The production of bacterial cellulose in Gluconacetobacter xylinus regulated by luxR overexpression of quorum sensing system

Quorum sensing is a mechanism that facilitates cell-to-cell communication. Through signal molecular density for signal recognition, which leads to the regulation of some physiological and biochemical functions. Gluconacetobacter xylinus CGMCC 2955, which produces bacterial cellulose (BC), synthesizes the LuxR protein belonging to the LuxI/LuxR type QS system. Here, a luxR overexpression vector was transformed into G. xylinus CGMCC 2955. The overexpression of luxR increased the yield of BC by 15.6% after 16 days static culture and reduced the cell density by 15.5% after 120-h-agitated culture. The glucose was used up by G. xylinus-pMV24-luxR at 72-h-agitated fermentation, which 12 h earlier than the wild-type (WT). The total N-acylhomoserine lactones (AHL) content of the luxR-overexpressing strain and the WT strain attained 1367.9 +/- 57.86 mg/L and 842.9 +/- 54.22 mg/L, respectively. The C-12-HSL and C-14-HSL contents of G. xylinus-pMV24-luxR were 202 +/- 21.66 mg/L and 409.6 +/- 0.91 mg/L, which were significantly lower than that of WT. In contrast, C-6-HSL showed opposite results. The difference of AHL content proved that overexpression of luxR improved the binding of AHL and showed preference for some specific AHL. The metabolic results demonstrated that upon glucose exhaustion, the consumption of gluconic acid was promoted by luxR overexpression, and the content of D- ( +)-trehalose, an antiretrograde metabolite, increased significantly.

Automated summary

The overexpression of luxR in Gluconacetobacter xylinus CGMCC 2955 significantly increased the production of bacterial cellulose and promoted the metabolism of certain compounds. The difference in AHL content between the luxR-overexpressing strain and the wild-type strain indicated an improved AHL binding and preference for specific AHLs.