Methylobacterium nonmethylotrophicum sp. nov., isolated from tungsten mine tailing.

A novel pink-pigmented strain, designated 6HR-1T, was isolated from tungsten mine tailings in Jiangxi Province, PR China. Cells were Gram-stain-negative, aerobic, non-spore-forming, rod-shaped and motile with a polar flagellum (monotrichous). It could not utilize methanol, methylamine, formaldehyde or formate as a sole carbon source. The methanol dehydrogenase mxaF gene was absent but the xoxF gene was present. Phylogenomic and 16S rRNA gene phylogenetic analyses clearly showed that strain 6HR-1T was affiliated to the genus Methylobacterium and closely related to 'Methylobacterium terrae' 17Sr1-28T (98.6 %), Methylobacterium platani JCM 14648T (97.7 %), Methylobacterium variabile DSM 16961T (97.7 %) and Methylobacterium currus KACC 19662T (97.4 %). The average nucleotide identity and digital DNA-DNA hybridization values between strain 6HR-1T and its closely related type species were 87.4-88.7 and 33.2-36.3 %, respectively. It had summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) as the major fatty acid and ubiquinone 10 as the predominant respiratory quinone. Polyphasic characterization supported that strain 6HR-1T represents a novel species of the genus Methylobacterium, for which the name Methylobacterium nonmethylotrophicum sp. nov. is proposed with the type strain 6HR-1T (=GDMCC 1.662T=KCTC 42760T).

Sphingomonas lenta sp. nov., a slowly growing bacterium isolated from an abandoned lead-zinc mine.

A novel slowly growing member of the genus Sphingomonas, designated 1PNM-20T, was isolated from an abandoned lead-zinc mine in Meizhou, Guangdong Province, PR China. A polyphasic taxonomic study was performed to characterize the novel strain. Growth occurred on Reasoner's 2A (R2A) agar and peptone-yeast extract (PYE) agar, but not in liquid R2A or PYE media. Cells were Gram-stain-negative, aerobic, non-spore-forming, rod-shaped and motile with a polar flagellum (monotrichous). 16S rRNA gene sequence comparison showed that it shared the highest similarity with Sphingomonas carriPR0302T (97.2 %), followed by Sphingomonas spermidinifaciens 9NM-10T (97.0 %), Sphingomonas floccifaciens FQM01T (97.0 %) and other species of Sphingomonas (<97 %). Phylogenetic analyses clearly showed that strain 1PNM-20T fell into the cluster of Sphingomonas, and was most closely related to S. carri. The draft genome sequence was 3.76 Mb in length with a DNA G+C content of 69.8 mol%. Major fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and 11-methyl C18 : 1ω7c, with C14 : 0 2-OH as the main hydroxy fatty acid. Ubiquinone 10 (Q-10) was the predominant respiratory quinone, and sym-homospermidine was displayed as the major polyamine. The polar lipids were composed of sphingoglycolipid, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified phospholipid and an unidentified glycolipid. The phenotypic, phylogenetic and chemotaxonomic results supported the hypothesis that strain 1PNM-20T represents a novel species of the genus Sphingomonas, for which the name Sphingomonas lenta sp. nov. is proposed. The type strain is 1PNM-20T (=GDMCC 1.660T=DSM 27572T).

A high ratio of dietary n-3/n-6 polyunsaturated fatty acids improves obesity-linked inflammation and insulin resistance through suppressing activation of TLR4 in SD rats.

Dietary ratios of n-3/n-6 polyunsaturated fatty acids (PUFAs) have been implicated in controlling markers of metabolic disorders, including obesity, insulin resistance (IR), inflammation, and lipid profiles, which are also presumed to be partly related to type 2 diabetes mellitus (T2DM). However, molecular mechanisms of the different PUFAs related to metabolic disorders have not been systematically addressed. The present study aimed to investigate the impact of dietary n-3/n-6 PUFA ratios on obesity and IR and, further, to determine the underlying mechanisms. For 16 weeks, 32 SD male rats, randomly divided into four groups (n = 8 per group), received one of the following diets: normal chow, high saturated fatty acid (SFA), high n-3/n-6 PUFA ratio (1∶1, PUFA¹:¹), or low n-3/n-6 PUFA ratio (1∶4, PUFA¹:4). Following the experimental diet period, metabolic parameters related to obesity and IR were measured. Compared to SFA diet-fed rats, PUFA¹:¹ diet-fed rats exhibited decreased body and visceral fat weight, lowered blood lipids, and improved glucose tolerance and insulin sensitivity. Interestingly, these changes were accompanied with decreased expression levels of circulating pro-inflammatory cytokines, including tumor necrosis factor α, interleukin-6, and C-reactive protein. Moreover, the TLR4 protein and mRNA levels were markedly down-regulated by PUFA¹:¹ compared with SFA; however, PUFA¹:4 diet-fed rats failed to exhibit these changes. Cumulatively, our data highlight a role for a PUFA¹:¹ diet in the prevention of obesity and related metabolic disorders by suppressing the activation of TLR4, a critical modulator of pro-inflammatory cytokines.