Biological delignification of rice straw using laccase from Bacillus ligniniphilus L1 for bioethanol production: A clean approach for agro-biomass utilization

Characterization and rational engineering of a novel laccase from Geobacillus thermocatenulatus M17 for improved lignin degradation activity

Lignin, with its complex, high-molecular-weight aromatic polymer structure and stable ether or ester bonds, greatly impedes the efficient degradation of lignocellulosic waste. Bacterial laccases have gained attention for their potential in lignocellulosic waste degradation due to their resilience in extreme conditions and ability to be produced in large quantities. In this study, a novel laccase from Geobacillus thermocatenulatus M17 was identified and expressed in E. coli BL21 (DE3). The enzymatic properties of this M17 laccase, including its tolerance to pH, temperature, metal ions, inhibitors, and organic solvents, were thoroughly investigated. The M17 laccase demonstrated optimal activity at pH 3-6 and at temperatures of 50-60 °C, with Co2+ enhancing its activity over Cu2+, and exhibited strong resistance to organic solvents. Further optimization through mutagenesis led to the engineered D217K variant. The efficiency of the engineered laccase was validated with alkali lignin and various sources of plant biomass. The degradation rate of D217K variant for alkali lignin increased significantly, rising from 66.33 % to 83.27 %. Additionally, for high-lignin-content biomass, the degradation rates improved as follows: wheat stover increased from 7.63 % to 10.29 %, switchgrass from 6.02 % to 7.00 %, and corn stalk from 4.51 % to 6.59 %. In conclusion, this study identified a new bacterial laccase and further enhanced its activity through rational engineering, suggesting its promising application in plant biomass degradation.

Deep eutectic solvents assisted laccase pretreatment for improving enzymatic hydrolysis of corn stover

The efficient and eco-friendly removal of lignin is a critical challenge for bioethanol production from lignocellulosic biomass. Herein, we report the integration of laccase with deep eutectic solvents (DESs) for the pretreatment of corn stover to enhance the production of reducing sugars. Three betaine-based DESs were prepared and tested for their effects on the activity and stability of a bacterial laccase from Bacillus amyloliquefaciens LC02. The aqueous solution of DESs showed no adverse influence on laccase activity, and the laccase thermostability was improved in the presence of DESs. More than 95% of the laccase activity was retained in the DESs solution during the first hour of incubation at 70 °C. A red shift in the fluorescence spectra was observed for the laccase in the presence of DESs, indicating conformational changes. The laccase was able to degrade a dimeric lignin model compound by cleaving its β-O-4 bond. The transformation products were identified using LC-MS. The maximal lignin removal from corn stover was achieved by pretreatment using laccase in combination with the betaine-glycerol DES, which also resulted in a yield of fermentable sugar that was 130% higher than the control. This combination strategy provides guidance on the application of laccase and DESs in the pretreatment of lignocellulosic biomass.

Novel strategy to understand the bacteria-enzyme synergy action regulates the ensiling performance of wheat straw silage by multi-omics analysis

BACKGROUND

Ensiling technology shows promise for preserving and providing high-quality forage. However, the high polymeric content and compact properties of fiber result in low biodigestibility. This study aimed to evaluate the use of ensiling technology for storing wheat straw. It also analyzed changes in fermentation-related products, chemical components, bacterial communities, and metabolite profiles of wheat straw ensiled with or without cellulase or Lactiplantibacillus plantarum (L. plantarum).

RESULTS

The results showed that inoculation with L. plantarum, either alone or with cellulase, produced abundant organic acids, degraded fiber, suppressed most microbes, and increased certain metabolites in wheat straw silage. Wheat straw inoculated with L. plantarum, either alone or with cellulase, exhibited significantly lower neutral detergent fiber and acid detergent fiber contents compared to the control treatment. Additionally, higher lactic acid and acetic acid contents were observed in these treatments. The microbiome analysis revealed that Lactobacillus was dominant, while Kosakonia was suppressed. Metabolic analysis showed a significant increase in amino acids, peptides, analogues, and organic acid derivatives.

CONCLUSIONS

Overall, wheat straw inoculated with L. plantarum, either alone or with cellulase, produced well-preserved silage, providing new insights into recycling and utilizing wheat straw through bacterial-enzyme synergy.

