Thermophagus xiamenensis gen. nov., sp. nov., a moderately thermophilic and strictly anaerobic bacterium isolated from hot spring sediment

Abstract

A moderately thermophilic and strictly anaerobic bacterium, designated HS1T, was isolated from offshore hot spring sediment in Xiamen, China. Cells were Gram-negative, catalase-positive, oxidase-negative, slender and flexible rods without flagella. The strain could grow at 35–55 °C (optimum at 50 °C) and in 1–8 % NaCl (w/v; optimum 2–4 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain HS1T was affiliated with the family Marinilabiliaceae and shared a distant relationship with the previously described genera. The isolate was most closely related to Anaerophaga thermohalophila Fru22T with 16S rRNA gene sequence similarity of 92.4 %, followed by the other members of the family Marinilabiliaceae with 88.7–91.1 % similarity. The dominant cellular fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The predominant quinone was MK-7. The major polar lipids were phosphatidylethanolamine (PE) and an unknown polar lipid. The genomic DNA G+C content was 38.7 mol%. Besides the phylogenetically distant relationship, strain HS1T was obviously distinguished from the most closely related genera in several phenotypic properties including colony colour and pigment production, optimal temperature, optimal NaCl, relation to O2, bicarbonate/carbonate requirement, catalase activity, nitrate reduction, fermentation products and cellular fatty acid profile. Based on the phenotypic and phylogenetic data, strain HS1T represents a novel species of a new genus, for which the name Thermophagus xiamenensis gen. nov., sp. nov. is proposed. The type strain of the type species is HS1T ( = DSM 19012T = CGMCCC 1.5071T).

Carboxylicivirga gen. nov. in the family Marinilabiliaceae with two novel species, Carboxylicivirga mesophila sp. nov. and Carboxylicivirga taeanensis sp. nov., and reclassification of Cytophaga fermentans as Saccharicrinis fermentans gen. nov., comb. nov.

“…Members of the genus Geofilum and Cytophaga xylanolytica could be distinguished from other members of the family Marinilabiliaceae by relatively higher proportions of Two novel genera in the family Marinilabiliaceae Table 1. Differential phenotypic characteristics between the two novel isolates, [Cytophaga] fermentans DSM 9555 T and the type strains of other species in the family Marinilabiliaceae Strains: 1, MEBiC 07026 T (data from this study); 2, MEBiC 08903 T (data from this study); 3, [Cytophaga] fermentans DSM 9555 T (data from this study ;Bachmann, 1955;Nakagawa, 2011); 4, Thermophagus xiamenensis HS1 T (Gao et al, 2013); 5, Geofilum rubicundum JAM-BA0501 T (Miyazaki et al, 2012); 6, Alkaliflexus imshenetskii Z-7010 T (Zhilina et al, 2004); 7, Marinilabilia salmonicolor ATCC 19041 T (Suzuki, 2011;Suzuki et al, 1999); 8, Anaerophaga thermohalophila Fru22 T (Denger et al, 2002); 9, Cytophaga xylanolytica DSM 6779 T (Haack & Breznak, 1993); 10, Natronoflexus pectinivorans AP1 T (Sorokin et al, 2011); 11, Alkalitalea saponilacus SC/BZ-SP2 T (Zhao & Chen, 2012) 22-39 (35) pH 6-9 (7) 6-8.5 (7.5) 7-9 (8) 5.5-8.0 (7) (7.3-8.3) 7.2-10.2 (8.5) ND (7-7.5) (6.8) 6.1-8.7 (7.2-8.2) 8.5-10.5 (9.5) 7.5-10.5 (9.7) 5-8.5 (7-7.5) NaCl (%) 0-8 (2.5) 0-10 (2.5) 1-6 (2.5)) 1-8 (2-4) 0.5-6 (1) 0.08-5.3 (2) 1-3 2-12 (2-6) 0-3 0.2-4.6 (0.9-1.4) 0-6 (0.5-2) 0.2-3.5 (0 anteiso-branched saturated fatty acids. The two new isolates and [Cytophaga] fermentans DSM 9555 T could be differentiated based on carbon source utilization and cellular fatty acid compositions (Tables 1 and 2, Table S1), these reflecting differences in the metabolic system.…”

Saccharicrinis marinus sp. nov., isolated from marine sediment

“…Subsequently, a further seven genera, Geofilum, Mangroviflexus, Natronoflexus, Alkalitalea, Thermophagus, Carboxylicivirga and Saccharicrinis, have been classified as members of the family Marinilabiliaceae. These recognized members have been isolated from different habitats such as marine environments (Veldkamp, 1961;Miyazaki et al, 2012;Shalley et al, 2013;Liu et al, 2014;Yang et al, 2014), while some were obtained from soda lakes (Zhilina et al, 2004;Sorokin et al, 2011;Zhao & Chen, 2012), oily sludge (Denger et al, 2002) and hot spring sediment (Gao et al, 2013).…”

Labilibacter aurantiacus gen. nov., sp. nov., isolated from sea squirt (Styela clava) and reclassification of Saccharicrinis marinus as Labilibacter marinus comb. nov.

“…Species in the genera Alkaliflexus, Alkalitalea, Anaerophaga, Mangroviflexus, Natronoflexus and Thermophagus are anaerobic, while species in the genera Geofilum, Marinilabilia, Carboxylicivirga and Saccharicrinis are capable of fermentative metabolism. Members of the family Marinilabiliaceae are Gram-stain-negative rods and contain MK-7 as the respiratory quinone [2][3][4][5][6][7][8][9][10][11][12].…”