Pretreatment of Miscanthus with biomass‐degrading bacteria for increasing delignification and enzymatic hydrolysability

Abstract

Summary Biomass recalcitrance is still a main challenge for the production of biofuels and high‐value products. Here, an alternative Miscanthus pretreatment method by using lignin‐degrading bacteria was developed. Six efficient Miscanthus‐degrading bacteria were first cultured to produce laccase by using 0.5% Miscanthus biomass as carbon source. After 1–5 days of incubation, the maximum laccase activities induced by Miscanthus in the six strains were ranged from 103 to 8091 U l−1. Then, the crude enzymes were directly diluted by equal volumes of citrate buffer and added Miscanthus biomass to a solid concentration at 4% (w/v). The results showed that all bacterial pretreatments significantly decreased the lignin content, especially in the presence of two laccase mediators (ABTS and HBT). The lignin removal directly correlated with increases in total sugar and glucose yields after enzymatic hydrolysis. When ABTS was used as a mediator, the best lignin‐degrading bacteria (Pseudomonas sp. AS1) can remove up to 50.1% lignin of Miscanthus by obtaining 2.2‐fold glucose yield, compared with that of untreated biomass. Therefore, this study provided an effective Miscanthus pretreatment method by using lignin‐degrading bacteria, which may be potentially used in improving enzymatic hydrolysability of biomass.

Pretreatment for biorefineries: a review of common methods for efficient utilisation of lignocellulosic materials

“…In addition to fungi, bacteria exists that have the capability to degrade various lignocellulosic components. Guo et al tested various genera from bacteria for laccase production and for their hydrolytic capacity on miscanthus [186]. The strains included, for instance, Bacillus , Pseudomonas , Exiguobacterium and Aeromonas .…”

Recent Advances in Miscanthus Macromolecule Conversion: A Brief Overview

“…Similar to other lignocellulosic feedstocks, several pretreatment methods are applicable to miscanthus. Some methods are already reckoned to be conventional (ball milling, acid treatment, alkaline treatment, ammonia treatment, organosolv treatment, ionic liquid treatment, hot water treatment, steam explosion treatment), and new methods are under development (microwave, ultrasound, deep eutectic solvent, irradiation, high force-assisted pretreatment methods, biological pretreatment) [ 69 , 70 ]. That said, the conventional methods continue to be investigated for a deeper understanding of fractionation, optimization and process scale-up [ 71 ].…”

Application of ligninolytic bacteria to the enhancement of lignocellulose breakdown and methane production from oil palm empty fruit bunches (OPEFB)

“…Biodegradation of lignocellulosic biomass has been widely carried out using biological pretreatment, especially using white and brown rot fungi that produce extracellular peroxidases and laccase (Bugg et al, 2020;Ren et al, 2019;Wan and Li, 2012). However, the use of fungi in lignocellulose biodegradation often requires a long period of incubation to be able to produce specific enzymes in degrading lignin (Guo et al, 2019). The use of fungal enzymes is challenging to express in high yield, and fungi are also difficult to be genetically modified.…”