have been shown to biodegrade PBSA, a biodegradable plastic. The type strains of A. plasticivorans and A. infirmus are 4NK60-0013^T (=NBRC 116180^T=TBRC 19146^T) and 4NH20-0068^T (=NBRC 116181^T=TBRC 19147^T), respectively.