Muriiphilus fusiformis gen. nov., sp. nov., a novel non-marine bacterium belonging to the Roseobacter group, and reclassification of Maritimibacter lacisalsi (Zhong et al. 2015) as Muriicola lacisalsi gen. nov., comb. nov

Phylotaxonomic assessment based on four core gene sets and proposal of a genus definition among the families Paracoccaceae and Roseobacteraceae

The families Paracoccaceae and Roseobacteraceae comprise metabolically, phenotypically and genotypically diverse members, and their descriptions rely heavily on 16S rRNA gene analysis. Hundreds of genera have been reported within the two families and misclassifications have been a reoccurring problem, even when the taxonomies have been established based on genome-scale phylogenetic reconstructions. In this study, we conducted a comprehensive phylotaxonomic assessment of the families Paracoccaceae and Roseobacteraceae based on four ubiquitous gene sets, bac120 (120 genes in Bacteria), rhodo268 (268 genes in ‘ Rhodobacteraceae ’, defined in this study), rp1 (16 ribosomal protein genes in Prokaryote) and rp2 (23 ribosomal protein genes in Prokaryote), using two tree-inferring applications and two approaches (supermatrix and consensus). The results suggested that the four supermatrix trees based on bac120 and rhodo268 shared a high proportion of common nodes (>88.4 %) and the topology was reproducible among all the trees within most of the genera. The evolutionary distance (ED) analysis showed significant overlapping between the intergeneric and intrageneric comparisons, implying that the proposal of some genera seemed to be unnecessary. In addition, the bac120 gene set and the FastTree program were found to be the most cost-effective way to conduct phylogenomic analysis of the families Paracoccaceae and Roseobacteraceae . An ED threshold of 0.21–0.23 based on either bac120 or rhodo268 was proposed as one standard for later genus delimitation in these families. A comprehensive phylogenetic framework is presented in this study and the proposed genus definition will help to establish a more reasonable taxonomy in the families Paracoccaceae and Roseobacteraceae .

Maritimibacter dapengensis sp. nov., a poly-β-hydroxyalkanoates-producing bacterium isolated from sediment of the Dapeng peninsula (Guangdong, China)

A Gram-negative, obligate aerobic, non-motile, rod-shaped bacterium lacking a flagellum, was isolated from sediment sampled at the Dapeng peninsula of Shenzhen, Guangdong, China, and designated strain DP4N28-5T. Growth of strain DP4N28-5T occurred at 15–45 °C (optimum at 30 °C), pH 6.0–8.0 (optimum at 6.0) and in 2.0–10.0 % NaCl (w/v; optimum at 2.0–3.0 %). The 16S rRNA gene sequence analysis revealed that strain DP4N28-5T was most closely related to Maritimibacter alkaliphilus DSM 100037T (97.6 %; sequence similarity). The strain synthesized a trace amount of poly-β-hydroxybutyrate. The dominant cellular fatty acids were summed feature 8 (C18 : 1  ω6c and/or C18 : 1  ω7c), C16 : 0, 11-mehtyl C18 : 1  ω7c and C16 : 0 2-OH. The major polar lipids included phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanolamine, one unidentified aminophospholipid, three unidentified aminolipids and four unidentified lipids. The respiratory quinone was Q-10. The DNA G+C content was 62.0 mol% and the estimated genome size was 3.9 Mbp. The calculated average nucleotide value between strain DP4N28-5T and M. alkaliphilus DSM 100037T was 78.1 %. The phenotypic, genotypic and chemotaxonomic differences between strain DP4N28-5T and its phylogenetic relatives indicate that DP4N28-5T represents a novel species in the genus Maritimibacter , for which the name Maritimibacter dapengensis sp. nov. is proposed. The type strain is DP4N28-5T (=MCCC 1K05640T=KCTC 82805T). The description of genus Maritimibacter was emended to include this new species.