Microbial cellulases and their industrial applications

Biochemical characterization of a bilfunctional endoglucanase/glucomannanase derived from mountain soil

Metagenomics is increasingly recognized as a vital technique for exploring uncultured microorganisms, with one key application being the discovery of novel enzymes for industrial use. This study identified an endoglucanase gene from soil metagenome, termed ZFEG1801, which was expressed in E. coli BL21, purified, and characterized for its biochemical properties. The 72.8 kDa recombinant protein exhibited hydrolytic activity against sodium carboxymethyl cellulose (CMC) and konjac glucomannan (KG), with activities of 12.1 U/mg and 42.1 U/mg, respectively. The enzyme displayed optimal activity at pH 5 for CMC and pH 6 for KG, with broad pH stability ranging from 5 to 9. The optimal temperature was 40 °C, and it remained thermally stable between 20 and 40 °C, retaining over 60% of its activity. The enzyme activity remained stable in the presence of most metal ions; however, CMCase activity was inhibited by Cu2+, while glucomannanase activity was inhibited by Mn2+, Fe3+, and Ca2+. The catalytic efficiency towards both substrates was reduced by addition of SDS, DMSO, ethanol, isopropanol and acetonitrile. The Vmax and Km of the purified recombinant enzyme were 106.4 μmol/L/min and 4.9 mg/mL for CMC, and 833.3 μmol/L/min and 11.1 mg/mL for KG, respectively. The dual catalytic properties of ZFEG1801, broad pH stability and resistance to additives, demonstrate its potential for use in various biomass degradation processes.

Recombinant expression and characterization of the family 5 cellulase from Bacillus velezensis in Escherichia coli BL21-CodonPlus (DE3)-RIPL

B. velezensis RB. IBE29 is a chitinolytic bacterium originally isolated from agricultural soil of Vietnam. Previous studies demonstrated this bacterium was a promising chitinase producer, biocontrol agent, and biofertilizer for crop production. The complete genome sequence of the bacterium was reported and possesses the gene encoding family 5 cellulase; however, role of this enzyme has not been experimentally characterized. This work aimed to express and biologically characterize family 5 cellulase of strain RB. IBE29. The ORF (without signal peptide) of the celA of strain RB. IBE29 was expressed in E. coli BL21-CodonPlus (DE3)-RIPL using the vector pColdII, and the corresponding product (rBvCelA, 55.17 kDa) was successfully purified using the HisTrap FF column. The purified rBvCelA showed the highest cellulase activity against CMC, followed by sugarcane bagasse and rice straw, and had optimal temperature and pH at 60 °C and 6.0, respectively. Metal salts ZnCl2, FeCl2, MgCl2, CuSO4, and MnCl2 enhanced the cellulase activity by 103.85, 124.24, 109.38, 105.64, and 115.12 %, respectively. In addition, the supplementation of the purified rBvCelA in the feed enhanced the growth and improved the feed intake of broiler chickens by 5.88 and 5.19 %, respectively. These results indicated that family 5 cellulase of B. velezensis has a promising role in crop production and poultry breeding. As far as we know, this is the first report describing the contribution of family 5 cellulase from B. velezensis in broiler breeding.

Studies on the preparation of a sufficient carrier from egg protein and carrageenan for cellulase with optimization and application

Egg protein (EP) concentration, pH, and glutaraldehyde (GA) concentration were optimized using Box Behnken design (BBD) to prepare GA-EP-Carr (Carrageenan) beads as a carrier for Aspergillus niger MK981235 cellulase. It was recommended that the concentrations of GA, and EP be set at 11.21% (w/v), 8% (w/w), and pH 3, respectively. It was determined that 60 °C and 2% for free form and 60 °C and 3% for im-cellulase were the optimum temperature and CMC concentration parameters for maximum enzyme activity. Free and im-cellulase were determined to have Km and Vmax of 2.22 mg.ml-1 and 1.76 µmol.ml-1.min-1, and 4.55 mg.ml-1 and 3.33 µmol.ml-1.min-1, respectively. Covalent coupling of A. niger cellulase to GA- EP- Carr beads improved its thermodynamic parameters T1/2 and D-values by 2.48, 2.01, and 2.36 times at 40, 50, and 60 °C, respectively. GA- EP- Carr im-cellulase was 100% active for 60 days at 4 °C and can be used for CMC hydrolysis for 20 successive cycles. GA- EP- Carr im-cellulase showed remarkable efficiency in the clarification of mango, peach, grape, and orange juices emphasized by TSS (total soluble solids), turbidity, and reducing sugar measurements for 3 successive cycles. GA- EP- Carr im-cellulase can be applied with high efficiency in juice industry.

A draft genome sequence of Cellulomonas sp. ICMP 17802, isolated from root nodules of Vicia faba

Here, we report the draft genome sequence of Cellulomonas sp. ICMP 17802. This bacterium was obtained from the International Collection of Microorganisms from Plants and was originally isolated from root nodules of Vicia faba. The draft genome contains 154 predicted carbohydrate-active enzyme genes.

A carboxymethyl cellulase from the yeast Cryptococcus gattii WM276: Expression, purification and characterisation

Cryptococcus gattii and its medical implications have been extensively studied. There is, however, a significant knowledge gap regarding cryptococcal survival in its environmental niche, namely woody material, which is glaring given that infection is linked to environmental populations. A gene from C. gattii (WM276), the predominant global molecular type (VGI), has been sequenced and annotated as a putative cellulase. It is therefore, of both medical and industrial intertest to delineate the structure and function of this enzyme. A homology model of the enzyme was constructed as a fusion protein to a maltose binding protein (MBP). The CGB_E4160W gene was overexpressed as an MBP fusion enzyme in Escherichia coli T7 cells and purified to homogeneity using amylose affinity chromatography. The structural and functional character of the enzyme was investigated using fluorescence spectroscopy and enzyme activity assays, respectively. The optimal enzyme pH and temperature were found to be 6.0 and 50 °C, respectively, with an optimal salt concentration of 500 mM. Secondary structure analysis using Far-UV CD reveals that the MBP fusion protein is primarily α-helical with some β-sheets. Intrinsic tryptophan fluorescence illustrates that the MBP-cellulase undergoes a conformational change in the presence of its substrate, CMC-Na+. The thermotolerant and halotolerant nature of this particular cellulase, makes it useful for industrial applications, and adds to our understanding of the pathogen's environmental physiology.

Isolation and screening of wood-decaying fungi for lignocellulolytic enzyme production and bioremediation processes

The growing demand for novel enzyme producers to meet industrial and environmental needs has driven interest in lignocellulose-degrading fungi. In this study, lignocellulolytic enzyme production capabilities of environmental fungal isolates collected from boreal coniferous and nemoral summer green deciduous forests were investigated, using Congo Red, ABTS, and Azure B as indicators of cellulolytic and ligninolytic enzyme productions. Through qualitative and quantitative assays, the study aimed to identify promising species for lignocellulose-degrading enzyme secretion and assess their potential for biotechnological applications. Primary screening tests showed intensive enzyme secretion by certain isolates, particularly white rot fungi identified as Trametes pubescens and Cerrena unicolor. These fungi exhibited high efficiency in degrading Congo Red and Azure B. The isolates achieved up to a 93.30% decrease in Congo Red induced color intensity and over 78% decolorization of Azure B within 168 hours. Within 336 hours, these fungi reached nearly 99% removal of Congo Red and up to 99.79% decolorization of Azure B. Enzyme activity analysis confirmed the lignin-degrading capabilities of T. pubescens, which exhibited laccase activity exceeding 208 U/mL. Furthermore, Fomitopsis pinicola showed the highest cellulose-degrading potential among the studied fungi, achieving cellulase activity over 107 U/L during Congo Red decolorization. Previously undescribed enzyme-producing species, such as Peniophora cinerea, Phacidium subcorticalis, and Cladosporium pseudocladosporioides, also demonstrated promising lignocellulolytic enzyme production potential, achieving up to 98.65% and 99.80% decolorization of Congo Red and Azure B, respectively. The study demonstrates novel candidates for efficient lignocellulolytic enzyme production with broad biotechnological applications such as biomass conversion, wastewater treatment, textile dye and other complex chemical removal, and environmental remediation.

