To reduce the cost of fermentation and improve the efficiency of microbial oil recovery,we carried out an open fermentation exploration of oil-producing 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 fermenta-tion.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 fermen-tation 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 mono-rhamnolipids 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.
Pseudomonas aeruginosaopen fermentationrhamnolipidsinhibition rate of miscellaneous bacteria
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