Propionic acid, a major inhibitor to yeast cells, was accumulated during continuous ethanol fermentation from corn meal hydrolysate by the flocculating yeast under stillage backset conditions. Based on its inhibition mechanism in yeast cells, strategies were developed for alleviating this effect. Firstly, high temperature processes such as medium sterilization generated more propionic acid, which should be avoided. Propionic acid was reduced significantly during ethanol fermentation without medium sterilization, and concentrations of biomass and ethanol increased by 59.3% and 7.4%, respectively. Secondly, the running time of stillage backset should be controlled so that propionic acid accumulated would be lower than its half inhibition concentration IC50 (40 mmol/L). Finally, because low pH augmented propionic acid inhibition in yeast cells, a higher pH of 5.5 was validated to be suitable for ethanol fermentation under the stillage backset condition.
Biomass ; Ethanol ; metabolism ; Fermentation ; Flocculation ; Propionates ; chemistry ; Yeasts ; metabolism

The production of propionic acid by Propionibacterium freudenreichii CCTCC M207015 was investigated in a Fibrous-bed bioreactor (FBB). The FBB was constructed by packing spiral cotton fibrous and immobilized into a bioreactor. By applying this bioreactor to propionic acid fermentation, the propionic acid yield had a significant improvement and reached 20.41 g/L, compared with the cell-free culture of 14.58 g/L (40 g/L of glucose). At the same time, the glucose exhausting time decreased from 120 h to 60 h. Batch fermentations at various glucose concentrations were carried out with FBB. Based on the analysis of the time course of production, fed-batch fermentation was also applied to produce propionic acid with FBB, the maximal propionic acid yield reached 45.91 g/L, and the proportion of propionic acid to total acids was about 72.31%.
Bioreactors ; microbiology ; Fermentation ; Glucose ; metabolism ; Propionates ; metabolism ; Propionibacterium ; classification ; metabolism

p-coumaric acid is an important natural phenolic compound with a variety of pharmacological activities, and also a precursor for the biosynthesis of many natural compounds. It is widely used in foods, cosmetics and medicines. Compared with the chemical synthesis and plant extraction, microbial production of p-coumaric acid has many advantages, such as energy saving and emission reduction. However, the yield of p-coumaric acid by microbial synthesis is too low to meet the requirements of large-scale industrial production. Here, to further improve p-coumaric acid production, the directed evolution of tyrosine ammonia lyase (TAL) encoded by Rhodotorula glutinis tal gene was conducted, and a high-throughput screening method was established to screen the mutant library for improve the property of TAL. A mutant with a doubled TAL catalytic activity was screened from about 10,000 colonies of the mutant library. There were three mutational amino acid sites in this TAL, namely S9Y, A11N, and E518A. It was further verified by a single point saturation mutation. When S9 was mutated to Y, I or N, or A11 was mutated to N, T or Y, the catalytic activity of TAL increased by more than 1-fold. Through combinatorial mutation of three types of mutations at the S9 and A11, the TAL catalytic activity of S9Y/A11N or S9N/A11Y mutants were significantly higher than that of other mutants. Then, the plasmid containing S9N/A11Y mutant was transformed into CP032, a tyrosine-producing E. coli strain. The engineered strain produced 394.2 mg/L p-coumaric acid, which is 2.2-fold higher than that of the control strain, via shake flask fermentation at 48 h. This work provides a new insight for the biosynthesis study of p-coumaric acid.
Ammonia-Lyases/genetics* ; Escherichia coli/genetics* ; Propionates ; Rhodotorula ; Tyrosine/genetics*

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

Ten alkaloids(1-10) were isolated from the ethyl acetate extract of the fruit of Lycium chinense var. potaninii by silica gel, ODS, and preparative high performance liquid chromatography(HPLC), and identified by NMR and MS as methyl(2S)-[2-formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl]-3-(phenyl)propanoate(1), methyl(2R)-[2-formyl-5-(methoxymethyl)-1H-pyrrol-1-yl]-3-(phenyl)propanoate(2), 3-hydroxy-4-ethyl ketone pyridine(3), indolyl-3-carbaldehyde(4),(R)-4-isobutyl-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde(5),(R)-4-isopropyl-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-car-baldehyde(6), methyl(2R)-[2-formyl-5-(methoxymethyl)-1H-pyrrol-1-yl]-3-(4-hydroxyphenyl)propanoate(7), dimethyl(2R)-[2-formyl-5-(methoxymethyl)-1H-pyrrol-1-yl]butanedioate(8), 4-[formyl-5-(methoxymethyl)-1H-pyrrol-1-yl]butanoate(9), 4-[2-formyl-5-(methoxymethyl)-1H-pyrrol-1-yl]butanoic acid(10). All the compounds were isolated from the plant for the first time. Among them, compounds 1-3 were new compounds. Compounds 1-9 were evaluated for hypoglycemic activity in vitro with the palmitic acid-induced insulin resistance in HepG2 cells. At 10 μmol·L~(-1), compounds 4, 6, 7, and 9 can promote the glucose consumption of HepG2 cells with insulin resistance.
Lycium/chemistry* ; Fruit/chemistry* ; Insulin Resistance ; Propionates ; Alkaloids/pharmacology*

