This study is to investigate and characterize the microbiota composition on eggshells from 3 different areas of Shaanxi province (Yulin, Hanzhong and Xi'an). The eggs were stored at 25 °C for 56 days and bacterial samples were collected from eggshells on day 0, 14, 28, 42 and 56. Denaturing gradient gel electrophoresis and high-throughput sequencing of 16S rRNA hypervariable region V3-V4 were performed. Alpha diversity was applied for analyzing the diversity of samples through 6 indices, including Observed-species, Chao1, Shannon, Simpson, ACE and Good's-coverage. Beta diversity was used to study the similarities or differences in the community composition of the samples. Totally, 36 phyla and 595 genera were classified by 16S rRNA gene sequencing. The composition of the microbial communities of different regions was quite different. Firmicutes (33-38% of total phyla) and Actinobacteria (36-61% of total phyla) were the most abundant phyla in all three regions. Proteobacteria were relatively more abundant (about 18% of total phyla) on eggs from Hanzhong. During storage time, the microbial communities mainly changed from Firmicutes to Actinobacteria on eggs from Yulin and Xi'an. Lactobacillus, Kocuria and Streptomyces were much higher at the genus level. Spoilage bacteria Staphylococcus, Streptococcus, Pseudomonas and Enterococcus were detected at the genus level. Campylobacter jejuni (< 1% of total bacteria), which might be related to human illness, was also detected. In conclusion, the structure, abundance, and composition of microbiota on eggshells differ among areas. The microbiota changed regularly during storage time. The current study may offer a new insight into bacterial species on eggshells.

中文翻译：

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非培养方法对不同地区和不同储存时间蛋壳微生物群落的分析

本研究旨在调查和表征陕西省 3 个不同地区（榆林、汉中和西安）蛋壳上的微生物群组成。鸡蛋在 25°C 下储存 56 天，并在第 0、14、28、42 和 56 天从蛋壳中收集细菌样本。进行变性梯度凝胶电泳和 16S rRNA 高变区 V3-V4 的高通量测序。应用Alpha多样性通过6个指标分析样本的多样性，包括Observed-species、Chao1、Shannon、Simpson、ACE和Good's-coverage。Beta多样性用于研究样本群落组成的异同。16S rRNA基因测序共分类36门595属。不同地区微生物群落组成差异较大。厚壁菌门（占总门的 33-38%）和放线菌（占总门的 36-61%）是所有三个区域中最丰富的门。汉中鸡蛋上的变形菌相对较多（约占总门的 18%）。在贮藏期间，榆林和西安鸡蛋上的微生物群落主要由厚壁菌门转变为放线菌门。乳酸杆菌、Kocuria 和链霉菌在属水平上要高得多。在属水平上检测到腐败菌葡萄球菌、链球菌、假单胞菌和肠球菌。还检测到可能与人类疾病有关的空肠弯曲杆菌（< 总细菌的 1%）。总之，蛋壳上微生物群的结构、丰度和组成因地区而异。微生物群在储存期间有规律地变化。