Evaluating the impact of Bt rice straw return on Eisenia fetida: AHP analysis, biomarkers, and Bt protein fate

A 90-d laboratory experiment was carried out using Bacillus thuringiensis (Bt) rice straws (BTTY and GK775) and non-Bt rice straws (MXZ2, HH1179, and HH38). The objective was to investigate the differences in the effects of Bt and non-Bt rice straws on the earthworm Eisenia fetida. The analytic hierarchy process was applied to assess the risk of returning rice straw to soil on E. fetida by measuring their survival rate, relative growth rate, reproduction, total protein, superoxide dismutase, and glutathione peroxidase (GSH-PX). The results showed that returning Bt rice straw to soil poses no risk to E. fetida over time and that the impacts varied depending on the rice variety. The correlation analysis indicated that GSH-PX activity can be regarded as a biomarker to evaluate the impact of returning rice straw to soil on E. fetida, with GSH-PX activity negatively correlated with potential risk. Cry1Ab protein degraded rapidly, with E. fetida activity slightly accelerating the process. The rice variety was a key factor affecting soil nutrients among the different rice straw treatments, which significantly affected E. fetida's biological and biochemical parameters. Therefore, returning rice straw to soil presented different effects on E. fetida owing to the differences in rice variety rather than the presence of Cry1Ab protein.

Elucidating the bioremediation potential of laccase and peroxidase enzymes from Bacillus ligniniphilus L1 in antibiotic degradation: A computationally guided study

This study showcased the antibiotic degradation abilities of laccase and catalase-peroxidase from Bacillus ligniniphilus L1, an extremophile, against 18 common antibiotics using computationally guided approach. Molecular docking and simulation identified six enzyme-antibiotic complexes for laccase and four for catalase-peroxidase, demonstrating significant binding affinity and stability. Enzyme activity assays corroborated computational results, indicating both enzymes could degrade all tested antibiotics with varying efficiencies. L1 laccase outperformed commercial laccase against five antibiotics, notably vancomycin, levofloxacin, tobramycin, linezolid, and rifamycin, with enhanced degradation potential upon ABTS addition. Catalase-peroxidase from L1 exhibited superior degradation efficiency over commercial peroxidase against vancomycin, linezolid, tobramycin, and clindamycin. Overall, this study underscores the computational approach's utility in understanding enzyme-mediated antibiotic degradation, offering insights into environmental contaminant remediation.

Evaluating the estrogen degradation potential of laccase and peroxidase from Bacillus ligniniphilus L1 through integrated computational and experimental approaches

This study investigated the degradation potential of laccase and catalase-peroxidase from the extremophilic marine bacterium Bacillus ligniniphilus L1 against endogenous and synthetic estrogen compounds using an integrated computational and experimental approach. Molecular docking identified five estrogen compounds exhibiting reliable bindings with enzymes, which were then subjected to enzyme activity assays. The degradation potential of the two enzymes against five selected estrogen compounds were investigated and compared with their commercial counterparts. Laccase from L1 showed higher degradation potential against estrone (47.02 % without and 62.21 % with ABTS) compared to commercial laccase (39 % without and 54.20 % with ABTS). For estradiol valerate, commercial laccase showed a slightly higher degradation (52.47 %) than L1 laccase (49.94 %), but with ABTS, L1 laccase performed better (74.15 % vs. 68.03 %). Notably, L1 catalase-peroxidase demonstrated significantly higher degradation for all tested compounds compared to its commercial counterpart with efficiencies of 96.16 %, 89.09 %, 74.94 %, 64.91 %, and 62.80 % against estropipate, quinestrol, estradiol valerate, estriol and estrone, respectively, revealing its potential for commercial applications. Molecular dynamics simulations revealed the interaction and stability of enzyme-estrogen complexes, with MMGBSA binding energy calculations supporting experimental results. These findings highlight the usefulness of the computational approach in elucidating the molecular mechanisms underlying enzyme-mediated bioremediation of environmental contaminants.

Adaptation of Chlorella vulgaris immobilization on rice straw with liquid manure to create a sustainable feedstock for biogas production and potential feed applications

