嗜热链球菌胞外多糖的结构生物合成与遗传调控

介绍了嗜热链球菌胞外多糖的组成结构、生物合成、代谢途径和针对途径中关键酶的遗传调控,为胞外多糖研究提供参考.     

A comprehensive review of spermidine: Safety,health effects,absorption and metabolism,food materials evaluation,physical and chemical processing,and bioprocessing

Spermidine, a natural autophagy inducer, has a variety of health effects, such as antitumor, antiaging, anti-inflammation, cardiovascular protection, and neuromodulation. It has been a hot topic in the field of food processing, and current research findings suggest that spermidine-rich foods may be used in intervention and prevention of age-related diseases. In this article, recent findings on the safety, health effects, absorption and metabolism of spermidine were reviewed, and advances in food processing, including the raw materials evaluation, physical and chemical processing, and biological processing of spermidine, were highlighted. In particular, the core metabolic pathways, key gene targets, and efficient metabolic engineering strategies involved in the biosynthesis of spermidine and its precursors were discussed. Moreover, limitations and future perspectives of spermidine research were proposed. The purpose of this review is to provide new insights on spermidine from its safety to its food processing, which will advance the commercial production and applications of spermidine-rich foods and nutraceuticals.     

生物合成茶氨酸的研究进展及构建基因工程菌合成茶氨酸的可行性探讨

综述了近年来应用微生物发酵法、茶树细胞培养法生物合成茶氨酸的研究进展 ,讨论了构建基因工程菌生物合成茶氨酸的可行性。     

Biosynthesis of sesqui- and diterpenes by the gibberellin producer Fusarium fujikuroi

The fungus Fusarium fujikuroi IMI58289 emits a complex pattern of volatile terpenoids including two major compounds, the sesquiterpene alcohol α-acorenol and the diterpene ent-kaurene. ent-Kaurene is the precursor for the phytohormone gibberellic acid (GA(3)) and is produced from geranylgeranyl diphosphate (GGPP) via ent-copalyl diphosphate by the bifunctional ent-copalyl diphosphate/ent-kaurene synthase (CPS/KS). Several structurally related diterpenes were identified as side products of the CPS/KS. Deletion of the cps/ks gene or the whole GA(3) biosynthetic gene cluster resulted in completely abolished diterpene production. Mutants with deletions of the cytochrome P450 monooxygenase gene P450-4, which is responsible for the three oxidation steps from ent-kaurene to ent-kaurenoic acid en route to GA(3), accumulate diterpene hydrocarbons. Feeding with [6,6,6-(2) H(3)] mevalonolactone gave insights into the stereochemistry of the GGPP cyclisation, which operates with a chair-chair-"antipodal" fold. A rational biosynthetic scheme for all identified sesquiterpenes demonstrated their formation from farnesyl diphosphate (FPP) via three alternative initial cyclisations. Genome sequencing revealed the presence of five putative sesquiterpene synthase genes in the F. fujikuroi genome. The structures of several trace compounds from other classes have been identified as new natural products; these were delineated from their mass spectra and unambiguously assigned by comparison to synthetic references.