Production of a novel cellulase by Bacillus amyloliquefaciens OKB3 isolated from soil: Purification and characterization

Microbial cellulases have become significant biocatalysts because of their complex composition and extensive industrial applications. This study aimed to isolate an efficient cellulase-producing strain, followed by molecular identification, enzyme purification, and characterization. Among 110 isolates, Bacillus amyloliquefaciens OKB3 was selected for its significant cellulase production, with optimal activity at pH 5.0 and 34 °C. The purification using ammonium sulfate and Sephadex G-100 chromatography resulted in specific activity of 2720.76 U/mg, 2.91 fold purification, and 29.44 % yield. The purified cellulase named CelB was a dimeric macromolecule of 123 kDa consisting of 67 and 54 kDa subunits. CelB was most active at 60 °C and pH 6, and it was stable at pH 5.5 to 6.0 and 0 °C to 4 °C. CelB was unaffected by metal cofactors and inhibited in the presence of divalent cations Cu2+, Hg2+, Cd2+, and Ag2+. The CelB has higher specificity of CMC compared to other substrates. The Km, Vmax, and Kcat values were 0.037 mM, 188.67 μmole/min, and 7430 S-1 respectively. The unique attributes of CelB make it a very promising candidate for various biotechnological applications.

Metabolome and Metagenome Integration Unveiled Synthesis Pathways of Novel Antioxidant Peptides in Fermented Lignocellulosic Biomass of Palm Kernel Meal

Approximately one-third of the entire world's food resources are deemed to be wasted. Palm kernel meal (PKM), a product that is extensively generated by the palm oil industry, exhibits a unique nutrient-rich composition. However, its recycling is seldom prioritized due to numerous factors. To evaluate the impact of enzymatic pretreatment and Lactobacillus plantarum and Lactobacillus reuteri fermentation upon the antioxidant activity of PKM, we implemented integrated metagenomics and metabolomics approaches. The substantially enhanced (p < 0.05) property of free radicals scavenging, as well as total flavonoids and polyphenols, demonstrated that the biotreated PKM exhibited superior antioxidant capacity. Non-targeted metabolomics disclosed that the Lactobacillus fermentation resulted in substantial (p < 0.05) biosynthesis of 25 unique antioxidant biopeptides, along with the increased (p < 0.05) enrichment ratio of the isoflavonoids and secondary metabolites biosynthesis pathways. The 16sRNA sequencing and correlation analysis revealed that Limosilactobacillus reuteri, Pediococcus acidilactici, Lacticaseibacillus paracasei, Pediococcus pentosaceus, Lactiplantibacillus plantarum, Limosilactobacillus fermentum, and polysaccharide lyases had significantly dominated (p < 0.05) proportions in PMEL, and these bacterial species were strongly (p < 0.05) positively interrelated with antioxidants peptides. Fermented PKM improves nutritional value by enhancing beneficial probiotics, enzymes, and antioxidants and minimizing anti-nutritional factors, rendering it an invaluable feed ingredient and gut health promoter for animals, multifunctional food elements, or as an ingredient in sustainable plant-based diets for human utilization, and functioning as a culture substrate in the food sector.

Draft genome sequence of two Aspergillus aculeatus isolated from cashew nuts from coastal Kenya

Aspergillus aculeatus is a common saprophyte and ubiquitous fungus belonging to section Nigri. They produce diverse secondary metabolites which are important in biological processes and industrial applications. We present the draft genome sequences of two A. aculeatus isolated from cashew nuts from coastal Kenya.

Simultaneous Expression of Recombinant Cellulase and Protease in An Indigenous Bacillus Cereus Strain

Background

Gene manipulation has a wide array of applications in microorganisms. We can construct multifunctional bacterial strains by gene manipulation and gene editing in order to produce several industrial biomaterials including enzymes at the same time.

Objective

According to the importance of cellulase in various industries, including food industry, the purpose of this study was aimed to produce cellulase in an indigenous Bacillus cereus EG296 strain through gene manipulation.

Materials and Methods

The Bacillus subtilis 168 cellulase gene, located between the regulatory upstream and downstream regions of Bacillus cereus protease gene (aprE), was amplified by SOEing PCR and transformed into the Bacillus cereus EG296 by natural transformation. After selection of the strains with cellulase activity, the scoC gene (Negative transcriptional regulator of aprE gene) was also deleted from the genome of the transformant by homologous recombination in order to increase the cellulase and protease activities simultaneously.

Results

The Bacillus cereus cells were acquired the cellulase gene into their genome with cellulase activity of about 0.61 u.mL-1. By scoC gene deletion, the protease activity reached to 363.14 u.mL-1 from 230 u.mL-1. Meanwhile, the cellulase activity under the control of the protease promoter was also increased to 0.78 u.mL-1 from 0.61 u.mL-1. The cellulase and protease expressed in B. cereus have an instability index of 26.16 and 20.18 respectively, which is much lower than threshold of 40. Accordingly, it can be concluded that both enzymes are considered to be stable.

Conclusion

As a result, we obtained a genetically engineered strain that had the ability to produce and secrete two important industrial extracellular enzymes (cellulase and protease), with easy downstream purification processes.

Production of cellulases by Xylaria sp. and Nemania sp. using lignocellulose substrates for bioethanol production from maize cobs

Two species of Xylaria (KM01, KM03) and Nemania sp.KM02 isolated from decaying plant biomass were evaluated for their ability to produce cellulases on maize cob, eucalyptus, and cypress substrates under solid-state fermentation. A total of 10 fungal samples from decaying plant biomass were collected from Karura forest based on morphological variations. The fungi isolated were screened for cellulase activity and positive isolates were selected for the study. ITS4 R and ITS86 F primers were used to identify the fungal isolates with accuracy ranging from 98 % to 100 %. The crude cellulases produced was assayed for FPase, exoglucanase, endoglucanase and β-glucosidase. Cellulases of Xylaria sp. KM01 produced higher FPase and exoglucanase (2.01 ± 0.13 IU/ml and 0.94 ± 0.08 IU/ml) on pretreated maize cobs with 0.1M HCl at 121oC, while that of Xylaria sp.KM03 produced higher β-glucosidase and endoglucanase (588.6 ± 64.2 IU/ml and 3.59 ± 0.02 IU/ml) on maize cobs pretreated with 0.1M NaOH at 121oC. However, cellulases of Xylaria sp. KM01 produced higher β-glucosidase and FPase (629.7 ± 20.2 IU/ml and 1.67 ± 0.03 IU/ml) on untreated maize cobs after the 9th day of incubation, whereas cellulases of Xylaria sp.KM03 and Nemania sp.KM02 produced higher endoglucanase and exoglucanase (2.80 ± 0.21 IU/ml and 0.83 ± 0.02 IU/ml) on untreated maize cobs after the 3rd and 6th day of incubation. Saccharification of maize cobs by cellulase of Xylaria sp.KM03 produced the highest reducing sugars at 8 % substrate loading (10.17 ± 0.37 mg/ml) after 72 h of incubation. Simultaneous hydrolysis and fermentation of maize cobs by cellulase of Nemania sp.KM02 and Saccharomyces cerevisiae yielded higher bioethanol (28.72 ± 3.82 mg/ml) after 96 h of fermentation. Maize cob is established as a suitable feedstock for cellulases and bioethanol production.

The Phylogenomic Characterization of Planotetraspora Species and Their Cellulases for Biotechnological Applications

This study aims to evaluate the in silico genomic characteristics of five species of the genus Planotetraspora: P. kaengkrachanensis, P. mira, P. phitsanulokensis, P. silvatica, and P. thailandica, with a view to their application in therapeutic research. The 16S rRNA comparison indicated that these species were phylogenetically distinct. Pairwise comparisons of digital DNA-DNA hybridization (dDDH) and OrthoANI values between these studied type strains indicated that dDDH values were below 62.5%, while OrthoANI values were lower than 95.3%, suggesting that the five species represent distinct genomospecies. These results were consistent with the phylogenomic study based on core genes and the pangenome analysis of these five species within the genus Planotetraspora. However, the genome annotation showed some differences between these species, such as variations in the number of subsystem category distributions across whole genomes (ranging between 1979 and 2024). Additionally, the number of CAZYme (Carbohydrate-Active enZYme) genes ranged between 298 and 325, highlighting the potential of these bacteria for therapeutic research applications. The in silico physico-chemical characteristics of cellulases from Planotetraspora species were analyzed. Their 3D structure was modeled, refined, and validated. A molecular docking analysis of this cellulase protein structural model was conducted with cellobiose, cellotetraose, laminaribiose, carboxymethyl cellulose, glucose, and xylose ligand. Our study revealed significant interaction between the Planotetraspora cellulase and cellotetraose substrate, evidenced by stable binding energies. This suggests that this bacterial enzyme holds great potential for utilizing cellotetraose as a substrate in various applications. This study enriches our understanding of the potential applications of Planotetraspora species in therapeutic research.

