Development of hybrid biomicroparticles: cellulose exposing functionalized fusion proteins

BACKGROUND

One of the leading current trends in technology is the miniaturization of devices to the microscale and nanoscale. The highly advanced approaches are based on biological systems, subjected to bioengineering using chemical, enzymatic and recombinant methods. Here we have utilised the biological affinity towards cellulose of the cellulose binding domain (CBD) fused with recombinant proteins.

RESULTS

Here we focused on fusions with 'artificial', concatemeric proteins with preprogrammed functions, constructed using DNA FACE™ technology. Such CBD fusions can be efficiently attached to micro-/nanocellulose to form functional, hybrid bionanoparticles. Microcellulose (MCC) particles were generated by a novel approach to enzymatic hydrolysis using Aspergillus sp. cellulase. The interaction between the constructs components - MCC, CBD and fused concatemeric proteins - was evaluated. Obtaining of hybrid biomicroparticles of a natural cellulose biocarrier with proteins with therapeutic properties, fused with CBD, was confirmed. Further, biological tests on the hybrid bioMCC particles confirmed the lack of their cytotoxicity on 46BR.1 N fibroblasts and human adipose derived stem cells (ASCs). The XTT analysis showed a slight inhibition of the proliferation of 46BR.1 N fibroblasts and ACSs cells stimulated with the hybrid biomicroparticles. However, in both cases no changes in the morphology of the examined cells after incubation with the hybrid biomicroparticles' MCC were detected.

CONCLUSIONS

Microcellulose display with recombinant proteins involves utilizing cellulose, a natural polymer found in plants, as a platform for presenting or displaying proteins. This approach harnesses the structural properties of cellulose to express or exhibit various recombinant proteins on its surface. It offers a novel method for protein expression, presentation, or immobilization, enabling various applications in biotechnology, biomedicine, and other fields. Microcellulose shows promise in biomedical fields for wound healing materials, drug delivery systems, tissue engineering scaffolds, and as a component in bio-sensors due to its biocompatibility and structural properties.

Metabolomics-based study of chemical compositions in cellulase additives derived from a tobacco-origin Bacillus subtilis and their impact on tobacco sensory attributes

To enhance the quality of tobacco leaves and optimize the smoking experience, diverse strains of functional bacteria and their associated metabolites have been used in tobacco aging. Exogenous cellulase additives are frequently employed to facilitate the degradation of cellulose and other macromolecular matrices and enhance the quality of the tobacco product. However, little is known about how microbial metabolites present in exogenous enzyme additives affect tobacco quality. In this study, crude cellulase solutions, produced by a tobacco-originating bacterium Bacillus subtilis FX-1 were employed on flue-cured tobacco. The incorporation of cellulase solutions resulted in the reduction of cellulose crystallinity in tobacco and the enhancement of the overall sensory quality of tobacco. Notably, tobacco treated with cellulase obtained from laboratory flask fermentation demonstrated superior scent and flavor attributes in comparison to tobacco treated with enzymes derived from industrial bioreactor fermentation. The targeted and untargeted metabolomic analysis revealed the presence of diverse flavor-related precursors and components in the cellulase additives, encompassing sugars, alcohols, amino acids, organic acids, and others. The majority of these metabolites exhibited significantly higher levels in the flask group compared to the bioreactor group, probably contributing to a pronounced enhancement in the sensory quality of tobacco. Our findings suggest that the utilization of metabolic products derived from B. subtilis FX-1 as additives in flue-cured tobacco holds promise as a viable approach for enhancing sensory attributes, establishing a solid theoretical foundation for the potential development of innovative tobacco aging additives.

Enhancement of cellulolytic enzyme production from intrageneric protoplast fusion of Aspergillus species and evaluating the hydrolysate scavenging activity

BACKGROUND

Lignocellulosic biomass provides a great starting point for the production of energy, chemicals, and fuels. The major component of lignocellulosic biomass is cellulose, the employment of highly effective enzymatic cocktails, which can be produced by a variety of microorganisms including species of the genus Aspergillus, is necessary for its utilization in a more productive manner. In this regard, molecular biology techniques should be utilized to promote the economics of enzyme production, whereas strategies like protoplast fusion could be employed to improve the efficacy of the hydrolytic process.

