Growth, laccase activity and role in 2,4-D degradation of Lentinus crinitus (L.) Fr. in a liquid medium

Abstract

This study aimed to evaluate the role of L. crinitus laccase in the biotransformation of 2,4-D pesticide and the adsorption capacity and/or accumulation in the fungal biomass. Preliminary tests were carried out in liquid medium containing L. crinitus to detect the maximum concentration of 2,4-D in which the mycelium developed (5.025 g L-1). The growth and laccase activity for L. crinitus were analyzed using a complete factorial experimental design with variations in concentrations of glucose (16.65 – 33.35 g L-1), malt extract (0.825 – 9.175 g L-1), and 2,4-D (0.01 – 5 gL-1), and the mycelial samples were evaluated by SEM-EDS. The ability of L. crinitus to remove 2,4-D after 28 days was demonstrated by a decrease in concentrations of 2,4-D by up to 15.7% more than control treatments and occurred with both low (< 2 g L-1) and high (> 10 g L-1) glucose consumption conditions, reaching biomass concentrations below 2 g L-1, and presenting laccase activity between 3 and 6 g L-1. The laccase activity of the fungus depends on the initial amount of glucose and 2,4-D (up to 18 g L-1 and 4 g L-1). Lower concentrations of 2,4-DCP (0.01 - 2.70 mg L-1) may be an indicative of L. crinitus as its transformation agent. The presence of chlorine in the fungal mycelium (up to 4.0%) may represent its adsorption and/or accumulation by L. crinitus. L. crinitus can be described as a biotransformator of 2,4-D and 2,4-DCP through laccase activity, highlighting its potential for treatment of agricultural effluents.