Multiplex PCR‐based serotyping profile of Flavobacterium psychrophilum isolated from farmed salmonids in Turkey

Turkey was the largest rainbow trout producer of the European countriesin 20161, and the reason for this production is mainly attributed toits egg and fry production. Flavobacteriumpsychrophilum cause the highest rates of mortality in the starting to feeding stages of the fish2. Diversityamong F. psychrophilum isolates was reported at different levels, and a varietyof typing schemes (e.g., biotypes, serotypes, and genotypes) was proposed accordingly3. Serologicaldifferences among F. psychrophilumisolates were reported since thepioneering studies in the nineties, anddifferent serotyping schemes were proposed4,5,6.  Serotyping byconventional serological methods is costly, labor-intensive and requiressignificant technical expertise. Therefore, molecular serotyping using mPCR is a relevant alternative to traditionalserotyping3. The objective of this study was to determine theserotyping differences of F. psychrophilum isolated from Turkey. In the presentstudy twenty‐five,F. psychrophilum isolates recovered from rainbow trout, coruh trout and brook trout were identified by Duplex PCR using F. psychrophilum specificprimers of gyrA and gyrB genes. Also molecular serotyping was done by multiplex PCR. The MultiplexPCR‐based serotyping study showed that three Turkish F. psychrophilum isolateswere type‐0, eight isolates were type‐1, ten isolates were type‐2 and threeisolates were type‐3. Isolate FP‐123 from East Anatolia showed a different bandpattern could not be assigned to anymolecular serotyping profile. In conclusion, this study reports the no connection between the serotyping profile of F. psychrophilum,sampling sites or geographical origin could beidentified. F. psychrophilum isolates from Turkey were serotyped by using molecular serotypingfor the first time. Additionally, one F. psychrophilum isolate showed a unique serotype profile different from the recognizedfour serotypes. The unique serotype should be studied by using ELISA and slideagglutination tests and full genome sequencing.