Cellulolytic enzymes in Microbulbifer sp. Strain GL-2, a marine fish intestinal bacterium, with emphasis on endo-1,4-β-glucanases Cel5A and Cel8

Cellulose is an abundant biomass on the planet. Various cellulases from environmental microbes have been explored for industrial use of cellulose. Marine fish intestine is of interest as one source of new enzymes. Here, we report the discovery of genes encoding two β-glucosidases (Bgl3A and Bgl3B) and four endo-1,4-β-glucanases (Cel5A, Cel8, Cel5B, and Cel9) as part of the genome sequence of a cellulolytic marine bacterium, Microbulbifer sp. Strain GL-2. Five of these six enzymes (excepting Cel5B) are presumed to localize to the periplasm or outer membrane. Transcriptional analysis demonstrated that all six genes were highly expressed in stationary phase. The transcription was induced by cello-oligosaccharides rather than by glucose, suggesting that the cellulases are produced primarily for nutrient acquisition following initial growth, facilitating the secondary growth phase. We cloned the genes encoding two of the endo-1,4-β-glucanases, Cel5A and Cel8, and purified the corresponding recombinant enzymes following expression in Escherichia coli. The activity of Cel5A was observed across a wide range of temperatures (10-40 ˚C) and pHs (6-8). This pattern differed from those of Cel8 and the commercial cellulase Enthiron, both of which exhibit decreased activities below 30 ˚C and at alkaline pHs. These characteristics suggest that Cel5A might find use in industrial applications. Overall, our results reinforce the hypothesis that marine bacteria remain a possible source of novel cellulolytic activities.

Statistical Modelling of Thermostable Cellulase Production Conditions of Thermophilic Geobacillus sp. TP-1 Isolated from Tapovan Hot Springs of the Garhwal Himalayan Mountain Ranges, India

A thermo-alkali stable cellulase from Geobacillus sp. TP-1 was isolated from Tapovan hot spring soil sample. The BLASTn sequence analysis of 16S rRNA sequence revealed that the isolate belonged to the Geobacillus genus and shared the highest degree of sequence similarity (99.43%) with the different strains of Geobacillus subterraneus. The neighbour joining method of multiple sequence alignment revealed that the 16S rRNA sequence of Geobacillus sp. TP-1 shows maximum similarity with Geobacillus stearothermophilus strain S_YE6-1017-022. One-Factor-At-a-Time analysis was used to optimize the carbon source, nitrogen source, pH, temperature, inoculum size and growth profile with respect to cellulase production. When compared to un-optimized basal media, optimised medium increased cellulase production by around 3.6 times. The Plackett Burman factorial design was employed to identify the critical medium components influencing cellulase activity and temperature was determined to have a significant effect on overall cellulase production. The current strain was capable of utilising lignocellulosic waste as an alternative carbon source. The use of sugarcane molasses and wheat bran as carbon sources resulted in a significant increase (~ 7.2 fold) in cellulase production in the current study, indicating the bacterium's potential for valorising lignocellulosic biomass into value-added products, which encourages its use in lignocellulosic-based bio refineries.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-024-01258-x.

Lignocellulolytic Enzymes Production by Four Wild Filamentous Fungi for Olive Stones Valorization: Comparing Three Fermentation Regimens

Lignocellulolytic enzymes play a crucial role in efficiently converting lignocellulose into valuable platform molecules in various industries. However, they are limited by their production yields, costs, and stability. Consequently, their production by producers adapted to local environments and the choice of low-cost raw materials can address these limitations. Due to the large amounts of olive stones (OS) generated in Morocco which are still undervalued, Penicillium crustosum, Fusarium nygamai, Trichoderma capillare, and Aspergillus calidoustus, are cultivated under different fermentation techniques using this by-product as a local lignocellulosic substrate. Based on a multilevel factorial design, their potential to produce lignocellulolytic enzymes during 15 days of dark incubation was evaluated. The results revealed that P. crustosum expressed a maximum total cellulase activity of 10.9 IU/ml under sequential fermentation (SF) and 3.6 IU/ml of β-glucosidase activity under submerged fermentation (SmF). F. nygamai recorded the best laccase activity of 9 IU/ml under solid-state fermentation (SSF). Unlike T. capillare, SF was the inducive culture for the former activity with 7.6 IU/ml. A. calidoustus produced, respectively, 1,009 μg/ml of proteins and 11.5 IU/ml of endoglucanase activity as the best results achieved. Optimum cellulase production took place after the 5th day under SF, while ligninases occurred between the 9th and the 11th days under SSF. This study reports for the first time the lignocellulolytic activities of F. nygamai and A. calidoustus. Furthermore, it underlines the potential of the four fungi as biomass decomposers for environmentally-friendly applications, emphasizing the efficiency of OS as an inducing substrate for enzyme production.

Histone H2B lysine 122 and lysine 130, as the putative targets of Penicillium oxalicum LaeA, play important roles in asexual development, expression of secondary metabolite gene clusters, and extracellular glycoside hydrolase synthesis

Core histones in the nucleosome are subject to a wide variety of posttranslational modifications (PTMs), such as methylation, phosphorylation, ubiquitylation, and acetylation, all of which are crucial in shaping the structure of the chromatin and the expression of the target genes. A putative histone methyltransferase LaeA/Lae1, which is conserved in numerous filamentous fungi, functions as a global regulator of fungal growth, virulence, secondary metabolite formation, and the production of extracellular glycoside hydrolases (GHs). LaeA's direct histone targets, however, were not yet recognized. Previous research has shown that LaeA interacts with core histone H2B. Using S-adenosyl-L-methionine (SAM) as a methyl group donor and recombinant human histone H2B as the substrate, it was found that Penicillium oxalicum LaeA can transfer the methyl groups to the C-terminal lysine (K) 108 and K116 residues in vitro. The H2BK108 and H2BK116 sites on recombinant histone correspond to P. oxalicum H2BK122 and H2BK130, respectively. H2BK122A and H2BK130A, two mutants with histone H2B K122 or K130 mutation to alanine (A), were constructed in P. oxalicum. The mutants H2BK122A and H2BK130A demonstrated altered asexual development and decreased extracellular GH production, consistent with the findings of the laeA gene deletion strain (ΔlaeA). The transcriptome data showed that when compared to wild-type (WT) of P. oxalicum, 38 of the 47 differentially expressed (fold change ≥ 2, FDR ≤ 0.05) genes that encode extracellular GHs showed the same expression pattern in the three mutants ΔlaeA, H2BK122A, and H2BK130A. The four secondary metabolic gene clusters that considerably decreased expression in ΔlaeA also significantly decreased in H2BK122A or H2BK130A. The chromatin of promotor regions of the key cellulolytic genes cel7A/cbh1 and cel7B/eg1 compacted in the ΔlaeA, H2BK122A, and H2BK130A mutants, according to the results of chromatin accessibility real-time PCR (CHART-PCR). The chromatin accessibility index dropped. The histone binding pocket of the LaeA-methyltransf_23 domain is compatible with particular histone H2B peptides, providing appropriate electrostatic and steric compatibility to stabilize these peptides, according to molecular docking. The findings of the study demonstrate that H2BK122 and H2BK130, which are histone targets of P. oxalicum LaeA in vitro, are crucial for fungal conidiation, the expression of gene clusters encoding secondary metabolites, and the production of extracellular GHs.

