基于宏基因组学技术分析不同贮藏条件下鲶鱼片中的菌相变化

Metagenomic Analysis of Bacterial Phases of Catfish Fillets Under Different Storage Conditions

【目的】分析鲶鱼肉片贮藏过程中微生物多样性和菌群动态变化,探究天然保鲜剂对鲶鱼肉片菌相及菌落组成的影响。【方法】试验分8组,即新鲜鲶鱼片(CK0);空气包装(air-package,AP)鲶鱼片低温贮藏(4±1)℃第4、7天(AP4和AP7)样品;气调包装(modified atmosphere package,MAP,60%CO_2/40%N_2)鲶鱼片冰温贮藏(-0.7±0.02℃)第10、30天(MAP10和MAP30)样品;添加5%天然保鲜液(由壳聚糖、蜂胶、溶菌酶、Nisin和茶多酚复配而成)MAP鲶鱼片冰温贮藏第10、30和40天(MAPP10、MAPP30和MAPP40)样品。采用宏基因组学技术,测定并分析不同贮藏方式鲶鱼片全部微生物的16S r DNA序列,比较各组菌群的物种组成和丰度信息,通过Alpha多样性分析和主成分分析,考察包装方式、贮藏温度和天然保鲜液对微生物的抑制作用。【结果】8组样品中454焦磷酸测序共鉴定出25个门、433个属的细菌。MAP10、MAPP10、MAPP30中的最优势菌属和CK0一致,均为Actinomyces;而AP4和AP7中的最优势菌分别为Aeromonas(70.49%)和Pseudomonas(59.01%)。从微生物角度来看,MAP+冰温贮藏优于AP+冷藏。随着贮藏时间的延长,气调包装中的Lactococcus丰度由15.78%(MAP10)急剧上升为82.85%(MAP30)。添加天然保鲜液的MAPP10和MAPP30中Lactococcus几乎检测不到。【结论】气调包装协同冰温贮藏显著降低了鲶鱼片中细菌菌群的丰度和多样性,有利于延长鲶鱼肉的保质期。天然保鲜液中的茶多酚、Nisin和壳聚糖等能显著抑制MAP+冰温贮藏的鲶鱼片中的主要腐败菌属Lactococcus的生长繁殖。

【Objective】The objective of this experiment is to analyze the dynamic changes of bacterial phase of catfish fillet stored under different storage conditions, evaluate the effect of natural preservative on the special spoilage bacteria. 【Method】There were 8 groups in this experiment including fresh catfish(Calarias gariepinus) fillets(CK0), AP(air-package) catfish fillets stored at(4±1)℃ for 4 and 7 d(AP4, AP7),MAP(modified atmosphere package, 60%CO_2/40%N_2) catfish fillets stored at controlled freezing-point temperature(0.7±0.02)℃ for 10 and 30 d(MAP10,MAP30), MAP catfish fillets added with 5% natural preservative stored at controlled freezing-point temperature(0.7±0.02)℃ for 10, 30 and 40 d(MAPP10, MAPP30 and MAPP40). The natural preservative consists of 0.5% chitosan, 0.1% propolis, 0.075% lysozyme, 0.075% Nisin and 0.5% tea polyphenol. Microbial16 S r DNA of different samples were sequenced in metagenomics analysis, bacterial composition and abundance of these groups were compared. Alpha diversity and principal component analysis were carried out to investigate the effect of the natural preservative, package and storage temperature on bacterial phase changing.【Result】Totally 25 phylum, 433 genuses of bacteria were identified in 8 sample groups. The same as CK0, the principal genus in MAP10, MAPP10, MAPP30 was Actinomyces, while it was Aeromonas(70.49%) and Pseudomonas(59.01%) in AP4 and AP7, respectively. From the respect of microbiology, MAP + controlled freezing-point temperature was better than AP + low temperature storage. During the storage, the abundance of Lactococcus increased sharply from 15.78%(MAP10) to 82.85%(MAP30), while in the MAPP group(MAPP10 and MAPP30) which supplemented with natural preservatives Lactococcus rarely could be detected. 【 Conclusion 】 MAP + controlled freezing-point storage significantly lowered the bacterial abundance and diversity, therefore is useful to prolong the shelf life of catfish fillets. The components of tea polyphenol, Nisin and chitosan in the natural preservative used in this study markedly inhibited the growth and the multiplication of Lactococcus which is the special spoilage bacteria in the MAP fillets stored at controlled freezing point. This is important for improving the security of catfish meat against microbial contamination through precise target inhibition.