Quorum sensing as a potential target for increased production of rhamnolipid biosurfactant in Burkholderia thailandensis E264

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 . Electronic supplementary material The online version of this article (10.1007/s00253-019-09942-5) contains supplementary material, which is available to authorized users.

Quorum Sensing Controls Both Rhamnolipid and Polyhydroxyalkanoate Production in Burkholderia thailandensis Through ScmR Regulation

“…Plus, no involvement of QS into the regulation of known PHA synthesis genes was described in this transcriptomic study, again suggesting the use of culture conditions not appropriate to induce biosynthesis. The production of both rhamnolipids and PHAs was specifically studied with the btaI1 btaI2 btaI3 QS-defective mutant (Irorere et al, 2019) and was affected. Indeed, rhamnolipid production was increased while PHA biosynthesis was decreased (Irorere et al, 2019) which correlates with our observations.…”

“…The production of both rhamnolipids and PHAs was specifically studied with the btaI1 btaI2 btaI3 QS-defective mutant (Irorere et al, 2019) and was affected. Indeed, rhamnolipid production was increased while PHA biosynthesis was decreased (Irorere et al, 2019) which correlates with our observations. Interestingly, in B. thailandensis, QS appears to have an opposite effect on rhamnolipid production compared to in P. aeruginosa or B. glumae.…”

“…In P. aeruginosa and in Burkholderia glumae, rhl biosynthesis genes are under the control of distinct quorum sensing (QS) systems (Soberón-Chávez et al, 2005;Majerczyk et al, 2014a;Nickzad and Déziel, 2016). Although a relationship between QS and the biosynthesis of rhamnolipids has been previously noted in B. thailandensis (Majerczyk et al, 2014b;Irorere et al, 2019), there is very limited information on how QS regulates rhamnolipid production.…”

Characterization of Biofilm Extracts from Two Marine Bacteria

“…Different metabolic pathways that remain inactive under the planktonic growth conditions are commonly used in the research laboratories where they can be activated [5,6]. Many biosynthetic pathways are regulated by QS, including the production of metabolites [7,8], of biosurfactants [9,10], and of antimicrobials [11].…”

“…Different metabolic pathways that remain inactive under the planktonic growth conditions are commonly used in the research laboratories where they can be activated [5,6]. Many biosynthetic pathways are regulated by QS, including the production of metabolites [7,8], of biosurfactants [9,10], and of antimicrobials [11].Biofilm-specific EPM substances may be endowed with diverse physical/chemical properties and with biological activities and functionalities. Polysaccharides (PSs) have been evidenced as the most common components of a bacterial biofilm matrix [12][13][14].…”