Optimization of weathered coal biodegradation by Penicillium aculeatum 13-2-1 and UV-visible spectral characteristics of active degraded products

Abstract

Weathered coal is widely distributed in many provinces in China. It has great potential utilization values as soil ameliorant in sustainable agriculture. To find the optimal condition for the biodegradation of weathered coal and obtain the spectral characteristics of active degraded products of coal, the bioactivation of humic acid in weathered coal is essential. In this study, a fungal strain (Penicillium aculeatum 13-2-1) capable of degrading weathered coal was isolated from the rhizosphere of Zelkova serrata. The experimental results using classical one factor at a time method showed that weathered coal of 1.0 g, inoculum of 150 µL, and sodium nitrate of 0.10 g in 100 mL broth were the optimal conditions for the biodegradation of coal, respectively. The variance analysis of orthogonal tests illustrated that the three factors had little effects on biodegradation of weathered coal, but the weathered coal significantly negatively affected the contents of soluble humic acids in liquid coal products. Different diluted solutions of liquid coal products for all orthogonal combinations promoted the growth of the seeds of Brassica napus L., especially on radicles. The UV-visible spectra of the liquid coal products for all combinations presented the differential absorbance closely associated with the quantity of sodium nitrate in medium.