Seafood quality analysis: Molecular identification of dominant microbiota after ice storage on several general growth media

This study points out the limitations of several general growth media frequently used in seafood research by a systematic identification of the microorganisms on fish samples during ice storage unable to grow on those media. Aerobic psychrotrophic count (APC), replication on various general media and total cultivable microbial community denaturing gradient gel electrophoresis (DGGE) analysis revealed that many potential spoilage microorganisms were overlooked. Those microorganisms overlooked by using only one single growth medium were identified by partial 16S rRNA gene and gyrB gene sequencing. Members of the genera Shewanella, Vibrio, Aliivibrio, Photobacterium, Pseudoalteromonas and Psychrobacter, including Photobacterium phosphoreum, Shewanella baltica and Pseudomonas fluorescens are unable to grow on PCA. APC analysis also confirmed that on plate count agar (PCA) the enumeration of the microbiota was underestimated. Although Long and Hammer agar (LH) and marine agar (MA) obtained the best quantitative (APC analysis) and qualitative (replication and DGGE analyses) results for fish quality analysis, analysts have to keep in mind that some species were also unable to grow on those media, such as Pseudomonas fragi and Acinetobacter sp.

► Limitations of general growth media in seafood research, including Plate Count Agar. ► Aerobic psychrotrophic count, replication and DGGE analyses on various iced fish. ► gyrB gene identification of microorganisms not growing on one of the media. ► Many genera with spoilage potential are unable to grow on all media. ► Most, not all, microorganisms are detectable on Long and Hammer agar and Marine Agar.