Abstract: Two bacteria were isolated from anoxic denitrifying reactor for treatment of domestic wastewater. The identification of isolates revealed that the isolates are Bacillus cereus and Bacillus tequilensis. The isolates were affiliated with Firmicutes. Denitrification was compared between Bacillus cereus and Bacillus tequilensis in this study. Two bacilli are able to denitrify and Bacillus cereus is more efficient than Bacillus tequilensis. Bacillus cereus reduces 80% of high amount of nitrate; however, Bacillus tequilensis could reduce 37.4% of nitrate. These heterotrophic bacteria are able to eliminate organic matter with the same trend reducing 74.5% for Bacillus tequilensis and 70.2% for Bacillus cereus.