Enhanced crystalline cellulose degradation by a novel metagenome-derived cellulase enzyme

Metagenomics has revolutionized access to genomic information of microorganisms inhabiting the gut of herbivorous animals, circumventing the need for their isolation and cultivation. Exploring these microorganisms for novel hydrolytic enzymes becomes unattainable without utilizing metagenome sequencing. In this study, we harnessed a suite of bioinformatic analyses to discover a novel cellulase-degrading enzyme from the camel rumen metagenome. Among the protein-coding sequences containing cellulase-encoding domains, we identified and subsequently cloned and purified a promising candidate cellulase enzyme, Celcm05-2, to a state of homogeneity. The enzyme belonged to GH5 subfamily 4 and exhibited robust enzymatic activity under acidic pH conditions. It maintained hydrolytic activity under various environmental conditions, including the presence of metal ions, non-ionic surfactant Triton X-100, organic solvents, and varying temperatures. With an optimal temperature of 40 °C, Celcm05-2 showcased remarkable efficiency when deployed on crystalline cellulose (> 3.6 IU/mL), specifically Avicel, thereby positioning it as an attractive candidate for a myriad of biotechnological applications spanning biofuel production, paper and pulp processing, and textile manufacturing. Efficient biodegradation of waste paper pulp residues and the evidence of biopolishing suggested that Celcm05-2 can be used in the bioprocessing of cellulosic craft fabrics in the textile industry. Our findings suggest that the camel rumen microbiome can be mined for novel cellulase enzymes that can find potential applications across diverse biotechnological processes.

Current perspective in research and industrial applications of microbial cellulases

The natural interactions between various bacteria, fungi, and other cellulolytic microorganisms destroy lignocellulosic polymers. The efficacy of this process is determined by the combined action of three main enzymes: endoglucanases, exo-glucanases, and β-glucosidase. The enzyme attacks the polymeric structure's β-1,4-linkages during the cellulose breakdown reaction. This mechanism is crucial for the environment as it recycles cellulose in the biosphere. However, there are problems with enzymatic cellulose breakdown, including complex cellulase structure, insufficient degradation efficacy, high production costs, and post-translational alterations, many of which are closely related to certain unidentified cellulase properties. These issues impede the practical use of cellulases. A developing area of research is the application of this similar paradigm for industrial objectives. Cellulase enzyme exhibits greater promise in many critical industries, including biofuel manufacture, textile smoothing and finishing, paper and pulp manufacturing, and farming. However, the study on cellulolytic enzymes must move forward in various directions, including increasing the activity of cellulase as well as designing peptides to give biocatalysts their desired attributes. This manuscript includes an overview of current research on different sources of cellulases, their production, and biochemical characterization.

Nocardiopsis synnemataformans NBRM9, an extremophilic actinomycete producing extremozyme cellulase, using lignocellulosic agro-wastes and its biotechnological applications

Actinomycetes are an attractive source of lignocellulose-degrading enzymes. The search for actinomycetes producing extremozyme cellulase using cheap lignocellulosic waste remains a priority goal of enzyme research. In this context, the extremophilic actinomycete NBRM9 showed promising cellulolytic activity in solid and liquid assays. This actinomycete was identified as Nocardiopsis synnemataformans based on its phenotypic characteristics alongside phylogenetic analyses of 16S rRNA gene sequencing (OQ380604.1). Using bean straw as the best agro-waste, the production of cellulase from this strain was statistically optimized using a response surface methodology, with the maximum activity (13.20 U/mL) achieved at an incubation temperature of 40 °C, a pH of 9, an incubation time of 7 days, and a 2% substrate concentration. The partially purified cellulase (PPC) showed promising activity and stability over a wide range of temperatures (20-90 °C), pH values (3-11), and NaCl concentrations (1-19%), with optimal activity at 50 °C, pH 9.0, and 10% salinity. Under these conditions, the enzyme retained >95% of its activity, thus indicating its extremozyme nature. The kinetics of cellulase showed that it has a Vmax of 20.19 ± 1.88 U/mL and a Km of 0.25 ± 0.07 mM. The immobilized PPC had a relative activity of 69.58 ± 0.13%. In the in vitro microtiter assay, the PPC was found to have a concentration-dependent anti-biofilm activity (up to 85.15 ± 1.60%). Additionally, the fermentative conversion of the hydrolyzed bean straw by Saccharomyces cerevisiae (KM504287.1) amounted to 65.80 ± 0.52% of the theoretical ethanol yield. Overall, for the first time, the present work reports the production of extremozymatic (thermo, alkali-, and halo-stable) cellulase from N. synnemataformans NBRM9. Therefore, this strain is recommended for use as a biotool in many lignocellulosic-based applications operating under harsh conditions.

Eco-friendly biopolishing of cotton fabric through wasted sugarcane bagasse-derived enzymes

Enzymatic processing has been a suitable bio-based sustainable application for the textile industry, mitigates the use of harsh chemicals, and minimises environmental impact. Among these enzymes, cellulase enzymes have been extensively used for biopolishing applications. This study introduces an eco-friendly biopolishing of cotton fabric that has been developed by using enzymes extracted from wasted sugarcane bagasse waste in an aqueous medium. Various extraction conditions were explored, and experiments were conducted under diverse time, pH, and temperature settings. The qualitative BUTEXDCE2022C01 testing method was used to assess the biopolishing effects, resulting in a considerable reduction in fabric weight (up to 5.26%) and strength (up to 10.54%). The optimum biopolishing condition was identified to be 1 h at pH 4.8, 55 °C from the fermented solution on day three, indicating the presence of acid cellulase enzyme. The viability of cellulase enzymes has been verified through comparative analysis with commercial samples that had undergone enzyme-biopolishing. Extracted and filtered enzymes exhibited pH stability at room temperature and proved equally effective as industrial enzymes. As textile industries pursue eco-friendly solutions, extracting cellulase from wasted sugarcane bagasse could be a sustainable and alternative option, which also can be sourced locally. Therefore, these findings have wider implications for sustainable enzyme extraction methods and contributions to environmental conservation.

Influence of Salinity on the Extracellular Enzymatic Activities of Marine Pelagic Fungi

Even though fungi are ubiquitous in the biosphere, the ecological knowledge of marine fungi remains rather rudimentary. Also, little is known about their tolerance to salinity and how it influences their activities. Extracellular enzymatic activities (EEAs) are widely used to determine heterotrophic microbes' enzymatic capabilities and substrate preferences. Five marine fungal species belonging to the most abundant pelagic phyla (Ascomycota and Basidiomycota) were grown under non-saline and saline conditions (0 g/L and 35 g/L, respectively). Due to their sensitivity and specificity, fluorogenic substrate analogues were used to determine hydrolytic activity on carbohydrates (β-glucosidase, β-xylosidase, and N-acetyl-β-D-glucosaminidase); peptides (leucine aminopeptidase and trypsin); lipids (lipase); organic phosphorus (alkaline phosphatase), and sulfur compounds (sulfatase). Afterwards, kinetic parameters such as maximum velocity (Vmax) and half-saturation constant (Km) were calculated. All fungal species investigated cleaved these substrates, but some species were more efficient than others. Moreover, most enzymatic activities were reduced in the saline medium, with some exceptions like sulfatase. In non-saline conditions, the average Vmax ranged between 208.5 to 0.02 μmol/g biomass/h, and in saline conditions, 88.4 to 0.02 μmol/g biomass/h. The average Km ranged between 1553.2 and 0.02 μM with no clear influence of salinity. Taken together, our results highlight a potential tolerance of marine fungi to freshwater conditions and indicate that changes in salinity (due to freshwater input or evaporation) might impact their enzymatic activities spectrum and, therefore, their contribution to the oceanic elemental cycles.

