Bacterial composition associated with different traditions of salted and dried fish across countries

Drying of fish to improve storage capabilities, often under hyperosmotic conditions, is a widespread and longstanding practice in many cultures throughout the world. Several drying practices are applied, and they often reflect a cultural influence. The purpose of drying is to preserve fish by lowering the availability of water to microorganisms. However, because drying of fish is globally widespread and drying procedures are very diverse, microbial communities occurring in the dried fish products might differ. In this study, 63 dried fish products, prepared from 8 different fish species, were collected from several parts of the world (Greenland, Iceland, Denmark, Norway, the Faroe Islands, Japan, and Bangladesh) and the microbiotas from these products were analysed and compared following amplification and sequencing of the V4-region of the 16S rRNA. Overall, the dominant bacterial taxa associated with the fish were the genera Photobacterium, Psychrobacteria, Vibrio, and Pseudomonas, but large differences occurred across samples with a strong influence of the country of origin (in particular samples from Bangladesh) and salinity of the fish products. Moreover, industrially processed filets were readily distinguishable from traditionally processed ones. In contrast, the fish species from which the filets were prepared appeared to have less effect. These results suggest that drying practices can have a strong effect on the microbiota of the resulting products. For several of the fish species tested, this constitutes the first report regarding the composition of the microbiota associated with the resulting fish products.