(S)-3,5-bistrifluoromethylphenyl ethanol is a key chiral intermediate for the synthesis of NK-1 receptor antagonists. Enantioselective synthesis of (S)-3,5-bistrifluoromethylphenyl ethanol was successfully performed i...(S)-3,5-bistrifluoromethylphenyl ethanol is a key chiral intermediate for the synthesis of NK-1 receptor antagonists. Enantioselective synthesis of (S)-3,5-bistrifluoromethylphenyl ethanol was successfully performed in high enantiomeric excess (e.e.) through asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone catalyzed by Candida tropicalis 104 cells. The influence of some key reaction parameters such as substrate concentration, co-substrate and its concentration, biomass and reaction time was examined, respectively. The results showed that these factors obviously influence the yield, but the optical purity of the prepared product remains intact. The opti-mum conditions for the preparation of (S)-3,5-bistrifluoromethylphenyl ethanol were found to be as follows: sub-strate concentration 50 mmol?L?1; 50 g·L-1 of maltose as co-substrate; wet cell concentration 300 g·L-1; reaction for 30 h. Under above optimal conditions, the maximum yield for (S)-3,5-bistrifluoromethylphenyl ethanol reached 70.3% with 100% of product e.e.展开更多
[Objective] The aim was to select the optimum conditions of xylitol Candida tropicalis conversion production. [Method] The effect of cell culture time,conversion time,conversion pH value,conversion initial sugar conce...[Objective] The aim was to select the optimum conditions of xylitol Candida tropicalis conversion production. [Method] The effect of cell culture time,conversion time,conversion pH value,conversion initial sugar concentration,speed and inoculation rate were determined respectively.[Result] Optimum fermentation conditions were obtained as follows:cell culture 16 h,conversion time 10 h,conversion pH value 5.5,conversion initial sugar concentration 20 g/L,conversion shaking speed 150 r/min,inoculation rate 10% (volume ratio). The yield of xylitol has increased to 90%. [Conclusion] This study had provided basis for the further study on xylitol.展开更多
1089 strains of yeasts were obtained from seawater,sea sediments,mud of sea salterns,guts of marine fishes,mangroveplants and marine algae.The results of routine identification and molecular analysis methods show that...1089 strains of yeasts were obtained from seawater,sea sediments,mud of sea salterns,guts of marine fishes,mangroveplants and marine algae.The results of routine identification and molecular analysis methods show that 44 strains among the marineyeasts obtained in this study belong to Candida tropicalis,which may indicate its wide distribution in different environment,especially in the tropical and subtropical marine environment.The wide distribution of C.tropicalis indicates that it may play an important role in marine environment and the marine environment in turn is a good source for obtaining C.tropicalis.展开更多
From April 2008 to November 2009, the nitrogen （N） cycle of plant-soil system in seepweed （Suaeda salsa） wetland in the intertidal zone of the Huanghe （Yellow） River estuary was studied. Results showed that soil...From April 2008 to November 2009, the nitrogen （N） cycle of plant-soil system in seepweed （Suaeda salsa） wetland in the intertidal zone of the Huanghe （Yellow） River estuary was studied. Results showed that soil N had sig- nificant seasonal fluctuations and vertical distribution, and the net N mineralization rates in topsoil were significantly different in growing season （p 〈 0.01）. The N/P ratio （9.87 ±1.23） of S. salsa was less than 14, indicating that plant growth was limited by N. The N accumulated in S. salsa litter at all times during decomposition, which was ascribed to the N immobilization by microbes from the environment. Soil organic N was the main N stock of plant-soil system, accounting for 97.35% of the total N stock. The N absorption and utilization coefficients of S. salsa were very low （0.0145 and 0.3844, respectively）, while the N cycle coefficient was high （0.7108）. The results of the N turnovers among compartments of S. salsa wetland showed that the N uptake amount of aboveground part and root were 7.764 g/m2and 4.332 g/m2, respectively. The N translocation amounts from aboveground part to root and from root to soil were 3.881 g/m2 and 0.626 g/m2, respectively. The N translocation amount from aboveground living body to litter was 3.883 g/m2, the annual N return amount from litter to soil was more than 0.125（-） g/m2 （minus represented immobili- zation）, and the net N mineralization amount in topsoil （0-15 cm） in growing season was 1.190 g/m2. The assessment of N biological cycle status orS. salsa wetland indicated that N was a very important limiting factor and the ecosystem was situated in unstable and vulnerable status. The S. salsa was seemingly well adapted to the low-nutrient status and vulnerable habitat, and the N quantitative relationships determined in the compartment model might provide scientific base for us to reveal the special adaptive strategy orS. salsa to the vulnerable habitat in the following studies.展开更多
基金Supported by the National＇Natural Science Foundation of China （21076193） and Foundation of Zhejiang Key Developing Discipline of Pharmacy （20100609）.
