Fermentation experiments to produce validamycins from crude substrates by Streptomyces hygroscopicus were carried out in an external-loop airlift bioreactor (0.0115 m^3 ) with a low ratio of height to diameter of the ...Fermentation experiments to produce validamycins from crude substrates by Streptomyces hygroscopicus were carried out in an external-loop airlift bioreactor (0.0115 m^3 ) with a low ratio of height to diameter of the riser of 2.9 and a ratio of riser to downcomer diameter of 6.6. The influences of gas flow rate and liquid volume on fermentation of validamycins were investigated. Comparisons of validamycin fermentation were made among the external-loop airlift bioreactor, a mechanically stirred tank bioreactor (0.010m^3 ) and shaking flasks. Under the same operation conditions including fermentation medium composition, inoculum ratio and culture temperature, the fermentation time in the external-loop airlift bioreactor (45 h) was shorter than that in the shaking flasks (100 h) and the same as that in the mechanically stirred tank bioreactor. After a total fermentation time of 45 h under optimized operation conditions, average validamycin concentration obtained in the external-loop airlift bioreactor was close to 19630 μg·ml^-1 validamycin concentration in the mechanically stirred tank bioreactor. It was demonstrated that the external-loop airlift bioreactor could substitute for the mechanically stirred tank bioreactor in production of validamycins from crude substrates with dregs by Streptomyces hygroscopicus.展开更多
As an important medicinal intermediate with broad uses, validamine, an aminocyclitol, isolated from the enzymolysis broth of validamycins, has gained more and more attention. The absolute configuration of validamine i...As an important medicinal intermediate with broad uses, validamine, an aminocyclitol, isolated from the enzymolysis broth of validamycins, has gained more and more attention. The absolute configuration of validamine is similar to that of a-D-glucose, and it demonstrates powerful inhibition activity on glycosidase. In this paper, the inhibitory effect of validamine on porcine small intestinal sucrase was investigated. Validamine was found to be a potent, competitive inhibitor to porcine small intestinal sucrase in vitro with an IC50 value of 6.85 X 10(-4) mol center dot L-1. Validamine exhibited a dose-dependent inhibition effect on porcine small intestinal sucrase, whereby the inhibition interaction of validamine and porcine small intestinal sucrase was a fast binding process. The inhibition of validamine on porcine small intestinal sucrase was pH-dependent.展开更多
The Asian citrus psyllid,Diaphorina citri is the principal vector of huanglongbing,which transmits Candidatus Liberibacter asiaticus.Trehalase is a key enzyme involved in trehalose hydrolysis and plays an important ro...The Asian citrus psyllid,Diaphorina citri is the principal vector of huanglongbing,which transmits Candidatus Liberibacter asiaticus.Trehalase is a key enzyme involved in trehalose hydrolysis and plays an important role in insect growth and development.The specific functions of this enzyme in D.citri have not been determined.In this study,three trehalase genes(DcTreJ-1,DcTrel-2,and DcTre2)were identified based on the D.citri genome database.Bioinformatic analysis showed that DcTrel-1 and DcTrel-2 are related to soluble trehalase,whereas DcTre2 is associated with membrane-bound trehalase.Spatiotemporal expression analysis indicated that DcTrel-1 and DcTrel-2 had the highest expression levels in the head and wing,respectively,and DcTre2 had high expression levels in the fat body.Furthermore,DcTrel-1 and DcTrel-2 expression levels were induced by 20-hydroxyecdysone and juvenile hormone III,but DcTre2 was unaffected.The expression levels of DcTrel-1,DcTrel-2,and DcTre2 were significantly up-regulated,which resulted in high mortality after treatment with validamycin.Trehalase activities and glucose contents were downregulated,but the trehalose content increased after treatment with validamycin.In addition,the expression levels of chitin metabolism-related genes significantly decreased at 24 and 48 h after treatment with validamycin.Furthermore,silencing of DcTrel-1,DcTrel-2,and DcTre2 reduced the expression levels of chitin metabolism-related genes and led to a malformed phenotype of D.citri.These results indicate that D.citri trehalase plays an essential role in regulating chitin metabolism and provides a new target for control of D.citri.展开更多
基金Supported by the Natural Science Foundation of Zhejiang Province (No. ZB0106)the National Natural Science Foundation of China (No. 20176055).
