d-psicose-3-epimerase (DPEase) catalyses the isomerisation of d-fructose to d-psicose, a rare sugar in nature with unique nutritional and biological functions. An effective industrial-scale method is needed for d-psicose production. Herein, the expression of a neutral and a slightly acidic pH DPEase in Bacillus subtilis was evaluated. Two DPEase genes from Clostridium bolteae and Dorea sp. were separately expressed in B. subtilis via plasmid pSTOP1622, and an extra P43 promoter was employed to the expression cassette. The fermentation conditions of the engineered B. subtilis strains were also optimised, to facilitate both cell growth and enzyme production. The introduction of P43 promoter to the two DPEase genes increased enzyme production by about 20%. Optimisation of fermentation conditions increased DPEase production to 21.90 U/g at 55 °C and 24.01 U/g at 70 °C in B. subtilis expressing C. bolteae or Dorea sp. DPEase, equating to a 94.67% and 369.94% increase, respectively, relative to controls. Enhanced DPEase production was achieved in B. subtilis expressing C. bolteae or Dorea sp. DPEase genes.

中文翻译：

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的表达d -psicose -3-差向异构酶从难辨梭菌和Dorea藻。枯草芽孢杆菌中d - psose的合成和全细胞产生

d- psoseose-3-epimerase（DPEase）催化d-果糖异构化为d-psose，这是自然界中稀有的糖，具有独特的营养和生物学功能。d-阿胶糖生产需要有效的工业规模方法。在此，对枯草芽孢杆菌中的中性pH和弱酸性pH DPEase的表达进行了评价。来自博氏梭状芽胞杆菌和Dorea sp。的两个DPEase基因。枯草芽孢杆菌通过质粒pSTOP1622在枯草芽孢杆菌中单独表达，并且额外的P43启动子用于表达盒。还优化了工程化枯草芽孢杆菌菌株的发酵条件，以促进细胞生长和酶产生。将P43启动子引入两个DPEase基因可将酶的产量提高约20％。发酵条件的优化使DPEase产量增加到21。在表达C.bolteaae或Dorea sp。的枯草芽孢杆菌中，55°C时90 U / g和70°C时24.01 U / g。相对于对照，DPEase分别增加了94.67％和369.94％。在表达C.bolteaae或Dorea sp。的枯草芽孢杆菌中实现了增强的DPEase产生。DPEase基因。