文摘(S)-3,5-bistrifluoromethylphenyl ethanol is a key chiral intermediate for the synthesis of NK-1 receptor antagonists. Enantioselective synthesis of (S)-3,5-bistrifluoromethylphenyl ethanol was successfully performed in high enantiomeric excess (e.e.) through asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone catalyzed by Candida tropicalis 104 cells. The influence of some key reaction parameters such as substrate concentration, co-substrate and its concentration, biomass and reaction time was examined, respectively. The results showed that these factors obviously influence the yield, but the optical purity of the prepared product remains intact. The opti-mum conditions for the preparation of (S)-3,5-bistrifluoromethylphenyl ethanol were found to be as follows: sub-strate concentration 50 mmol?L?1; 50 g·L-1 of maltose as co-substrate; wet cell concentration 300 g·L-1; reaction for 30 h. Under above optimal conditions, the maximum yield for (S)-3,5-bistrifluoromethylphenyl ethanol reached 70.3% with 100% of product e.e.
文摘[Objective] The aim was to select the optimum conditions of xylitol Candida tropicalis conversion production. [Method] The effect of cell culture time,conversion time,conversion pH value,conversion initial sugar concentration,speed and inoculation rate were determined respectively.[Result] Optimum fermentation conditions were obtained as follows:cell culture 16 h,conversion time 10 h,conversion pH value 5.5,conversion initial sugar concentration 20 g/L,conversion shaking speed 150 r/min,inoculation rate 10% (volume ratio). The yield of xylitol has increased to 90%. [Conclusion] This study had provided basis for the further study on xylitol.
基金supported by the National Infrastructure of Natural Resources for Science and Technology Program of China(Grant No.2005DKA21209)
文摘1089 strains of yeasts were obtained from seawater,sea sediments,mud of sea salterns,guts of marine fishes,mangroveplants and marine algae.The results of routine identification and molecular analysis methods show that 44 strains among the marineyeasts obtained in this study belong to Candida tropicalis,which may indicate its wide distribution in different environment,especially in the tropical and subtropical marine environment.The wide distribution of C.tropicalis indicates that it may play an important role in marine environment and the marine environment in turn is a good source for obtaining C.tropicalis.
基金Under the auspices of Open Research Fund Program of Shandong Key Laboratory for Yellow River Delta Eco-Environmental Science,Binzhou,China (No.2007KFJJ01)Knowledge Innovation Programs of Chinese Academy of Sciences (No.KZCX2-YW-223)+1 种基金National Natural Science Foundation of China (No.40803023,41171424)Key Program of Natural Science Foundation of Shandong Province (No.ZR2010DZ001)
文摘From April 2008 to November 2009, the nitrogen （N） cycle of plant-soil system in seepweed （Suaeda salsa） wetland in the intertidal zone of the Huanghe （Yellow） River estuary was studied. Results showed that soil N had sig- nificant seasonal fluctuations and vertical distribution, and the net N mineralization rates in topsoil were significantly different in growing season （p 〈 0.01）. The N/P ratio （9.87 ±1.23） of S. salsa was less than 14, indicating that plant growth was limited by N. The N accumulated in S. salsa litter at all times during decomposition, which was ascribed to the N immobilization by microbes from the environment. Soil organic N was the main N stock of plant-soil system, accounting for 97.35% of the total N stock. The N absorption and utilization coefficients of S. salsa were very low （0.0145 and 0.3844, respectively）, while the N cycle coefficient was high （0.7108）. The results of the N turnovers among compartments of S. salsa wetland showed that the N uptake amount of aboveground part and root were 7.764 g/m2and 4.332 g/m2, respectively. The N translocation amounts from aboveground part to root and from root to soil were 3.881 g/m2 and 0.626 g/m2, respectively. The N translocation amount from aboveground living body to litter was 3.883 g/m2, the annual N return amount from litter to soil was more than 0.125（-） g/m2 （minus represented immobili- zation）, and the net N mineralization amount in topsoil （0-15 cm） in growing season was 1.190 g/m2. The assessment of N biological cycle status orS. salsa wetland indicated that N was a very important limiting factor and the ecosystem was situated in unstable and vulnerable status. The S. salsa was seemingly well adapted to the low-nutrient status and vulnerable habitat, and the N quantitative relationships determined in the compartment model might provide scientific base for us to reveal the special adaptive strategy orS. salsa to the vulnerable habitat in the following studies.
