Zirou Yu,Chunjie Hou,Chenyu Shi,Ya Huang,Hu Liu,Fenglai Wang
Dietary fibers are classified into soluble and insoluble dietary fibers according to different solubility, which play different physiological roles. The study aimed to investigate the mechanism of dietary fiber solubility affecting thermogenesis and gut microbiota in rats. Twenty-four Sprague Dawley male rats were selected and divided randomly into 3 treatments. Dietary treatments included diet without dietary fiber (CON), control diet supplemented with 10 % inulin (SDF) and control diet supplemented with 10 % cellulose (IDF). The results showed that rats in the SDF group gained less body weight and had lower feed intake ( P < 0.001). The glucose tolerance of rats fed SDF and IDF was significantly improved ( P < 0.05). Compared with the CON group, the mRNA expression of thermogenesis-related genes CIDEA, HOXC8 and TMEM26 in inguinal white adipose tissue of rats in the SDF group and IDF group was significantly activated ( P < 0.05). The expression of brown adipose tissue thermogenesis-related proteins UCP1, CIDEA and HOXC8 in rats of SDF group was significantly increased ( P < 0.01). The abundance of Faecalibaculum and Gemmiger at the genus level, which both belonged to the order Clostridiales in the SDF group, was significantly increased ( P < 0.001). In conclusion, both SDF and IDF can regulate body thermogenesis by promoting browning of white adipose tissue. Particularly, SDF was able to further promote thermogenesis in rats by increasing the expression of UCP1 protein in brown adipose tissue and modulating the abundance of order Clostridium.
Due to the persistence in residue and the emission to environment, antibiotics have become the emerging contaminants. Tetracyclines, as the largest amount of antibiotics in the breeding industry, were investigated in this study. For eliminating the tetracyclines, anaerobic culture was enriched from livestock waste after four generations and FeOn(OH)m modified oyster shell powders (OSPs) were amended into the enrichment culture as auxiliary method. Tetracycline and oxytetracycline were selected as the model compounds. The adsorption models (Langmuir and Freundlich isotherms) of tetracycline and microbes on OSPs were simulated respectively. With the addition of FeOn(OH)m modified OSPs, the transformation efficiency of oxytetracycline achieved 81.5% after 22 days’ incubation, approximately 1.85 times higher than the 4th generation (G-IV) enrichment culture without modified OSPs. Dehydration, demethylation, dehydroxylation and decarboxylation took place under anaerobic condition, inferred from the detected metabolites transformed from oxytetracycline. Genus Methanosarcina and two operational taxonomic units (OTUs) assigned to order Clostridiales , showed an increasing trend on abundance, indicating the contribution to transformation of oxytetracycline. Therefore, the FeOn(OH)m modified OSPs and enrichment culture can accelerate the transformation of oxytetracycline simultaneously, indicating a promising utilization not only for waste water system but also for antibiotic contaminated biomass treatment.
Lei Wang,Kecai Chen,Peng Zheng,Xiang Huo,Fei Liao,Liping Zhu,Meirong Hu,Yong Tao
D -Psicose, a new-generation sugar substitute, has been enzymatically synthesized through D -fructose isomerization. However, isomerization often causes low yields due to unfavorable thermodynamic equilibria, which limited its further industrial application. In this study, we present a redox-driven multi-enzyme cascade, two-step biotransformation system to produce D -psicose from D -fructose. Compared to D -fructose isomerization, this method has a maximized theoretical conversion rate of 100%. D -Psicose-3-epimerase from Clostridiales (CBDPE), ribitol 2-dehydrogenase from Providencia alcalifaciens (PRDH), and formate dehydrogenase from Starkeya (SFDH) were co-expressed in Escherichia coli in the first step to produce D -allitol from D -fructose. Afterward, NADH oxidase from Streptococcus pyogenes (SPNOX), and ribitol 2-dehydrogenase from Rubrivivax sp. (RSRDH) were co-expressed in E. coli to oxidize D -allitol into D -psicose in the second step. The two-step biotransformation system was optimized to maximize the D -fructose-to- D -psicose conversion rate (up to 90%), corresponding to a concentration of 450 mM. This study suggests that this redox-driven multi-enzyme cascade strategy through a sugar-to-alcohol-to-sugar pathway has the advantage of great application for enhanced production of D -psicose and other rare sugars.
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