Komagataella phaffii as a Platform for Heterologous Expression of Enzymes Used for Industry

In the 1980s, Escherichia coli was the preferred host for heterologous protein expression owing to its capacity for rapid growth in complex media; well-studied genetics; rapid and direct transformation with foreign DNA; and easily scalable fermentation. Despite the relative ease of use of E. coli for achieving the high expression of many recombinant proteins, for some proteins, e.g., membrane proteins or proteins of eukaryotic origin, this approach can be rather ineffective. Another microorganism long-used and popular as an expression system is baker's yeast, Saccharomyces cerevisiae. In spite of a number of obvious advantages of these yeasts as host cells, there are some limitations on their use as expression systems, for example, inefficient secretion, misfolding, hyperglycosylation, and aberrant proteolytic processing of proteins. Over the past decade, nontraditional yeast species have been adapted to the role of alternative hosts for the production of recombinant proteins, e.g., Komagataella phaffii, Yarrowia lipolytica, and Schizosaccharomyces pombe. These yeast species' several physiological characteristics (that are different from those of S. cerevisiae), such as faster growth on cheap carbon sources and higher secretion capacity, make them practical alternative hosts for biotechnological purposes. Currently, the K. phaffii-based expression system is one of the most popular for the production of heterologous proteins. Along with the low secretion of endogenous proteins, K. phaffii efficiently produces and secretes heterologous proteins in high yields, thereby reducing the cost of purifying the latter. This review will discuss practical approaches and technological solutions for the efficient expression of recombinant proteins in K. phaffii, mainly based on the example of enzymes used for the feed industry.

A review of the principles and biotechnological applications of glycoside hydrolases from extreme environments

It is apparent that Biocatalysts are shaping the future by providing a more sustainable approach to established chemical processes. Industrial processes rely heavily on the use of toxic compounds and high energy or pH reactions, factors that both contributes to the worsening climate crisis. Enzymes found in bacterial systems and other microorganisms, from the glaciers of the Arctic to the sandy deserts of Abu Dhabi, provide key tools and understanding as to how we can progress in the biotechnology sector. These extremophilic bacteria harness the adaptive enzymes capable of withstanding harsh reaction conditions in terms of stability and reactivity. Carbohydrate-active enzymes, including glycoside hydrolases or carbohydrate esterases, are extremely beneficial for the presence and future of biocatalysis. Their involvement in the industry spans from laundry detergents to paper and pulp treatment by degrading oligo/polysaccharides into their monomeric products in almost all detrimental environments. This includes exceedingly high temperatures, pHs or even in the absence of water. In this review, we discuss the structure and function of different glycoside hydrolases from extremophiles, and how they can be applied to industrial-scale reactions to replace the use of harsh chemicals, reduce waste, or decrease energy consumption.

Impact of Synergy Partner Cel7B on Cel7A Binding Rates: Insights from Single-Molecule Data

Enzymatic degradation of cellulosic biomass is a well-established route for the sustainable production of biofuels, chemicals, and materials. A strategy employed by nature and industry to achieve an efficient degradation of cellulose is that cellobiohydrolases (or exocellulases), such as Cel7A, work synergistically with endoglucanases, such as Cel7B, to achieve the complete degradation of cellulose. However, a complete mechanistic understanding of this exo-endo synergy is still lacking. Here, we used single-molecule fluorescence microscopy to quantify the binding kinetics of Cel7A on cellulose when it is acting alone on the cellulose fibrils and in the presence of its synergy partner, the endoglucanase Cel7B. To this end, we used a fluorescently tagged Cel7A and studied its binding in the presence of the unlabeled Cel7B. This provided the single-molecule data necessary for the estimation of the rate constants of association kON and dissociation kOFF of Cel7A for the substrate. We show that the presence of Cel7B does not impact the dissociation rate constant, kOFF. But, the association rate of Cel7A decreases by a factor of 2 when Cel7B is present at a molar proportion of 10:1. This ratio has previously been shown to lead to synergy. This decrease in association rate is observed in a wide range of total enzyme concentrations, from sub nM to μM concentrations. This decrease in kON is consistent with the formation of cellulase clusters recently observed by others using atomic force microscopy.

Enhancement effect of AgO nanoparticles on fermentative cellulase activity from thermophilic Bacillus subtilis Ag-PQ

BACKGROUND

Cellulase is an important bioprocessing enzyme used in various industries. This study was conducted with the aim of improving the biodegradation activity of cellulase obtained from the Bacillus subtilis AG-PQ strain. For this purpose, AgO and FeO NPs were fabricated using AgNO3 and FeSO4·7H2O salt respectively through a hydro-thermal method based on five major steps; selection of research-grade materials, optimization of temperature, pH, centrifuge, sample washed with distilled water, dry completely in the oven at the optimized temperature and finally ground for characterization. The synthesized NPs were characterized by scanning electron microscope (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) to confirm the morphology, elemental composition, and structure of the sample respectively. The diameter of the NPs was recorded through SEM which lay in the range of 70-95 nm.

RESULTS

Cultural parameters were optimized to achieve better cellulase production, where incubation time of 56 h, inoculum size of 5%, 1% coconut cake, 0.43% ammonium nitrate, pH 8, and 37 °C temperature were found optimal. The enhancing effect of AgO NPs was observed on cellulase activity (57.804 U/ml/min) at 50 ppm concentration while FeO NPs exhibited an inhibitory effect on cellulase activity at all concentrations. Molecular docking analysis was also performed to understand the underlying mechanism of improved enzymatic activity by nanocatalysts.

CONCLUSION

This study authenticates AgO NPs as better nanocatalysts for improved thermostable cellulase biodegradation activity with the extraordinary capability to be potentially utilized in bioethanol production.

Lignocellulolytic extremozymes and their biotechnological applications

Lignocellulolytic enzymes are used in different industrial and environmental processes. The rigorous operating circumstances of these industries, however, might prevent these enzymes from performing as intended. On the other side, extremozymes are enzymes produced by extremophiles that can function in extremely acidic or basic; hot or cold; under high or low salinity conditions. These severe conditions might denature the normal enzymes that are produced by mesophilic microorganisms. The increased stability of these enzymes has been contributed to a number of conformational modifications in their structures. These modifications may result from a few amino acid substitutions, an improved hydrophobic core, the existence of extra ion pairs and salt bridges, an increase in compactness, or an increase in positively charged amino acids. These enzymes are the best option for industrial and bioremediation activities that must be carried out under difficult conditions due to their improved stability. The review, therefore, discusses lignocellulolytic extremozymes, their structure and mechanisms along with industrial and biotechnological applications.

Purification, Characterization, and Application of Endoglucanase from Rhizopus oryzae as Antibiofilm Agent

The enzyme endoglucanase is responsible for the depolymerization of cellulose. This study focuses on characterization and purification of endoglucanase from Rhizopus oryzae MTCC 9642 through a simple size exclusion method and its effective application as an antibiofilm agent. Extracellular ß-1,4-endoglucanase, an enzyme that catalyzes the hydrolysis of carboxymethyl cellulose, was found to be synthesized by Rhizopus oryzae MTCC 9642. The enzyme was purified up to homogeneity simply by size exclusion process through ultrafiltration and gel chromatography. The molecular weight of purified enzyme protein was estimated to be 39.8 kDa and it showed the highest substrate affinity towards carboxymethyl-cellulose with Km and Vmax values of 0.833 mg ml-1 and of 0.33 mmol glucose min-1 mg-1protein, respectively. The purified enzyme exhibited optimal activity at pH 6 with a broad stability range of pH 3-8. The most preferred temperature was 35 °C and 50% of activity could be retained after the thermal exposure at 40 °C for 25 min. The purified enzyme protein was inactivated by Cu2+, while the activity could be enhanced by the addition of exogenous thiols. Since biofilm is a challenge for health sector, with the aim of eradicating the biofilm, the purified endoglucanase was used to remove biofilm produced by two nosocomial bacteria. As predicted by in silico molecular docking interaction, the purified enzyme could effectively degrade biofilm architecture of bacterial strains S. aureus and P. aeruginosa by 76.52 ± 6.52% and 61.67 ± 8.76%, respectively. The properties of purified enzyme protein, as elucidated by in vitro and in silico characterization, may be favourable for its commercial applications as a potent antibiofilm agent.

