盐单胞菌利用短链脂肪酸合成聚羟基脂肪酸酯

Halomonas uses short-chain fatty acids to synthesize polyhydroxyalkanoates

摘要:

盐单胞菌(Halomonas)能够利用多种底物为碳源生长,由于其能在高盐条件下进行不灭菌的开放发酵,已被开发用作下一代生物技术的底盘细胞。包括乙酸、丙酸和丁酸在内的短链挥发性脂肪酸能够以生物质为原料制备,有望成为用于微生物发酵的新型碳源。利用10-50 g/L浓度的丁酸为碳源对Halomonassp.TD01和TD08进行摇瓶培养,结果发现Halomonassp.TD01和TD08能够有效利用丁酸合成聚-3-羟基丁酸酯,20 g/L丁酸获得的聚酯产量最高,分别达到9.12 g/L和7.37 g/L;更高浓度的丁酸抑制了细胞生长,50 g/L丁酸条件下的聚酯产量下降至4.00 g/L以下。此外,Halomonassp.TD08可以利用丁酸和丙酸为混合碳源合成3-羟基丁酸和3-羟基戊酸共聚酯,但丙酸对细胞生长具有较大毒性,2 g/L丙酸和20 g/L丁酸为混合碳源时的细胞干重仅为0.83 g/L,聚酯产量仅为0.15 g/L。通过添加甘油为辅助碳源,明显改善了细胞生长,使得共聚酯的产量提高至3.95 g/L,其中3-羟基戊酸单体含量为8.76 mol%。短链挥发性脂肪酸在盐单胞菌生产聚羟基脂肪酸酯中具有良好的应用前景。

Abstract:

Halomonas can grow on diverse carbon sources.As it can be used for unsterile fermentation under high-salt conditions,it has been applied as a chassis for next-generation industrial biotechnology.Short-chain volatile fatty acids,including acetate,propionate,and butyrate,can be prepared from biomass and are expected to be novel carbon sources for microbial fermentation.Halomonas sp.TD01 and TD08 were subjected to shaking culture with 10-50 g/L butyrate,and they were found to effectively synthesize poly-3-hydroxybutyrate with butyrate as the carbon source.The highest yield of poly-3-hydroxybutyrate was achieved at butyrate concentration of 20 g/L (9.12 g/L and 7.37 g/L,respectively).Butyrate at the concentration>20 g/L inhibited cell growth,and the yield of poly-3-hydroxybutyrate decreased to<4 g/L when butyrate concentration was 50 g/L.Moreover,Halomonas sp.TD08 can accumulate the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate by using propionate and butyrate as carbon sources.However,propionate was toxic to cells.To be specific,when 2 g/L propionate and 20 g/L butyrate were simultaneously provided,cell dry weight and polymer titer were 0.83 g/L and 0.15 g/L,respectively.The addition of glycerol significantly improved cell growth and boosted the copolymer titer to 3.95 g/L,with 3-hydroxyvalerate monomer content of 8.76 mol%.Short-chain volatile fatty acids would be promising carbon sources for the production of polyhydroxyalkanoates by Halomonas.