Tabrizicola rongguiensis sp. nov., isolated from the sediment of a river in Ronggui, Foshan city, China.

A novel Gram-negative, aerobic, non-spore-forming, non-motile and rod-shaped bacterium, designated J26T, was isolated from the sediment of a river in Ronggui, Foshan city, China. Strain J26T grew optimally at 0 % (w/v) NaCl, pH 6.5-7.5, and 30 °C, and it formed milky white irregular colonies on Reasoner's 2A agar medium. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain J26T had the highest similarity to Tabrizicola aquatica RCRI19T (97.1 %) and formed a distinct clade in the genus Tabrizicola. Cellular components of J26T supported this strain as a member of the genus Tabrizicola. The predominant fatty acids were C18 : 1 ω7c, C18 : 1 ω7c-11 methyl and C16 : 0. Polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphorylethanolamine. Ubiquinone Q-10 was the major respiratory quinone, and the DNA G+C content was 64.2 mol%. However, low 16S rRNA gene sequence similarity and average nucleotide identity (73.56 % for ANIb between strain J26T with RCRI19T) demonstrated that strain J26T should be assigned to a novel species. Moreover, the differences between J26T and RCRI19T in terms of physiological and biochemical properties, such as carbon, nitrogen and sulphur metabolism, further supported that J26T represents a novel species, for which the name Tabrizicola rongguiensis sp. nov. is proposed. The type strain is J26T (=GDMCC 1.2843T=KCTC 92112T).

Water quality drives the distribution of freshwater cable bacteria.

Cable bacteria are a group of recently found filamentous sulfide-oxidizing Desulfobulbaceae that significantly impact biogeochemical cycling. However, the limited understanding of cable bacteria distribution patterns and the driving force hindered our abilities to evaluate and maximize their contribution to environmental health. We evaluated cable bacteria assemblages from ten river sediments in the Pearl River Delta, China. The results revealed a clear biogeographic distribution pattern of cable bacteria, and their communities were deterministically assembled through water quality-driven selection. Cable bacteria are diverse in the river sediments with a few generalists and many specialists, and the water quality IV and V environments are the "hot spot." We then provided evidence on their morphology, function, and genome to demonstrate how water quality might shape the cable bacteria assemblages. Reduced cell width, inhibited function, and water quality-related adaptive genomic traits were detected in sulfide-limited water quality III and contaminant-stressed water quality VI environments. Specifically, those genomic traits were contributed to carbon and sulfur metabolism in the water quality III environment and stress resistance in the water quality VI environment. Overall, these findings provided a helpful baseline in evaluating the contribution of cable bacteria in the freshwater ecosystem and suggested that their high diversity and flexibility in phylogeny, morphology, and genome allowed them to adapt and contribute to various environmental conditions.