Flavobacterium poyangense sp. nov., an ammonifying bacterium isolated from a freshwater lake.

A Gram-stain-negative, aerobic, non-spore-forming, nonmotile, rod-shaped, and yellow-pigmented bacterium, designated strain JXAS1T, was isolated from a freshwater sample collected from Poyang Lake in China. Phylogenetic analysis based on 16S rRNA gene sequence revealed that the isolate belonged to the genus Flavobacterium, being closest to Flavobacterium pectinovorum DSM 6368T (98.61 %). The genome size of strain JXAS1T was 4.66 Mb with DNA G+C content 35.7 mol%. The average nucleotide identity and in silico DNA-DNA hybridization values between strain JXAS1T and its closest relatives were below the threshold values of 95 and 70 %, respectively. The strain contained menaquinone 6 (MK-6) as the predominant menaquinone and the major polar lipids were phosphatidylethanolamine, one unidentified glycolipid, and one unidentified polar lipid. The major fatty acids (>5 %) were iso-C15 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C15 : 0, iso-C17 : 0 3OH, iso-C15 : 0 3OH, and summed feature 9 (iso-C17 : 1 ω9c and/or 10-methyl C16 : 0). Based on phylogenetic, genotypic, and phenotypic evidence, the isolated strain represents a new species in the genus Flavobacterium, and the name Flavobacterium poyangense is proposed. The type strain is JXAS1T (=GDMCC 1.1378T=KCTC 62719T).

The correlation analyses of bacterial community composition and spatial factors between freshwater and sediment in Poyang Lake wetland by using artificial neural network (ANN) modeling.

As one of the most important components of the lake ecosystem, microorganisms from the freshwater and sediment play an important role in many ecological processes. However, the difference and correlation of bacterial community between these two niches were not clear. This study investigated the diversity of microbial community of freshwater and sediment samples from fifteen locations in Poyang Lake wetland. The correlation between the bacterial community and physicochemical property of Poyang Lake wetland was analyzed by artificial neural network (ANN). Our results demonstrated that the freshwater and sediment bacterial community were dominated by groups of the Bacteroidetes (23.33%) and ß-Proteobacteria (22.54%) separately, whereas, Canalipalpata, Bacillariophyta, Gemmatimonadetes, and Verrucomicrobia were detected in freshwater niches only. Phylogenetic analysis further indicated that bacterial composition in freshwater significantly differed with the sediment niches. There are 34 unique species accounted for 85% in fresh water samples and 28 unique species accounted for 82% in sediment samples. Cluster analysis further proved that all the samples from freshwater niches clustered closely together, far from the rest sediment samples. ANN analysis revealed that the freshwater with high N and P nutrients will greatly increase the diversity of the bacterial communities. In general, both environmental physicochemical properties, not each factor independently, contributed to the shift in the bacterial community structure. The five tributaries (Gan, Fu, Xin, Rao, Xiu Rivers) play a vital role in shaping the bacterial communities of Poyang Lake. This study provides new insights for understanding of microbial community compositions and structures of Poyang Lake wetland.