Abstract Most foods have either a neutral or a slightly acidic pH, whereas only a limited number of products have a pH above 8. The Nordic traditional fish dish lutefisk is an exception, with a pH around 12 during production and a ready for consumption pH above 10. Lutefisk is prepared from dried Atlantic cod (Gadus morhua), soaked in water and thereafter treated in a lye solution. During this process, the muscle proteins are partially hydrolyzed and a characteristic smell and a gel like appearance are developed. Due to its high pH, lutefisk has previously been considered not to harbour any microbiota. However, in our study of commercially available lutefisk, aerobic and anaerobic plate counts of up to 1.4 × 106 and 5.5× 104 CFU g−1, respectively were found. The pure culture isolates from Plate count agar, Iron agar Lyngby and Alkaline Nutrient agar, were identified by 16S rRNA gene sequencing as Carnobacterium maltaromaticum, Pseudomonas fragi, Staphylococcus warneri, S. hominis, Aeromonas salmonicida, Kurthia zopfii, Microbacterium oxydans, Exiguobacterium oxidotolerans, Alishewanella tabrizica and Bacillus licheniformis. This is the first report on the microbiota of lutefisk based on cultivation and 16S rRNA gene sequencing.

中文翻译：

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lutefisk 的微生物群，一种具有高 pH 值的北欧传统鳕鱼菜肴

摘要 大多数食物的 pH 值为中性或微酸性，而只有少数产品的 pH 值高于 8。北欧传统鱼菜 lutefisk 是一个例外，其在生产过程中的 pH 值约为 12，准备食用的 pH 值高于10. Lutefisk 由干燥的大西洋鳕鱼 (Gadus morhua) 制成，浸泡在水中，然后在碱液中处理。在此过程中，肌肉蛋白质部分水解，并产生特有的气味和凝胶状外观。由于其高 pH 值，lutefisk 以前被认为不包含任何微生物群。然而，在我们对市售 lutefisk 的研究中，发现需氧菌和厌氧菌菌落数分别高达 1.4 × 106 和 5.5 × 104 CFU g-1。从平板计数琼脂中分离出纯培养物，铁琼脂 Lyngby 和碱性营养琼脂，通过 16S rRNA 基因测序鉴定为 Carnobacterium maltaromaticum、Pseudomonas fragi、Staphylococcus warneri、S. hominis、Aeromonas salicida、Kurthia zopfii、Microbacterium oxydans、Exiguobacterium oxidotolerans 和 Alishewaniac。这是第一份基于培养和 16S rRNA 基因测序的 lutefisk 微生物群的报告。