复合生物保鲜剂对松鼠葡萄球菌的抑菌性能及其作用机理研究

以冷藏带鱼中分离出的革兰氏阳性优势菌——松鼠葡萄球菌(Staphylococcus sciuri)为试验菌,研究复合生物保鲜剂(配比浓度为:壳聚糖10.0 g/L,溶菌酶0.3 g/L与茶多酚3.0 g/L)对松鼠葡萄球菌的抑菌效果与作用机理。通过牛津杯法确定复合保鲜剂对松鼠葡萄球菌的最小抑菌浓度(MIC)与最小杀菌浓度(MBC),结合抑菌活力、细菌生长曲线、碱性磷酸酶(AKP)活性、细胞膜完整性、膜通透性与细菌超微结构观察等,综合评价不同浓度复合保鲜剂在不同处理时间内对松鼠葡萄球菌的作用效果。结果表明,复合保鲜剂对松鼠葡萄球菌的MIC与MBC分别为0.8与1.6 mg/mL,随着处理时间的延长,复合生物保鲜剂明显抑制松鼠葡萄球菌的生长,使菌体细胞外的AKP量增多,造成细菌菌体细胞壁通透性增大,细胞结构的完整性受到破坏,菌液电导率值显著升高,菌体电解质等内容物外泄,影响细胞内环境和细胞膜的稳定性,菌体皱缩变形,表面粗糙,细胞壁塌陷,细胞质外泄渗出,导致菌体死亡。

Antimicrobial Activity and Mechanism of Complex Biological Fresh-keeping Agents against Staphylococcus sciuri

In this paper,gram-positive Staphylococcus sciuri was selected to study the antimicrobial activity and mechanism of complex biological fresh-keeping agents(CBFA),which was composed of chitosan 10.0 g/L,lysozyme 0.3 g/L and tea polyphenol 3.0 g/L.Minimal inhibitory concentration(MIC) and minimal bactericidal concentration(MBC) of CBFA against S.sciuri were determined by oxford plate assay system,and the effects of CBFA with different concentration on bacteria in different time were studied by cell damage experiments,such as antimicrobial kinetics,alkaline phosphatase(AKP) activity,the integrity and permeability of cell membrane,and ultra microstructure of bacteria.The results showed that the MIC and MBC of CBFA against S.sciuri were 0.8 and 1.6 mg/mL.With the extension of treated time,the growth of bacteria was significantly inhibited,the level of AKP increased,the membrane became permeable,the integrity of the cellular structure was undermined,and the electronic conductivity and ultraviolet absorbance of extracellular fluid increased.S.sciuri began to shrink,distorted,surface rough,the cell walls were sunk,the cytoplasm leaked from cells and led to cell death ultimately.