Comparative evaluation of 1,3,5-triazine-2,4,6-triamine biodegradation by Penicillium hetheringtonii and Fusarium sp.

Melamine is a nitrogen rich compound belonging to the triazine family. The excessive use of melamine is one of the major concerns due to its ability to cause nephrotoxicity, and acute, and chronic kidney disease. In the present study, two fungal strains namely Penicillium hetheringtonii AJ6 and Fusarium sp. MDF3 was isolated using the enrichment technique. These strains were screened for their melamine tolerance ability and could tolerate up to 20 mg/L (P. hetheringtonii), and 29 mg/L (Fusarium sp.) of the contaminant. The degradation studied in an aqueous medium proved that Penicillium hetheringtonii and Fusarium sp. could degrade 78% (initial substrate concentration, 14 mg/L; final substrate concentration, 3.08 ± 0.20 mg/L), and 32% (initial substrate concentration, 20 mg/L; final substrate concentration, 13.6 ± 1.78 mg/L) of introduced melamine respectively. The strains degraded melamine into 2-Propen-1-ol, and 5-methyl-2-hexanone. The degradation kinetics study showed that strains followed zero-order model (P. hetheringtonii), and pseudo second-order model (Fusarium sp.) of kinetics. The significance of kinetic models was assessed using p-value which was reported as 0.007 (zero-order model) and 0.005 (pseudo second-order model). The extracellular enzyme studies revealed that the laccase enzyme system could be responsible for the degradation of melamine. Therefore, the study suggests that the strain P. hetheringtonii AJ6 can be used for melamine remediation from contaminated surfaces.