Polyhydroxyalkanoates (PHA) synthesis by activated sludge using volatile fatty acids (VFAs) in fermentation liquid of excess sludge as carbon source is a hotspot in the field of environmental biotechnology. However, there is no unified conclusion on the effects of non-VFAs, mainly dissolved organic matter (DOM), on PHA production. Thus, this critical review mainly introduces the main characteristics and common analysis methods of DOM in anaerobic fermentation liquid. The effects of DOM on PHA production are analyzed from the aspects of microbiology, metabolic regulation and sludge properties. The results of different studies showed that high concentration of DOM is bad for PHA production, but an appropriate amount of DOM is conducive to the stability of sludge properties, reducing the final PHA purification cost. Finally, suitable strategies were proposed to regulate the PHA synthesis by activated sludge with DOM for PHA production by anaerobic fermentation liquid.
Anaerobiosis ; Bioreactors ; Fatty Acids, Volatile ; Fermentation ; Polyhydroxyalkanoates ; Sewage

With the development of intestinal flora, short chain fatty acid(SCFA), produced by the intestinal microbiota, has been found to be important for the host. It also plays an important role in the part of the occurrence and development of some diseases. The relationship between SCFA produced by intestinal microbiota and the host body has become the research focus in recent years. The physiological function and clinical application of SCFA were reviewed in this article.
Fatty Acids, Volatile ; biosynthesis ; physiology ; Humans ; Intestines ; microbiology ; Microbiota

OBJECTIVE: To compare the levels of short-chain fatty acids in enterobacteria-related metabolites in feces between infants with cholestatic hepatopathy and healthy infants. METHODS: Thirty infants with cholestatic hepatopathy were enrolled in this study as the disease group, while 30 healthy infants were enrolled as the control group. Fecal specimens were collected from the disease group before and after treatment and from the control group. Gas chromatography was used to quantitatively determine the content of short-chain fatty acids in the feces of both groups including acetic acid, propionic acid, butyric acid, isobutyric acid, and isovaleric acid. RESULTS: There were no significant differences in the concentrations of acetic acid and propionic acid between the control and disease groups before and after treatment, as well as no significant changes in the two markers in the disease group after treatment (P>0.05). The disease group had a significantly increased concentration of butyric acid after treatment (P<0.05). The concentrations of isobutyric acid and isovaleric acid in the control group were significantly higher than those in the disease group before and after treatment (P<0.05). CONCLUSIONS Intestinal protein metabolites in infants with cholestatic hepatopathy are significantly different from those in healthy infants, whereas there is no significant difference with respect to carbohydrate metabolites.
Acetates ; Butyric Acid ; Enterobacteriaceae ; Fatty Acids, Volatile ; Feces ; Humans ; Infant

Halomonas can grow on diverse carbon sources. As it can be used for unsterile fermentation under high-salt conditions, it has been applied as a chassis for next-generation industrial biotechnology. Short-chain volatile fatty acids, including acetate, propionate, and butyrate, can be prepared from biomass and are expected to be novel carbon sources for microbial fermentation. Halomonas sp. TD01 and TD08 were subjected to shaking culture with 10-50 g/L butyrate, and they were found to effectively synthesize poly-3-hydroxybutyrate with butyrate as the carbon source. The highest yield of poly-3-hydroxybutyrate was achieved at butyrate concentration of 20 g/L (9.12 g/L and 7.37 g/L, respectively). Butyrate at the concentration > 20 g/L inhibited cell growth, and the yield of poly-3-hydroxybutyrate decreased to < 4 g/L when butyrate concentration was 50 g/L. Moreover, Halomonas sp. TD08 can accumulate the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate by using propionate and butyrate as carbon sources. However, propionate was toxic to cells. To be specific, when 2 g/L propionate and 20 g/L butyrate were simultaneously provided, cell dry weight and polymer titer were 0.83 g/L and 0.15 g/L, respectively. The addition of glycerol significantly improved cell growth and boosted the copolymer titer to 3.95 g/L, with 3-hydroxyvalerate monomer content of 8.76 mol%. Short-chain volatile fatty acids would be promising carbon sources for the production of polyhydroxyalkanoates by Halomonas.
Butyrates ; Carbon ; Fatty Acids, Volatile ; Halomonas ; Polyhydroxyalkanoates ; Propionates

Gut microbiota plays critical physiological roles in the energy extraction and in the control of local or systemic immunity. Gut microbiota and its disturbance also appear to be involved in the pathogenesis of diverse diseases including metabolic disorders, gastrointestinal diseases, cancer, etc. In the metabolic point of view, gut microbiota can modulate lipid accumulation, lipopolysaccharide content and the production of short-chain fatty acids that affect food intake, inflammatory tone, or insulin signaling. Several strategies have been developed to change gut microbiota such as prebiotics, probiotics, certain antidiabetic drugs or fecal microbiota transplantation, which have diverse effects on body metabolism and on the development of metabolic disorders.
Eating ; Fatty Acids, Volatile ; Gastrointestinal Diseases ; Hypoglycemic Agents ; Insulin ; Metabolism ; Metformin ; Microbiota* ; Obesity ; Prebiotics ; Probiotics