Polyhydroxyalkanoates (PHAs) are a class of polyesters biosynthesized by microorganisms (esp. Ralstonia eutropha) under an unbalanced growth condition, and which are supposed to partly take the place of traditional plastics made from petroleum in the near future since they are harmless to the environment and biodegradable. Organic acids (mainly butyrate, lactate, propionate and acetate) produced from anaerobic digested food wastes, industrial wastes and sewage may be used as cheap carbon sources since the large amounts of the above wastes disposed by industry and family each year. In order to better understand the process of PHAs formation with acids as carbon sources, so as to increase the yields of PHAs. Biosynthesis of PHAs by R. eutropha during the dual nutrient-limitation-zone was investigated with mixed organic acids (the mass ratio of the four component acids was butyrate: propionate: acetate: lactate = 3: 3: 1: 1, which was simulated as once the result of anaerobic digestion of food wastes) as carbon sources and (NH4)2 SO4 as nitrogen source. Two different manners of maintaining the dual-nutrient-limitation zone were adopted by feeding mixed acids and (NH4 )2SO4 at determined rates to the fermentation culture which were free of carbon sources (manner A) or nitrogen sources (manner B) firstly. The results suggest that, first of all, the meaning of the limitation of mixed acids or (NH4)2 SO4 does not mean to limit the supply of them, but mean to feed as more as possible of carbon and nitrogen sources in order to meet the cell growth and PHAs formation of R. eutropha by the largest extent. However, it's indispensable to make the residual concentration of carbon and nitrogen sources as low as possible since organic acids are inhibitive to the cell growth, and most importantly, only under the presence of nitrogen during the PHAS formation period of the fermentation could R. eutropha produce more PHAs than any other unbalanced growth condition. Secondly, with the increase of the width of the dual-nutrient-limitation zone, the yield of PHAs would also increase, it suggest that most of the PHAs were biosynthesized during the dual-nutrient-limitation zone. Finally, in contrast with the dual-nutrient-limitation manner of limiting the nitrogen source at first (manner B), the dual-nutrient-limitation manner of limiting the carbon source at first (manner A) was more favorable for the production of PHAs, and the maximum production of PHAs of these two manners are 3.72 g/L and 2.55 g/L, respectively. It may be because that PHAs formation required enzymes could not be well developed when R. eutropha grow under the state of nitrogen limitation from the beginning of fermentation. Besides, yield of PHAs produced by the dual-nutrient-limitation fermentation is larger than that of the single-nutrient-limitation batch culture. Therefore, it seems that to increase the output of PHAs production, the strategy of maintaining as wide as possible the width of dual-nutrient (C, N)-limitation zone may be effective.
Acetates ; metabolism ; Butyrates ; metabolism ; Cupriavidus necator ; metabolism ; Fermentation ; physiology ; Lactates ; metabolism ; Polyhydroxyalkanoates ; biosynthesis ; Propionates ; metabolism

Acute Disease ; Female ; Humans ; Infant ; Infant, Newborn ; Propionates ; blood ; Pyruvate Carboxylase Deficiency Disease

Xuezhikang capsule (ethanol extract of red yeast rice) which produced by Beijing WBL Peking University Biotech Co., Ltd., is a traditional Chinese medication with 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibiting activity. Clinical trials indicated that Xuezhikang with lipid-lowering action could reduce the risk of cardiac events and total mortality of Chinese coronary heart disease patients. To exactly explain the clinical features of Xuezhikang, we undertook a complete study of the chemical constituents of Xuezhikang. This study resulted in the isolation of a new monacolin analogue, named alpha, beta-dehydromonacolin L (1), along with two known compounds: monacolin L (2) and 3-(2, 6-dimethyl-1, 2, 4a, 5, 6, 7, 8, 8a-octahydronaphthalen-1-yl)propanoic acid (3). The chemical structures were determined by extensive 1D and 2D NMR and MS spectroscopic analysis.
Drugs, Chinese Herbal ; chemistry ; Molecular Structure ; Naphthalenes ; chemistry ; isolation & purification ; Propionates ; chemistry ; isolation & purification

