Short-term effects of maize residue biochar on kinetic and thermodynamic parameters of soil β-glucosidase

Abstract

Soil β-glucosidase (BG), the rate-limiting enzyme in the final step of cellulose hydrolysis, plays a key role in microbial metabolism, carbon (C) cycling and sequestration in terrestrial ecosystems. Biochar application is known to affect soil BG activity; however, most of the biochar studies have focused on the potential activity of BG, and it is not clear how biochar influences the kinetic and thermodynamic behavior of BG in the soil. The objective of this study was to investigate the effect of maize residue biochar on soil BG kinetic and thermodynamic parameters. Soil BG kinetic (V max and K m ) and thermodynamic (E a , ΔH a and Q 10 ) parameters were determined within soils (clayey and sandy loam soils) amended with either maize residue (as positive control) or its biochar (600 °C) at 0.5 and 1.0% ratios (w/w), and the mixtures were incubated for 90 days. BG showed an increase in potential enzymatic activity (81%), enzyme concentration (higher V max value) (25%) and substrate affinity (lower K m value) (32%) in the biochar-amended sandy loam soil only at high addition rates compared with the control, and an increase by about 86% of the catalytic efficiency (V max /K m ). In the clayey soil, biochar addition decreased potential BG activity (by 10-29%), increased the V max value (by 20-25%) and had no impact on enzyme-substrate binding affinity, but still increased the catalytic efficiency by 47-72%. Adsorption of soil BG by biochar particles did not affect the catalytic efficiency in the soil. Generally, application of maize residue biochar to the soil decreased the E a , ΔH a and Q 10 values of BG compared with the negative controls at both biochar rates in the light-textured soil and only at low biochar rate in heavy-textured soil. The direction and magnitude of BG responses (activity, kinetics, and thermodynamics) to biochar were more related to the soil characteristics. Biochar would increase soil BG thermal stability and decrease its sensitivity to increasing temperature and global warming.

Effects of biochar on waterlogging and the associated change in micro-ecological environment of maize rhizosphere soil in saline-alkali land

“…Similarly, the activities of enzymes (e.g., DHA, BG, and Alka PME) secreted from the microbes remained quite high in the soil with biochar addition after waterlogging. This concurs with the findings of other studies that biochar addition provides a substantial improvement to the DHA activity in soil (Yang 2015;Raiesi and Khadem 2019). These findings demonstrate that biochar addition reduces the level of disturbance in the soil from the adverse environmental conditions of waterlogging.…”

“…This enriches the source of DHA enzymes in the soil (Tischer et al 2015). BG is an important class of enzymes involved in the soil carbon cycle whose activity is positively correlated with soil organic carbon (Raiesi and Khadem 2019). It seems that the significant increase in the soil SOC content after biochar addition may be the cause of the enhanced activity of BG in the soil.…”

The Importance of the Targeted Design of Biochar Physicochemical Properties in Microbial Inoculation for Improved Agricultural Productivity—A Review

“…Laboratory experiment [231] No significant effect of biochar was observed on microbial biomass content. In a higher dose of BGC, only a minor effect on the soil community composition was observed.…”

“…Biochar application can improve the action of dehydrogenase, catalase, urease, alkaline phosphatase, β-glucosidase, arylsulfatase, oxidase, and fluorescein diacetate hydrolase, which are involved in microorganisms activity [227,230]. According to Raiesi et al [231] and Sandhu et al [232], sorption of enzyme molecules to functional groups present on the biochar surface affects the course of enzymatic reactions. Biochar influences the activity of soil extracellular enzymes responsible for C degradation, N mineralization, or P solubilization.…”