RESULTS

The current study focuses on cellulase production in Aspergillus species using intrageneric protoplast fusion, statistical optimization of growth parameters, and determination of antioxidant activity of fermentation hydrolysate. Protoplast fusion was conducted between A. flavus X A. terreus (PFFT), A. nidulans X A. tamarii (PFNT) and A. oryzae X A. tubingensis (PFOT), and the resultant fusant PFNT revealed higher activity level compared with the other fusants. Thus, this study aimed to optimize lignocellulosic wastes-based medium for cellulase production by Aspergillus spp. fusant (PFNT) and studying the antioxidant effect of fermentation hydrolysate. The experimental strategy Plackett-Burman (PBD) was used to assess how culture conditions affected cellulase output, the best level of the three major variables namely, SCB, pH, and incubation temperature were then determined using Box-Behnken design (BBD). Consequently, by utilizing an optimized medium instead of a basal medium, cellulase activity increased from 3.11 U/ml to 7.689 U/ml CMCase. The following medium composition was thought to be ideal based on this optimization: sugarcane bagasse (SCB), 6.82 gm; wheat bran (WB), 4; Moisture, 80%; pH, 4; inoculum size, (3 × 106 spores/ml); and incubation Temp. 31.8 °C for 4 days and the fermentation hydrolysate has 28.13% scavenging activities.

CONCLUSION

The results obtained in this study demonstrated the significant activity of the selected fusant and the higher sugar yield from cellulose hydrolysis over its parental strains, suggesting the possibility of enhancing cellulase activity by protoplast fusion using an experimental strategy and the fermentation hydrolysate showed antioxidant activity.

Upgrading pectin methylation for consistently enhanced biomass enzymatic saccharification and cadmium phytoremediation in rice Ospmes site-mutants

Crop straws provide enormous biomass residues applicable for biofuel production and trace metal phytoremediation. However, as lignocellulose recalcitrance determines a costly process with potential secondary waste liberation, genetic modification of plant cell walls is deemed as a promising solution. Although pectin methylation plays an important role for plant cell wall construction and integrity, little is known about its regulation roles on lignocellulose hydrolysis and trace metal elimination. In this study, we initially performed a typical CRISPR/Cas9 gene-editing for site mutations of OsPME31, OsPME34 and OsPME79 in rice, and then determined significantly upgraded pectin methylation degrees in the young seedlings of three distinct site-mutants compared to their wild type. We then examined distinctively improved lignocellulose recalcitrance in three mutants including reduced cellulose levels, crystallinity and polymerization or raised hemicellulose deposition and cellulose accessibility, which led to specifically enlarged biomass porosity either for consistently enhanced biomass enzymatic saccharification under mild alkali pretreatments or for cadmium (Cd) accumulation up to 2.4-fold. Therefore, this study proposed a novel model to elucidate how pectin methylation could play a unique enhancement role for both lignocellulose enzymatic hydrolysis and Cd phytoremediation, providing insights into precise pectin modification for effective biomass utilization and efficient trace metal exclusion.

Dual assistance of surfactants in glycerol organosolv pretreatment and enzymatic hydrolysis of lignocellulosic biomass for bioethanol production

This study investigated an innovative strategy of incorporating surfactants into alkaline-catalyzed glycerol pretreatment and enzymatic hydrolysis to improve lignocellulosic biomass (LCB) conversion efficiency. Results revealed that adding 40 mg/g PEG 4000 to the pretreatment at 195 °C obtained the highest glucose yield (84.6%). This yield was comparable to that achieved without surfactants at a higher temperature (240 °C), indicating a reduction of 18.8% in the required heat input. Subsequently, Triton X-100 addition during enzymatic hydrolysis of PEG 4000-assisted pretreated substrate increased glucose yields to 92.1% at 6 FPU/g enzyme loading. High-solid fed-batch semi-simultaneous saccharification and co-fermentation using this dual surfactant strategy gave 56.4 g/L ethanol and a positive net energy gain of 1.4 MJ/kg. Significantly, dual assistance with surfactants rendered 56.3% enzyme cost savings compared to controls without surfactants. Therefore, the proposed surfactant dual-assisted promising approach opens the gateway to economically viable enzyme-mediated LCB biorefinery.

