No abstract available.
Animals ; Ethanol* ; Metabolism* ; Phenobarbital* ; Rats* ; Trichloroethylene*

Plackett-Burman (PB) design and central composite design (CCD) were applied to optimize of xylose fermentation for ethanol production by Candida shehatae HDYXHT-01. The PB results showed that (NH4)2SO4, KH2PO4, yeast extract and inoculum volume were the main affecting factors. With ethanol productivity as the target response, the optimal fermentation was determined by CCD and response surface analysis (RSM). The optimal fermentation conditions were (NH4)2SO4 1.73 g/L, KH2PO4 3.56 g/L, yeast extract 2.62 g/L and inoculum volume 5.66%. Other fermentation conditions were xylose 80 g/L, MgSO47H20 0.1 g/L, pH 5.0 and 250 mL flask containing 100 mL medium and cultivated at 30 degrees C for 48 h and the agitation speed was 140 r/min. Under this fermentation conditions, ethanol productivity was 26.18 g/L, which was 1.15 times of the initial.
Candida ; metabolism ; Ethanol ; metabolism ; Fermentation ; Industrial Microbiology ; Xylose ; metabolism

Prior research reported the oscillatory behavior characterized by long period and high amplitude during high gravity continuous ethanol fermentations at the dilution rate of 0.027 h(-1). In this paper, high gravity continuous ethanol fermentations using Saccharomyces cerevisia at different dilution rates were carried out. Similar oscillations were observed when the dilution rate was switched to 0.04 h(-1). Both oscillatory and steady processes can be achieved at dilution rates of 0.027 or 0.04 h(-1), which depends on the initial status of the fermentation system. However, compared to steady process at the same dilution rate of 0.04 h(-1), the average residual sugar concentration was lowered by 14.8% for the oscillatory process, while the average ethanol concentration and productivity were increased by 12.6% and 12.3%, respectively. Further investigation revealed that besides the lag time, oscillatory processes were different from steady ones in kinetics because a higher specific growth rate can be achieved at the same residual sugar and ethanol concentrations (increased by 53.8% in average).
Bioreactors ; microbiology ; Carbohydrates ; Ethanol ; metabolism ; Fermentation ; Hypergravity ; Saccharomyces cerevisiae ; metabolism

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 regions suitable for growing cassava include five provinces in Southern China, with Guangxi alone accounting for over 65% of the total cassava production in the country. In this article, the state-of-the-art development of fuel ethanol production from cassava in China is illustrated by the construction of the cassava fuel ethanol plant with its annual production capacity of 200 000 metric tons. And in the meantime, problems and challenges encountered in the development of China's cassava fuel ethanol are highlighted and the strategies to address them are proposed.
Biofuels ; China ; Conservation of Energy Resources ; Ethanol ; metabolism ; Manihot ; metabolism

Very high gravity (VHG) ethanolic fermentation is a new perspective technology for the fuel ethanol production. Compared with traditional hot cook process in most ethanol plants, uncooked process using milled grain slurry in combination with granular starch hydrolyzing enzymes makes high gravity fermentation much easier to control. In this study, dry solids staging technique was first time reported in uncooked process for fermentation ethanol. We further studied the difference between the new process and the batch fermentation, including different initial fermentation concentrations and different starting times. The results showed that at the same dry solid concentration of 30% and the same enzyme dose at 0.22% (W/W), the final ethanol output of new process was increased to 18.50% (V/V) from 17.06% (V/V) of the conventional process. This study demonstrated the new application of uncooked fermentation technology.
Biofuels ; Bioreactors ; Ethanol ; metabolism ; Fermentation ; Zea mays ; metabolism

A continuous ethanol fermentation system composed of three-stage tanks in series coupled with two sedimentation tanks was established. A self-flocculating yeast strain developed by protoplast fusion from Saccharomyces cerevisiae and Schizosaccharomyces pombe was applied. Two-stage enzymatic hydrolysate of corn powder containing 220g/L of reducing sugar, supplemented with 1.5g/L (NH4)2HPO4 and 2.5g/L KH2PO4, was used as the ethanol fermentation substrate and fed into the first fermentor at the dilution rate of 0.057h(-1). The yeast flocs separated by sedimentation were recycled into the first fermentor as two different models: activation-recycle and direct recycle. The quasi-steady states were obtained for both operation models after the fermentation systems experienced short periods of transitions. Activation process helped enhance the performance of ethanol fermentation at the high dilution rates. The broth containing more than 101g/L ethanol, 3.2g/L residual reducing sugar and 7.7g/L residual total sugar was produced. The ethanol productivity was calculated to be 5.77g/(L x h), which increased by more than 70% compared with that achieved in the same tank in series system without recycling of yeast cells.
Biomass ; Ethanol ; metabolism ; Fermentation ; Flocculation ; Saccharomyces cerevisiae ; metabolism

