Lignocellulosic fermentation

Overexpression of a gene with unknown function in Kluyveromyces marxianus markedly improved tolerance to lignocellulosic biomass-derived inhibitors. This overexpression also enhanced tolerance to elevated temperatures, ethanol, and high concentrations of NaCl and glucose. Inhibitor degradation and transcriptome analyses related this K. marxianusMultiple Stress Resistance (KmMSR) gene to the robustness of yeast cells. Nuclear localization and DNA-binding domain analyses indicate that KmMsr is a putative transcriptional regulator...

Biohydrogen (BioH2 ) is widely recognized as a sustainable and environmentally friendly energy source, devoid of any detrimental impact on the environment. Lignocellulosic biomass (LB) is a readily accessible and plentiful source material that can be effectively employed as a cost-effective and sustainable substrate for Bio-H2 production. Despite the numerous challenges, the ongoing progress in LB pretreatment technology, microbial fermentation, and the integration of molecular biology techniques have the potential to enhance Bio-H2 productivity and yield...

Lignocellulosic biomass holds a crucial position in the prospective bio-based economy, serving as a sustainable and renewable source for a variety of biobased products. These products play a vital role in displacing fossil fuels and contributing to environmental well-being. However, the inherent recalcitrance of biomass poses a significant obstacle to the efficient access of sugar polymers. Consequently, the bioconversion of lignocellulosic biomass into fermentable sugars remains a prominent challenge in biorefinery processes to produce biofuels and biochemicals...

The utilization of anaerobic hydrolysate from agroforestry wastes is limited by dissolved lignin and aromatics, which have received insufficient attention despite their potential as excellent carbon sources for denitrification. This study aims to investigate the influence of hematite on lignin-derived aromatic compounds and denitrifying carbon sources, as well as to identify iron-reducing bacteria that utilize lignin-derived aromatic compounds as electron donors. The findings revealed that hematite facilitated the anaerobic fermentation of plant biomass, resulting in the production of small molecular organic acids...

The hydrolysis of lignocellulose into fermentable monosaccharides using cellulases represents a critical stage in lignocellulosic bioconversion. However, the inactivation of cellulase in the presence of lignin is attributed to the high cost of biofinery. To address this challenge, a comprehensive investigation into the structure-function relationship underlying lignin-driven cellulase inactivation is essential. In this study, molecular docking and molecular dynamics (MD) simulations were employed to explore the impacts of lignin fragments on the catalytic efficiency of cellulase at the atomic level...

Cellulose is the basic component of lignocellulosic biomass (LCB) making it a suitable substrate for bioethanol fermentation. Cellulolytic and ethanologenic bacteria possess cellulases that convert cellulose to glucose, which in turn yields ethanol subsequently. Heterotermes indicola is a subterranean termite that causes destructive damage by consuming wooden structures of infrastructure, LCB products, etc. Prospectively, the study envisioned the screening of cellulolytic and ethanologenic bacteria from the termite gut...

Microbial oils are a sustainable biomass-derived substitute for liquid fuels and vegetable oils. Oilcane, an engineered sugarcane with superior feedstock characteristics for biodiesel production, is a promising candidate for bioconversion. This study describes the processing of oilcane stems into juice and hydrothermally pretreated lignocellulosic hydrolysate and their valorization to ethanol and microbial oil using Saccharomyces cerevisiae and engineered Rhodosporidium toruloides strains, respectively. A bioethanol titer of 106 g/L was obtained from S...

Parageobacillus thermoglucosidasius is a thermophilic and facultatively anaerobic microbe, which is emerging as one of the most promising thermophilic model organisms for metabolic engineering. The use of thermophilic microorganisms for industrial bioprocesses provides the advantages of increased reaction rates and reduced cooling costs for bioreactors compared to their mesophilic counterparts. Moreover, it enables starch or lignocellulose degradation and fermentation to occur at the same temperature in a Simultaneous Saccharification and Fermentation (SSF) or Consolidated Bioprocessing (CBP) approach...

The lignocellulose bioconversion process is an eco-friendly and green-economy alternative technology that allows the reduction of pollution and global warming, so it is necessary for thermophilic and thermostable hydrolytic enzymes from natural sources. This research aimed to isolate cellulolytic and xylanolytic microbial consortia from Huancarhuaz hot spring (Peru) from sludge or in situ baiting cultured with or without sugarcane bagasse. According to the hydrolytic activities consortium T4 from in situ baiting was selected...

BACKGROUND: Spathaspora passalidarum is a yeast with the highly effective capability of fermenting several monosaccharides in lignocellulosic hydrolysates, especially xylose. However, this yeast was shown to be sensitive to furfural released during pretreatment and hydrolysis processes of lignocellulose biomass. We aimed to improve furfural tolerance in a previously isolated S. passalidarum CMUWF1-2, which presented thermotolerance and no detectable glucose repression, via adaptive laboratory evolution (ALE)...

