Development of probiotics determination of LD50 of previously isolated indigenous vibriolytic bacteria, <i>Pseudomonas aerugginosa</i> JP4, to <i>Penaeus monodon</i> postlarvae

Abstract

Previous studies showed that Pseudomonas aeruginosa JP4 is effective in eliminating pathogenic Vibrio spp. on shrimp. However, virulence studies on this strain are lacking. Hence, this study was conducted to test the pathogenicity of P. aeruginosa JP4, using different bacterial densities of 105, 106, 107, 108, 109 and 1010 CFU/ml. These were introduced to Penaeus monodon postlarvae 13 (PL13)and early juvenile (PL25) stages. After 3 days of monitoring, mortality rates and LD50 values were determined using Reed-Muench method. Results showed that shrimps can not tolerate higher bacterial densities with LD50 of 1.15 x 107 CFU/ml and 1.12 x 108 CFU/ml for PL13 and PL25 respectively. The relatively high LD50 values on shrimp stages PL13 and PL25 indicate a low virulence of the bacterial strain. Hence, P. aeruginosa JP4 maybe used as potential vibriolytic bacteria.