The invention discloses a multi-
gene stacking knockout method for bacillus. The multi-
gene stacking knockout method includes: inserting homologous arm
gene segments of upstream and downstream of multiple genes to be knocked out of the bacillus into thermo-sensitive type plasmids to convert the bacillus, forcing homologous single-
crossover to happen to knockout plasmids in the bacillus and
genome DNA (
deoxyribose nucleic acid) of the knockout plasmids through high-temperature culture, and screening double-
crossover bacterial strains through high-temperature subculture; extracting the
genome DNAs of the multiple bacterial strains successful in gene single-
crossover, performing double-crossover screening, stacking the bacterial strains successful in knockout as host strains for the
nest round of stacking knockout, and sequentially stacking to finally realize multi-
gene knockout of the bacillus. Traceless
gene knockout of the bacillus is realized with the thermo-sensitive type plasmids, conversion efficiency can be improved by using the single-crossover hose
genome DNAs to convert the bacillus, restoration of the knockout genes in the host strains can be effectively avoided, and multi-gene stacking knockout efficiency is remarkably improved.