Thiobacillus denitrificans is a species of bacteria that obtains its energy from carbon dioxide and inorganic compounds such as nitrogen in its environment. It is used in bioremediation (natural cleansing) of groundwater that contains excess nitrate, allowing the nitrates to be removed. Through what process does Thiobacillus denitrificans help bioremediate groundwater?

Thiobacillus denitrificans helps remove excess nitrate by converting nitrate into nitrogen gas, which can leave the groundwater and return to the atmosphere. This process is denitrification, so the correct choice is denitrification. Nitrogen fixation does the opposite kind of transformation, converting atmospheric nitrogen into usable nitrogen compounds.

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