Surface display of Lys0859, a Streptococcus suis prophage Lysin, on Bacillus subtilis spores and its antibacterial activity against Streptococcus suis

Ping Qian ^* Linkang Wang Xiaochao Duan Mengyuan Zhu Haiyan Wang Xinxin Li Dayue Hu Xiangmin Li

• Key Laboratory of Agricultural Microbial Resources Utilization, Huazhong Agricultural University, Wuhan, Hubei, China

Streptococcus suis, an important zoonotic and opportunistic pathogen in pigs, can cause diverse diseases. It brings huge economic losses to the pig -raising industry and infects humans with diseases like pneumonia, arthritis and meningitis, threatening public health. Phage lysin is regarded as a promising substitute for antibiotics due to its ability to quickly and efficiently kill bacteria without easily developing resistance.However, the poor resistance of phage lysin to environmental attacks (high temperature, strong acid, and proteases etc.) has restricted their practical applications.In this study, the Lys0859 protein was successfully displayed on the surface of B. subtilis spores using spore coat protein CotG as an anchoring motif. The resistance of tethered Lys0859 to environmental attacks was significantly enhanced, compared with that of the free Lys0859. Moreover, the bactericidal activity of 1×10 6 CFU rBS CotG-0859 spores was equivalent to the efficacy of 39.11 μg of free Lys0859 against S. suis SC19.In vivo, the bacterial load of S. suis SC19 in all organs and blood of mice treatment with rBS CotG-0859 spores decreased 0.47 to 1.96 logs (p < 0.05) compared with the PBS treated group. Collectively, our findings suggest that the rBS CotG-0859 is a promising biological agent provides a new strategy against streptococci infection.