Physiological, transcriptome and gene functional analysis provide novel sights into cadmium accumulation and tolerance mechanisms in kenaf

Kenaf is considered to have great potential for remediation of heavy metals in ecosystems. However, studies on molecular mechanisms of root Cd accumulation and tolerance are still inadequate. In this study, two differently tolerant kenaf cultivars were selected as materials and the physiological and transcriptomic effects were evaluated under Cd stress. This study showed that 200 µmol/L CdCl2 treatment triggered the reactive oxygen species (ROS) explosion and membrane lipid peroxidation. Compared with the Cd-sensitive cultivar 'Z', the Cd-tolerant cultivar 'F' was able to resist oxidative stress in cells by producing higher antioxidant enzyme activities and increasing the contents of ascorbic acid (AsA) and glutathione (GSH). The root cell wall of 'F' exhibited higher polysaccharide contents under Cd treatment, providing more Cd-binding sites. There were 3,439 differentially expressed genes (DEGs) that were co-regulated by Cd treatment in two cultivars. Phenylpropanoid biosynthesis and plant hormone signal transduction pathways were significantly enriched by functional annotation analysis. DEGs associated with pectin, cellulose, and hemi-cellulose metabolism were involved in Cd chelation of root cell wall; V-ATPases, ABCC3 and Narmp3 could participated in vacuolar compartmentalization of Cd; PDR1 was responsible for Cd efflux; the organic acid transporters contributed to the absorption of Cd in soil. These genes might have played key roles in kenaf Cd tolerance and Cd accumulation. Moreover, HcZIP2 was identified to be involved in Cd uptake and transport in kenaf. Our findings provide a deeper understanding of the molecular pathways underlying Cd accumulation and detoxification mechanisms in kenaf.

Barley consumption under a high-fat diet suppresses lipogenic genes through altered intestinal bile acid composition

We evaluated whether barley flour consumption in a high-fat environment affects lipid metabolism through signals mediated by bile acids. Four-week-old mice were fed a high-fat diet supplemented with cellulose (HC) or β-glucan-rich barley flour (HB) for 12 weeks. Bile acid composition in the intestinal tract and feces was measured by GC/MS. Gene expression levels involved in bile acid metabolism in the liver and intestinal tract were determined by RT-PCR. Similar parameters were measured in mice treated with antibiotics (antibiotics-cellulose [AC] and antibiotics-barley [AB]) to reduce the activity of intestinal bacteria. The Results showed that the HB group had lower liver blood cholesterol and triglyceride levels than the HC group. The HB group showed a significant decrease in primary bile acids in the gastrointestinal tract compared to the HC group. On the other hand, the concentration of secondary bile acids relatively increased in the cecum and feces. In the liver, Fxr activation suppressed gene expression levels in synthesizing bile acids and lipids. Furthermore, in the gastrointestinal tract, Tgr5 was activated by increased secondary bile acids. Correspondingly, AMP levels were increased in the HB group compared to the HC group, AMPK was phosphorylated in the liver, and gene expression involved in lipid synthesis was downregulated. A comparison of the AC and AB groups treated with antibiotics did not confirm these effects of barley intake. In summary, our results suggest that the prevention of lipid accumulation by barley consumption involves signaling through changes in bile acid composition in the intestinal tract.

Co-immobilized multi-enzyme biocatalytic system on reversible and soluble carrier for saccharification of corn straw cellulose

Herein, three enzymes (cellulase, β-glucosidase, and pectinase) with synergistic effects were co-immobilized on the Eudragit L-100, and the recovery of co-immobilized enzymes from solid substrates were achieved through the reversible and soluble property of the carrier. The optimization of enzyme ratio overcomed the problem of inappropriate enzyme activity ratio caused by different immobilization efficiencies among enzymes during the preparation process of co-immobilized enzymes. The co-immobilized enzymes were utilized to catalytically hydrolyze cellulose from corn straw into glucose, achieving a cellulose conversion rate of 74.45% under conditions optimized for their enzymatic characteristics and hydrolytic reaction conditions. As a result of the reversibility and solubility of the carrier, the co-immobilized enzymes were recovered from the solid substrate after five cycles, retaining 54.67% of the enzyme activity. The aim of this study is to investigate the potential of co-immobilizing multiple enzymes onto the Eudragit L-100 carrier for the synergistic degradation of straw cellulose.

