Seramator thermalis gen. nov., sp. nov., a novel cellulose- and xylan-degrading member of the family Dysgonamonadaceae isolated from a hot spring.

Two anaerobic bacteria, designated strains SYSU GA16112T and SYSU GA16107, were isolated from a hot spring in Tengchong County, Yunnan Province, south-west PR China. Phylogenetic analyses based on 16S rRNA gene sequences showed that strains SYSU GA16112T and SYSU GA16107 belong to the family Dysgonamonadaceae. Cells of strains SYSU GA16112T and SYSU GA16107 were Gram-stain-negative, rod-shaped and non-motile. The major fatty acids (>10 %) of strains SYSU GA16112T and SYSU GA16107 were identified as anteiso-C15 : 0 and anteiso-C17 : 0 3OH. The polar lipid profile of strain SYSU GA16112T was found to consist of phosphatidylethanolamine, two unidentified aminophospholipids, two unidentified phosphoglycolipids, two unidentified aminolipids and one unidentified polar lipid, while that of strain SYSU GA16107 consisted of phosphatidylethanolamine, two unidentified polar lipids, three unidentified aminophospholipids, two unidentified phosphoglycolipids and one unidentified aminolipid. The genomic DNA G+C contents of strains SYSU GA16112T and SYSU GA16107 were determined to be 41.90 and 41.89 %, respectively, and the average nucleotide identity value between them was 99.99 %. Based on their morphological and physiological properties, and results of phylogenetic analyses, strains SYSU GA16112T and SYSU GA16107 are considered to represent a novel species of a novel genus, for which the name Seramator thermalis gen. nov., sp. nov. (type strain SYSU GA16112T=CGMCC 1.5281T=KCTC 15753T) is proposed.

Unraveling microbe-mediated degradation of lignin and lignin-derived aromatic fragments in the Pearl River Estuary sediments.

Estuaries are one of the most crucial areas for the transformation and burial of terrestrial organic carbon (TerrOC), playing an important role in the global carbon cycle. While the transformation and degradation of TerrOC are mainly driven by microorganisms, the specific taxa and degradation processes involved remain largely unknown in estuaries. We collected surface sediments from 14 stations along the longitudinal section of the Pearl River Estuary (PRE), P. R. China. By combining analytical chemistry, metagenomics, and bioinformatics methods, we analyzed composition, source and degradation pathways of lignin/lignin-derived aromatic fragments and their potential decomposers in these samples. A diversity of bacterial and archaeal taxa, mostly those from Proteobacteria (Deltaproteobacteria, Gammaproteobacteria etc.), including some lineages (e.g., Nitrospria, Polyangia, Tectomicrobia_uc) not previously implicated in lignin degradation, were identified as potential polymeric lignin or its aromatic fragments degraders. The abundance of lignin degradation pathways genes exhibited distinct spatial distribution patterns with the area adjacent to the outlet of Modaomen as a potential degradation hot zone and the Syringyl lignin fragments, 3,4-PDOG, and 4,5-PDOG pathways as the primary potential lignin aromatic fragments degradation processes. Notably, the abundance of ferulic acid metabolic pathway genes exhibited significant correlations with degree of lignin oxidation and demethylation/demethoxylization and vegetation source. Additionally, the abundance of 2,3-PDOG degradation pathways genes also showed a positive significant correlation with degree of lignin oxidation. Our study provides a meaningful insight into the microbial ecology of TerrOC degradation in the estuary.

Isolation of Clostridium from Yunnan-Tibet hot springs and description of Clostridium thermarum sp. nov. with lignocellulosic ethanol production.

Lignocellulose is considered a major source of renewable energy that serve as an alternative to the fossil fuels. Members of the genus Clostridium are some of the many microorganisms that have the ability to degrade lignocellulose efficiently to sugar, which can be further converted to biofuel. In this study, we isolated twelve Clostridium strains from hot spring samples of Yunnan and Tibet, of which isolates SYSU GA15002T and SYSU GA17076 showed low 16S rRNA gene sequence identity profiles to any of the validly named Clostridium strains (<94.0%). Studies using a polyphasic taxonomy approach concluded that the two isolates represent one novel species of the genus Clostridium, for which we propose the name Clostridium thermarum sp. nov., with SYSU GA15002T as the type strain of the species. Isolate SYSU GA15002T has an optimum growth temperature at 45°C. Fermentation of the substrates cellobiose, cellulose, xylan and untreated straw powder by this strain results in the production of ethanol, along with acetate and formate. The complete pathways for the conversion of cellulose and xylan to ethanol is also predicted from the genome of isolate SYSU GA15002T, which revealed a single step conversion of lignocellulosic biomass through consolidated bioprocessing. This paper is a comprehensive study encompassing isolation, polyphasic taxonomy, lignocellulose biodegradation and the genomic information of Clostridium in Yunnan-Tibet hot springs.