Investigation in our laboratory has been undertaken to study the effect of ethanol on the triglyceride (TG) content in the liver, the free fatty acid (FFA) content in the serum and the glycogen in the liver of rats which were fed on various diets. Four hours after administration of a sing1e dose of glucose (5g/kg BW.) and ethanol (6g/kg BW.) by gavage tube to rats fed a norma1 diet for 20 days then fasted for 18 hours, TG content in the liver increased by 80%, 10% compared to the control. When a sing1e dose of equal amounts of both glucose and ethanol were administered to another group, TG content in the liver was 42% higher than the control. There was no great change in serum FFA content in the glucose treated group as compared with the control, however, there was an increment of serum FFA content in the ethanol treated group and in the group treated with both ethanol and glucose by 81% and 71% of the control, respectively. The results indicate that ethanol administration had an inhibitory effect on the TG accumulation in the liver of rats fed by glucose. There is a correlation between TG accumulation in the liver and FFA content in the serum, and it appears that the ethanol administration did not induce the TG accumulation in the liver but the increment of serum FFA content in rats is probably due to the increased fatty acid mobilization from adipose tissue. However, countercurrent results were observed in the glucose treated group as compared with the ethanol treated group suggesting that glucose administration does induce TG accumulation in the liver but does not increase the serum FFA content in rats. The increment of serum FFA content in rats. The increment of serum FFA content by ethanol treatment was not ameliorated by glucose administration. In the liver perfusion experiment with rats fed both ethanol and various other diets, the results of incorporation of ethanol-1-14C into the total lipid in the high carbohydrate, high fat, low carbohydrate and control diet group were 1925 +/- 257 (cpm/g liver), 1237 +/- 76, 1269 +/- 105, 2041 +/- 74, respective1y. The results indicate that amount of dietary carbohydrate and high fat had an effect on the total lipid accumulation derived from ethanol-1-14C molecule in the liver. Liver glycogen content in the control on rats, high fat, 1ow carbohydrate and high carbohydrate diets were 91.5 +/- 7.9(mg%), 93.0 +/- 1.8, 99.1 +/- 4.4, and 153.7 +/- 26.0, respectively. There were no great differences between each dietary group and the rest control group except in the case of the high carbohydrate group which was over 1.5 times greater than that of the control. The incorporation of labelled ethanol into liver glycogen in the control rats and those on high fatdiet, low carbohydrate diet and high carbohydrate diet were 525, 401, 351 and 806 cpm/g liver, respectively. The increased incorporation of ethanol-1-14C into liver glycogen in the high carbohydrate diet group is thought to be due to the increased gluconeogenesis from acetyl CoA derived from 14C from ethanol because rats were fasted for 18 hours before perfusion. It might be the result of increased gluconegenesis of acetyl CoA derived from ethanol-1-14C by spare action of high carbohydrate on acetyl CoA. During the liver perfusion, 14CO2 production from ethanol-1-14C was higher in the high fat diet and low carbohydrate diet groups than in the control group, however, no great difference was observed between the high carbohydrate and control groups. The higher production of 14CO2 from the single ethanol-1-14C dose in rats on the high fat diet and low carbohydrate diet groups than in the control group is probably due to the increased metabolism of ethanol through Kreb's cycle rather than the incorporation of it into the liver fat.
Animal ; Diet ; Ethanol/metabolism ; Ethanol/pharmacology* ; Fatty Acids, Nonesterified/blood ; Glucose/pharmacology ; In Vitro ; Liver/metabolism* ; Male ; Rats ; Triglycerides/metabolism*

Some degradation products from lignocellulose pretreatment strongly inhibit the activities of cellulolytic enzymes and ethanol fermentation strains, thus the efficient removal of the inhibitor substances ("detoxification") is the inevitable step for the biotransformation processes. In this study, the biological detoxification of furfural by a newly isolated fungus, Amorphotheca resinae ZN1, was studied and the metabolic pathways of furfural degradation was analyzed. The metabolic pathway of furfural degradation in A. resinae ZN1 was described as follows: first, furfural was quickly converted into the low toxic furfuryl alcohol; then the furfuryl alcohol was gradually converted into furfural again but under the low concentration under aerobic condition, which was not lethal to the growth of the fungi; furfural continued to be oxidized to furoic acid by A. resinae ZN1. It is likely that furoic acid was further degraded in the TCA cycle to complete the biological degradation of furfural. The present study provided the important experimental basis for speeding up the biodetoxification of furfural by A. resinae ZN1 and the rate-limiting step in the lignocellulose biotransformation to ethanol.
Biodegradation, Environmental ; Biotransformation ; Ethanol ; metabolism ; Fermentation ; Fungi ; metabolism ; Furaldehyde ; isolation & purification ; metabolism ; Furans ; metabolism ; Lignin ; metabolism

Kenaf stalk was pretreated by the white-rot fungus Pleurotus sajor-caju incubated in solid-state kenaf stalk cultivation medium. Delignification and subsequent enzymatic saccharification and fermentation of kenaf stalk were investigated in order to evaluate effects of microbial pretreatment on bioconversion of kenaf lignocellulose to fuel ethanol production. The highest delignification rate of 50.20% was obtained after 25-35 days cultivation by P. sajor-caju, which could improve subsequent enzymatic hydrolysis efficiency of kenaf cellulose. And the saccharification rate of pretreated kenaf stalk reached 69.33 to 78.64%, 4.5-5.1 times higher than the control. Simultaneous saccharification and fermentation (SSF) with microbial-pretreatment kenaf stalk as substrate was performed. The highest overall ethanol yield of 68.31% with 18.35 to 18.90 mg/mL was achieved after 72 h of SSF.
Biofuels ; Ethanol ; metabolism ; Fermentation ; Hibiscus ; metabolism ; microbiology ; Lignin ; metabolism ; Plant Stems ; metabolism ; Pleurotus ; metabolism