Knockdown of motility-related genes of Komagataeibacter xylinus and its effect on bacterial cellulose synthesis

Abstract

Bacterial cellulose (BC) is a biopolymer synthesized by bacteria, which possess excellent characteristics such as high water holding capacity, high crystallinity, and high purity. It is widely used in food, medical, cosmetics, and functional films. Komagataeibacter xylinus is a model strain used in BC synthesis research. In bacteria, motility-related genes are associated with BC synthesis, whereas in Komagataeibacter xylinus CGMCC 2955, the functions of motility-related genes and their effects on BC synthesis are not known. To address this gap, we used the λ Red recombinant system to individually knock out motA, motB, and mot2A respectively, and constructed the knockout strains K. x-ΔmotA, K. x-ΔmotB, and K. x-Δmot2A. Additionally, both motA and motB were disrupted to construct the K. x-ΔmotAB mutant. The results demonstrated that knockout strain K. x-ΔmotAB exhibited the highest BC yield, reaching (5.05±0.26) g/L, which represented an increase of approximately 24% compared to wild-type strains. Furthermore, the BC synthesized by this strain exhibited the lowest porosity, 54.35%, and displayed superior mechanical properties with a Young's modulus of up to 5.21 GPa. As knocking out motA and motB genes in K. xylinus CGMCC 2955 did not reduce BC yield; instead, it promoted BC synthesis. Consequently, this research further deepened our understanding of the relationship between motility and BC synthesis in acetic acid bacteria. The knockouts of motA and motB genes resulted in reduced BC porosity and improved mechanical properties, provides a reference for BC synthesis and membrane structure regulation modification.