Molecular identification of the bacterial isolates from the skin and gills of sea bass and sea bream from farms on the island Cres and Vrgada

Oportunističke bakterije na uzgajalištima brancina i orade jedan su od najčešćih uzročnika bolesti. Pored toga određene bakterije mogu utjecati na sigurnost proizvoda ili ubrzati kvarenje ribe. Zato je poznavanje prisutne bakterijske mikroflore značajno ne samo za pravilno planiranje zdravstvenog menadžmenta već i za kompletnu organizaciju proizvodnje. Cilj ovog rada je primjenom PCR molekularne analize identificirati bakterijske izolate s kože i škrga brancina i orade na dva uzgajališta, Veli Bok na Cresu i na Vrgadi. Analizirani izolati PCR-om su prethodno identificirani MALDI TOF metodom te su rezultati uspoređeni. Ukupno 79 izolata prethodno determiniranih MALDI TOF metodom, 51 kao pripadnik roda Vibrio, 17 roda Shewanella te 11 ostalih, korišteno je za PCR analizu. Nakon određivanja sljedova nukleotida za gen gyrB svi izolati roda Shewanella su identificirane kao vrsta Shewanella baltica. Filogenetska analiza roda Vibrio na temelju sekvenci odsječaka gena rpoD pokazala je grupiranje bakterija ovog roda u dva klastera: V. harveyi i V. splendidus. Iako MALDI-TOF ima veliki potencijal za brzu identifikaciju, PCR metode su preciznije ali je za točnu determinaciju potrebno koristiti više specifičnih gena.Opportunistic bacteria in sea bass and sea bream farms are one of the most frequent causes of disease. In addition, certain bacteria can affect product safety or accelerate fish spoilage. That is why knowledge on the present bacterial microflora is important not only for proper planning of health management, but also for the complete organization of production. The aim of this work is to identify bacterial isolates from the skin and gills of sea bass and sea bream at two farms, Veli Bok on Cres and Vrgada, by applying PCR molecular analysis. The analyzed isolates were previously identified by the MALDI TOF method, and the results of the methods were compared. A total of 79 isolates previously determined by the MALDI TOF method, 51 as members of the genus Vibrio, 17 of the genus Shewanella and 11 others, were used for PCR analysis. After determining the nucleotide sequences of the gyrB gene, all isolates of the genus Shewanella were identified as Shewanella baltica. The phylogenetic analysis of the genus Vibrio based on the sequences of rpoD gene segments showed the grouping of bacteria of this genus into two clusters: V. harveyi and V. splendidus. Although MALDI-TOF has great potential for rapid identification, PCR methods are more precise, but for accurate determination, it is necessary to use more specific genes