Paracoccus simplex sp. nov., a New Methylamine-Utilizing Facultative Methylotroph

Abstract—A facultative methylotroph, strain F5^Т, which uses methylamine and a broad spectrum of polycarbon substrates as carbon and energy sources, was isolated from silt of a freshwater lake in the southern Moscow region. The cells were gram-negative, coccoid, non-spore-forming, nonmotile, colorless, reproducing by binary fission and possessing a capsule. The organism was mesophilic, neutrophilic, not halophilic, oxidase- and catalase-positive, and capable of nitrate reduction to nitrite. Methylamine was oxidized by amine dehydrogenase and via the icl^- serine pathway of С₁ metabolism, as was indicated by activities of hydroxypyruvate reductase and serine-glyoxylate aminotransferase and by the absence of hexulosephosphate synthase and ribulose bisphosphate carboxylase. Predominant fatty acids were C_18:1ω7c (72.3%) and C_16:0 (11.6%). Phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylethanolamine were the dominant phospholipids. The G + C DNA content was 65.8 mol % (T_m). Q₁₀ was the dominant ubiquinone. Strain F5^T exhibited high similarity of the 16S rRNA gene sequences with Paracoccus strains: P. aminovorans JCM7685^T = VKM B-2140^Т (98.0%), P. huijuniae FLN-7^Т (97.9%), and P. limosus NB88^T (97.5%). However, the level of DNA-DNA relatedness between the strains F5^Т and P. aminovorans^Т was only 21 ± 3%. Based on the data obtained, strain F5^Т was identified as a new Paracoccus species with proposed name Paracoccus simplex sp. nov. (= VKM B-3226^T = CCUG 71989^T).