Characterization of Thermostable Cellulase from Bacillus licheniformis PANG L Isolated from the Himalayan Soil

This study aimed to isolate, purify, and characterize a potential thermophilic cellulase-producing bacterium from the Himalayan soil. Eleven thermophilic bacteria were isolated, and the strain PANG L was found to be the most potent cellulolytic producer. Morphological, physiological, biochemical, and molecular characterization identified PANG L as Bacillus licheniformis. This is the first study on the isolation of thermostable cellulase-producing Bacillus licheniformis from the Himalayan soil. This bacterium was processed for the production of cellulase enzyme. The optimum conditions for cellulase production were achieved at 45°C after 48 h of incubation at pH 6.5 in media-containing carboxymethyl cellulose (CMC) and yeast extract as carbon and nitrogen sources, respectively, in a thermo-shaker at 100 rpm. The enzyme was partially purified by 80% ammonium sulphate precipitation followed by dialysis, resulting in a 1.52-fold purification. The optimal activity of partially purified cellulase was observed at a temperature of 60°C and pH 5. The cellulase enzyme was stable within the pH ranges of 3-5 and retained 67% of activity even at 55°C. Cellulase activity was found to be enhanced in the presence of metal ions such as Cd2+, Pb2+, and Ba2+. The enzyme showed the highest activity when CMC was used as a substrate, followed by cellobiose. The Km and Vmax values of the enzyme were 1.8 mg/ml and 10.92 μg/ml/min, respectively. The cellulase enzyme obtained from Bacillus licheniformis PANG L had suitable catalytic properties for use in industrial applications.

An insight into microbial sources, classification, and industrial applications of xylanases: A rapid review

Endo 1,4-β-d-xylanases (EC3.2.1.8) are one of the key lignocellulose hydrolyzing enzymes. Xylan, which is present in copious amounts on earth, forms the primary substrate of endo-xylanases, which can unchain the constituent monosaccharides linked via β-1,4-glycosidic bonds from the xylan backbone. Researchers have shown keen interest in the xylanases belonging to glycoside hydrolase families 10 and 11, whereas those placed in other glycoside hydrolase families are yet to be investigated. Various microbes such as bacteria and fungi harbor these enzymes for the metabolism of their lignocellulose fibers. These microbes can be used as miniature biofactories of xylanase enzymes for a plethora of environmentally benign applications in pulp and paper industry, biofuel production, and for improving the quality of food in bread baking and fruit juice industry. This review highlights the potential of microbes in production of xylanase for industrial biotechnology.

South Africa's indigenous microbial diversity for industrial applications: A review of the current status and opportunities

The unique metagenomic, metaviromic libraries and indigenous micro diversity within Southern Africa have the potential for global beneficiation in academia and industry. Microorganisms that flourish at high temperatures, adverse pH conditions, and high salinity are likely to have enzyme systems that function efficiently under those conditions. These attributes afford researchers and industries alternative approaches that could replace existing chemical processes. Thus, a better understanding of African microbial/genetic diversity is crucial for the development of "greener" industries. A concerted drive to exploit the potential locked in biological resources has been previously seen with companies such as Diversa Incorporated and Verenium (Badische Anilin-und SodaFabrik-BASF) both building business models that pioneered the production of high-performance specialty enzymes for a variety of different industrial applications. The market potential and accompanying industry offerings have not been fully exploited in South Africa, nor in Africa at large. Utilization of the continent's indigenous microbial repositories could create long-lasting, sustainable growth in various production sectors, providing economic growth in resource-poor regions. By bolstering local manufacture of high-value bio-based products, scientific and engineering discoveries have the potential to generate new industries which in turn would provide employment avenues for many skilled and unskilled laborers. The positive implications of this could play a role in altering the face of business markets on the continent from costly import-driven markets to income-generating export markets. This review focuses on identifying microbially diverse areas located in South Africa while providing a profile for all associated microbial/genetically derived libraries in this country. A comprehensive list of all the relevant researchers and potential key players is presented, mapping out existing research networks for the facilitation of collaboration. The overall aim of this review is to facilitate a coordinated journey of exploration, one which will hopefully realize the value that South Africa's microbial diversity has to offer.

Isolation and characterization of detergent-compatible amylase-, protease-, lipase-, and cellulase-producing bacteria

Detergent-compatible enzymes are the new trend followed by most in the detergent industry. Cellulases, lipases, proteases, and amylases are among the enzymes frequently used in detergents. Detergent-compatible enzymes can be obtained from many organisms, but the stability, cheapness, and availability of microbial enzymes make them preferable in industrial areas. In the present study, soil samples contaminated with household waste were collected from different regions of Trabzon (Turkey) for amylase-, cellulase-, protease-, and lipase-producing bacteria. A total of 55 bacterial isolates differing in colony morphology were purified from the samples and 25 of the isolates gave positive results in enzyme screening. The enzyme screening experiments revealed that 10 isolates produced amylase, 9 produced lipase, 7 produced cellulase, and 6 produced protease. While 2 isolates showed both protease and lipase activity, for 2 different isolates cellulose and amylase activity were detected together. It was also observed that one isolate, C37PLCA, produced all four enzymes. The morphological, physiological, and biochemical analyses of the bacteria from which we obtained the enzymes were performed and species close to them were determined using 16S rRNA sequences. Based on the results obtained, our enzymes show tremendous promise for the detergent industry.

Current Insights in Fungal Importance-A Comprehensive Review

Besides plants and animals, the Fungi kingdom describes several species characterized by various forms and applications. They can be found in all habitats and play an essential role in the excellent functioning of the ecosystem, for example, as decomposers of plant material for the cycling of carbon and nutrients or as symbionts of plants. Furthermore, fungi have been used in many sectors for centuries, from producing food, beverages, and medications. Recently, they have gained significant recognition for protecting the environment, agriculture, and several industrial applications. The current article intends to review the beneficial roles of fungi used for a vast range of applications, such as the production of several enzymes and pigments, applications regarding food and pharmaceutical industries, the environment, and research domains, as well as the negative impacts of fungi (secondary metabolites production, etiological agents of diseases in plants, animals, and humans, as well as deteriogenic agents).

Sono-activation of food enzymes: From principles to practice

Over the last decade, sono-activation of enzymes as an emerging research area has received considerable attention from food researchers. This kind of relatively new application of ultrasound has demonstrated promising potential in facilitating the modern food industry by broadening the application of various food enzymes, improving relevant industrial unit operation and productivity, as well as increasing the yield of target products. This review aims to provide insight into the fundamental principles and possible industrialization strategies of the sono-activation of food enzymes to facilitate its commercialization. This review first provides an overview of ultrasound application in the activation of food protease, carbohydrase, and lipase. Then, the recent development on ultrasound activation of food enzymes is discussed on aspects including mechanisms, influencing factors, modification effects, and its applications in real food systems for free and immobilized enzymes. Despite the far fewer studies on sono-activation of immobilized enzymes compared with those on free enzymes, we endeavored to summarize the relevant aspects in three stages: ultrasound pretreatment of free enzyme/carrier, assistance in immobilization process, and modification of the already immobilized enzyme. Lastly, challenges for the scalability of ultrasound in these target areas are discussed and future research prospects are proposed.

Construction of a constitutively active type III secretion system for heterologous protein secretion

Proteins comprise a multibillion-dollar industry in enzymes and therapeutics, but bacterial protein production can be costly and inefficient. Proteins of interest (POIs) must be extracted from lysed cells and inclusion bodies, purified, and resolubilized, which adds significant time and cost to the protein-manufacturing process. The Salmonella pathogenicity island 1 (SPI-1) type III secretion system (T3SS) has been engineered to address these problems by secreting soluble, active proteins directly into the culture media, reducing the number of purification steps. However, the current best practices method of T3SS pathway activation is not ideal for industrial scaleup. Previously, the T3SS was activated by plasmid-based overexpression of the T3SS transcriptional regulator, hilA, which requires the addition of a small molecule inducer (IPTG) to the culture media. IPTG adds significant cost to production and plasmid-based expression is subject to instability in large-scale fermentation. Here, we modulate the upstream transcriptional regulator, hilD, to activate the T3SS via three distinct methods. In doing so, we develop a toolbox of T3SS activation methods and construct constitutively active T3SS strains capable of secreting a range of heterologous proteins at titers comparable to plasmid-based hilA overexpression. We also explore how each activation method in our toolbox impacts the SPI-1 regulatory cascade and discover an epistatic relationship between T3SS regulators, hilE and the hilD 3' untranslated region (hilD 3'UTR). Together, these findings further our goal of making an industrially competitive protein production strain that reduces the challenges associated with plasmid induction and maintenance. KEY POINTS: • Characterized 3 new type III secretion system (T3SS) activation methods for heterologous protein secretion, including 2 constitutive activation methods. • Eliminated the need for a second plasmid and a small molecule inducer to activate the system, making it more suitable for industrial production. • Discovered new regulatory insights into the SPI-1 T3SS, including an epistatic relationship between regulators hilE and the hilD 3' untranslated region.

