High cell-density fermentation, expression and purification of bacteriophage lysin TSPphg, a thermostable antimicrobial protein from extremophilic Thermus bacteriophage TSP4.

Feng Wang, Guanling Zhang, Jiani Peng, Xinyu Ji, Jun Hai, Xianyu Deng, Lianbing Lin

Protein expression and purification 2020 Oct

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Recently, high cell-density (HCD) cultivation has become an important tool for production of many microbial products. However, to the best of our knowledge, no study regarding HCD fermentation, overproduction and purification of thermostable bacteriophage lysin has been reported. Here, by employing a glucose-limited fed-batch strategy, we performed high density fermentation of the host Escherichia coli BL21(DE3) cells, compared the efficiency of high pressure homogenization, ultrasonication and thermolysis in bacterial cell disruption after HCD cultivation, and purified TSPphg, a thermostable lysin derived from extremophilic bacteriophage TSP4. On the 20-L scale, the overproduction level of TSPphg was up to 67.8 ± 0.7%. In total, we obtained a broth titer of 3322.8 ± 26 mg/L TSPphg with a purity of 95.5 ± 0.7% from a bacterial cell mass of 86.3 ± 4.9 g/L after 26 h of fermentation. The overall productivity of TSPphg was 127.8 ± 1 mg/L/h. Additionally, the antimicrobial activity of purified TSPphg against both Gram-negative (Escherichia coli O157) and Gram-positive (Staphylococcus aureus) pathogenic bacteria was further confirmed by scanning electron microscope analysis. Summarily, for the first time, we have established a relatively stable and efficient HCD cultivation and purification process for recovery of thermostable lysins from extremophilic Thermus bacteriophages. Our results provide insights into the strategies for time-saving and cost-effective production of antimicrobial proteins to replace or supplement antibiotics in the current age of mounting antibiotic resistance. Copyright © 2020 Elsevier Inc. All rights reserved.

Citation

Feng Wang, Guanling Zhang, Jiani Peng, Xinyu Ji, Jun Hai, Xianyu Deng, Lianbing Lin. High cell-density fermentation, expression and purification of bacteriophage lysin TSPphg, a thermostable antimicrobial protein from extremophilic Thermus bacteriophage TSP4. Protein expression and purification. 2020 Oct;174:105676