Influence of Carbon and Nitrogen Nutrient Supplementations on Biodegradation of Lignin by Interkingdom Fusants

Abstract

Lignin degradation by three interkingdom fusants (PE-6, PE-7, and PE-9) of Psathyrella candolleana and Enterobacter cloacae were investigated. The influence of nitrogen and carbon supplementations on the growth, lignin degradation, and laccase activity of fusants was also discussed. The results showed that NH4Cl and sucrose were the best for nitrogen and carbon supplementations, respectively. PE-9 had the highest lignin degradation efficiency (46.3 ± 1.2%) and laccase activity (16.0 ± 0.4 units/g of cell). Moreover, the growth kinetics of the fusants was studied by a logistic model. The correlation coefficient R2 values of three fusants were 0.999, 0.997, and 0.998, respectively. PE-6 had the maximal CM value of 2.04, and PE-9 had the largest k value of 0.505. Finally, the Andrews model was employed to analyze the lignin degradation kinetics. The results indicated that lignin degradation would be inhibited when the lignin concentration reached 120–160 mg/L. PE-9 was less sensitive to substrate inhibition in lignin degradation with the largest qmax, Ks, and Ki values of 1.88 mg L–1 h–1, 52.8 mg/L, and 516.4 mg/L, respectively.