Forty eight individually fed Awassi male lambs were used in factorial experiment to investigate their responses to feeding concentrate diets containing three levels of dietary crude protein （CP）, each was offered wi...Forty eight individually fed Awassi male lambs were used in factorial experiment to investigate their responses to feeding concentrate diets containing three levels of dietary crude protein （CP）, each was offered without or with baker＇s yeast （SC） at rate of 0.5% （on dry matter （DM） basis）. Concentrates were offered at rate of 3% of live body weight with free choice of barley straw. Results revealed that higher （P 〈 0.05） digestible dry matter （DDM） and digestible organic matter （DOM） intakes were achieved due to feeding medium level of CP and to the addition of SC. Addition of SC improved （P 〈 0.05） gain, lambs fed medium and high levels gained higher （P 〈 0.05） than those fed the low level of dietary CP. Feed conversion ratio （FCR） based on DM and organic matter （OM） intakes was not significantly affected by level of dietary CP or addition of yeast. Even though, less amount of N required per unit of gain was achieved with low and medium as compared to high levels. Higher DM, nitrogen free extract （NFE） and hemicellulose （P 〈 0.05）, OM, CP, crude fiber （CF） and cellulose （P 〈 0.01） digestibilities were achieved in lambs fed the medium level of CP, whereas, no significant effect was observed on ether extract （EE）, neutral detergent fiber （NDF） and acid detergent fiber （ADF） digestibilities. Results also revealed that digestibility of almost all nutrients was improved with different extent due to addition of SC. Effect of interaction between levels of dietary CP and addition of SC referred to the preferability of addition of SC with medium level of dietary protein.展开更多
By the addition of rice wine koji, enhancement of the reactivity was observed for the baker＇s yeast reduction of β-keto esters into （S）-β-hydroxy esters with high enantiomeric purity （73-98%）.
Baker’s yeast number 6 was selected by screening. It showed good catalytic activity and enantioselec-tivity for asymmetric reduction of 2,5-hexanedione to produce (2S,5S)-2,5-hexanediol. Gas chromatography-mass spect...Baker’s yeast number 6 was selected by screening. It showed good catalytic activity and enantioselec-tivity for asymmetric reduction of 2,5-hexanedione to produce (2S,5S)-2,5-hexanediol. Gas chromatography-mass spectrometry (GC-MS) revealed that the intermediate was (S)-5-hydroxyhexane-2-one. Reduction of 2,5-hexanedione proceeded in a two-step reaction. The hydroxyketone was initially formed, and this intermediate was further re-duced to the diol. Factors influencing the product yield and the enantiomeric excess of the reduction of 2,5-hexandione catalyzed by baker’s yeast number 6 were investigated. Higher concentration (≤100 mmol·L-1) of 2,5-hexandione did not influence 5-hydroxyhexane-2-one production, but 2,5-hexanediol production was inhibited by excess accumulation (>30 mmol·L-1) of intermediate. The optimal conditions were glucose as the co-substrate at an initial glucose concentration of 20 g·L-1, 34°C, pH 7.0 and cell concentration 60 g·L-1 (cell dry mass). Under the optimal condition and an initial substrate concentration of 30 mmol·L-1, the yield of 2,5-hexandiol was 78.7% and the enantiomeric excess of (2S,5S)-2,5-hexandiol was 94.4% for 24-h reduction.展开更多
文摘Forty eight individually fed Awassi male lambs were used in factorial experiment to investigate their responses to feeding concentrate diets containing three levels of dietary crude protein （CP）, each was offered without or with baker＇s yeast （SC） at rate of 0.5% （on dry matter （DM） basis）. Concentrates were offered at rate of 3% of live body weight with free choice of barley straw. Results revealed that higher （P 〈 0.05） digestible dry matter （DDM） and digestible organic matter （DOM） intakes were achieved due to feeding medium level of CP and to the addition of SC. Addition of SC improved （P 〈 0.05） gain, lambs fed medium and high levels gained higher （P 〈 0.05） than those fed the low level of dietary CP. Feed conversion ratio （FCR） based on DM and organic matter （OM） intakes was not significantly affected by level of dietary CP or addition of yeast. Even though, less amount of N required per unit of gain was achieved with low and medium as compared to high levels. Higher DM, nitrogen free extract （NFE） and hemicellulose （P 〈 0.05）, OM, CP, crude fiber （CF） and cellulose （P 〈 0.01） digestibilities were achieved in lambs fed the medium level of CP, whereas, no significant effect was observed on ether extract （EE）, neutral detergent fiber （NDF） and acid detergent fiber （ADF） digestibilities. Results also revealed that digestibility of almost all nutrients was improved with different extent due to addition of SC. Effect of interaction between levels of dietary CP and addition of SC referred to the preferability of addition of SC with medium level of dietary protein.
文摘By the addition of rice wine koji, enhancement of the reactivity was observed for the baker＇s yeast reduction of β-keto esters into （S）-β-hydroxy esters with high enantiomeric purity （73-98%）.
基金Supported by the Key Project of Science and Technology of Fujian Province (2008N0120)the Key Discipline of Biochemical Engineering of Fujian Province (Huaqiao University)
文摘Baker’s yeast number 6 was selected by screening. It showed good catalytic activity and enantioselec-tivity for asymmetric reduction of 2,5-hexanedione to produce (2S,5S)-2,5-hexanediol. Gas chromatography-mass spectrometry (GC-MS) revealed that the intermediate was (S)-5-hydroxyhexane-2-one. Reduction of 2,5-hexanedione proceeded in a two-step reaction. The hydroxyketone was initially formed, and this intermediate was further re-duced to the diol. Factors influencing the product yield and the enantiomeric excess of the reduction of 2,5-hexandione catalyzed by baker’s yeast number 6 were investigated. Higher concentration (≤100 mmol·L-1) of 2,5-hexandione did not influence 5-hydroxyhexane-2-one production, but 2,5-hexanediol production was inhibited by excess accumulation (>30 mmol·L-1) of intermediate. The optimal conditions were glucose as the co-substrate at an initial glucose concentration of 20 g·L-1, 34°C, pH 7.0 and cell concentration 60 g·L-1 (cell dry mass). Under the optimal condition and an initial substrate concentration of 30 mmol·L-1, the yield of 2,5-hexandiol was 78.7% and the enantiomeric excess of (2S,5S)-2,5-hexandiol was 94.4% for 24-h reduction.