Silencing ScGUX2 reduces xylan glucuronidation and improves biomass saccharification in sugarcane

There is an increasing need for renewable energy sources to replace part of our fossil fuel-based economy and reduce greenhouse gas emission. Sugarcane bagasse is a prominent feedstock to produce cellulosic bioethanol, but strategies are still needed to improve the cost-effective exploitation of this potential energy source. In model plants, it has been shown that GUX genes are involved in cell wall hemicellulose decoration, adding glucuronic acid substitutions on the xylan backbone. Mutation of GUX genes increases enzyme access to cell wall polysaccharides, reducing biomass recalcitrance in Arabidopsis thaliana. Here, we characterized the sugarcane GUX genes and silenced GUX2 in commercial hybrid sugarcane. The transgenic lines had no penalty in development under greenhouse conditions. The sugarcane GUX1 and GUX2 enzymes generated different patterns of xylan glucuronidation, suggesting they may differently influence the molecular interaction of xylan with cellulose and lignin. Studies using biomass without chemical or steam pretreatment showed that the cell wall polysaccharides, particularly xylan, were less recalcitrant in sugarcane with GUX2 silenced than in WT plants. Our findings suggest that manipulation of GUX in sugarcane can reduce the costs of second-generation ethanol production and enhance the contribution of biofuels to lowering the emission of greenhouse gases.

δ13C of bulk organic matter and cellulose reveal post-photosynthetic fractionation during ontogeny in C4 grass leaves

The 13C isotope composition (δ13C) of leaf dry matter is a useful tool for physiological and ecological studies. However, how post-photosynthetic fractionation associated with respiration and carbon export influences δ13C remains uncertain. We investigated the effects of post-photosynthetic fractionation on δ13C of mature leaves of Cleistogenes squarrosa, a perennial C4 grass, in controlled experiments with different levels of vapour pressure deficit and nitrogen supply. With increasing leaf age class, the 12C/13C fractionation of leaf organic matter relative to the δ13C of atmosphere CO2 (ΔDM) increased while that of cellulose (Δcel) was almost constant. The divergence between ΔDM and Δcel increased with leaf age class, with a maximum value of 1.6‰, indicating the accumulation of post-photosynthetic fractionation. Applying a new mass balance model that accounts for respiration and export of photosynthates, we found an apparent 12C/13C fractionation associated with carbon export of -0.5‰ to -1.0‰. Different ΔDM among leaves, pseudostems, daughter tillers, and roots indicate that post-photosynthetic fractionation happens at the whole-plant level. Compared with ΔDM of old leaves, ΔDM of young leaves and Δcel are more reliable proxies for predicting physiological parameters due to the lower sensitivity to post-photosynthetic fractionation and the similar sensitivity in responses to environmental changes.

Degradation of Cell Wall Polysaccharides during Traditional and Tank Fermentation of Chinese Liupao Tea

The increase of polysaccharides in the dark tea pile process is thought to be connected to the cell wall polysaccharides' breakdown. However, the relationship between tea polysaccharides (TPSs) and tea cell wall polysaccharides has not been further explored. In this study, the structural changes in the cell wall polysaccharides [e.g., cellulose, hemicellulose (HC), and pectin] in Liupao tea were characterized before and after traditional fermentation and tank fermentation. Additionally, the degradation mechanism of tea cell wall polysaccharides during fermentation was assessed. The results showed that cellulose crystallinity decreased by 11.9-49.6% after fermentation. The molar ratio of monosaccharides, such as arabinose, rhamnose, and glucose in HC, was significantly reduced, and the molecular weight decreased. The esterification degree and linearity of water-soluble pectin (WSP) were reduced. TPS content increases during pile fermentation, which may be due to HC degradation and the increase in WSP caused by cell wall structure damage. Microorganisms were shown to be closely associated with the degradation of cell wall polysaccharides during fermentation according to correlation analyses. Traditional fermentation had a greater effect on the cellulose structure, while tank fermentation had a more noticeable impact on HC and WSP.

