School of Pharmacy and Medical Sciences, University of South Australia, GPO Box 2471, Adelaide, South Australia 5001, Australia; South Australian Research and Development Institute, Waite Campus, GPO Box 397, Adelaide, South Australia 5001, Australia.
Food Microbiol. 2014 Apr;38:219-27. doi: 10.1016/j.fm.2013.09.005. Epub 2013 Oct 9.
This study aimed to assess bacterial spoilage of half shell Pacific and Sydney rock oysters during storage using microbial culture and 16S rRNA pyrosequencing. Odour and pH of oyster meats were also investigated. Estimation of microbiological counts by microbial culture highlighted growth of psychrotrophic bacteria. During storage, odour scores (a score describing deterioration of fresh odours where a score of 1 is fresh and 4 is completely spoiled) increased from 1.0 to 3.0 for Pacific oysters and from 1.3 to 3.4 for Sydney rock oysters. pH results obtained for both species fluctuated during storage (range 6.28-6.73) with an overall increase at end of storage. Pyrosequencing revealed that the majority of bacteria at Day 0 represented taxa from amongst the Proteobacteria, Tenericutes and Spirochaetes that have not been cultured and systematically described. During storage, Proteobacteria became abundant with Pseudoalteromonas and Vibrio found to be dominant in both oyster species at Day 7. Analysis of the pyrosequencing data showed significant differences in bacterial profiles between oyster species and storage time (both P = 0.001). As oysters spoiled, bacterial profiles between oyster species became more similar indicating a common spoilage profile. Data presented here provides detailed insight into the changing bacterial profile of shucked oysters during storage and has identified two genera, Pseudoalteromonas and Vibrio, as being important in spoilage of shucked oysters.
本研究旨在通过微生物培养和 16S rRNA 焦磷酸测序评估半壳太平洋和悉尼岩蚝在储存过程中的细菌腐败情况。还研究了蚝肉的气味和 pH 值。微生物培养估计微生物计数突出了嗜冷菌的生长。在储存过程中，太平洋蚝的气味评分（描述新鲜气味恶化的评分，其中 1 表示新鲜，4 表示完全变质）从 1.0 增加到 3.0，悉尼岩蚝从 1.3 增加到 3.4。两种物种的 pH 值结果在储存过程中波动（范围为 6.28-6.73），在储存结束时总体呈上升趋势。焦磷酸测序显示，大多数细菌在第 0 天代表了未培养和系统描述的变形菌门、无壁菌门和螺旋体门的分类群。在储存过程中，变形菌门变得丰富，假交替单胞菌和弧菌被发现是两种牡蛎物种在第 7 天的优势菌。焦磷酸测序数据分析表明，牡蛎物种和储存时间之间的细菌图谱存在显著差异（均 P=0.001）。随着牡蛎变质，牡蛎物种之间的细菌图谱变得更加相似，表明存在共同的变质图谱。这里呈现的数据提供了关于储存过程中去壳牡蛎细菌图谱变化的详细信息，并确定了两个属，假交替单胞菌和弧菌，是去壳牡蛎变质的重要因素。
