球孢白僵菌基于前体物固态发酵合成D-HPPA

D-HPPA synthesis using precursor solid-state fermentation by Beauveria bassiana

[目的]建立球孢白僵菌(Beauveria bassiana)基于前体物固态发酵合成R-(+)-2-(4-羟基苯氧基)丙酸(D-HPPA)的工艺,提高球孢白僵菌催化R-(+)-2-苯氧基丙酸(D-PPA)合成D-HPPA的能力。[方法]对前体物(D-PPA)添加量及添加时机进行了探索,同时对影响固态发酵的因素如固态基质种类、料水比、培养基水分pH、接种量及发酵温度等进行了优化。[结果]前体物添加量低于30 g D-PPA/kg固态培养基时,球孢白僵菌能够在7 d内完成D-PPA的转化,且在固态发酵起始阶段即可加入前体物进行催化。以麸皮为固态培养基基质,培养基料水比为1∶1.5、初始水分pH为7.5、接种量15%,培养温度为26℃时球孢白僵菌的催化效率最高。在40 g/kg的前体物存在下发酵7 d,D-HPPA产量达到37.34 g/kg,前体物D-PPA转化率为93.35%,较液态发酵方式的转化率提高283.38%。[结论]球孢白僵菌基于前体物固态发酵能够有效合成D-HPPA,为其生物合成提供了一条新的途径。

[Aims]This study aims to improve the ability of Beauveria bassiana to catalyze the synthesis of R-(+)-2-(4-hydroxyphenoxy)propionic acid(D-HPPA)from R-(+)-2-phenoxypropionic acid(D-PPA),a process was established for the synthesis of D-HPPA by B.bassiana based on precursor solid-state fermentation.[Methods]The amount and time of precursor(D-PPA)addition were explored,and the factors affecting solid-state fermentation such as solid-state fermentation media,ratio of material to water,medium moisture pH,fermentation temperature and inoculation amount were optimized.[Results]B.bassiana is able to complete the conversion of D-PPA within 7 d if precursor addition was less than 30 g D-PPA/kg solid medium.The precursor can be added for catalysis at the initial stage of solid fermentation.The highest catalytic efficiency of B.bassiana was obtained when wheat bran was used as carbon source in solid medium,solid-to-water ratio was 1∶1.5,initial water pH was 7.5,inoculation amount was 15%and culture temperature was 26℃.The yield of D-HPPA reach 37.34 g/kg after 7 d of fermentation in the presence of 40 g D-PPA/kg solid medium,with a conversion rate of 93.35%,which is 283.38%higher than that of the liquid fermentation method.[Conclusions]B.bassiana can catalyze the synthesis of D-HPPA by precursor solid-state fermentation,providing a new pathway for the biosynthesis of D-HPPA.