Molecular Mechanisms Underlying the Effects of Small Intestinal Fermentation on Enhancement of Prebiotic Characteristics of Cellulose in the Large Intestine

Knowledge about the prebiotic characteristics of cellulose by in vitro fermentation is not complete due to the neglect of small intestinal fermentation. This study investigated the effects of small intestinal fermentation on the prebiotic characteristics of cellulose in the large intestine and potential mechanisms through an approach of combined in vivo small intestinal fermentation and in vitro fermentation. The structural similarity between cellulose in feces and after processing by the approach of this study confirmed the validity of the approach employed. Results showed that small intestinal fermentation of cellulose increased both acetate and propionate content and enriched Corynebacterium selectively. Compared to in vitro fermentation after in vitro digestion of cellulose, the in vitro fermentation of cellulose after in vivo small intestinal fermentation produced higher contents of acetate and propionate as well as the abundance of probiotics like Ruminococcaceae_UCG-002, Blautia, and Bifidobaterium. The changes in the structural features of cellulose after in vivo small intestinal fermentation were more obvious than those after in vitro digestion, which may account for the greater production of short-chain fatty acids (SCFAs) and the abundance of probiotics. In summary, small intestinal fermentation enhanced the prebiotic characteristics of cellulose in the large intestine by predisrupting its structure.

Tip Growth Defective1 interacts with the cellulose synthase complex to regulate cellulose synthesis in Arabidopsis thaliana

Plant cells possess robust and flexible cell walls composed primarily of cellulose, a polysaccharide that provides structural support and enables cell expansion. Cellulose is synthesised by the Cellulose Synthase A (CESA) catalytic subunits, which form cellulose synthase complexes (CSCs). While significant progress has been made in unravelling CSC function, the trafficking of CSCs and the involvement of post-translational modifications in cellulose synthesis remain poorly understood. In order to deepen our understanding of cellulose biosynthesis, this study utilised immunoprecipitation techniques with CESA6 as the bait protein to explore the CSC and its interactors. We have successfully identified the essential components of the CSC complex and, notably, uncovered novel interactors associated with CSC trafficking, post-translational modifications, and the coordination of cell wall synthesis. Moreover, we identified TIP GROWTH DEFECTIVE 1 (TIP1) protein S-acyl transferases (PATs) as an interactor of the CSC complex. We confirmed the interaction between TIP1 and the CSC complex through multiple independent approaches. Further analysis revealed that tip1 mutants exhibited stunted growth and reduced levels of crystalline cellulose in leaves. These findings suggest that TIP1 positively influences cellulose biosynthesis, potentially mediated by its role in the S-acylation of the CSC complex.

Functional characterisation of a new halotolerant seawater active glycoside hydrolase family 6 cellobiohydrolase from a salt marsh

Realising a fully circular bioeconomy requires the valorisation of lignocellulosic biomass. Cellulose is the most attractive component of lignocellulose but depolymerisation is inefficient, expensive and resource intensive requiring substantial volumes of potable water. Seawater is an attractive prospective replacement, however seawater tolerant enzymes are required for the development of seawater-based biorefineries. Here, we report a halophilic cellobiohydrolase SMECel6A, identified and isolated from a salt marsh meta-exo-proteome dataset with high sequence divergence to previously characterised cellobiohydrolases. SMECel6A contains a glycoside hydrolase family 6 (GH6) domain and a carbohydrate binding module family 2 (CBM2) domain. Characterisation of recombinant SMECel6A revealed SMECel6A to be active upon crystalline and amorphous cellulose. Mono- and oligosaccharide product profiles revealed cellobiose as the major hydrolysis product confirming SMECel6A as a cellobiohydrolase. We show SMECel6A to be halophilic with optimal activity achieved in 0.5X seawater displaying 80.6 ± 6.93% activity in 1 × seawater. Structural predictions revealed similarity to a characterised halophilic cellobiohydrolase despite sharing only 57% sequence identity. Sequential thermocycling revealed SMECel6A had the ability to partially reversibly denature exclusively in seawater retaining significant activity. Our study confirms that salt marsh ecosystems harbour enzymes with attractive traits with biotechnological potential for implementation in ionic solution based bioprocessing systems.

Molecular-level architecture of Chlamydomonas reinhardtii's glycoprotein-rich cell wall

Microalgae are a renewable and promising biomass for large-scale biofuel, food and nutrient production. However, their efficient exploitation depends on our knowledge of the cell wall composition and organization as it can limit access to high-value molecules. Here we provide an atomic-level model of the non-crystalline and water-insoluble glycoprotein-rich cell wall of Chlamydomonas reinhardtii. Using in situ solid-state and sensitivity-enhanced nuclear magnetic resonance, we reveal unprecedented details on the protein and carbohydrate composition and their nanoscale heterogeneity, as well as the presence of spatially segregated protein- and glycan-rich regions with different dynamics and hydration levels. We show that mannose-rich lower-molecular-weight proteins likely contribute to the cell wall cohesion by binding to high-molecular weight protein components, and that water provides plasticity to the cell-wall architecture. The structural insight exemplifies strategies used by nature to form cell walls devoid of cellulose or other glycan polymers.