Medicinal plant-associated rhizobacteria enhance the production of pharmaceutically important bioactive compounds under abiotic stress conditions

Interest in cultivating valuable medicinal plants to collect bioactive components has risen extensively over the world to meet the demands of health care systems, pharmaceuticals, and food businesses. Farmers commonly use chemical fertilizers to attain maximal biomass and yield, which have negative effects on the growth, development, and bioactive constituents of such medicinally important plants. Because of its low cost, environmentally friendly behavior, and nondestructive impact on soil fertility, plant health, and human health, the use of beneficial rhizobial microbiota is an alternative strategy for increasing the production of useful medicinal plants under both standard and stressed conditions. Plant growth-promoting rhizobacteria (PGPR) associated with medicinal plants belong to the genera Azotobacter, Acinetobacter, Bacillus, Brevibacterium, Burkholderia, Exiguobacterium, Pseudomonas, Pantoea, Mycobacterium, Methylobacterium, and Serratia. These microbes enhance plant growth parameters by producing secondary metabolites, including enzymes and antibiotics, which help in nutrient uptake, enhance soil fertility, improve plant growth, and protect against plant pathogens. The role of PGPR in the production of biomass and their effect on the quality of bioactive compounds (phytochemicals) is described in this review. Additionally, the mitigation of environmental stresses including drought stress, saline stress, alkaline stress, and flooding stress to herbal plants is illustrated.

Decrypting the multi-functional biological activators and inducers of defense responses against biotic stresses in plants

Plant diseases are still the main problem for the reduction in crop yield and a threat to global food security. Additionally, excessive usage of chemical inputs such as pesticides and fungicides to control plant diseases have created another serious problem for human and environmental health. In view of this, the application of plant growth-promoting rhizobacteria (PGPR) for controlling plant disease incidences has been identified as an eco-friendly approach for coping with the food security issue. In this review, we have identified different ways by which PGPRs are capable of reducing phytopathogenic infestations and enhancing crop yield. PGPR suppresses plant diseases, both directly and indirectly, mediated by microbial metabolites and signaling components. Microbial synthesized anti-pathogenic metabolites such as siderophores, antibiotics, lytic enzymes, hydrogen cyanide, and several others act directly on phytopathogens. The indirect mechanisms of reducing plant disease infestation are caused by the stimulation of plant immune responses known as initiation of systemic resistance (ISR) which is mediated by triggering plant immune responses elicited through pathogen-associated molecular patterns (PAMPs). The ISR triggered in the infected region of the plant leads to the development of systemic acquired resistance (SAR) throughout the plant making the plant resistant to a wide range of pathogens. A number of PGPRs including Pseudomonas and Bacillus genera have proven their ability to stimulate ISR. However, there are still some challenges in the large-scale application and acceptance of PGPR for pest and disease management. Further, we discuss the newly formulated PGPR inoculants possessing both plant growth-promoting activities and plant disease suppression ability for a holistic approach to sustaining plant health and enhancing crop productivity.

(Magnetic) Cross-Linked Enzyme Aggregates of Cellulase from T. reesei: A Stable and Efficient Biocatalyst

Cross-linked enzyme aggregates (CLEAs) represent an effective tool for carrier-free immobilization of enzymes. The present study promotes a successful application of functionalized magnetic nanoparticles (MNPs) for stabilization of cellulase CLEAs. Catalytically active CLEAs and magnetic cross-linked enzyme aggregates (mCLEAs) of cellulase from Trichoderma reesei were prepared using glutaraldehyde (GA) as a cross-linking agent and the catalytic activity and stability of the CLEAs/mCLEAs were investigated. The influence of precipitation agents, cross-linker concentration, concentration of enzyme, addition of bovine serum albumin (BSA), and addition of sodium cyanoborohydride (NaBH₃CN) on expressed activity and immobilization yield of CLEAs/mCLEAs was studied. Particularly, reducing the unsaturated Schiff's base to form irreversible linkages is important and improved the activity of CLEAs (86%) and mCLEAs (91%). For increased applicability of CLEAs/mCLEAs, we enhanced the activity and stability at mild biochemical process conditions. The reusability after 10 cycles of both CLEAs and mCLEAs was investigated, which retained 72% and 65% of the initial activity, respectively. The thermal stability of CLEAs and mCLEAs in comparison with the non-immobilized enzyme was obtained at 30 °C (145.65% and 188.7%, respectively) and 50 °C (185.1% and 141.4%, respectively). Kinetic parameters were determined for CLEAs and mCLEAs, and the K_M constant was found at 0.055 ± 0.0102 mM and 0.037 ± 0.0012 mM, respectively. The maximum velocity rate (V_max) was calculated as 1.12 ± 0.0012 µmol/min for CLEA and 1.17 ± 0.0023 µmol/min for mCLEA. Structural characterization was studied using XRD, SEM, and FT-IR. Catalytical properties of immobilized enzyme were improved with the addition of reducent NaBH₃CN by enhancing the activity of CLEAs and with addition of functionalized aminosilane MNPs by enhancing the activity of mCLEAs.

TtCel7A: A Native Thermophilic Bifunctional Cellulose/Xylanase Exogluclanase from the Thermophilic Biomass-Degrading Fungus Thielavia terrestris Co3Bag1, and Its Application in Enzymatic Hydrolysis of Agroindustrial Derivatives

The biomass-degrading thermophilic ascomycete fungus Thielavia terrestris Co3Bag1 produces TtCel7A, a native bifunctional cellulase/xylanase GH7 family. The purified TtCel7A, with an estimated molecular weight of 71 kDa, was biochemically characterized. TtCel7A displayed an optimal pH of 5.5 for both activities and an optimal temperature of 60 and 50 °C for cellulolytic and xylanolytic activities, respectively. The half-lives determined for cellulase activity were 140, 106, and 41 min at 50, 60, and 70 °C, respectively, whereas the half-lives observed for xylanase activity were 24, 10, and 1.4 h at 50, 60, and 70 °C, respectively. The K_M and V_max values were 3.12 mg/mL and 50 U/mg for cellulase activity and 0.17 mg/mL and 42.75 U/mg for xylanase activity. Circular dichroism analysis suggests changes in the secondary structure of TtCel7A in the presence of CMC as the substrate, whereas no modifications were observed with beechwood xylan. TtCel7A displayed the excellent capability to hydrolyze CMC, beechwood xylan, and complex substrates such as oat bran, wheat bran, and sugarcane bagasse, with glucose and cellobiose being the main products released; also, slightly less endo cellulase and xylanase activities were observed. Thus, suggesting TtCel7A has an exo- and endomode of action. Based on the characteristics of the enzyme, it might be considered a good candidate for industrial applications.

A Combined Study on Optimization, In Silico Modeling, and Genetic Modification of Large Scale Microbial Cellulase Production

Cellulase is a biocatalyst that hydrolyzes cellulosic biomass and is considered a major group of industrial enzymes for its applications. Extensive work has been done on microbial cellulase but fungi are considered a novel strain for their maximum cellulase production. Production cost and novel microbial strains are major challenges for its improvement where cheap agro wastes can be essential sources of cellulose as substrates. The researcher searches for more cellulolytic microbes from natural sources but the production level of isolated strains is comparatively low. So genetic modification or mutation can be employed for large-scale cellulase production before optimization. After genetic modification than in silico molecular modeling can be evaluated for substrate molecule's binding affinity. In this review, we focus not only on the conventional methods of cellulase production but also on modern biotechnological approaches applied to cellulase production by a sequential study on common cellulase-producing microbes, modified microbes, culture media, carbon sources, substrate pretreatment process, and the importance of optimum pH and temperature on fermentation. In this review, we also compare different cellulase activity determination methods. As a result, this review provides insights into the interrelationship between the characteristics of optimizing different culture conditions, genetic modification, and in silico enzyme modeling for the production of cellulase enzymes, which may aid in the advancement of large-scale integrated enzyme manufacturing of substrate-specific enzymes.

