Abstract: The research of probiotics for aquatic animals is increasing with the demand of aquacultures sustainable development. To evaluate the effect of new developed probiotcs MP\|1 and MP\|2 and investigate their water purifying mechanism， experiments were conducted in shrimp pools at the later stage of cultivation. Water samples were sampled from the shrimp pools to determine the CODMn， ammonia， nitrite， nitrate and total nitrogen every week， and the bacterial community structure in shrimp pools were analyzed by PCR\|DGGE. Results showed the contents of nitrite in shrimp pools were all below 001 mg·L-1 after a week when the probotics were added. The contents of ammonia in shrimp pools kept within 026 mg·L-1 to 033 mg·L-1 and 035 mg·L-1 to 048 mg·L-1 after two weeks when probiotics MP\|1 and MP\|2 were added. The contents of nirate and CODMn remained statistical unchanged in the experiments. And the total nitrogen was found a removal rate over 341%. PCR\|DGGE showed the main bacterial populations and bacterial community structure changed significantly. The results suggested that probiotcs MP\|1 and MP\|2 could significantly improve the water quality while they were used in shrimp pools. It might be a result of the change in autochthonal bacterial community caused by probiotics.

Key words: probiotic, aquaculture, water quality, shrimp pool, bacterial community