Abstract: Probiotics are a kind of microorganisms that contribute to the health of animals.They play an important role in improving the immunity of animals,the balance of intestinal microorganisms and the environment of livestock farms.In recent years,scholars in domestic and foreign have gradually deepened their exploration of genetic engineering technology which applied it in practical production.However,the vast majority of research has focused on eukaryotes.On this basis,how to apply gene editing technology to probiotics and make probiotics play a greater potential is the current research upsurge.Therefore,through genetic engineering technology,specific genes and probiotics can be gene edited and expressed,and the edited probiotics can express specific genes or target to play an immunomodulatory role on the host.In this paper,the interaction between probiotics gene-edited and host have been summarized.The application of CRISPR-Cas9 technology in gene editing lactic acid bacteria and animal production is reviewed.Meanwhile,the methods of gene editing of lactic acid bacteria by different gene editing technologies are analyzed and compared.It is found that CRISPR-Cas9 technology is a relatively flexible gene editing tool for food-grade probiotics such as lactobacillus and bifidobacteria,so as to realize the purpose that probiotics can play multiple health effects in the host body,and the future application of CRISPR-Cas9 technology in gene editing lactobacillus is prospected.In the future,CRISPR-Cas9 technology will be combined with other gene editing methods to explore faster,more efficient and simple probiotic gene editing technology.

Key words: genetic engineering; probiotics; lactic acid bacteria; CRISPR-Cas9 technology; immune regulation