Aliiroseovarius subalbicans sp. nov. and Aliiroseovarius sediminis sp. nov., isolated from marine sediment.

Two novel strains (N1Y82T and N1F302T) were isolated from a marine sediment sample taken from the coastal zone of Weihai, PR China. Cells of the two strains were Gram-strain-negative, catalase-positive, oxidase-positive, non-motile and ovoid- to rod-shaped. Strain N1Y82T grew optimally at 16 °C, pH 7.5 and in the presence of 3.0 % (w/v) NaCl. Strain N1F302T grew optimally at 28 °C, pH 7.0-7.5 and in the presence of 2.0-2.5 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strains N1Y82T and N1F302T belonged to the genus Aliiroseovarius, and were mostly related to Aliiroseovarius sediminilitoris KCTC 23959T with sequence similarity of 96.5 and 97.1 %, respectively. For these two novel strains, C18 : 1 ω7c was the major fatty acid, ubiquinone 10 was the predominant respiratory quinone, and phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, one unidentified aminolipid and one unidentified phospholipid were the major polar lipids. The DNA G+C contents of strain N1Y82T and N1F302T were 61.3 and 59.0 %, respectively. Consequently, strains N1Y82T and N1F302T are considered to represent two novel species of the genus Aliiroseovarius, for which the names Aliiroseovarius subalbicans sp. nov. and Aliiroseovarius sediminis sp. nov. are proposed. The type strains are N1Y82T (=KCTC 82768T=MCCC 1H00524T) and N1F302T (=KCTC 82412T=MCCC 1H00525T), respectively.

Predation capacity of Bradymonabacteria, a recently discovered group in the order Bradymonadales, isolated from marine sediments.

Bacterial predation is a vital feeding behavior that affects community structure and maintains biodiversity. However, predatory bacterial species in coastal sediments are comparatively poorly described. In this study, the predation capacity of all nine culturable Bradymonabacteria strains belonging to the recently discovered order Bradymonadales was determined against different types of prey. The predatory efficiency of Bradymonabacteria increased as the initial prey proportion in a mixed culture decreased. When the initial prey proportion was 0.5, the number of surviving prey bacterial cells significantly decreased after 4 h of predation with the Bradymonabacteria strains TMQ1, SEH01, B210 and FA350. However, growth of the prey strain occurred in the presence of the Bradymonabacteria strains TMQ4, TMQ2, TMQ3, V1718 and YN101. When the initial prey proportion decreased to 0.1 or 0.01, most of the Bradymonabacteria strains preyed efficiently. Furthermore, established neighboring colonies of prey were destroyed by Bradymonabacteria. This invading predation capacity was determined by the predation ability of the strain and its motility on the agar surface. Our findings provide new insights into the potential ecological significance of predatory Bradymonabacteria, which may serve as a potential probiotic for use in the aquaculture.

Psychroserpens luteolus sp. nov., isolated from Gelidium, reclassification of Ichthyenterobacterium magnum as Psychroserpens magnus comb. nov., Flavihalobacter algicola as Psychroserpens algicola comb. nov., Arcticiflavibacter luteus as Psychroserpens luteus comb. nov.

A Gram-stain-negative, motile by gliding, catalase positive, facultative anaerobic strain, designated strain XSD401T, was isolated from an unidentified Gelidium species of Xiaoshi Island, Shandong Province, China. The 16S rRNA gene sequence comparisons indicated strain XSD401T had a sequence similarity of 96.9% with Psychroserpens damuponensis KCTC 23539T and 96.3% with Psychroserpens burtonensis DSM 12212T. The G + C content of the genomic DNA was 33.9%. The ANI values between strain XSD401T and P. damuponensis KCTC 23539T, P. burtonensis DSM 12212T, were 76.9% and 76.9%, respectively. The dDDH values between strain XSD401T and P. damuponensis KCTC 23539T, P. burtonensis DSM 12212T, were 20.4% and 20.3%, respectively. The AAI values and POCP values of these 8 species were all over 72% and 50%. Combined with the results of comparative genomic analysis, Ichthyenterobacterium magnum, Flavihalobacter algicola and Arcticiflavibacter luteus were reclassified into Psychroserpens. Furthermore, the differences in morphology, physiology and genotype from the previously described taxa support the classification of strain XSD401T as a representative of the genus Psychroserpens, for which the name Psychroserpens luteolus sp. nov. is proposed. The type strain is XSD401T (= MCCC 1H00396T = KCTC 72684T = JCM 33931T).