Rice straw (RS) is a widely available agricultural residue with significant potential for biogas production and feed applications; however, its poor digestibility and nutritional value limit its utilization. This study explores an innovative approach to enhance the digestibility and nutritional value of RS by cultivating Chlorella vulgaris through immobilization technology on RS, using liquid manure (LM) as an alternative to the traditional BG11 medium. The results showed an increase in chlorophyll a (Chl a) after 12 days for both the BG11 medium and LM-based treatments, from 0.13 to 0.34 and 0.24 mg Chl a/g product (DM), respectively. Additionally, the immobilized microalgal biomass increased to 284.18 and 170.14 mg algal biomass/g product (DM), respectively. Soaking under microaerobic conditions during cultivation led to the partial degradation of RS. This, combined with the formed microalgal biofilm, contributed to an improved digestibility of the dry matter, reaching 69.1% and 65.9% for the final products based on the BG11 medium and LM mediums, respectively, compared to 52.1% for the raw RS. Furthermore, the crude protein and lipids contents were significantly improved with the potential for applications in feed, reaching 21.4% and 4.1% for the BG11 medium-based product, while they were observed to be 12.8% and 3.0%, respectively, for the LM-based product. Additionally, carbon-to-nitrogen ratio was significantly reduced compared to the raw RS. The higher digestibility and improved nutritional value contributed to increased biogas production, reaching 129.3 and 118.7 mL/g (TS) for the products based on the traditional medium and LM medium, respectively, compared to 86.7 mL/g (TS) for the raw RS. The immobilization mechanism and biofilm development could be attributed to the roughness of the RS and extracellular polymer substances. This study demonstrates that integrating C. vulgaris cultivation on RS with LM as a nutrient source not only enhances the digestibility and nutritional value of RS but also offers a sustainable waste management solution with potential applications in biogas production and animal feed.

Bacterial valorization of lignin for the sustainable production of value-added bioproducts

As the most abundant aromatic biopolymer in the biosphere, lignin represents a promising alternative feedstock for the industrial production of various value-added bioproducts with enhanced economical value. However, the large-scale implementation of lignin valorization remains challenging because of the heterogeneity and irregular structure of lignin. General fragmentation and depolymerization processes often yield various products, but these approaches necessitate tedious purification steps to isolate target products. Moreover, microbial biocatalytic processes, especially bacterial-based systems with high metabolic activity, can depolymerize and further utilize lignin in an eco-friendly way. Considering that wild bacterial strains have evolved several metabolic pathways and enzymatic systems for lignin degradation, substantial efforts have been made to exploit their potential for lignin valorization. This review summarizes recent advances in lignin valorization for the production of value-added bioproducts based on bacterial systems. Additionally, the remaining challenges and available strategies for lignin biodegradation processes and future trends of bacterial lignin valorization are discussed.

Lignin valorization through the oxidative activity of β-etherases: Recent advances and perspectives

The increasing interest in lignin, a complex and abundant biopolymer, stems from its ability to produce environmentally beneficial biobased products. β-Etherases play a crucial role by breaking down the β-aryl ether bonds in lignin. This comprehensive review covers the latest advancements in β-etherase-mediated lignin valorization, focusing on substrate selectivity, enzymatic oxidative activity, and engineering methods. Research on the microbial origin, protein modification, and molecular structure determination of β-etherases has improved our understanding of their effectiveness. Furthermore, the use of these enzymes in biorefinery processes is promising for enhancing lignin breakdown and creating more valuable products. The review also discusses the challenges and future potential of β-etherases in advancing lignin valorization for biorefinery applications that are economically viable and environmentally sustainable.

Laccase: Sustainable production strategies, heterologous expression and potential biotechnological applications

Laccase is a multicopper oxidase enzyme that target different types of phenols and aromatic amines. The enzyme can be isolated and characterized from microbes, plants and insects. Its ubiquitous nature and delignification ability makes it a valuable tool for research and development. Sustainable production methods are being employed to develop low cost biomanufacturing of the enzyme while achieving high titers. Laccase have significant industrial application ranging from food industry where it can be used for wine stabilization, texture improvement and detection of phenolic compounds in food products, to cosmetics offering benefits such as skin brightening and hair colouring. Dye decolourization/degradation, removal of pharmaceutical products/emerging pollutants and hydrocarbons from wastewater, biobleaching of textile fabrics, biofuel production and delignification of biomass making laccase a promising green biocatalyst. Innovative methods such as using inducers, microbial co-culturing, recombinant DNA technology, protein engineering have pivotal role in developing laccase with tailored properties. Enzyme immobilization using new age compounds including nanoparticles, carbonaceous components, agro-industrial residues enhance activity, stability and reusability. Commercial formulations of laccase have been prepared and readily available for a variety of applications. Certain challenges including production cost, metabolic stress in response to heterologous expression, difficulty in purification needs to be addressed.

