Enhancement mechanism of xanthan gum production in Xanthomonas campestris induced by atmospheric and room-temperature plasma (ARTP) mutagenesis

Xanthan gum, produced by the aerobic fermentation of carbohydrates by Xanthomonas campestris, is a significant natural and industrial biopolymer known for its exceptional properties. Enhancing the yield of xanthan gum production remains a critical challenge. This study employed atmospheric and room temperature plasma (ARTP) technology to induce mutagenesis in X. campestris, resulting in a high-yielding strain, X20. The X20 mutant exhibited a substantial increase in xanthan gum yield, ranging from 13.3 % to 30.0 % over the starting strain across NaCl concentrations of 0, 6.0, and 8.0 g/L, along with improved viscosity and molecular weight. In the whole genome of X20 mutant, a total of 80 variant sites differing from the reference genome were identified, involving 76 mutated genes. Among these, 19 were missense mutations primarily associated with the two-component system. Transcriptome analysis highlighted their role in enhancing flagellar movement, biofilm formation, and metabolic synthesis, thereby elevating the capability of the mutant strain in xanthan gum production. This study demonstrates the potential of ARTP as an effective tool for microbial mutagenesis breeding, providing theoretical guidance for future studies on the synthesis regulation of xanthan gum and the engineering modification of X. campestris.