Plasticicumulans acidivorans gen. nov., sp. nov., a polyhydroxyalkanoate-accumulating gammaproteobacterium from a sequencing-batch bioreactor

Here, we describe a novel bacterium, strain TUD-YJ37(T), which can accumulate polyhydroxybutyrate (PHB) to more than 85 % (w/w) dry cell weight. The bacterium was isolated from a mixed-culture bioreactor by using a feast-famine regime and its properties were characterized. Phylogenetic analysis based on full 16S rRNA gene sequences revealed that the isolate is a member of the Gammaproteobacteria, forming an independent, deep phylogenetic lineage. It is most closely related to members of the genera Methylocaldum, Methylococcus and Natronocella, with sequence similarities below 91 %. Strain TUD-YJ37(T) was an obligately aerobic, ovoid, Gram-negative bacterium, motile by means of a polar flagellum. It utilized C₂-C₁₀ fatty acids as carbon and energy sources. The temperature range for growth was 20-35 °C, with an optimum of 30 °C; the pH range was 6.0-8.0, without a clear optimum. The major respiratory quinone was Q-8. Polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unidentified phospholipids, an unidentified aminolipid and another unidentified lipid. The predominant fatty acids in the membrane polar lipids were C₁₆:₁ω7c, C₁₆:₀ and C₁₈:₁ω7c. The G+C content of the genomic DNA was 67.4 mol%. On the basis of phenotypic, chemotaxonomic and molecular data, the isolate is proposed to represent a novel genus and species, for which the name Plasticicumulans acidivorans gen. nov., sp. nov. is proposed. The type strain of Plasticicumulans acidivorans is TUD-YJ37(T) ( = DSM 23606(T) = CBS 122990(T)).