Nitrofurazone biodegradation kinetics by batch fermentation of Aspergillus tamarii

Abstract

Nitrofurazone (NFZ) compound contains a 5-nitrofuran ring structure that has been widely used as feed additives in animal husbandry. Due to the benzene ring structure, the residues are highly toxic to humans and animals. A kinetics study of NFZ biodegradation in batch fermentation with Aspergillus tamarii KX610719.1 was conducted. The main objectives were to determine the kinetic parameters of fungal growth, glucose consumption, protein production, and biodegradation of NFZ using fungal biomass. Kinetic parameters were determined using Polymath 6.0 software, and regression analysis was done using linear and non-linear methods. After 168 hours of batch fermentation, the maximum specific growth rate (µmax), and maximum cell concentration (Xmax) for cultivation without NFZ were 0.062 h-1, and 0.529 g L-1, respectively. The maximum specific growth rate (µmax), and maximum cell concentration (Xmax) for cultivation with NFZ were 0.092 h-1, and 0.327 g L-1, respectively. For glucose consumption, kinetic parameters of Yield of biomass over the substrate (YXS) and cell maintenance (mS) were estimated at 0.139 g g-1 and 0.239 h-1, respectively. Based on the Luedeking Piret model, the estimated growth-associated (α) and non-growth-associated (β) constants were 1.142×10-2 g g-1 and 5.680×10-5 h-1, respectively. The rate constant (k1) of NFZ biodegradation was estimated at 2.696×10-2 h-1 following the first-order model where the rate constant of NFZ removal is dependent on the NFZ concentration. The application of A. tamarii batch fermentation in the removal of NFZ compound was sufficient with a total percentage removal of 85.9 % or 0.430 g L-1 recorded.