Molecular identification of non-lactic acid bacteria isolated on MRS medium and associated to the production of biogenic amines in adjuevan, a fermented fish of Côte d’Ivoire

Biogenic amines (BAs) are important nitrogenous compounds formed mainly by decarboxylation of amino acids or by amination and transamination of aldehydes and ketones. That compounds have been detected in adjuvant, a fermented fish very used as condiments in Côte d’Ivoire. The aim of this study was to identify non-lactic acid bacteria (non-LAB) populations isolated in adjuevan on MRS agar and producing biogenic amines. Thus, non-LAB were isolated on MRS agar, then their biogenic amines production was highlighted on Niven agar. Finally, the isolates which produce biogenic amines were identified by sequencing the 16S DNA region. The results showed that non-LAB was able to grow on MRS agar. Their charges obtained in adjuevan were between 1.3x103 and 1.95x105 UFC/g. Those bacteria were also detected during the storage of adjuevan at ambient temperature and 4°C until six weeks. The prevalence of non-LAB producing biogenic amines was from 8.8 to 100% at ambient temperature and 57% at 4°C in adjuevan produced with Chloroscombrus chysurus. This prevalence was between 21 and 50% at ambient temperature and 55% at 4°C in adjuevan produced with Galeoides decadactylus during six weeks of storage. However, this prevalence was low in the adjuevan produced with Thunnus thynnus. The species found by molecular identification were Staphylococcus saprophyticus, Staphylococcus kloosi, Staphylococcus gallinarum, Staphylococcus arlettae, Staphylococcus cohnii, Bacillus subtilis subsp. subtilis, Pseudomonas sp., Enterococcus faecalis, Streptococcus pyogènes and Enterobacter sichuanensis. Staphylococcus saprophyticus was the most detected biogenic amines-producing species with over 71% of strains.