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other·biotechnology, bioenergy, environmental science, microbiology, biochemical engineering·PMC10064694

Degradation of lignin in different lignocellulosic biomass by steam explosion combined with microbial consortium treatment

Biotechnology for Biofuels and Bioproducts · 3 authors, 4 centres

AI SUMMARY

FIDELITY 100%

POPULATIONThree lignocellulosic biomass types: eucalyptus root (lignin 26.31±2.94%, cellulose 40.48±1.95%, hemicellulose 18.80±1.54%), bagasse (lignin 20.76±2.73%, cellulose 42.95±4.42%, hemicellulose 20.82±0.94%), and corn straw (lignin 16.37±3.69%, cellulose 39.54±5.43%, hemicellulose 24.91±4.80%)

INTERVENTIONSteam explosion pretreatment at 1.2, 1.6, and 2.0 MPa for 180 seconds followed by microbial consortium (J-6 or J-1) degradation at pH 4, 30°C, 180 rpm for up to 28 days

COMPARISONUntreated biomass, steam explosion alone, and microbial consortium alone (without steam explosion)

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AGENT 01 · STRUCTURED SUMMARY

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TL;DR

This study demonstrates that combining steam explosion pretreatment with microbial consortium (J-6 and J-1) degradation significantly improves lignin degradation efficiency in three types of lignocellulosic biomass (eucalyptus root, bagasse, and corn straw). After 1.6 MPa steam explosion followed by 7 days of microbial treatment, lignin degradation reached 35.35% for eucalyptus root, 37.61–44.24% for bagasse and corn straw, with strong selective lignin degradation and enhanced enzymatic saccharification. The combined approach overcomes the slow degradation rate and poor adaptability of traditional biological pretreatment, facilitating high-value conversion of lignocellulosic biomass for biofuel production.

Full summary

3,981 CHARS

**Background:** Lignin is a natural barrier in lignocellulosic biomass that hinders its conversion into high-value products like biofuel ethanol. Biological pretreatment is environmentally friendly but suffers from slow degradation rates and poor adaptability. Microbial consortia, which leverage synergistic interactions between fungi and bacteria, offer advantages over single strains. This study investigates a combined steam explosion and microbial consortium approach to improve lignin degradation in three common Chinese biomass feedstocks.

**Methods:** Two microbial consortia (J-6 and J-1) previously screened from decayed wooden relics were used. J-6 fungi were dominated by Saccharomycetales (98.92%) and bacteria by Shinella sp. (47.38%), Cupriavidus sp. (29.84%), and Bosea sp. (7.96%). J-1 fungi were dominated by Saccharomycetales (98.56%) and bacteria by Serratia sp. (95.23%) and Yersinia sp. (2.33%). Biomass (eucalyptus root, bagasse, corn straw) was crushed, sieved (40-80 mesh), and dried at 105°C for 72h. Steam explosion pretreatment was performed at 1.2, 1.6, and 2.0 MPa for 180 seconds after 10 min water immersion. Microbial consortia were domesticated at pH 5, 30°C, 160 rpm for 14 days, then cultured in degradation medium. Lignin degradation experiments varied pH (4-8), degradation time (3-28 days), and steam explosion pressure. Component analysis followed NREL methods using HPLC. Selectivity value (SV) was calculated as lignin degradation efficiency/cellulose degradation efficiency. Saccharification efficiency was measured using 20 FPU/g cellulase. Morphology was examined by SEM and XRD. Microbial community structure was analyzed by 16S rRNA and ITS gene sequencing on Illumina MiSeq/NovaSeq platforms.

**Key Results:** Optimal pH was 4.0-5.0. After 1.6 MPa steam explosion treatment, lignin degradation efficiency of eucalyptus root reached 35.35% on day 7 by J-1 (34.36% by J-6). Bagasse reached 37.61% (J-1) and corn straw reached 44.24% (J-6) after 7 days. Steam explosion alone achieved only 7.72% (eucalyptus root), 5.31% (bagasse), and 8.83% (corn straw) lignin degradation. SV values after 1.6 MPa treatment ranged from 2.35-3.59 for J-6 and 2.33-2.85 for J-1, with J-6 reaching SV of 3.59 for corn straw. Enzymatic saccharification efficiency was significantly improved after combined treatment; direct biological pretreatment of corn straw (without steam explosion) achieved 40.76% saccharification efficiency. SEM showed structural damage and increased porosity after combined treatment. Cellulose crystallinity decreased by an average of 10.3% after steam explosion but was not significantly changed by microbial treatment alone. Fungal communities remained stable (Saccharomycetales dominant), while bacterial composition shifted significantly. Dominant bacteria in J-6 eucalyptus root system: Staphylococcaceae (26.32%), Ralstonia (22.12%), Pseudomonadaceae (18.55%). In bagasse: Geobacter (48.25%), Ralstonia (7.81%). In corn straw: Pseudomonadaceae (30.04%), Ralstonia (20.53%). J-1 in eucalyptus root: Ralstonia (24.65%), Pseudomonadaceae (36.33%); in bagasse: Ralstonia (32.05%), Pseudomonadaceae (21.24%); in corn straw: Alcaligenaceae (90.15%). Shannon diversity index showed J-6 maintained higher bacterial diversity than J-1.

