外源AHLs信號分子對假單胞菌(Pseudomonas)致腐能力的影響

張玉華，孟一，王順意，陳東杰

1(山東商業職業技術學院,國家農產品現代物流工程技術研究中心,山東 濟南， 250103)2(山東農業工程學院，山東 濟南， 250100)

EffectofexogenousAHLssignalmoleculesonthespoilageabilityofPseudomonas

ZHANG Yuhua1*,MENG Yi1,WANG Shunyi2,CHEN Dongjie1

1(Shandong Institute of Commerce and Technology National Engineering Research Center for Agricultural Products Logistics， Jinan 250103, China)2(Shandong Agriculture and Engineering University, Jinan 250100, China)

ABSTRACTIn order to explore the quorum sensing (QS) ofPseudomonasand its effect on meat spoilage, exogenous acylhomoserine lactone (AHLs) -like signal molecules were added to the culture medium ofPseudomonasto measure the growth curves and biofilm change. Sterile pork chunks were treated withPseudomonassolution 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) andN-tetradecanoyl-L-homoserine lactone(C14-HSL) had no obvious influence on the growth ofPseudomonas(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 ofPseudomonas. However, they could promote the spoilage ability ofPseudomonas, and the effects of different signal molecules were different.

Keywordsacylhomoserine lactone(AHLs);signaling molecule;quorum sensing;Pseudomonas； spoilage ability

大量研究表明，食品腐敗菌的致腐性受群體感應(quorum sensing，QS)系統的調控，腐敗菌的作用與QS密不可分[1-2]。QS是微生物之間的信息交流傳遞機制[3]，當細菌空間數量達到一定密度時，能夠自發地產生并釋放信號分子，當信號分子濃度達到閾值濃度時，細菌就會啟動相關基因的表達，從而調控某些生物行為[4]，如生物發光、毒性因子分泌、孢子產生、生物膜形成和抗生素合成等[5-6]。肉的腐敗變質主要是由分解蛋白質、脂肪的特定腐敗菌(specific spoilage organism, SSO)引起的，在有氧條件下，假單胞菌(Pseudomonas)是冷卻肉主要的SSO[7-8]。因此，研究肉中假單胞菌的QS現象并進行調控，可以控制肉的腐敗進程，對于靶向抑菌及保障肉品質量安全具有重要意義[9]。假單胞菌的QS系統主要是酰基高絲氨酸內酯(acylhomoserine lactone, AHLs)系統，其信號分子為不同長度的AHLs類化合物[10]。

國內外研究者針對肉類腐敗過程中信號分子的種類及其作用開展了廣泛的研究[3]，但在外源信號分子對假單胞菌生長繁殖及對肉品質的影響方面的研究較缺乏。本文研究了4種不同外源信號分子N-己基-L-高絲氨酸內酯(N-hexanoyl-L-homoserine lactone,C6-HSL)、N-辛酰-L-高絲氨酸內酯(N-octanoyl-L-homoserine lactone，C8-HSL)、N-十二烷基-L-高絲氨酸內酯(N-dodecanoyl-L-homoserine lactone,C12-HSL)、N-十四烷基-L-高絲氨酸內酯(N-tetradecanoyl-L-homoserine lactone,C14-HSL)對假單胞菌生長的影響，通過測定冷卻豬肉貯藏過程中感官、揮發性鹽基氮(total volatile basic nitrogen，TVB-N)以及揮發性有機物等指標，探究在外源AHLs信號分子誘導下假單胞菌對冷卻豬肉致腐能力的影響，為進一步明確QS在肉品腐敗中的作用，以及基于干擾腐敗菌QS的冷卻肉防腐保鮮提供依據。