外源AHLs信号分子对假单胞菌(Pseudomonas)致腐能力的影响

Effect of exogenous AHLs signal molecules on the spoilage ability of Pseudomonas

该文为探究假单胞菌的群体感应(quorum sensing,QS)现象及其对肉品腐败变质的影响,将外源酰基高丝氨酸内酯(acylhomoserine lactone,AHLs)类信号分子添加至假单胞菌培养液中,测定其生长曲线和生物膜变化。用添加AHLs的假单胞菌菌液处理无菌猪肉块,在贮藏过程中进行感官评价,测定挥发性盐基氮(total volatile basic nitrogen,TVB-N),利用气相离子迁移谱(gas chromatography-ion mobility spectrometry,GC-IMS)分析挥发性有机物。结果表明,4种信号分子N-己基-L-高丝氨酸内酯(N-hexanoyl-L-homoserine lactone,C6-HSL)、N-辛酰-L-高丝氨酸内酯(N-octanoyl-L-homoserine lactone,C8-HSL)、N-十二烷基-L-高丝氨酸内酯(N-dodecanoyl-L-homoserine lactone,C12-HSL)和N-十四烷基-L-高丝氨酸内酯(N-tetradecanoyl-L-homoserine lactone,C14-HSL)对假单胞菌的生长繁殖无明显影响(P>0.05),但能促进其生物被膜的形成(P<0.05),其中C8-HSL与C12-HSL的影响最显著。在猪肉贮藏后期,添加AHLs外源信号分子组感官评分明显低于对照组(P<0.05),挥发性盐基氮值高于对照组(P<0.05)。添加外源AHLs信号分子组与新鲜组、对照组所产生的挥发性有机物不同,添加不同信号分子组之间产生的挥发物也存在差异。C14-HSL组与对照组的相似度最高,C6-HSL组与对照组和新鲜组的相似度均最低。该研究说明,外源信号分子C6-HSL、C8-HSL、C12-HSL、C14-HSL对假单胞菌的生长繁殖无影响,但对其致腐能力具有促进作用,且不同信号分子的作用存在差异。

In order to explore the quorum sensing(QS)of Pseudomonas and its effect on meat spoilage,exogenous acylhomoserine lactone(AHLs)-like signal molecules were added to the culture medium of Pseudomonas to measure the growth curves and biofilm change.Sterile pork chunks were treated with Pseudomonas solution supplemented with AHLs.Sensory evaluation was carried out during storage.Total volatile basic nitrogen(TVB-N)was measured.Volatile organic compounds were analyzed by gas chromatography-ion mobility spectrometry(GC-IMS).The results showed that the four signal molecules,N-hexanoyl-L-homoserine lactone(C6-HSL),N-octanoyl-L-homoserine lactone(C8-HSL),N-dodecanoyl-L-homoserine lactone(C12-HSL)and N-tetradecanoyl-L-homoserine lactone(C14-HSL)had no obvious influence on the growth of Pseudomonas(P>0.05),but they could promote the formation of biofilm(P<0.05),of which C8-HSL and C12-HSL had the most significant influence.At the later stage of pork storage,sensory score in the group with exogenous AHLs signal molecules was significantly lower than that in the control group(P<0.05),and theTVB-N value was higher(P<0.05).The volatile organic compounds produced by adding exogenous AHLs signal molecules were different from the fresh group and the control group,and the volatiles produced were also different when adding different signal molecules.The C14-HSL group had the highest similarity with the control group,while the C6-HSL group had the lowest similarity with the control group and the fresh group.This study showed that exogenous signal molecules have no effects on the growth of Pseudomonas.However,they could promote the spoilage ability of Pseudomonas,and the effects of different signal molecules were different.