Bacterial ghosts (BGs) are nonliving empty bacterial shells without cytoplasm retaining original morphology and identical antigenicity of natural bacteria, making them high potential and promising vaccine candidates and delivery vehicles. However, the low yield of commonly used BGs preparation methods limits its mass production and widely application. In order to improve BGs production, E. coli phage ID52 lysis protein E was introduced to generating BGs for the first time. Above all, we compared the lysis activity of lysis protein of E. coli phage φX174 and E. coli phage ID52 as well as the effects of promoters on the lysis activity of ID52-E, which shown that the lysis activity and BGs formation rate of protein ID52-E was significantly higher than protein φX174-E. Further, the lysis activity of ID52-E was significantly improved under the control of L-arabinose inducible promoter which initial induction OD600 reached as high as 2.0. The applicability of lysis protein ID52-E induced by L-arabinose was proved by preparing probiotic E. coli Nissle 1917 BGs and pathogenic Salmonella typhimurium BGs in mass production. This paper introduced a novel and highly efficient method for BGs preparation depending on recombinant expression of E. coli phage ID52-E under eco-friendly and reasonable price inducer L-arabinose.

Tumor-associated macrophages (TAMs) promote tumor development and metastasis and are categorized into M1-like macrophages, suppressing tumor cells, and M2-like macrophages. M2-like macrophages, occupying a major role in TAMs, can be repolarized into anti-tumoral phenotypes. In this study, outer membrane vesicles (OMVs) secreted by Escherichia coli Nissle 1917 carry perhexiline (OMV@Perhx) to explore the influence of OMVs and perhexiline on TAM repolarization. OMV@Perhx was internalized by macrophages and regulated the phenotype of TAMs from M2-like to M1-like efficiently to increase the level of tumor suppressor accordingly. Re-polarized macrophages promoted apoptosis and inhibited the mobility of tumor, cells including invasion and migration. The results indicate that OMVs improve the efficacy of perhexiline and also represent a promising natural immunomodulator. Combining OMVs with perhexiline treatments shows powerfully synergistic anti-tumor effects through co-culturing with re-polarized macrophages. This work is promising to exploit the extensive applications of OMVs and chemical drugs, therefore developing a meaningful drug carrier and immunomodulator as well as expanding the purposes of traditional chemical drugs.