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Anaerobic biosynthesis of rhamnolipids by Pseudomonas aeruginosa: performance, mechanism and its application potential for enhanced oil recovery.
- Source :
-
Microbial cell factories [Microb Cell Fact] 2021 May 20; Vol. 20 (1), pp. 103. Date of Electronic Publication: 2021 May 20. - Publication Year :
- 2021
-
Abstract
- Background: Pseudomonas aeruginosa, the rhamnolipids-producer, is one of dominant bacteria in oil reservoirs. Although P. aeruginosa strains are facultative bacteria, the anaerobic biosynthesis mechanism of rhamnolipids is unclear. Considering the oxygen scarcity within oil reservoirs, revealing the anaerobic biosynthesis mechanism of rhamnolipids are significant for improving the in-situ production of rhamnolipids in oil reservoirs to enhance oil recovery.<br />Results: Pseudomonas aeruginosa SG anaerobically produced rhamnolipids using glycerol rather than glucose as carbon sources. Two possible hypotheses on anaerobic biosynthesis of rhamnolipids were proposed, the new anaerobic biosynthetic pathway (hypothesis 1) and the highly anaerobic expression of key genes (hypothesis 2). Knockout strain SGΔrmlB failed to anaerobically produce rhamnolipids using glycerol. Comparative transcriptomics analysis results revealed that glucose inhibited the anaerobic expression of genes rmlBDAC, fabABG, rhlABRI, rhlC and lasI. Using glycerol as carbon source, the anaerobic expression of key genes in P. aeruginosa SG was significantly up-regulated. The anaerobic biosynthetic pathway of rhamnolipids in P. aeruginosa SG were confirmed, involving the gluconeogenesis from glycerol, the biosynthesis of dTDP-L-rhamnose and β-hydroxy fatty acids, and the rhamnosyl transfer process. The engineered strain P. aeruginosa PrhlAB constructed in previous work enhanced 9.67% of oil recovery higher than the wild-type strain P. aeruginosa SG enhancing 8.33% of oil recovery.<br />Conclusion: The highly anaerobic expression of key genes enables P. aeruginosa SG to anaerobically biosynthesize rhamnolipids. The genes, rmlBDAC, fabABG, rhlABRI, rhlC and lasI, are key genes for anaerobic biosynthesis of rhamnolipid by P. aeruginosa. Improving the anaerobic production of rhamnolipids better enhanced oil recovery in core flooding test. This study fills the gaps in the anaerobic biosynthesis mechanism of rhamnolipids. Results are significant for the metabolic engineering of P. aeruginosa to enhance anaerobic production of rhamnolipids.
- Subjects :
- Anaerobiosis
Gene Expression Profiling
Gene Expression Regulation, Bacterial
Gene Knockout Techniques
Glucose metabolism
Industrial Microbiology
Oil and Gas Fields microbiology
Operon
Sequence Analysis, RNA
Biosynthetic Pathways
Glycerol metabolism
Glycolipids biosynthesis
Glycolipids genetics
Metabolic Engineering
Pseudomonas aeruginosa genetics
Pseudomonas aeruginosa metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1475-2859
- Volume :
- 20
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Microbial cell factories
- Publication Type :
- Academic Journal
- Accession number :
- 34016105
- Full Text :
- https://doi.org/10.1186/s12934-021-01593-4