Oligonucleotide synthesis

The strains, plasmids, and primers were defined in Supplementary Tables 1–3, respectively. The plasmids were constructed according to the conventional molecular biology techniques, such as PCR, DNA restriction, ligation, transformation, and positive colony selection (Aviv and Gal-Mor, 2018 (link)). Endonucleases and DNA polymerase were purchased from New England Biolabs (Ipswich, MA, United States). The DNA purification kit, oligonucleotide synthesis, and DNA sequencing were provided by Sangon Biotech (Shanghai, China). To construct the fluorescent reporter plasmid pDH116, both the promoter of the ompA gene and encoding region of enhanced green fluorescent protein (EGFP) were amplified by primers in Supplementary Table 3. The two DNA fragments were purified and combined to a fusion by overlap extension PCR and were subsequently inserted into the backbone of plasmid pDH113 (Liu et al., 2015 (link)).

Oligonucleotide synthesis (listed in Supplementary Table S1) and DNA sequencing were performed by Sangon Biotech Co., Ltd. (Shanghai, China). The isolation and manipulation of DNA were carried out using standard techniques. All enzymes were commercial preparations and were used as specified by the supplier (NEB, Shanghai, China).