Cellulase stimulation during biodegradation of lignocellulosic residues at increased biomass loading

Abstract

Microbial degradation of lignocellulosic biomass is primarily affected by the composition and structure of biomass, as well as enzyme activities that are influenced by the presence of in-process degradation products.This study focuses on the latter, and demonstrates that cellulase activity of Neurospora discreta is stimulated in the presence of in-process soluble lignin degradation products. Two types of biomass, cocopeat and sugarcane bagasse, with contrasting lignin content and cellulose structure were tested at two biomass loadings each. At the higher biomass loading, cocopeat showed the highest amount of hydrolyzed cellulose and cellulase activity, despite its low cellulose content and recalcitrant cellulose structure. A strong positive correlation was revealed between the amount of in-process degraded lignin and cellulase activity, indicating a stimulatory effect on cellulase, which contradicts most previous literature. Furthermore, the causal relationship between the amount of degraded lignin and cellulase activity was established in a model system of commercial cellulase and standard soluble lignin. This work could pave the way for using biomass loading as a process lever to enhance cellulose hydrolysis in microbial conversion of lignocellulosic biomass.

A comparative study of greener alternatives for nanocellulose production from sugarcane bagasse

“…In the spectra, the band between 1420 and 1430 cm −1 is known as ‘crystalline band’, while the band appearing between 893 and 898 cm −1 represents ‘amorphous band’ (Karimi and Taherzadeh 2016 ). To compare the degree of crystallinity in cellulose in different samples, the crystallinity indices, Lateral Order Index (LOI) and Total Crystallinity Index (TCI) were calculated by noting the absorbance values and taking ratios such as (Pamidipati and Ahmed 2019 ). Spectral ratio, 1420/893 cm −1 indicates LOI which is sensitive to the amount of crystalline versus amorphous regions in the cellulose, and therefore a lower value indicates more amorphous regions in the cellulose structure.…”

“…Sample pellets were prepared using 1 mg of sample and 100 mg of oven-dried potassium bromide. For each spectrum, 64 scans in the range of 400–4000 cm −1 with a resolution of 2 cm −1 were conducted in the transmittance mode and FT-IR spectra for the samples lie between ranges of 500–4500 cm −1 (Mandal and Chakrabarty 2011 ; Pamidipati and Ahmed 2019 ).…”

Effects of exogenous organic matter addition on agricultural soil microbial communities and relevant enzyme activities in southern China

“…Moreover, soil enzyme activity may be a rate-limiting step in mineralization process and has a rapid response to soil C and nutrient availability with fertilizer 15 . In the cycling of nutrients, some soil enzymes participate in the elemental biochemical process, such as cellulase and β-1,4-glucosidase (BG) play an important role in degrading cellulose, producing glucose and releasing available nutrients, while N -acetyl-β-Dglucosaminidase (NAG) and Urease can represent soil N turnover, and acid phosphomonoesterase (AcP) is involved in organic phosphorus hydrolysis 16 – 19 . These enzymes are sensitive indicators for the variables of soil properties and are useful for the sustainable management of soil quality 14 .…”

Production of Cocktail of Lignolytic, Cellulolytic and Hemicellulolytic Enzymes by the Novel Bacterium Burkholderia sp SMB1 Utilizing Rice Bran and Straw: Application in the Saccharification of Untreated Agro-wastes for Bioethanol Production

“…But the major drawback for their utilization is lignin which covers cellulose and hemicellulose part [6]. The production of bioethanol demands treatment to remove lignin and hydrolyze cellulosic and hemicellulosic part of LCAWs to produce fermentable sugars which are subsequently fermented to ethanol [7]. However, there are several pretreatments reported for this processes including chemical and thermochemical treatments which requires high energy and consequence negatively on the environment [3].…”