[Expression and degradation function analysis of the key genes from <i>Arthrobacter</i> <i>nitroquajacolicus</i> HW08 in <i>Lactococcus lactis</i> for the degradation of swainsonine].

In order to mitigate the adverse effects of madrassa poisoning disease on our livestock industry and to fully utilize the potential pasture resources, biodegradation of locoweed can remove swainsonine, the major toxic component of locoweed, so that the locoweed can be used as high-quality forage. <i>Arthrobacter nitroquajacolicus</i> HW08 can stably and efficiently degrade swainsonine. In this study, <i>Lactococcus lactis</i>, as a food-grade microorganism, was used as a vector to express four key degradation genes from <i>A</i>. <i>nitroquajacolicus</i> HW08. Subsequently, liquid chromatography was employed to evaluate the swainsonine-degrading performance. The crude enzyme solution extracted from the <i>L</i>. <i>lactis</i> strain transformed with the ethanol dehydrogenase gene <i>A1R6C3</i> degraded 323.4 μg of swainsonine in 24 h at 30 ℃. The crude enzyme solutions from the <i>L</i>. <i>lactis</i> strains transformed with the genes encoding glutathione synthase, esterase/acyl hydrolase, and glycosyltransferase did not show any degradation ability for swainsonine when being used alone but degraded about 140.5 μg of swainsonine when being used in mixture. The findings will help the clinical promotion of swainsonine-degrading engineering strains and provide new research ideas for the prevention and treatment of swainsonine poisoning in animals and the detoxification and utilization of locoweed.