Assessment throughout a whole fishing year of the dominant microbiota of peeled brown shrimp (Crangon crangon) stored for 7 days under modified atmosphere packaging at 4 °C without preservatives

• Brown shrimp were stored under MAP for 7 days at 4 °C without preservatives.
• Dominant microbiota was quantified and identified throughout a whole catching season.
• Both culture-dependent and culture-independent techniques were used.
• Most species found have been described as spoilage organism in different foods.
• Identification mainly led to the genera Shewanella, Brochothrix and Carnobacterium.

This study was performed to comprehensively reveal the composition of the microbial community of commercially cooked and machine peeled brown shrimp (Crangon crangon), packaged and stored under modified atmosphere without added preservatives. Three independent experiments, using both culture-dependent and culture-independent methods, were conducted over an entire shrimp season. Initial total aerobic psychrotrophic bacterial counts (APC) were relatively high on several general media ranging between 5.4 and 6.4 log cfu g−1. After 7 days of storage at 4 °C, samples were considered microbiologically spoiled with no apparent difference in APC between samples from different periods. The dominant microbiota present after 7 days of storage was assessed by (GTG)5 analysis of selected colonies and 16S rRNA gene sequence analysis. The dominant organism on general media was Arthrobacter bergerei, whereas on more selective media Shewanella putrefaciens, Brochothrix thermosphacta and Vagococcus salmoninarum were most abundant. Culture-independent denaturant gradient gel electrophoresis (DGGE) and Illumina next generation sequencing revealed Carnobacterium as a dominant genus at day 7 throughout the year, together with members of Shewanella and Psychrobacter. The differences in relative abundance of dominant genera between different months also indicated a possible seasonal influence on the microbial community. It could be concluded that the same major groups of spoilage bacteria were retrieved by culture dependent and independent approaches, but their relative abundance differed.