Isolation, identification, and pathogenicity tests of pathogenic bacterial associated with black body syndrome in white barramundi Lates calcarifer B.

摘要

ABSTRACTThis study aimed to obtain the pathogenicity of isolated bacteria from maribund barramundi Lates calcarifer with black body syndrome (BBS). Moribund barramundi was collected from the Center for Mariculture Development (BBPBL), Lampung Province. Five of pathogenic bacteria were found, i.e. Pseudomonas stutzeri L01, Vibrioharveyi, Bacillus cereus, Salinococcus roseus, and Pseudomonas stutzeri L02. The bacteria were tested for LD50 to obtain two types of high virulent bacteria to be used for the pathogenicity test. P. stutzeri L01 and V. harveyi were the most virulent bacteria with a bacterial density of 107 CFU/mL. Both bacteria were used for pathogenicity test with three treatments: injection of P. stutzeri L01, V. harveyi, mix P. stutzeri L01 and V. harveyi, and phosphatebuffered saline as control. Clinical symptoms showed a blackened body, bleeding under the belly, and inactive. Mortality of fish injected with P. stutzeri L01, V. harveyi and mix P. stutzeri L01 and V. harveyi was 53.33%, 55.00%, and 58.33%, respectively. Erythrocyte and hemoglobin in all treatments were not significantly different (P>0.05). However, there was significantly different in the total leukocytes of mixed P. stutzeri and V. harveyitreatment (P0,05). Namun, ada perbedaan yang signifikan dalam total leukosit perlakuan campuran P. stutzeri L01 dan V. harveyi(P<0,05). P. stutzeri L01, V. harveyi dan campuran P. stutzeri L01, V. harveyi dapat menyebabkan black bodysyndrome (BBS). Koinfeksi P. stutzeri L01 dan V. harveyi menghasilkan mortalitas lebih tinggi daripada infeksi tunggal.Kata kunci: barramundi, black body syndrome, histopatologi, patogenisitas