Study of Vibrio spp. and its Pathological changes in the organs of bivalve Meretrix meretrix from Kali and Aghanashini Estuary of Uttara Kannada, Karnataka

Abstract

The present study was carried out for the period ten months from September 2021 to June 2022, to isolate and identify the Vibrio spp. and to study the pathological changes in vital organs of bivalve Meretrix meretrix, one of the important edible bivalve of this region. Samples were collected from the two estuaries Kali Estuary (140 80’ 58” N and 740 14’26.2” E) and Aghanashini Estuary (14o 52` 25.6``N and 74o 36` 67.5``E) of Uttara Kannada, Karnataka. The present study was carried out to assess the presence of pathogenic Vibrio spp. The bivalve samples were collected in sterile condition and immediately processed for necropsy followed by bacterial isolation and then vital organs were fixed in Davidson fixative to study histopathological changes in vital organs. The Total Vibrio Count was observed in the range of 103 CFU/gm to 104 CFU/gm. The Green and yellow colonies were isolated and purified in TCBS agar. Purified colonies were further identified by using biochemical tests as Vibrio spp. 16S rDNA gene sequence was done for molecular identification and then confirmed as Vibrio parahaemolyticus and Vibrio alginolyticus. During the present study it was found that 50% were V.parahaemolyticus whereas 48% were V.alginolyticus and the remaining 2% constituted other Vibrio spp. Few histopathological changes were also seen in the mantle and gills of the Meretrix meretrix in the current study.