铜绿假单胞菌SQ6开放式发酵生产鼠李糖

Production of rhamnolipids by open fermentation of Pseudomonas aeruginosa SQ6

为降低发酵成本,提高微生物采油效率,本研究开展了采油功能菌SQ6(鼠李糖脂产生菌)的开放式发酵探索研究。考察了菌株SQ6在常规发酵和开放式发酵方式不同温度下的生长、鼠李糖脂产量、表面张力及乳化指数等参数,采用液相色谱高分辨质谱联用仪分析了鼠李糖脂产物同系物组成,高通量测序分析了开放式发酵的细菌群落结构和杂菌率。结果表明:菌株SQ6最高生长温度是45℃,能够合成大量鼠李糖脂的最高温度是40℃;开放式发酵产量最高、杂菌率最低的发酵温度是37℃,鼠李糖脂产量达到7050.1 mg·L^(-1),仅比常规发酵的10513.2 mg·L^(-1)降低了33%,杂菌率最低,达到3.13%;针对SQ6菌株,高温发酵并没有更好的杂菌抑制效果并且降低了鼠李糖脂产量,发酵产物结构显示产物以单鼠李糖脂为主,占比达到96.1%。高浓度单鼠李糖脂的合成可能是中温条件下开放式发酵具有较好杂菌抑制率的主要原因。菌株SQ6是一株具有较大开放式发酵潜力的采油功能菌。

To reduce the cost of fermentation and improve the efficiency of microbial oil recovery,we carried out an open fermentation exploration of oilproducing functional bacterium SQ6(rhamnolipids⁃producing strain).We investigated the growth at different temperatures,rhamnolipid production,surface tension,emulsification index and other parameters of strain SQ6 under two fermentation modes,i.e.,conventional fermentation and open fermentation.The homologous composition of rhamnolipid products was analyzed by liquid chromatography⁃high resolution mass spectrometry,and the bacterial community structure and percentage of microbial contaminants of open fermentation were analyzed by high⁃throughput sequencing.The results showed that the highest growth of strain SQ6 was at 45℃,and the highest temperature for synthesizing a large amount of rhamnolipids was 40℃.The fermentation temperature with the highest yield and lowest miscellaneous bacteria rate in open fermentation was 37℃,the yield of rhamnolipids reached 7050.1 mg·L^(-1),which was only 33%lower than that of conventional fermentation(10513.2 mg·L^(-1)),and miscellaneous bacteria rate was the lowest reaching 3.13%.For the SQ6 strain,high⁃temperature fermentation did not have a stronger inhibitory effect on microbial contaminants and reduced the pro⁃duction of rhamnolipids.The structure of fermentation product showed that the main product was mono⁃rhamnolip⁃ids,accounting for 96.1%.The synthesis of monorhamnolipids in high concentration may be the main reason for the stronger inhibition rate of bacterial contaminants in open fermentation under medium temperature.Therefore,strain SQ6 is a functional oil recovery bacterium with substantial open fermentation potential.