Influence of the carbon-to-nitrogen ratio in the atrazine biodegradation from contaminated waters in submerged fermentation by free and immobilized Penicillium chrysogenum NRRL 807

Atrazine is a pesticide commonly used in agriculture and is recognized as a potent endocrine disruptor. Due to its high recalcitrance, its residues have been found in drinking water sources throughout Brazil and the world. Therefore, this study aimed to evaluate the influence of the C/N ratio on the potential of the fungus Penicillium chrysogenum NRRL 807 to degrade atrazine from contaminated waters in submerged fermentation. Moreover, the free and immobilized forms of the fungus were compared. The fungus grown in suspended culture (free form) was able to degrade 40.08±5.71% of the atrazine present in the medium after 5 days, while the immobilized form (biofilm) degraded 48.31±1.53% in the same incubation time. Notably, atrazine was used as a carbon source, and degradation was led by the enzyme complex of the cytochrome P450. The amount of exogenous nitrogen was determined to interfere with the biodegradation efficiency, diverting the metabolism to the path of spore germination when nitrogen was present in high concentrations. Based on these results, P. chrysogenum both in its free form and when immobilized in biofilms can be used as bioremediation technologies for treating water contaminated by atrazine.