Microbial study of toothfish tissue in Divisions 58.4.1 in 2014/15

Dissostichus mawsoni, the Antarctic toothfish, is a local organism of the Southern Ocean. The fish is a member of the Notothenioidei, which lives in the sub-zero (-2 °C) continental shelf waters of Antarctica. The Antarctic toothfish are protected from freezing by the existence of antifreeze proteins in the tissue, which inhibit the ice making in the body fluids. In this project, we set a goal to explore the bacterial population which is present in the tissues of Antarctic toothfish by using both culture-dependent and independent methods. The bacterial strains were isolated from the fish tissues, skin, and gonad using standard serial plate method, which is a culture-dependent method. The bacteria were identified using 16S rRNA gene sequence analysis. For culture-independent methods, the bacterial DNAs were isolated from tissue, gonad, and skin by using DNA isolation kit, respectively. The bacterial 16S rRNA gene amplification and pyrosequencing were performed. The data was analysed using V and Mothur programs. The pyrosequence data present that the genus Psychrobacter, Snodgrassella, and Deinococcus are the predominant genera of the fish. Psychrobacter cibarius and Psychrobacter fozii were the dominant species which isolated and grew in the plate from the tissue. Meanwhile, Psychrobacter okhotskensis, Psychrobacter cibarius, Psychrobacter maritimus, and Psychrobacter fozii identified from gonad sample. This project showed that the significant existence of Psychrobacter in the fish tissue. However, the skin is dominated by Snodgrassella which determined by the culture-independent method.