鸭蛋及黑黄咸蛋壳外细菌多样性及PICRUSt基因功能预测分析

Duck Eggs and Black-Yolked Salted Duck Eggs:Bacterial Diversity on Eggshells and Gene Function Prediction Using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States(PICRUSt)

通过比较不同洁净程度鸭蛋及黑黄咸蛋(BSE)载菌数,发现重度脏污蛋(DE)壳外菌落总数对比无可视脏污蛋(CE)载菌量显著增大,BSE壳内及内容物载菌量大幅增加。进一步采用16S rDNA基因测序分析CE、DE与BSE的菌落种类和丰度差异,发现CE优势菌占比较高的为变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)和放线菌门(Actinobacteria),分别为34.35%、27.25%和17.28%,拟杆菌门(Bacteroidetes)占比相对较少为8.29%;而DE优势菌占比较高的是变形菌门为89.01%,厚壁菌门和放线菌门分别占6.16%和3.98%;BSE优势菌门为变形菌门(76.50%)、拟杆菌门(8.00%)、放线菌门(6.76%)、厚壁菌门(5.43%)。DE组及BSE组变形菌门丰度显著增加。CE优势菌属为涅斯特捷科氏菌属(Nesterenkonia)(9.08%)、弯曲杆菌属(Campylobacter)(7.91%)、链球菌属(Streptococcus)(3.41%)和寡养单胞菌属(Stenotrophomonas)(2.92%)等;DE优势菌属为嗜冷杆菌(Psychrobacter)占86.01%,不动杆菌属(Acinetobacter)占2.20%;BSE优势菌属为罗尔斯通氏菌属(Ralstonia)(22.91%)、沙雷氏菌属(Serratia)(5.05%)和放线菌属(Actinomyces)(3.32%)等。菌落多样性聚类分析表明BSE优势微生物与DE接近,微生物表型分析结果表明BSE微生物以革兰氏阴性菌为主,且BSE具有较高的氧化胁迫耐受力和致病性,BSE对氧化型清洁剂有耐受力。通过微生物功能预测及代谢通路物种组成分析得出,DE在碳水化合物分解和脂质的运输和代谢氧化上均强于CE,更多的辅酶运输和代谢通路让DE的生化反应更加迅速,产生更多的次级代谢产物,导致鸭蛋品质发生改变,与BSE组在次级代谢物生物合成、转运和分解代谢通路上微生物最高这一检测结果相符。该研究结果为鸭蛋清洁生产提供一定理论支撑。

After comparing the bacterial load of black-yolked salted duck eggs(BSE)and that of duck eggs with different cleanliness degrees,it was found that the total bacterial count on the shell of severely stained eggs(DE)was distinctly higher than that on the shell of non-visually stained eggs(CE),and the total bacterial count in the shell membrane and contents of BSE increased greatly.Furthermore,16S rDNA gene sequencing was used to analyze the differences in the composition and abundance of bacterial communities in CE,DE and BSE.It turned out that Proteobacteria,Firmicutes and Actinobacteria were the dominant phyla,accounting for 34.35%,27.25% and 17.28% of the total abundance,respectively,while Bacteroidetes accounted for 8.29% of the total abundance.Proteobacteria was the dominant bacteria in DE and accounted for 89.01% of the total abundance,while the relative abundance of Firmicutes and Actinobacteria were 6.16% and 3.98%.The dominant phyla in BSE were Proteobacteria(76.50%),Bacteroidetes(8.00%),Actinobacteria(6.76%)and Firmicutes(5.43%).The abundance of Proteobacteria in DE and BSE was significantly increased.The dominant bacterial genera in CE were Nesterdella(9.08%),Campylobacter(7.91%),Streptococcus(3.41%)and Oligomonas(2.92%).In DE,Psychrobacter was the dominant genus,accounting for 86.01% of the total abundance,and the relative abundance of Acinetobacter was 2.20%.The dominant bacteria in BSE were Rolstonia(22.91%),Serratia(5.05%)and Actinomycetes(3.32%).The cluster analysis of bacterial diversity showed that the dominant microorganisms of BSE were close to those of DE.The microbial phenotype analysis showed that the dominant microorganisms of BSE were Gram-negative bacteria,had high oxidative stress tolerance and pathogenicity,and could tolerate oxidizing detergents.The results of microbial gene function prediction and species composition of metabolic pathways demonstrated that bacterial carbohydrate decomposition,lipid transport and metabolic oxidation in DE were stronger than those in CE.More coenzyme transport and metabolic pathways could make the biochemical reactions of bacteria from DE faster to produce more secondary metabolites,thus resulting in changes in the quality of duck eggs.This is consistent with the highest bacterial abundance in the secondary metabolite biosynthesis,transport and catabolism pathways in BSE.The results of this study provide theoretical support for the cleaner production of duck eggs.