Abstract
Burkholderia thailandensis E264 is a potential non-pathogenic substitute for producing rhamnolipid biosurfactant, replacing the pathogenic Pseudomonas aeruginosa. However, it has low rhamnolipid production and longer fermentation time. We have earlier suggested that media supplementation with exogenous quorum sensing (QS) molecules could lead to early onset of biosynthesis and increased rhamnolipid yield. Here, we assessed the effect of single, double or triple mutations in the various QS systems of B. thailandensis on rhamnolipid production, with the view to see which system(s) have the most impact on rhamnolipid yield and subsequently use the QS molecule to potentially increase yield in the wild-type B. thailandensis. The triple mutant strain had a rhamnolipid yield of 4.46 ± 0.345 g/l at 240 h of fermentation which was significantly higher than that of the wild type (0.94 ± 0.06 g/l), an unexpected outcome. To gain more insight as to how this might occur, we studied substrate metabolism and energy storage in the form of polyhydroxyalkanoate (PHA) by both the triple mutant and the wild type. We observed increased glycerol metabolism and reduced PHA production in the triple mutant compared with the wild type. Glycerol concentration at 240 h and maximum PHA productivity (g/gDCB) were 8.76 g/l or 16.19 g/l and 21.80% or 31.4% in either the triple mutant or the wild type respectively. Complementation of the triple-mutant cultures with exogenous QS molecules restored rhamnolipid production to similar levels as the wild type. QS therefore is a potential target for increased rhamnolipid production in B. thailandensis.
Highlights
The term quorum sensing (QS) describes the cell-to-cell communication mechanism/s in bacteria, which produces coordinated behaviours within a bacterial population upon the establishment of a quorum
Low levels of rhamnolipid production and the significantly longer fermentation time required to produce substantial quantities of rhamnolipid are major factors affecting the implementation of B. thailandensis in the industrial production of rhamnolipid
Iron limitation in the production media and the introduction of exogenous quorum sensing molecules have been suggested as ways of inducing early rhamnolipid synthesis and improving overall rhamnolipid yield (Irorere et al 2018)
Summary
The term quorum sensing (QS) describes the cell-to-cell communication mechanism/s in bacteria, which produces coordinated behaviours within a bacterial population upon the establishment of a quorum This is achieved through the production, sensing and response to chemical signalling molecules known as pheromones, quorumones or autoinducers. QS-regulated processes are usually those that are costly or ineffective when carried out by a single bacterium, but become effective when carried out by a population of bacteria This phenomenon has been described as one that enables a bacterial population to act as a multicellular organism and obtain benefits which are unachievable should they act alone (Bassler and Losick 2006). QS has been implicated in the regulation of various bacterial physiological processes including antibiotic resistance, antibiotic synthesis, production of exopolysaccharide and rhamnolipid synthesis (Bjarnsholt et al 2005; Duerkop et al 2009; Marketon et al 2003; Nickzad and Déziel 2016; Nickzad et al 2015)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