Early-warning of compartmentalized anaerobic reactor (CAR) was investigated in lab-scale. The performance stability of CAR at high loading rate was worse than that at common loading rate. At high loading rate, the fluctuation of effluent chemical oxygen demand (COD) concentration and volatile fatty acids (VFA) concentration was larger than that of influent COD concentration. The average relative standard deviation of effluent COD concentration and VFA concentration was 32.95% and 40.46% respectively, while that of influent COD concentration was 8.08%. The saturation of volumetric loading rate (S(VLR)) and VFA (S(VFA)) could be used to alarm the performance of anaerobic reactors. The working performance was good when the CAR was operated at normal organic loading rate (OLR), in which S(VLR) and S(VFA) were below 0.89 and 0.40 respectively. The fluctuation of performance became larger when the CAR was operated at OLR near saturation, in which S(VLR) and S(VFA) were close to 1. The performance of CAR was deteriorated when the S(VLR) and S(VFA) were more than 1.
Anaerobiosis ; Biological Oxygen Demand Analysis ; Bioreactors ; microbiology ; Fatty Acids, Volatile ; analysis ; Sewage ; Waste Disposal, Fluid ; methods

AIMTo examine the liver mechanism with which clenbuterol (CL) is explained how to affect growth metabolism.

METHODSThe technique of chronic poly catheter was used to study the effects of CL (0.8 mg/kg b w) on the hepatic flux of nitrogen, VFA and glucose in 4 sheep.

RESULTSThe urea-nitrogen flux in CL-treated period always was lower than that in control during 24 h. The average flux of urea-nitrogen in hepatic and portal vein were decreased by 16.86% (P < 0.01) and 15.51% (P < 0.05), respectively, compared with that of control. The peptide level in hepatic vein was decreased with the treatment of CL, average flux of peptide was decreased by 38.71% (P < 0.01). But the peptide level of portal vein in CL treatment period was similar to control. Moreover, VFA level in the portal vein was enhanced by CL, the average flux of acetate in portal vein was increased by 19.49% (P < 0.01). No difference of VFA level in hepatic vein was noted between CL-treated period and control. In addition, the glucose flux in hepatic vein was obviously increased with CL treatment, the average flux of glucose was increased by 25.96% (P < 0.01). And glucose flux in portal vein was also elevated during CL-treated period.

CONCLUSIONCL can affect growth metabolism of animal with increasing nitrogen deposition, improving absorption and utilization of VFA and enhancing glucose synthesis in sheep liver.

Animals ; Clenbuterol ; pharmacology ; Fatty Acids, Volatile ; metabolism ; Glucose ; metabolism ; Liver ; drug effects ; metabolism ; Sheep

Clostridia inhabiting in jiupei and pit mud plays key roles in the formation of flavour during the fermentation process of Luzhou-flavour baijiu. However, the differences of Clostridial communities between jiupei and pit mud remains unclear. Here, the species assembly, succession, and metabolic capacity of Clostridial communities between jiupei and pit mud were analysed by high-throughput sequencing and pure culture approaches. The ratio of Clostridial biomass to bacterial biomass in the pit mud was relatively stable (71.5%-91.2%) throughout the fermentation process. However, it varied widely in jiupei (0.9%-36.5%). The dominant Clostridial bacteria in jiupei were Clostridium (19.9%), Sedimentibacter (8.8%), and Hydrogenispora (7.2%), while Hydrogenispora (57.2%), Sedimentibacter (5.4%), and Caproiciproducens (4.9%) dominated in the Clostridial communities in pit mud. The structures of Clostridial community in pit mud and jiupei were significantly different (P=0.001) throughout fermentation. Isolated Clostridial strains showed different metabolic capacities of volatile fatty acids in pure culture. Spatial and temporal heterogeneity of Clostridial communities existed in the baijiu fermentation pit, which was closely related to the main flavour components of Luzhou-flavour baijiu.
Alcoholic Beverages ; microbiology ; Bacteria ; classification ; metabolism ; Clostridium ; physiology ; Fatty Acids, Volatile ; metabolism ; Fermentation ; Food Microbiology

Resource utilization is an effective way to cope with the rapid increase of kitchen waste and excess sludge, and volatile fatty acids produced by anaerobic fermentation is an important way of recycling organic waste. However, the single substrate limits the efficient production of volatile fatty acids. In recent years, volatile fatty acids produced by anaerobic co-fermentation using different substrates has been widely studied and applied. In this paper, we analyze the characteristics of fermentation to produce acid using kitchen waste and excess sludge alone or mixture. Influences of environmental factors and microbial community structure on the type and yield of volatile fatty acids in the anaerobic fermentation system are discussed in detail. Moreover, we propose future research directions, to provide a reference for recycling kitchen waste and excess sludge.
Anaerobiosis ; Bioreactors ; Fatty Acids, Volatile ; Fermentation ; Hydrogen-Ion Concentration ; Microbiota ; Organic Chemicals ; Sewage

Emerging evidence demonstrates that the microbiota plays an essential role in shaping the development and function of host immune responses. A variety of environmental stimuli, including foods and commensals, are recognized by the host through the epithelium, acting as a physical barrier. Two allergic diseases, atopic dermatitis and food allergy, are closely linked to the microbiota, because inflammatory responses occur on the epidermal border. The microbiota generates metabolites such as short-chain fatty acids and poly-γ-glutamic acid (γPGA), which can modulate host immune responses. Here, we review how microbial metabolites can regulate allergic immune responses. Furthermore, we focus on the effect of γPGA on allergic T helper (Th) 2 responses and its therapeutic application.
Architectural Accessibility ; Dermatitis, Atopic ; Epithelium ; Fatty Acids, Volatile ; Food Hypersensitivity ; Microbiota ; Natural Killer T-Cells