The amplification of APB based on the pufM gene found that the most common species found in the shrimp ponds were closely to Roseobacter denitrificans OCh 114and Halorhodospira halophila Hincluding some PNSB. These bacteria might play a major role in the nutrient cycles, particularly on the species of nitrogen and sulfur that are related to the water quality for shrimp growth. The Hig contamination in the shrimp ponds tested seemingly had no effect on the APB; in particular the PNSB