Ruihua Su1,2,3, Tangfei Li2,3, Daming Fan1,2,3,4, Jianlian Huang1,3,5, Jianxin Zhao2,3,4, Bowen Yan2,3, Wenguo Zhou1,5, Wenhai Zhang1,5, Hao Zhang2,3,4. 1. Key Laboratory of Refrigeration and Conditioning Aquatie Products Processing, Ministry of Agriculture and Rural Affairs, Xiamen, China. 2. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China. 3. School of Food Science and Technology, Jiangnan University, Wuxi, China. 4. Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Wuxi, China. 5. Fujian Anjoyfood Share Co. Ltd., Xiamen, China.
Abstract
BACKGROUND: Refrigeration is commonly used in the processing and storage of surimi products. However, refrigerated surimi products are susceptible to microbial contamination, which leads to deterioration of the products and shortens their shelf life. The aims of the present study were therefore to evaluate the effects of ϵ-polylysine (ϵ-PL) on spoilage bacteria in surimi products, and to investigate the antibacterial mechanism of Bacillus cereus, which is the dominant spoilage bacterium. RESULTS: ϵ-Polylysine with a high degree of polymerization (20-30K) proved able to decrease the total number of colonies in surimi products and showed an obvious antibacterial effect against B. cereus. After ϵ-PL treatments, the distinct broken areas on the bacterial surfaces and the aggregations of cells were observed by scanning electron microscope (SEM). The intracellular materials, such as small molecules, soluble proteins, and deoxyribonucleic acids in the cells were analyzed, which revealed the destructive effects of ϵ-PL on bacterial cells. Experiments with propidium iodide (PI) infiltration experiments verified that the permeability of cell membranes was enhanced by ϵ-PL treatment. CONCLUSION: These results indicated that ϵ-PL could destroy the cell membranes and change the permeability of B. cereus, and subsequently the cell contents leaked out to achieve antibacterial effects.
BACKGROUND: Refrigeration is commonly used in the processing and storage of surimi products. However, refrigerated surimi products are susceptible to microbial contamination, which leads to deterioration of the products and shortens their shelf life. The aims of the present study were therefore to evaluate the effects of ϵ-polylysine (ϵ-PL) on spoilage bacteria in surimi products, and to investigate the antibacterial mechanism of Bacillus cereus, which is the dominant spoilage bacterium. RESULTS: ϵ-Polylysine with a high degree of polymerization (20-30K) proved able to decrease the total number of colonies in surimi products and showed an obvious antibacterial effect against B. cereus. After ϵ-PL treatments, the distinct broken areas on the bacterial surfaces and the aggregations of cells were observed by scanning electron microscope (SEM). The intracellular materials, such as small molecules, soluble proteins, and deoxyribonucleic acids in the cells were analyzed, which revealed the destructive effects of ϵ-PL on bacterial cells. Experiments with propidium iodide (PI) infiltration experiments verified that the permeability of cell membranes was enhanced by ϵ-PL treatment. CONCLUSION: These results indicated that ϵ-PL could destroy the cell membranes and change the permeability of B. cereus, and subsequently the cell contents leaked out to achieve antibacterial effects.