Evaluating the use of fatty acid profiles to identify deep-sea Vibrio isolates

Capillary gas chromatography with flame ionisation detection (GC-FID) was used to determine the cellular fatty acid (CFA) profiles of a number of Vibrio strains obtained from ATCC and grown on various media. This initial determination for optimal growth conditions, including type of medium and incubation temperature, for these various ATCC Vibrio species, was important for use in the subsequent evaluation of deep-sea Vibrio strains. The deep-sea Vibrios were obtained from Harbor Branch Oceanographic Institution (Fort Pierce, FL), and GC-FID analysis was used to determine whole cell fatty acid methyl esters (FAMEs) from the cells. The Vibrio strains were cultured for 24 h on a specific medium which included brain heart infusion (BHI) agar, trypticase soy agar (TSA), trypticase soy broth agar (TSBA), and Luria–Bertani (LB) agar. The temperature of incubation was 28 °C for cells grown on TSA, TSBA, and LB and 35 °C for BHI. A data set for each Vibrio species was prepared, using fatty acid profiles for a specific medium. Major fatty acids of the Vibrio strains evaluated in this study were straight-chain C_12:0, C_14:0, C_16:0, and unsaturated summed C_16:1 ω7c/C_16:1 ω6c, C_18:1 ω7c, and summed C_14:0 3-OH/iso-C_16:1. Most of the deep-sea Vibrio isolates were identified as Vibrio parahaemolyticus and Vibrio harveyi. Analysis of FAMEs from Vibro strains grown on a specific medium by this rapid GC-FID method can provide a sensitive procedure for the identification of these organisms, and the differentiation between Vibrio species.