Rice straw waste-based green synthesis and characterizations investigation of Fe-MoS2-derived nanohybrid

In present work, synthesis of a nanohybrid material using Fe and MoS2 has been performed via a cost-effective and environmentally friendly route for sustainable manufacturing innovation. Rice straw extract was prepared and used as a reducing and chelating agent to synthesize the nanohybrid material by mixing it with molybdenum disulfide (MoS2) and ferric nitrate [Fe (NO3)3.9H2O], followed by heating and calcination. The X-ray diffraction (XRD) pattern confirms the formation of a nanohybrid consisting of monoclinic Fe2(MoO4)3, cubic Fe2.957O4, and orthorhombic FeS with 86% consisting of Fe2(MoO4)3. The properties were analyzed through Fourier-transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results of the dynamic light scattering (DLS) study revealed a heterogeneous size distribution, with an average particle size of 48.42 nm for 18% of particles and 384.54 nm for 82% of particles. Additionally, the zeta potential was measured to be -18.88 mV, suggesting moderate stability. X-ray photoelectron spectroscopy (XPS) results confirmed the presence of both Fe2+ and Fe3+ oxidation states along with the presence of Molybdenum (Mo), oxygen (O), and Sulphur (S). The prepared nanohybrid material exhibited a band gap of 2.95 eV, and the photoluminescence intensity increased almost twice that of bare MoS2. The present work holds potential applications in photo luminescent nanoplatform for biomedical applications.

A Treatment for Rice Straw and Its Use for Mealworm (Tenebrio molitor L.) Feeding: Effect on Insect Performance and Diet Digestibility

The development of reuse processes for plant by-products for both animal and human food offers numerous possibilities for quality-of-life improvements that align with a circular economy model. For this reason, we divided this study into two experiments. First, we designed a combined treatment consisting of laccase, ultrasound, and ascorbic acid to hydrolyze rice straw plant fibers and used the resulting feed as the basis for T. molitor diets. Second, we formulated diets with different inclusion levels (0%, 25%, 50%, 75%, and 100%) of rice straw and treated rice straw to assess their impact on larvae growth and diet digestibility. For each treatment, six replicates were employed: four for the growth-performance-digestibility trial and two for complementary uric acid determination tests. The combined laccase enzyme, ultrasound, and ascorbic acid treatment hydrolyzed 13.2% of the vegetable fibers. The diets containing treated rice straw resulted in higher larvae weight and a better feed conversion ratio; however, reaching 100% by-product inclusion values led to similar results between both diets. In conclusion, these treatments improve the potential of low-nutritional-value vegetable by-products as part of a T. molitor diet, opening the possibility of new methodologies for the use of recalcitrant vegetable by-products for insect rearing.

Investigation of the Microbial Diversity in the Oryza sativa Cultivation Environment and Artificial Transplantation of Microorganisms to Improve Sustainable Mycobiota

Rice straw is not easy to decompose, it takes a long time to compost, and the anaerobic bacteria involved in the decomposition process produce a large amount of carbon dioxide (CO2), indicating that applications for rice straw need to be developed. Recycling rice straw in agricultural crops is an opportunity to increase the sustainability of grain production. Several studies have shown that the probiotic population gradually decreases in the soil, leading to an increased risk of plant diseases and decreased biomass yield. Because the microorganisms in the soil are related to the growth of plants, when the soil microbial community is imbalanced it seriously affects plant growth. We investigated the feasibility of using composted rice stalks to artificially cultivate microorganisms obtained from the Oryza sativa-planted environment for analyzing the mycobiota and evaluating applications for sustainable agriculture. Microbes obtained from the water-submerged part (group-A) and soil part (group-B) of O. sativa were cultured in an artificial medium, and the microbial diversity was analyzed with internal transcribed spacer sequencing. Paddy field soil was mixed with fermented paddy straw compost, and the microbes obtained from the soil used for O. sativa planting were designated as group-C. The paddy fields transplanted with artificially cultured microbes from group-A were designated as group-D and those from group-B were designated as group-E. We found that fungi and yeasts can be cultured in groups-A and -B. These microbes altered the soil mycobiota in the paddy fields after transplantation in groups-D and -E compared to groups-A and -B. Development in O. sativa post treatment with microbial transplantation was observed in the groups-D and -E compared to group-C. These results showed that artificially cultured microorganisms could be efficiently transplanted into the soil and improve the mycobiota. Phytohormones were involved in improving O. sativa growth and rice yield via the submerged part-derived microbial medium (group-D) or the soil part-derived microbial medium (group-E) treatments. Collectively, these fungi and yeasts may be applied in microbial transplantation via rice straw fermentation to repair soil mycobiota imbalances, facilitating plant growth and sustainable agriculture. These fungi and yeasts may be applied in microbial transplantation to repair soil mycobiota imbalances and sustainable agriculture.

