Which of the following is a bacterium involved in denitrification?...

Some bacteria such as Thiobacillus denitrificans, Pseudomonas aeruginosa, and Micrococcus denitrificans also occur in the soil which converts the nitrate and ammonia into atmospheric free elemental nitrogen. Such bacteria are called denitrifying bacteria and the process is called denitrification. These bacteria act very well in the soil where there are more water and less oxygen and there is a high level of the carbohydrate.