摘要
【背景】γ-聚谷氨酸(poly-γ-glutamic acid,γ-PGA)产生菌多为枯草芽孢杆菌(Bacillus subtilis)、解淀粉芽孢杆菌(Bacillus amyloliquefaciens)、地衣芽孢杆菌(Bacillus licheniformis)等,而暹罗芽孢杆菌(Bacillus siamensis)相关研究较少。【目的】研究暹罗芽孢杆菌产γ-PGA的液体发酵条件。【方法】以自行分离的暹罗芽孢杆菌CAU83为出发菌株进行液体发酵,通过单因素试验和正交试验法研究了碳氮源、前体物质、发酵温度及pH对菌株生产γ-PGA的影响。【结果】经摇瓶优化,γ-PGA的最适碳源、氮源和前体物质分别为乳糖30 g/L、酵母提取物5 g/L和L-谷氨酸钠60 g/L,最适培养条件为发酵温度37℃和pH 7.0,γ-PGA产量由8.4 g/L提升至30.1 g/L,比优化前提高了260%。经分批补料发酵,60 h时γ-PGA产量最高为59.5 g/L,比摇瓶提高了98%,产率为0.99 g/(L·h)。所产γ-PGA分子量为3.8×106 Da,聚合度较高。【结论】确定了暹罗芽孢杆菌CAU83产γ-PGA的最适发酵条件,为该菌株的工业化生产和应用提供了依据。
[Background]The commonly known poly-γ-glutamic acid(γ-PGA)producers are Bacillus subtilis,B.amyloliquefaciens,and B.licheniformis,while little is known about B.siamensis.[Objective]To study liquid fermentation conditions forγ-PGA production by B.siamensis.[Methods]B.siamensis CAU83,isolated by our laboratory,was used to produceγ-PGA by liquid fermentation.The effects of carbon sources,nitrogen sources,precursors,temperature,and pH on the synthesis ofγ-PGA in shake flasks were investigated by single factor test and orthogonal design.[Results]The optimal carbon source,nitrogen source,and precursor for the synthesis ofγ-PGA were 30 g/L lactose,5 g/L yeast extract,and 60 g/L L-sodium glutamate,respectively.The optimal fermentation conditions were 37℃ and pH 7.0.The yield ofγ-PGA increased by 260%from 8.4 g/L before optimization to 30.1 g/L after optimization.The fed-batch fermentation showed the peak yield(59.5 g/L)ofγ-PGA at the time point of 60 h,with a productivity of 0.99 g/(L·h),which increased by 98%compared with the yield in shake flasks.The producedγ-PGA had a molecular weight of 3.8×106 Da and a high polymerization degree.[Conclusion]The optimal fermentation conditions for B.siamensis CAU83 producingγ-PGA determined in this study provide a basis for the industrial production and application of this strain.
作者
林格儿
刘宏
刘海杰
闫巧娟
江正强
LIN Ge’er;LIU Hong;LIU Haijie;YAN Qiaojuan;JIANG Zhengqiang(College of Food Science and Nutritional Engineering,China Agricultural University,Beijing 100083,China;College of Engineering,China Agricultural University,Beijing 100083,China)
出处
《微生物学通报》
CAS
CSCD
北大核心
2022年第8期3335-3345,共11页
Microbiology China
基金
国家重点研发计划(2018YFD0400404)。