Functional study of a lytic polysaccharide monooxygenase MsLPMO3 from Morchella sextelata in the oxidative degradation of cellulose

Lytic polysaccharide monooxygenases (LPMOs) can improve the effectiveness with which agricultural waste is utilized. This study described the potent AA9 family protein MsLPMO3, derived from Morchella sextelata. It exhibited strong binding to phosphoric acid swollen cellulose (PASC), and had the considerable binding ability to Cu2+ with a Kd value of 2.70 μM by isothermal titration calorimetry (ITC). MsLPMO3 could also act on PASC at the C1 carbon via MALDI-TOF-MS results. Moreover, MsLPMO3 could boost the hydrolysis efficiency of corncob and wheat bran in combination with glycoside hydrolases. MsLPMO3 also exhibited strong oxidizing ability for 2,6-dimethoxyphenol (2,6-DMP), achieving the best Vmax value of 443.36 U·g-1 for pH 7.4 with a H2O2 concentration of 300 µM. The structure of MsLPMO3 was obtained using AlphaFold2, and the molecular docking results elucidated the specific interactions and key residues involved in the recognition process between MsLPMO3 and cellulose. Altogether, this study expands the knowledge of AA9 family proteins in cellulose degradation, providing valuable insights into the mechanisms of synergistic degradation of lignocellulose with cellulases.

Fungal loosenin-like proteins boost the cellulolytic enzyme conversion of pretreated wood fiber and cellulosic pulps

Microbial expansin-related proteins, including loosenins, can disrupt cellulose networks and increase enzyme accessibility to cellulosic substrates. Herein, four loosenins from Phanerochaete carnosa (PcaLOOLs), and a PcaLOOL fused to a family 63 carbohydrate-binding module, were compared for ability to boost the cellulolytic deconstruction of steam pretreated softwood (SSW) and kraft pulps from softwood (ND-BSKP) and hardwood (ND-BHKP). Amending the Cellic® CTec-2 cellulase cocktail with PcaLOOLs increased reducing products from SSW by up to 40 %, corresponding to 28 % higher glucose yield. Amending Cellic® CTec-2 with PcaLOOLs also increased the release of glucose from ND-BSKP and ND-BHKP by 82 % and 28 %, respectively. Xylose release from ND-BSKP and ND-BHKP increased by 47 % and 57 %, respectively, highlighting the potential of PcaLOOLs to enhance hemicellulose recovery. Scanning electron microscopy and fiber image analysis revealed fibrillation and curlation of ND-BSKP after PcaLOOL treatment, consistent with increasing enzyme accessibility to targeted substrates.

Comparative analysis of Chrysoporthe cubensis exoproteomes and their specificity for saccharification of sugarcane bagasse

The phytopathogenic fungus Chrysoporthe cubensis is a relevant source of lignocellulolytic enzymes. This work aimed to compare the profile of lignocellulose-degrading proteins secreted by C. cubensis grown under semi-solid state fermentation using wheat bran (WB) and sugarcane bagasse (SB). The exoproteomes of the fungus grown in wheat bran (WBE) and sugarcane bagasse (SBE) were qualitative and quantitatively analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Data are available via ProteomeXchange with identifier PXD046075. Label-free proteomic analysis of WBE and SBE showed that the fungus produced a spectrum of carbohydrate-active enzymes (CAZymes) with exclusive characteristics from each extract. While SBE resulted in an enzymatic profile directed towards the depolymerization of cellulose, the enzymes in WBE were more adaptable to the degradation of biomass rich in hemicellulose and other non-lignocellulosic polymers. Saccharification of alkaline pre-treated sugarcane bagasse with SBE promoted glucose release higher than commercial cocktails (8.11 g L-1), while WBE promoted the higher release of xylose (5.71 g L-1). Our results allowed an in-depth knowledge of the complex set of enzymes secreted by C. cubensis responsible for its high lignocellulolytic activity and still provided the identification of promising target proteins for biotechnological applications in the context of biorefinery.

