Identification of Seafood Bacteria from Cellular Fatty Acid Analysis via the Sherlock® Microbial Identification System

Abstract

The current taxonomic positions of psychrotrophic bacterial strains isolated from seafood and housed in the Kodiak Seafood Culture Collection (KSCC) were determined based on membrane fatty acid profiles and compared with profiles for representative American Type Culture Collection (ATCC) strains. Gram-positive organisms had a high percentage (64–96%) of branched-chain fatty acids, except for Streptococcus faecium. Gram-negative, oxidase-negative isolates were composed of 38–69% of saturated fatty acids and 19–50% of unsaturated fatty acids. Hydroxyl fatty acids were present in all the gram-negative, oxidase-positive isolates and the branched-chain fatty acids were <1–74%. Of the 33 strains tested, 55% were identified to species with a similarity index (SI) >0.5 and <0.1 SI in range of the first rank. Strains of Pseudomonas fluorescens and those belonging to the Enterobacteriaceae were responsible for this lower percentage. The modern taxonomic positions of three KSCC strains were found to be Shewanella putrefaciens, Psychrobacter immobilis and Myroides odoratus. Sherlock MIS proved to be an effective and rapid technique in the identification of bacteria associated with seafood.