应用PCR-DGGE研究冷却猪肉贮藏过程中的优势菌

Study on the dominant bacteria during the storage period on chilled pork using PCR-DGGE

【目的】研究冷却猪肉贮藏过程中优势细菌的分布，为研究冷却猪肉防腐剂和延长货架期提供参考。【方法】分别选择3个不同企业，取宰后24h的猪背长肌，于4℃托盘包装，分别贮藏2，4，6d提取细菌总DNA，对细菌16S rDNA的V6～V8区段进行PCR扩增，扩增产物进行变性梯度凝胶电泳（DGGE），对DGGE图谱进行微生物多样性分析，并对主要条带进行测序分析。【结果】对4℃贮藏的冷却猪肉DGGE图谱上的主要条带进行测序分析，获得6种不同的细菌。热杀索丝菌（Brochothrix thermosphacta）（条带1）在贮藏4d的样品中，A5没有相应条带，在贮藏6d的样品中，A7、A8上的条带不占优势，在其他样品中均以优势菌的形式出现；气单胞菌（Aeromonas．sp）所对应的条带3在贮藏4和6d的样品中都较亮，与贮藏2d的样品相比，在贮藏4d之前有所增加，于贮藏6d时趋于稳定，是优势菌之一；假单胞菌（Pseudomonas．sp）所对应的条带4一直较亮，并呈持续增加趋势，是主要的优势菌之一；葡萄球菌（Staphylococcus.sp）所对应的条带5在贮藏2d内条带不清晰，贮藏到6d时条带清晰明亮；莫拉氏菌（Moraxella．sp）（条带2）和节杆菌（Arthrobacter．sp）（条带6）所对应的条带一直不是很亮。【结论】假单胞菌、热杀索丝菌、气单胞菌（Aeromonas．sp）是冷却猪肉贮藏过程中的优势菌；葡萄球菌一旦存在，将逐步发展成优势菌。

[Objective] The study explored the distribution of dominant bacteria of chilled pork during the storage period in order to provide reference for the study of antiseptic and to extend shelf life of chilled pork. [Method] Pork loin steaks were obtained at 24 h postmortem in three commercial meat plants. All the steaks were tray-packaged at 4℃ for further 2,4,6 days respectively. The total bacteria DNA of meat samples was extracted to amplify the V6-V8 regions of the bacterial 16S rDNA gene. PCR products were used to denature gradient gel electrophoresis （DGGE）. The DGGE profiles were used to analyze the bacteria diversity and DNA in the main band on the DGGE profiles of bacteria community in chilled pork was sequenced and analyzed. [Result] Six types of bacteria were identified by DNA sequence and analyzed in the main band on the DGGE profiles in chilled pork stored at 4℃. The band one corresponding to Brochothrix thermosphacta was not observed on A5 on the 4th day of storing and on A7 and A8 on the 6th day of storing were not the dominant, except that others were the dominant microorganisms. The band three corresponding to Aerornonas. sp was bright on the 4th and 6th day of storing. Aeromonas. sp increased up to day 4 and then inclined to stabilize on day 6 compared to the samples stored for 2 days. It was one of the dominant microorganisms in chilled pork. The band four corresponding to Pseudornonas. sp was bright all through the storage and continued to increase during storage. It was demonstrated to be one of dominant flora. The band five corresponding to Staphylococcus. sp was faint on the 2nd day but bright on the 6th day,The band six and two corresponding to Moraxella. sp and Arthrobacter. sp were not bright during storage. [Conclusion] Pseudomonas. sp, Brochothrix therrnosphacta and Aerornonas. sp were the dominant microorganisms in chilled pork during storage. Once Staphylococcus. sp was observed,it would be gradually developed into the dominant microorganism in chilled pork.