Enhanced production of mono-rhamnolipid in Pseudomonas aeruginosa and application potential in agriculture and petroleum industry

Differences in the rhamnolipid structures must result in its different activities, thus affecting its application effect. The rhlC gene in Pseudomonas aeruginosa SG was knocked out to construct strain P. aeruginosa SG Delta rhlC. Rhamnolipid production was enhanced by 23.3% through knocking out rhlC gene. P. aeruginosa SGArhlC produced 14.22 g/L of rhamnolipid using glycerol and nitrate. Five kinds of mono-rhamnolipid but no dirhamnolipid were produced by strain SG Delta rhlC. The main rhamnolipid homologues were Rha-C-10-C-10, RhaC(10)-C-12:1 and Rha-C10-C12. Mono-rhamnolipid exhibited better antimicrobial activity to Escherichia coli, Staphylococcus aureus, Aspergillus niger and Penicillium chrysogenum. Rhamnolipid produced from strain SGArhlC showed greater emulsifying activity to crude oil with EI24 of 84.73%. Rhamnolipid produced from strain SGArhlC efficiently washed oily sludge at 35 degrees. High-producing strain P. aeruginosa SGArhlC and its produced mono-rhamnolipid are more promising in agriculture and petroleum industry. This study is a step forward to the tailor-made biosynthesis and application of rhamnolipid.

Automated summary

The study successfully enhanced rhamnolipid production by knocking out the rhlC gene, resulting in increased antimicrobial and emulsifying activities of the produced mono-rhamnolipids. The high-producing strain P. aeruginosa SGArhlC and its mono-rhamnolipids show promising potential for applications in agriculture and petroleum industry. This research represents a step forward in the tailor-made biosynthesis and application of rhamnolipids.