文摘Fermentation experiments to produce validamycins from crude substrates by Streptomyces hygroscopicus were carried out in an external-loop airlift bioreactor (0.0115 m^3 ) with a low ratio of height to diameter of the riser of 2.9 and a ratio of riser to downcomer diameter of 6.6. The influences of gas flow rate and liquid volume on fermentation of validamycins were investigated. Comparisons of validamycin fermentation were made among the external-loop airlift bioreactor, a mechanically stirred tank bioreactor (0.010m^3 ) and shaking flasks. Under the same operation conditions including fermentation medium composition, inoculum ratio and culture temperature, the fermentation time in the external-loop airlift bioreactor (45 h) was shorter than that in the shaking flasks (100 h) and the same as that in the mechanically stirred tank bioreactor. After a total fermentation time of 45 h under optimized operation conditions, average validamycin concentration obtained in the external-loop airlift bioreactor was close to 19630 μg·ml^-1 validamycin concentration in the mechanically stirred tank bioreactor. It was demonstrated that the external-loop airlift bioreactor could substitute for the mechanically stirred tank bioreactor in production of validamycins from crude substrates with dregs by Streptomyces hygroscopicus.
基金Supported by the National Fund of the Major Basic Research Development Program (973 Project) (No.2003CB716005)the National Natural Science Foundation of China (No. 20176055) the Natural Science Foundation of Zhejiang Province (No. ZB0106).
文摘As an important medicinal intermediate with broad uses, validamine, an aminocyclitol, isolated from the enzymolysis broth of validamycins, has gained more and more attention. The absolute configuration of validamine is similar to that of a-D-glucose, and it demonstrates powerful inhibition activity on glycosidase. In this paper, the inhibitory effect of validamine on porcine small intestinal sucrase was investigated. Validamine was found to be a potent, competitive inhibitor to porcine small intestinal sucrase in vitro with an IC50 value of 6.85 X 10(-4) mol center dot L-1. Validamine exhibited a dose-dependent inhibition effect on porcine small intestinal sucrase, whereby the inhibition interaction of validamine and porcine small intestinal sucrase was a fast binding process. The inhibition of validamine on porcine small intestinal sucrase was pH-dependent.
基金the National Natural Science Foundation of China(31960116)the Educational Commission of Jiangxi Province of China(GJJ180747)+1 种基金the National Key Research and Development Program of China(2018YFD0201504,the earmarked fund for Jiangxi Agriculture Research System(JXARS-07)Key Research and Development Plan of Jiangxi Province(20192BBF60057).
文摘The Asian citrus psyllid,Diaphorina citri is the principal vector of huanglongbing,which transmits Candidatus Liberibacter asiaticus.Trehalase is a key enzyme involved in trehalose hydrolysis and plays an important role in insect growth and development.The specific functions of this enzyme in D.citri have not been determined.In this study,three trehalase genes(DcTreJ-1,DcTrel-2,and DcTre2)were identified based on the D.citri genome database.Bioinformatic analysis showed that DcTrel-1 and DcTrel-2 are related to soluble trehalase,whereas DcTre2 is associated with membrane-bound trehalase.Spatiotemporal expression analysis indicated that DcTrel-1 and DcTrel-2 had the highest expression levels in the head and wing,respectively,and DcTre2 had high expression levels in the fat body.Furthermore,DcTrel-1 and DcTrel-2 expression levels were induced by 20-hydroxyecdysone and juvenile hormone III,but DcTre2 was unaffected.The expression levels of DcTrel-1,DcTrel-2,and DcTre2 were significantly up-regulated,which resulted in high mortality after treatment with validamycin.Trehalase activities and glucose contents were downregulated,but the trehalose content increased after treatment with validamycin.In addition,the expression levels of chitin metabolism-related genes significantly decreased at 24 and 48 h after treatment with validamycin.Furthermore,silencing of DcTrel-1,DcTrel-2,and DcTre2 reduced the expression levels of chitin metabolism-related genes and led to a malformed phenotype of D.citri.These results indicate that D.citri trehalase plays an essential role in regulating chitin metabolism and provides a new target for control of D.citri.