Bioconversion of spray corn husks into L-lactic acid with liquid hot water pretreatment

Agricultural by-products like rice husk, bran, and spray corn husks, often utilized as feed, are considered less desirable. This study aims to enhance the utilization rate of these materials by subjecting then to liquid hot water (LHW) pretreatment, followed by enzymatic hydrolysis to produce fermentable sugars. We investigated the production of L-lactic acid using two methods: simultaneous saccharification fermentation (SSF) and separate hydrolysis fermentation (SHF), following varying intensities of LHW pretreatment. The results showed that the optimal enzymatic hydrolysis efficiency was achieved from spray corn husks under the pretreatment conditions of 155 °C and 15 min. SHF was generally more effective than SSF. The glucose L-lactic acid conversion rate in SHF using spray corn husks can reach more than 90 %. Overall, this work proposed a novel, environmental-friendly strategy for efficient and for L- lactic acid production from spray corn husks.

Surfactant-assisted dilute ethylenediamine fractionation of corn stover for technical lignin valorization and biobutanol production

In this study, a surfactant-assisted diluted ethylenediamine (EDA) fractionation process was investigated for co-generation of technical lignin and biobutanol from corn stover. The results showed that the addition of PEG 8000 significantly enhanced cellulose recovery (88.9 %) and lignin removal (68.9 %) in the solid fraction. Moreover, the pulp achieved 86.5 % glucose yield and 82.6 % xylose yield in enzymatic hydrolysis. Structural characterization confirmed that the fractionation process promoted the preservation of active β-O-4 bonds (35.8/100R) in isolated lignin and functionalized the lignin through structural modification using EDA and surfactant grafting. The enzymatic hydrolysate of the pulps yielded a sugar solution for acetone-butanol-ethanol (ABE) fermentation, resulting in an ABE concentration of 15.4 g/L and an overall yield of 137.2 g/Kg of dried corn stalk. Thus, the surfactant-assisted diluted EDA fractionation has the potential to enhance the overall economic feasibility of second-generation biofuels production within the framework of biorefinery.

Toward a zero waste approach: Utilization of sugarcane bagasse for dye removal and multienzymes production

Global production of sugarcane bagasse (SB) by sugar industries exceeds more than 100 tons per annum. SB is rich in lignin and polysaccharide and hence can serve as a low-cost energy and carbon source for the growth of industrially important microorganism. However, various other applications of SB have also been investigated. In this study, SB was used as an adsorbent to remove an azo dye, malachite green. Subsequently, the dye-adsorbed SB was fermented by Trametes pubescens MB 89 for the production of laccase enzyme. The fungal pretreated SB was further utilized as a substrate for the simultaneous production of multiple plant cell wall degrading enzymes including, cellulase, xylanase, pectinase, and amylase by thermophilic bacterial strains. Results showed that 0.1% SB removed 97.04% malachite green at 30°C after 30 min from a solution containing 66 ppm of the dye. Fermentation of the dye-adsorbed SB by T. pubescens MB 89 yielded 667.203 IU mL-1 laccase. Moreover, Brevibacillus borstelensis UE10 produced 38.41 and 18.6 IU mL-1 β-glucosidase and pectinase, respectively, by using fungal-pretreated SB. Cultivation of B. borstelensis UE27 in the medium containing the same substrate yielded 32.14 IU mL-1 of endoglucanase and 27.23 IU mL-1 of β-glucosidase. Likewise, Neobacillus sedimentimangrovi UE25 could produce a mix of β-glucosidase (37.24 IU mL-1 ), xylanase (18.65 IU mL-1 ) and endoglucanase (26.65 IU mL-1 ). Hence, this study led to the development of a method through which dye-containing textile effluent can be treated by SB along with the production of industrially important enzymes.

