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The commercialized applications of rhamnolipid has seriously impeded by high cost of production caused by severe foaming. Effective low-foaming fermentation and mechanism study have become the most urgent requirement for larger-scale production of rhamnolipid. In this study, the low-foaming fermentation was realized by controlling fermentation at pH 5.5. Further, the production of rhamnolipid was enhanced 0.9-fold by the ultraviolet and ethyl methanesulfonate composite mutagenesis. To the best of our knowledge, this was the first report to enhance production of rhamnolipid by strain improvement at weak-acid conditions. The mechanisms exploration tests indicated that increasing surface tension and decreasing viscosity were conducive to reduce foaming ability of rhamnolipid fermentation. The decrease of negatively charged ions may weaken the electrostatic repulsion between charged substances adsorbed membranes of bubbles such as rhamnolipid and cells, leading to the liquid membranes to rupture easily. In addition, the structure of vesicle or lamellar of rhamnolipid formed at pH5.0-6.0 may also weaken the foaming ability of rhamnolipid fermentation. The work revealed the promising potentiality for genetic modification to enhance the production of rhamnolipid and facilitated the understanding of pH-associated foaming behavior, as well as were conducive to develop a more effective pH-associated control strategies for large-scale production of rhamnolipid.
Keywords
Rhamnolipid fermentation, Pseudomonas aeruginosa, weak-acid conditions, mutagenesis, zeta potential, morphology
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This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
The most recent version of this article is available here.
No community comments so far
Version 1
Posted 12 Jun, 2020
No comments provided
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Applied & Industrial Microbiology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
The most recent version of this article is available here.
The commercialized applications of rhamnolipid has seriously impeded by high cost of production caused by severe foaming. Effective low-foaming fermentation and mechanism study have become the most urgent requirement for larger-scale production of rhamnolipid. In this study, the low-foaming fermentation was realized by controlling fermentation at pH 5.5. Further, the production of rhamnolipid was enhanced 0.9-fold by the ultraviolet and ethyl methanesulfonate composite mutagenesis. To the best of our knowledge, this was the first report to enhance production of rhamnolipid by strain improvement at weak-acid conditions. The mechanisms exploration tests indicated that increasing surface tension and decreasing viscosity were conducive to reduce foaming ability of rhamnolipid fermentation. The decrease of negatively charged ions may weaken the electrostatic repulsion between charged substances adsorbed membranes of bubbles such as rhamnolipid and cells, leading to the liquid membranes to rupture easily. In addition, the structure of vesicle or lamellar of rhamnolipid formed at pH5.0-6.0 may also weaken the foaming ability of rhamnolipid fermentation. The work revealed the promising potentiality for genetic modification to enhance the production of rhamnolipid and facilitated the understanding of pH-associated foaming behavior, as well as were conducive to develop a more effective pH-associated control strategies for large-scale production of rhamnolipid.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
This is a list of supplementary files associated with this preprint. Click to download.
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