The perplexity of the complex multispecies community interactions is one of the many reasons why majority of the microorganisms are still uncultivated. We analyzed the entire co-occurrence networks between the OTUs of Tibet and Yunnan hot spring samples, and found that less abundant OTUs such as genus Tepidimonas (relative abundant <1%) had high-degree centricity (key nodes), while dominant OTUs particularly genus Chloroflexus (relative abundant, 13.9%) formed the peripheral vertexes. A preliminary growth-promotion assay determined that Tepidimonas sp. strain SYSU G00190W enhanced the growth of Chloroflexus sp. SYSU G00190R. Exploiting this result, an ameliorated isolation medium containing 10% spent-culture supernatant of Tepidimonas sp. strain SYSU G00190W was prepared for targeted isolation of Chloroflexi in the Tibet and Yunnan hot spring samples. 16S rRNA gene fingerprinting characterized majority of the colonies isolated from these media as previously uncultivated Chloroflexi, of which 36 are potential novel species (16S rRNA sequence identity <98.5%). Metabolomes studies indicated that the spent-culture supernatant comprises several low-molecular-weight organic substrates that can be utilized as potential nutrients for the growth of these bacteria. These findings suggested that limited knowledge on the interaction of microbes provide threshold to traditional isolation method.
A novel endoglucanase gene was cloned from Thermobifida halotolerans YIM 90462(T), designated as thcel6A for being a member of glycoside hydrolase family 6. The gene was 1332 bp long and encoded a 443-amino-acid protein with a molecular mass of 45.9 kDa. The purified recombinant endoglucanase had optimal activity at 55 °C and pH 8.5. Thcel6A showed high hydrolytic activities at 25-55 °C and retained 58% of initial activity after incubation at 90 °C for 1 h. It retained more than 80% of activity after incubation for 12 h at pH values from 4 to 12. Thcel6A displayed higher hydrolytic activities in 5-15% NaCl (w/v) than at 0% NaCl. Activity increased 2.5-fold after incubation with 20% (w/v) NaCl at 37 °C for 10 min. These properties suggest that this novel endoglucanase has potential for specific industrial application.
A slightly thermophilic, Gram-staining-negative and strictly aerobic bacteria, designated strain YIM 78141 T , was isolated from a sediment sample collected at Hehua hot spring, Tengchong, Yunnan province, south-west China. Cells of the strain were short-rod-shaped and colonies were yellowish and circular. The strain grew at pH 6.0-10.0 (optimum, pH 8.0-9.0) and 10-55 6C (optimum, 40-50 6C). Phylogenetic analyses based on 16S rRNA gene sequence comparison demonstrated that strain YIM 78141 T belongs to the family Neisseriaceae, and strain YIM 78141 T also showed low levels of 16S rRNA gene sequence similarity (below 93.4 %) with all other genera in this family. The only quinone was ubiquinone 8 and the genomic DNA G+C content was 67.3 mol%. Major fatty acids (.5 %) were C 12 : 0, C 16 : 0, C 18 : 1 v7c and summed feature 3. The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, phospholipids of unknown structure containing aminoglycophospholipid and three unidentified polar lipids. On the basis of the morphological, physiological and biochemical characteristics as well as genotypic data, this strain should be classified as a representative of a novel genus and species of the family Neisseriaceae, for which the name Crenobacter luteus gen. nov., sp. nov. is proposed. The type strain is YIM 78141 T (5BCRC 80650 T 5KCTC 32558 T 5 DSM 27258 T ).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.