ANAEROBIC, AEROBIC AND MIXOTROPHIC BIOELECTROCHEMICAL DENITRIFICATION

RODRIGUEZ SIMÓN, CARLOS NORBERTO; BUSALMEN J.P.; PEDETTA, ANDREA; BONANNI P. S.

Los Cocos, Cordoba

Congreso; Congreso de la Sociedad Argentina de Microbiología General; 2022

Samige

Bioelectrochemical denitrification allows surpassing an usual limitation of traditional denitrification processes which is the availability of electrons and carbon sources for denitrifying bacteria. Being thought of as an anaerobic process, it is mostly studied in the lack of oxygen. In denitrifying systems where oxygen is present it is proposed that denitrification is feasible due to the existence of anaerobic microenvironments that prevent denitrifying bacteria being inhibited by contact with oxygen. Oxygen does not have an inhibitory effect on the enzymes responsible for nitrate reduction, but on nitrate transporters at the internal membrane. In some denitrifiers nitrate reductases are located at the cytoplasm (NarGHI) and, as a consequence, nitrate reduction is then inhibited by the presence of oxygen. In other bacteria nitrate reductases are located in the periplasm (NapAB) and thus, the inhibition of internal membrane transporters by oxygen does not impede denitrification to occur. Some bacteria are not only tolerant to oxygen, but can also use it as an electron acceptorin a process called aerobic denitrification. In this process bacteria use oxygen and nitrate simultaneously as electron acceptors, in a mixotrophic way of growth. The possibility for denitrifiers to develop in the presence of oxygen expands the experimental and technological setups where bioelectrochemical denitrification can be applied but, still, aerobic denitrification is rarely considered.