12Aims: This study was conducted to assess the effects of different storage temperatures (4 to 13 20 °C), on bacterial concentrations, growth rates and community structure in fresh retail 14 sushi, a popular retail product with a claimed shelf life of two to three days. 15
Methods and Results:The maximum specific growth rate based on aerobic plate count 16 (APC) at 4 °C was 0.06 h -1 , and displayed a 6-fold increase (0.37 h -1 ) at 20 °C. Refrigeration 17 resulted in no growth of hydrogen sulfide (H2S)-producing bacteria, but this group had the 18 strongest temperature response. The bacterial community structure was determined by 19
PCR/DGGE (Denaturing gradient gel electrophoresis). Multivariate analysis based on Bray-20Curtis similarities demonstrated that temperature alone was not the major determinant for 21 the bacterial community structure. The total concentration of aerobic bacteria was the 22 variable that most successfully explained the differences between the communities. The 23 dominating organisms, detected by sequencing of DNA bands excised from the DGGE gel, 24were Brochothrix thermosphacta and genera of lactic acid bacteria (LAB). 25
Conclusion:The relationship between growth rates and storage temperatures clearly 26 demonstrates that these products are sensitive to deviations from optimal storage 27 temperature, possibly resulting in loss of quality during shelf life. Regardless of the storage 28 temperature, the bacterial communities converged towards a similar structure and density, 29 but the storage temperature determined how fast the community reached its carrying 30
capacity. 31Significance and Impact of the Study: Little information is available on the microbial 32 composition of ready-to-eat food that are prepared with raw fish, subjected to 33 contamination during handling, and susceptible to microbial growth during cold storage. 34Moreover, the data is a good first possibility to simulate growth of APC, H2S-producing 35 3 bacteria and LAB under different temperature scenarios that might occur during production, 36 distribution or storage. 37 38