Predicted metabolic roles and stress responses provide insights into candidate phyla Hydrogenedentota and Sumerlaeota as members of the rare biosphere in biofilms from various environments

Pustular mats from Shark Bay, Western Australia, host complex microbial communities bound within an organic matrix. These mats harbour many poorly characterized organisms with low relative abundances (<1%), such as candidate phyla Hydrogenedentota and Sumerlaeota. Here, we aim to constrain the metabolism and physiology of these candidate phyla by analyzing two representative metagenome-assembled genomes (MAGs) from a pustular mat. Metabolic reconstructions of these MAGs suggest facultatively anaerobic, chemoorganotrophic lifestyles of both organisms and predict that both MAGs can metabolize a diversity of carbohydrate substrates. Ca. Sumerlaeota possesses genes involved in degrading chitin, cellulose and other polysaccharides, while Ca. Hydrogenedentota can metabolize cellulose derivatives in addition to glycerol, fatty acids and phosphonates. Both Ca. phyla can respond to nitrosative stress and participate in nitrogen metabolism. Metabolic comparisons of MAGs from Shark Bay and those from various polyextreme environments (i.e., hot springs, hydrothermal vents, subsurface waters, anaerobic digesters, etc.) reveal similar metabolic capabilities and adaptations to hypersalinity, oxidative stress, antibiotics, UV radiation, nitrosative stress, heavy metal toxicity and life in surface-attached communities. These adaptations and capabilities may account for the widespread nature of these organisms and their contributions to biofilm communities in a range of extreme surface and subsurface environments.

Hydrodynamic cavitation-assisted acid pretreatment and fed-batch simultaneous saccharification and co-fermentation for ethanol production from sugarcane bagasse using immobilized cells of Scheffersomyces parashehatae

A new alternative for hydrodynamic cavitation-assisted pretreatment of sugarcane bagasse was proposed, along with a simultaneous saccharification and co-fermentation (SSCF) process performed in interconnected columns. Influential variables in the pretreatment were evaluated using a statistical design, indicating that an ozone flow rate of 10 mg min-1 and a pH of 5.10 resulted in 86 % and 72 % glucan and xylan hydrolysis yields, respectively, in the subsequent enzymatic hydrolysis process. Under these optimized conditions, iron sulfate (15 mg L-1) was added to assess Fenton pretreatment, resulting in glucan and xylan hydrolysis yields of 92 % and 71 %, respectively, in a material pretreated for 10 min. In SSCF, ethanol volumetric productivities of 0.33 g L-1 h-1 and of 0.54 g L-1 h-1 were obtained in batch and fed-batch operation modes, achieving 26 g L-1 of ethanol in 48 h in the latter mode.

Robust fabrication of sulfonated graphene oxide/poly (ether sulfone) catalytic membrane reactor for efficient cellulose hydrolysis and product separation

The efficient conversion of cellulose to high value-added products is important for the utilization of cellulose biomass. Achieving efficient cellulose hydrolysis and timely products separation is the essential target. Herein, a modified sulfonated graphene oxide/polydopamine deposited polyethersulfone (mGO(SO3H)-PDA/PES) membrane reactor, combining in the same unit a conversion effect and a separation effect, was prepared by suction filtration and subsequent polymerization and adhesion. The structure of PES membrane and deposition of PDA was regulated to sure that small molecules can pass through the membrane, while cellulose could not. As a result, the mGO(SO3H)-PDA/PES membrane realized the efficient cellulose hydrolysis and timely products separation under cross-flow circulation mode at 0.1 MPa, avoiding the further degradation of reducing sugar products. The yields of total reducing sugar (TRS) and glucose in separated hydrolysate reached 93.2 % and 85.5 %, respectively. This strategy provides potential guidance for efficient conversion of cellulose.

Applications of synthetic yeast consortia for the production of native and non-native chemicals

The application of microbial consortia is a new approach in synthetic biology. Synthetic yeast consortia, simple or complex synthetic mixed cultures, have been used for the production of various metabolites. Cooperation between the members of a consortium and cross-feeding can be applied to create stable microbial communication. These consortia can: consume a variety of substrates, perform more complex functions, produce metabolites in high titer, rate, and yield (TRY), and show higher stability during industrial fermentations. Due to the new research context of synthetic consortia, few yeasts were used to build these consortia, including Saccharomyces cerevisiae, Pichia pastoris, and Yarrowia lipolytica. Here, application of the yeasts for design of synthetic microbial consortia and their advantages and bottlenecks for effective and robust production of valuable metabolites from bioresource, including: cellulose, xylose, glycerol and so on, have been reviewed. Key trends and challenges are also discussed for the future development of synthetic yeast consortia.