Use of white-rot fungi for enzyme-based bioremediation of wastewater is of high interest. These fungi produce considerable amounts of extracellular ligninolytic enzymes during solid-state fermentation on lignocellulosic materials such as straw and sawdust. We used pure sawdust colonized by Pleurotus ostreatus, Trametes versicolor, and Ganoderma lucidum for extraction of ligninolytic enzymes in aqueous suspension. Crude enzyme suspensions of the three fungi, with laccase activity range 12-43 U/L and manganese peroxidase activity range 5-55 U/L, were evaluated for degradation of 11 selected pharmaceuticals spiked at environmentally relevant concentrations...

The present study reports a highly thermostable β-glucosidase (GH3) from Rasamsonia emersonii that was heterologously expressed in Pichia pastoris. Extracellular β-glucosidase was purified to homogeneity using single step affinity chromatography with molecular weight of ~ 110 kDa. Intriguingly, the purified enzyme displayed high tolerance to inhibitors mainly acetic acid, formic acid, ferulic acid, vanillin and 5-hydroxymethyl furfural at concentrations exceeding those present in acid steam pretreated rice straw slurry used for hydrolysis and subsequent fermentation in 2G ethanol plants...

Full conversion of glucose and xylose from lignocellulosic hydrolysates is required for obtaining a high ethanol yield. However, glucose and xylose share flux in the pentose phosphate pathway (PPP) and glycolysis pathway (EMP), with glucose having a competitive advantage in the shared metabolic pathways. In this work, we knocked down ZWF1 to preclude glucose from entering the PPP. This reduced the [NADPH] level and disturbed growth on both glucose or xylose, confirming that the oxidative PPP, which begins with Zwf1p and ultimately leads to CO2 production, is the primary source of NADPH in both glucose and xylose...

Our planet, which operates as a closed system, is facing increasing entropy due to human activities such as the overexploitation of natural resources and fossil fuel use. The COP28 in Dubai emphasized the urgency to abandon fossil fuels, recognizing them as the primary cause of human-induced environmental changes, while highlighting the need to transition to renewable energies. We promote the crucial role of microbes for sustaining biogenic cycles to combat climate change and the economic potential of synthetic biology tools for producing diverse non-fossil fuels and chemicals, thus contributing to emission reduction in transport and industry...

Low production costs and a potential feedstock supply make lignocellulosic ethanol (bioethanol) an important source of advanced biofuels. The physical and chemical preparation of this kind of lignocellulosic feedstock led to a high ethanol yield. In order to increase the yield of fermentable sugars, pretreatment is an essential process step that alters the lignocellulosic structure and improves its accessibility for the expensive hydrolytic enzymes. In this context, the chemical composition of sugarcane trash (dry leaves, green leaves, and tops) and jatropha (shell and seed cake) was determined to be mainly cellulose, hemicellulose, and lignin...

BACKGROUND: The polysaccharides in lignocellulosic biomass hold potential for production of biofuels and biochemicals. However, achieving efficient conversion of this resource into fermentable sugars faces challenges, especially when operating at industrially relevant high solid loadings. While it is clear that combining classical hydrolytic enzymes and lytic polysaccharide monooxygenases (LPMOs) is necessary to achieve high saccharification yields, exactly how these enzymes synergize at high solid loadings remains unclear...

Acidic pit lakes (APLs) emerge as reservoirs of acid mine drainage in flooded open-pit mines, representing extreme ecosystems and environmental challenges worldwide. The bioremediation of these oligotrophic waters necessitates the addition of organic matter, but the biogeochemical response of APLs to exogenous organic matter remains inadequately comprehended. This study delves into the biogeochemical impacts and remediation effects of digestate-derived organic matter within an APL, employing a multi-omics approach encompassing geochemical analyses, amplicon and metagenome sequencing, and ultra-high resolution mass spectrometry...

Disulfide bonds are important for maintaining the structural conformation and stability of the protein. The introduction of the disulfide bond is a promising strategy to increase the thermostability of the protein. In this report, cysteine residues are introduced to form disulfide bonds in the Glycoside Hydrolase family GH 7 cellobiohydrolase (GH7 CBHs) or Cel7A of Aspergillus fumigatus . Disulfide by Design 2.0 (DbD2), an online tool is used for the detection of the mutation sites. Mutations are created (D276C-G279C; DSB1, D322C-G327C; DSB2, T416C-I432C; DSB3, G460C-S465C; DSB4) inside and outside of the peripheral loops but, not in the catalytic region...

Microbial cellulases are highly versatile catalysts with significant potential in various industries, including pulp and paper, textile manufacturing, laundry, biofuel production, food and animal feed, brewing, and agriculture. Cellulases have attracted considerable attention from the scientific community owing to their broad industrial applications and the complex nature of enzymatic systems. In the present study, a novel fungal isolate of Aspergillus sp. IN5 was used to produce cellulases. We optimized each parameter, including carbon source, incubation temperature, pH, and incubation time, for maximum cellulase production using isolate IN5 under solid-state fermentation conditions...

Corn stover is the most abundant form of crop residue that can serve as a source of lignocellulosic biomass in biorefinery approaches, for instance for the production of bioethanol. In such biorefinery processes, the constituent polysaccharide biopolymers are typically broken down into simple monomeric sugars by enzymatic saccharification, for further downstream fermentation into bioethanol. However, the recalcitrance of this material to enzymatic saccharification invokes the need for innovative pre-treatment methods to increase sugar conversion yield...