Decisional tool development and application for techno-economic analysis of fungal laccase production

Textile and medical effluents causing bioaccumulation and biomagnification have been successfully biodegraded by fungal laccases. Here, a decision-making tool was developed and applied to evaluate 45 different laccase production strategies which determined the best potential source from a techno-economical perspective. Laccase production cost was calculated with a fixed output of 109 enzymatic units per batch (USD$per109U) and a sensitivity analysis was performed. Results indicate that optimization of enzymatic kinetics for each organism is essential to avoid exceeding the fermentation time point at which production titer reaches its peak and, therefore, higher production costs. Overall, the most cost-effective laccase-producing strategy was obtained when using Pseudolagarobasidium acaciicola with base production cost of USD $42.46 per 109 U. This works serves as platform for decision-making to find the optimal laccase production strategy based on techno-economic parameters.

Harnessing the power of bacterial laccases for xenobiotic degradation in water: A 10-year overview

Industrialization and population growth are leading to the production of significant amounts of sewage containing hazardous xenobiotic compounds. These compounds pose a threat to human and animal health, as well as the overall ecosystem. To combat this issue, chemical, physical, and biological techniques have been used to remove these contaminants from water bodies affected by human activity. Biotechnological methods have proven effective in utilizing microorganisms and enzymes, particularly laccases, to address this problem. Laccases possess versatile enzymatic characteristics and have shown promise in degrading different xenobiotic compounds found in municipal, industrial, and medical wastewater. Both free enzymes and crude enzyme extracts have demonstrated success in the biotransformation of these compounds. Despite these advancements, the widespread use of laccases for bioremediation and wastewater treatment faces challenges due to the complex composition, high salt concentration, and extreme pH often present in contaminated media. These factors negatively impact protein stability, recovery, and recycling processes, hindering their large-scale application. These issues can be addressed by focusing on large-scale production, resolving operation problems, and utilizing cutting-edge genetic and protein engineering techniques. Additionally, finding novel sources of laccases, understanding their biochemical properties, enhancing their catalytic activity and thermostability, and improving their production processes are crucial steps towards overcoming these limitations. By doing so, enzyme-based biological degradation processes can be improved, resulting in more efficient removal of xenobiotics from water systems. This review summarizes the latest research on bacterial laccases over the past decade. It covers the advancements in identifying their structures, characterizing their biochemical properties, exploring their modes of action, and discovering their potential applications in the biotransformation and bioremediation of xenobiotic pollutants commonly present in water sources.

Enhancing Bioethanol Production from Rice Straw through Environmentally Friendly Delignification Using Versatile Peroxidase

Rice straw (RS), an agricultural residue rich in carbohydrates, has substantial potential for bioethanol production. However, the presence of lignin impedes access to these carbohydrates, hindering efficient carbohydrate-to-bioethanol conversion. Here, we expressed versatile peroxidase (VP), a lignin-degrading enzyme, in Pichia pastoris and used it to delignify RS at 30 °C using a membrane bioreactor that continuously discarded the degraded lignin. Klason lignin analysis revealed that VP-treatment led to 35% delignification of RS. We then investigated the delignified RS by SEC, FTIR, and SEM. The results revealed the changes of RS caused by VP-mediated delignification. Additionally, we compared the saccharification and fermentation yields between RSs treated with and without VP, VP-RS, and Ctrl-RS, respectively. This examination unveiled an improvement in glucose and bioethanol production, VP-RS exhibiting up to 1.5-fold and 1.4-fold production, respectively. These findings underscore the potential of VP for delignifying RS and enhancing bioethanol production through an eco-friendly approach.

