10.22376/ijpbs.2019.10.1.p1-12 Volume 3 Issue 1 2012 (January - March) The bacterial species were isolated from the infected lessThan i greaterThan Penaeus monodon lessThan /i greaterThan intestinal sample. Bacterial colonies were investigated from the infected lessThan i greaterThan P. monodon lessThan /i greaterThan collected from coastal area at Mallippattinam, from April 2008 to September 2008. The isolated bacterial species were lessThan i greaterThan Echerrichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Vibrio cholerae, Enterococcus pseudoavium, Brucella canis lessThan /i greaterThan and lessThan i greaterThan Aeromicrobium lessThan /i greaterThan lessThan i greaterThan erythreum lessThan /i greaterThan . Gram staining, motility test and bio-chemical test methods were used for identification of bacterial species. The physico-chemical studies revealed that high level of temperature, pH and calcium, which are the important parameters, may be responsible for the mortality of shrimps. T. Senthil Kumar, A. Amsath, S.S. Jayaraj And R. Ravichelvan Bacterial infection, water parameters, Penaeus monodon. 605-609