A new genus Paramaribius gen. nov. with a new moderately halophilic species isolated from the surface of a polyethylene microplastic particle after incubation in a marine aquaria system

A bacterial strain, designated THAF1T, was isolated from the surface of a polyethylene microplastic particle after incubation in a marine microcosm containing several corals fragments. The strain was strictly aerobic and showed a pale-orange colour; cells were rod-shaped, Gram-stain negative, and non-motile. Phylogenetic analysis based on the nearly full-length 16S rRNA gene sequence placed the strain within family Rhodobacteraceae in between the genera Pseudomaribius, Palleronia, and Maribius. Strain THAF1T exhibited highest 16S rRNA gene sequence similarity to type strains of the species Maribius pontilimi (97.0 %), Pseudomaribius aestuariivivens (96.7 %), and Palleronia abyssalis (95.7 %). Strain THAF1T grew between 15 and 37 °C, in the presence of 1 to 12 % NaCl, and at pH 4.5 to 10.0. The predominant ubiquinone was Q-10 and the major cellular fatty acids were C18:1ω7c (61.1 %) and cyclo C19:0ω8c (20.0 %). The polar lipid profile contained phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, three aminolipids, one phospholipid, two lipids lacking a functional group and one glycolipid. Analysis of polyamine content showed that the major component was spermidine. The genomic DNA G+C content was 60.1 mol %. According to the evidence of the phylogenetic, chemotaxonomic, and phenotypic analyses, strain THAF1T is a member of a novel genus within the Rhodobacteraceae.