More recently, the development of cytosine base editors (CBEs) and adenine base editors (ABEs) have provided new strategies for precise genetic manipulation . The base editors composed of the fusion of a nucleotide deaminase and a dead Cas9 or a Cas9 nickase, can directly achieve precise C-to-T or A-to-G conversions by a catalytic deamination reaction without requiring HDR, and thus are widely applicable for precise genetic manipulation in a variety of microbes with different genetic background .