Genkwa Fols, Kansui Radix, and Euphorbiae Pekinensis Radix in Shizao Decoction(SZD) are toxic to intestinal tract. Jujubae Fructus in this prescription can alleviate the toxicity, but the mechanism is still unclear. Therefore, this study aims to explore the mechanism. To be specific, 40 normal Sprague-Dawley(SD) rats were classified into the normal group, high-dose and low-dose SZD groups, and high-dose and low-dose SZD without Jujubae Fructus(SZD-JF) groups. The SZD groups were given(ig) SZD, while SZD-JF groups received the decoction without Jujubae Fructus. The variation of body weight and spleen index were recorded. The patho-logical changes of intestinal tissue were observed based on hematoxylin and eosin(HE) staining. The content of malondialdehyde(MDA) and glutathione(GSH) and activity of superoxide dismutase(SOD) in intestinal tissue were measured to evaluate the intestinal injury. Fresh feces of rats were collected to detect intestinal flora structure by 16S ribosomal RNA gene(16S rDNA) sequencing technology. The content of fecal short chain fatty acids and fecal metabolites was determined by gas chromatography-mass spectrometer(GC-MS) and liquid chromatography-mass spectrometer ultra-fast liquid chromatography-quadrupole-time-of-flight mass spectrometer(UFLC-Q-TOF-MS), separately. Spearman's correlation analysis was employed to analyze the differential bacteria genera and differential metabolites. RESULTS:: showed that high-dose and low-dose SZD-JF groups had high content of MDA in intestinal tissue, low GSH content and SOD activity, short intestinal villi(P<0.05), low diversity and abundance of intestinal flora, variation in the intestinal flora structure, and low content of short chain fatty acids(P<0.05) compared with the normal group. Compared with high-dose and low-dose SZD-JF groups, high-dose and low-dose SZD groups displayed low content of MDA in intestinal tissue, high GSH content and SOD activity, recovery of the length of intestinal villi, increased abundance and diversity of intestinal flora, alleviation of dysbacteria, and recovery of the content of short chain fatty acids(P<0.05). According to the variation of intestinal flora and fecal metabolites after the addition of Jujubae Fructus, 6 differential bacterial genera(Lactobacillus, Butyricimonas, Clostridia＿UCG-014, Prevotella, Escherichia-Shigella, Alistipes),4 differential short chain fatty acids(such as acetic acid, propionic acid, butyric acid, valeric acid) and 18 differential metabolites(such as urolithin A, lithocholic acid, and creatinine) were screened out. Beneficial bacteria such as Lactobacillus were in positive correlation with butyric acid and urolithin A(P<0.05). The pathogenic bacteria such as Escherichia-Shigella were in negative correlation with propionic acid and urolithin A(P<0.05). In summary, SZD-JF caused obvious intestinal injury to normal rats, which could lead to intestinal flora disorder. The addition of Jujubae Fructus can alleviate the disorder and relieve the injury by regulating intestinal flora and the metabolites. This study discusses the effect of Jujubae Fructus in relieving the intestinal injury caused by SZD and the mechanism from the perspective of intestinal flora-host metabolism, which is expected to serve as a reference for clinical application of this prescription.
Rats ; Animals ; Rats, Sprague-Dawley ; Propionates/pharmacology* ; Gastrointestinal Microbiome ; Fatty Acids, Volatile/pharmacology* ; Butyrates/pharmacology*

Congenital insensitivity to pain with anhidrosis (CIPA) is a rare, autosomal-recessive disorder characterized by the clinical triad of indifference of pain, anhidrosis and heat intolerance.Because of their lack of autonomic response to noxious stimuli, the determination of adequate depth of anesthesia in the CIPA patient undergoing surgery is a major challenge.We experienced a patient with CIPA who had minor procedures three times under the general anesthesia, in which bispectral index (BIS) was maintained at 40-50 by adjusting sevoflurane concentrations with 50% nitrous oxide.The low end-tidal sevoflurane concentrations (<1.2 vol%) were required to keep the target BIS while vital signs remained stable throughout the surgery in each operation.BIS monitor may be a valuable tool to guide the depth of anesthesia in patients with CIPA.
Anesthesia ; Anesthesia, General ; Hereditary Sensory and Autonomic Neuropathies ; Hot Temperature ; Humans ; Hypohidrosis ; Indoles ; Methyl Ethers ; Organothiophosphorus Compounds ; Propionates ; Vital Signs