Effect of fungal pretreatment by Pycnoporus sanguineus and Trichoderma longibrachiatum on the anaerobic digestion of rice straw

Rice straw is composed of complex lignocellulosic biomass, representing a major obstacle in its conversion to bioenergy. The objective of this study was to evaluate the usefulness of less explored fungal strains Trichoderma longibrachiatum (TL) and Pycnoporus sanguineus (PS) in improving hydrolysis and bioavailability of rice straw in anaerobic digestion (AD). The fungal treatment of rice straw for 10 days by PS and TL increased biogas production by 20.79% and 17.85% and reduced soluble chemical oxygen demand (sCOD) by 71.43% and 64.70%, respectively. The AD samples containing fungal-treated rice straw showed higher lignocellulolytic enzyme activities contributing to better process performance. The taxonomic profile of microbial communities in treated samples showed increased diversity that could sustain consistent system performance and exhibit enhanced resilience against pH fluctuations. Metagenomic analysis revealed 60.82% increase in Proteobacteria in PS and 11.58% increase in Bacteroidetes in TL-treated rice straw samples resulting in improved hydrolysis.

Papermaking wastewater treatment coupled to 2,3-butanediol production by engineered psychrotrophic Raoultella terrigena

The simultaneous bioremediation and bioconversion of papermaking wastewater by psychrotrophic microorganisms holds great promise for developing sustainable environments and economies in cold regions. Here, the psychrotrophic bacterium Raoultella terrigena HC6 presented high endoglucanase (26.3 U/mL), xylosidase (732 U/mL), and laccase (8.07 U/mL) activities for lignocellulose deconstruction at 15 °C. mRNA monitoring and phenotypic variation analyses confirmed that cold-inducible cold shock protein A (CspA) facilitated the expression of the cel208, xynB68, and lac432 genes to increase the enzyme activities in strain HC6. Furthermore, the cspA gene-overexpressing mutant (strain HC6-cspA) was deployed in actual papermaking wastewater and achieved 44.3%, 34.1%, 18.4%, 80.2% and 100% removal rates for cellulose, hemicellulose, lignin, COD, and NO3--N at 15 °C. Simultaneously, 2,3-butanediol (2,3-BD) was produced from the effluent with a titer of 2.98 g/L and productivity of 0.154 g/L/h. This study reveals an association between the cold regulon and lignocellulolytic enzymes and provides a promising candidate for simultaneous papermaking wastewater treatment and 2,3-BD production.

Biological saccharification coupled with anaerobic digestion using corn straw for sustainable methane production

In this study, accumulated fermentable sugars from biosaccharified corn straw were used to generate methane through anaerobic digestion (AD). The results showed that reducing sugars from biosaccharification expanded corn straw (BECS) treated with Clostridium thermocellum XF811 accumulated with yields of 94.9 mg/g. The BECS used for AD was converted into a high methane yield (7436 mL), which was 49.3 % higher than that of expanded corn straw (ECS). High-throughput microbial analysis suggested that Methanoculleus and Methanobacterium greatly contributed to the high methane yield. Industrial experiments demonstrated that the methane production from BECS by AD was 72,955 m³, which increased by 13.2 % compared to that from ECS. Biosaccharification pretreatment accelerated ECS destruction and accumulated sugars, thereby increasing methane yields. This study provides a strategy for producing clean energy from lignocellulose biomass.

Effects of laccase and lactic acid bacteria on the fermentation quality, nutrient composition, enzymatic hydrolysis, and bacterial community of alfalfa silage

Ensiling has long been as a mainstream technology of preserving forage for ruminant production. This study investigated the effects of bioaugmented ensiling with laccase and Pediococcus pentosaceus on the fermentation quality, nutritive value, enzymatic hydrolysis, and bacterial community of alfalfa. The application of laccase and Pediococcus pentosaceus combination was more potent in modulating the fermentation quality of silage than laccase and Pediococcus pentosaceus alone, as indicated by higher lactic acid contents and lactic acid to acetic acid ratios, and lower pH, dry matter losses, and ammonia nitrogen contents. Moreover, treatments with additive enhanced protein preservation and structural carbohydrate degradation, while increasing true protein and water-soluble carbohydrate contents. By promoting lignin degradation, treatments containing laccase further facilitated the release of sugars from cellulose compared with treatment with Pediococcus pentosaceus alone. The additive treatments reduced the bacterial diversity and optimized the bacterial community composition of silage, with an increase in the relative abundance of desirable Lactobacillus and a decrease in the relative abundance of undesirable Enterobacter and Klebsiella. PICRUSt functional prediction based on Kyoto Encyclopedia of Genes and Genomes (KEGG) databases revealed that PL and LPL treatments increased the metabolism of membrane transport, carbohydrate, and terpenoids and polyketides related to fermentation activities. It can be concluded that bioaugmented ensiling with laccase and Pediococcus pentosaceus combination can be an effective and practical strategy to improve silage fermentation and nutrient preservation of alfalfa silage.