Intracellular Expression of Antifreeze Peptides in Food Grade Lactococcus lactisand Evaluation of Their Cryoprotective Activity

• Autores: Li Zhang, Quan Jin, Jing Luo, Jihong Wu, Shaoyun Wang, Zhengfu Wang, Shengxiang Gong, Wei Zhang, Xiaohong Lan
• Localización: Journal of food science, ISSN 0022-1147, Vol. 83, Nº 5, 2018, págs. 1311-1320
• Idioma: inglés
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• Resumen

  • Antifreeze peptides can protect living organisms from low temperatures by preventing damage or killing due to ice crystal formation between cells. Therefore, antifreeze peptides can be used as a low temperature protectant for cryopreservation of cells and tissues, and also in food production. In this study, a recombinant SF‐P gene was constructed and inserted into pNZ8149 to construct a food grade expression vector, which was then electroporated into Lactococcus lactisNZ3900. The expression of the target protein was induced using Nisin, and the optimal expression condition was determined to be a pH of 6.0, Nisin concentration of 25 ng/mL, temperature of 37 °C, and incubation time of 6 hr. Compared to the strain NZ3900 and the recombinant strain SF‐P1without addition of Nisin, the recombinant strain SF‐P2showed the highest cell survival and thermal hysteresis activity, and had a reduction in the changes of activities of extracellular and intracellular lactate dehydrogenase and β‐galactosidase after freezing. Moreover, analysis by SEM showed that SF‐P2cells were more completely and regularly shaped than other strains, displayed no obvious leakage of cell contents, and had an intact boundary between cells after freezing. These results indicate that the recombinant strain SF‐P2has a protective effect against freezing. This paper presents a food grade expression system for an antifreeze peptide SF‐P using L. lactisas a host, and shows that the intracellular expression of antifreeze peptide could protect the cellular integrity and physiological functions of L. lactis. The recombinant Lactococcus lactiswith intracellular expression of antifreeze peptides SF‐P could reduce the damage of bacteria cells induced by freezing or freeze drying, so, it could be applied in the process of freezing food without separation, such as the manufacture of yoghurt ice cream, frozen dough, and so on.