**Clinical Implications:** This is not a clinical study. The findings have implications for industrial biotechnology and renewable energy production. The combined steam explosion-microbial consortium pretreatment technology significantly improves lignin degradation efficiency (over 40% for corn straw in 7 days) compared to traditional biological methods (typically 24-34% over 11-29 days), reduces treatment time, and enhances enzymatic saccharification. This approach could enable more efficient and economically viable conversion of agricultural and forestry waste into bioethanol and other high-value products, contributing to carbon emission reduction and sustainable energy production.

PICO

PPOPULATION

Three lignocellulosic biomass types: eucalyptus root (lignin 26.31±2.94%, cellulose 40.48±1.95%, hemicellulose 18.80±1.54%), bagasse (lignin 20.76±2.73%, cellulose 42.95±4.42%, hemicellulose 20.82±0.94%), and corn straw (lignin 16.37±3.69%, cellulose 39.54±5.43%, hemicellulose 24.91±4.80%)

IINTERVENTION

Steam explosion pretreatment at 1.2, 1.6, and 2.0 MPa for 180 seconds followed by microbial consortium (J-6 or J-1) degradation at pH 4, 30°C, 180 rpm for up to 28 days

OOUTCOME

Lignin degradation efficiency (%), selectivity value (SV = lignin degradation/cellulose degradation), enzymatic saccharification efficiency (%), and structural/microbial community changes

STUDY TYPE

other

SPECIALTY

biotechnology

SUMMARISED BY

AI pipeline

FIDELITY CHECK

100% · A

ORIGINAL PAPER

PMC10064694

Degradation of lignin in different lignocellulosic biomass by steam explosion combined with microbial consortium treatment

Biotechnology for Biofuels and Bioproducts

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ABSTRACT

The difficulty of degrading lignin is the main factor limiting the high-value conversion process of lignocellulosic biomass. The biodegradation of lignin has attracted much attention because of its strong environmental friendliness, but it still faces some dilemmas such as slow degradation rate and poor adaptability. The microbial consortia with high lignin degradation efficiency and strong environmental adaptability were obtained in our previous research. To further increase the lignin degradation efficiency, this paper proposes a composite treatment technology of steam explosion combined with microbial consortium degradation to treat three kinds of biomass. We measured the lignin degradation efficiency, selectivity value (SV) and enzymatic saccharification efficiency. The structural changes of the biomass materials and microbial consortium structure were also investigated. The experimental results showed that after 1.6 MPa steam explosion treatment, the lignin degradation efficiency of the eucalyptus root reached 35.35% on the 7th days by microbial consortium. At the same time, the lignin degradation efficiency of the bagasse and corn straw treated by steam explosion followed by microbial biotreatment was 37.61–44.24%, respectively, after only 7 days of biotreatment. The microbial consortium also showed strong selectivity degradation to lignin. The composite treatment technology can significantly improve the enzymatic saccharification efficiency. Saccharomycetales, Ralstonia and Pseudomonadaceae were the dominant microorganisms in the biomass degradation systems. It was proved that the combined treatment technology of steam explosion and microbial consortium degradation could overcome the drawbacks of traditional microbial pretreatment technology, and can facilitate the subsequent high-value conversion of lignocellulose.

CITATION EXPORT

Wen Zhang, Chenyang Diao, Lei Wang. Degradation of lignin in different lignocellulosic biomass by steam explosion combined with microbial consortium treatment. Biotechnology for Biofuels and Bioproducts. (2023). https://doi.org/10.1186/s13068-023-02306-2

AUTHORS

3 · 4 CENTRES

Wen Zhang, Chenyang Diao, Lei Wang

1grid.413073.20000 0004 1758 9341College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou, 310015 Zhejiang China
2grid.413073.20000 0004 1758 9341Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Zhejiang Shuren University, Hangzhou, 310015 Zhejiang China
3grid.494629.40000 0004 8008 9315School of Engineering, Westlake University, Hangzhou, 310024 Zhejiang China
4grid.494629.40000 0004 8008 9315Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, 310024 Zhejiang China