Enzyme Discovery in Anaerobic Fungi (Neocallimastigomycetes) Enables Lignocellulosic Biorefinery Innovation

Lignocellulosic biorefineries require innovative solutions to realize their full potential, and the discovery of novel lignocellulose-active enzymes could improve biorefinery deconstruction processes. Enzymatic deconstruction of plant cell walls is challenging, as noncarbohydrate linkages in hemicellulosic sidechains and lignin protect labile carbohydrates from hydrolysis. Highly specialized microbes that degrade plant biomass are attractive sources of enzymes for improving lignocellulose deconstruction, and the anaerobic gut fungi (Neocallimastigomycetes) stand out as having great potential for harboring novel lignocellulose-active enzymes. We discuss the known aspects of Neocallimastigomycetes lignocellulose deconstruction, including their extensive carbohydrate-active enzyme content, proficiency at deconstructing complex lignocellulose, unique physiology, synergistic enzyme complexes, and sizeable uncharacterized gene content. Progress describing Neocallimastigomycetes and their enzymes has been rapid in recent years, and it will only continue to expand. In particular, direct manipulation of anaerobic fungal genomes, effective heterologous expression of anaerobic fungal enzymes, and the ability to directly relate chemical changes in lignocellulose to fungal gene regulation will accelerate the discovery and subsequent deployment of Neocallimastigomycetes lignocellulose-active enzymes.

Screening for cellulases and preliminary optimisation of glucose tolerant β-glucosidase production and characterisation

The search for a novel microbial producer of cellulases including a glucose tolerant β-glucosidase is a challenge as most are inhibited by their product glucose. This study aims to screen for cellulolytic fungi using qualitative and quantitative screening methods. Primary screening revealed 34 of 46 fungal isolates with β-glucosidase activity. Eleven and 13 of these also displayed endoglucanase and exoglucanase activities, respectively. During secondary screening, this number was reduced to 26 β-glucosidase producers with 13 also having endoglucanase and exoglucanase activities. Isolate C1 displayed enhanced production of β-glucosidases in the presence of 0.05 M glucose (69% higher activity). Optimisation of growth conditions for β-glucosidase production by one variable at a time experiments improved production for (isolates) PS1 (64%), MB5 (84%), and C2 (69%). Isolate PS1 identified as Chaetomella sp. BBA70074 displayed the highest tolerance to glucose, retaining 10% of β-glucosidase activity in the presence of 0.8 M glucose. Tolerance to glucose increased to 14% when produced under optimal conditions. β-Glucosidase had a molecular weight of 170 kDa with a pH and temperature optima of 6 and 70°C, respectively. Future studies will include optimisation of the production of the glucose tolerant enzyme by Chaetomella sp. BBA70074.

Characterization of plant growth promoting activities of indigenous bacteria of phosphate mine wastes, a first step toward revegetation

Morocco holds the vast majority of the world's phosphate reserves, but due to the processes involved in extracting and commercializing these reserves, large quantities of de-structured, nutritionally deficient mine phosphate wastes are produced each year. In a semi-arid climate, these wastes severely hamper plant growth and development leading to huge unvegetated areas. Soil indigenous Plant Growth-Promoting Bacteria (PGPB) play a pivotal role in restauration of these phosphate mining wastes by revegetation, by increasing plants development, soil functioning, and nutrient cycling. The development of a vegetative cover above the degraded phosphate wastes, could stabilize and reintegrate these wastes in the surrounding environment. The current study's objectives were to isolate, characterize, and identify indigenous bacterial strains, and test their PGP activity in vitro and, for the best-performing strains in planta, in order to assess their potential for acting as biofertilizers. A quantitative test for the synthesis of auxin and the production of siderophores as well as a qualitative test for the solubilization of phosphate were performed on all isolated bacterial strains. The production of hydrogen cyanide (HCN), exopolysaccharides (EPS), and enzymes were also examined. Three bacteria, selected among the best PGPB of this study, were tested in planta to determine whether such indigenous bacteria could aid plant growth in this de-structured and nutrient-poor mining soil. Using 16S rRNA gene sequencing, 41 bacterial strains were isolated and 11 genera were identified: Acinetobacter, Agrococcus, Bacillus, Brevibacterium, Microbacterium, Neobacillus, Paenibacillus, Peribacillus, Pseudarthrobacter, Stenotrophomonas, and Raoultella. Among the three best performing bacteria (related to Bacillus paramycoides, Brevibacterium anseongense, and Stenotrophomonas rhizophila), only Stenotrophomonas rhizophila and Brevibacterium anseongense were able to significantly enhance Lupinus albus L. growth. The best inoculation results were obtained using the strain related to Stenotrophomonas rhizophila, improving the plant's root dry weight and chlorophyll content. This is also, to our knowledge, the first study to show a PGP activity of Brevibacterium anseongense.

Bioactive compounds of Curvularia species as a source of various biological activities and biotechnological applications

Many filamentous fungi are known to produce several secondary metabolites or bioactive compounds during their growth and reproduction with sort of various biological activities. Genus Curvularia (Pleosporaceae) is a dematiaceous filamentous fungus that exhibits a facultative pathogenic and endophytic lifestyle. It contains ~213 species among which Curvularia lunata, C. geniculata, C. clavata, C. pallescens, and C. andropogonis are well-known. Among them, C. lunata is a major pathogenic species of various economical important crops especially cereals of tropical regions while other species like C. geniculata is of endophytic nature with numerous bioactive compounds. Curvularia species contain several diverse groups of secondary metabolites including alkaloids, terpenes, polyketides, and quinones. Which possess various biological activities including anti-cancer, anti-inflammatory, anti-microbial, anti-oxidant, and phytotoxicity. Several genes and gene factors are involved to carry and regulate the expression of these activities which are influenced by environmental signals. Some species of Curvularia also show negative impacts on humans and animals. Apart from their negative effects, there are some beneficial implications like production of enzymes of industrial value, bioherbicides, and source of nanoparticles is reported. Many researchers are working on these aspects all over the world but there is no review in literature which provides significant understanding about these all aspects. Thus, this review will provide significant information about secondary metabolic diversity, their biological activities and biotechnological implications of Curvularia species.

Cross-habitat distribution pattern of Bacillus communities and their capacities of producing industrial hydrolytic enzymes in Paracel Islands: Habitat-dependent differential contributions of the environment

Bacillus as a predominant genus of enzyme-producing bacteria presents desirable features to fulfill the vast demand of specific industries, whereas the knowledge of the Bacillus communities and their capacities of producing industrial hydrolytic enzymes across the microhabitats of the Paracel Islands is limited. Herein, a total of 193 culturable Bacillus strains belonging to 19 species were isolated across the microhabitats of seawater, sediment, coral and seagrass, covering 39 stations of the Paracel Islands. Each microhabitat displayed its unique species, while the species of Bacillus paramycoides besides being the dominant species with an abundance of 54.94% also was the only species shared by all microhabitats of the Paracel Islands. Of the Bacillus communities, 97.41% of the isolates exhibited the capacity of producing one-or-more types of enzymes with comparatively higher and broader ranges of enzyme activities, including 163 protease-, 27 cellulase-, 118 alginate lyase-, 140 K-carrageenase- and 158 agarose-producing strains. By the correlation analyses of "Bacillus-environmental factors" and "Enzyme-producing Bacillus-environmental factors", the cross-habitat distribution and enzyme-producing capacity pattern of the Bacillus communities were strongly driven by habitat type, and the environmental factors made habitat-dependent differential contributions to that in the Paracel Islands. It's worth noting that the cellulase-producing strain wasn't detected in seagrass due to its survival strategy to prevent cellulose degradation by inhibiting cellulase-producing bacteria, while coral contained more stable microbial metabolic functions to protect against environmental fluctuations. These findings besides providing large quantities of promising enzyme-producing candidates for specific industrial desires, also facilitate the development and utilization of marine microbial resources and the environmental policy- and/or law-making according to environmental features across the microhabitats of the Paracel Islands.

Microfluidic screening and genomic mutation identification for enhancing cellulase production in Pichia pastoris

Background

Pichia pastoris is a widely used host organism for heterologous production of industrial proteins, such as cellulases. Although great progress has been achieved in improving protein expression in P. pastoris, the potential of the P. pastoris expression system has not been fully explored due to unknown genomic impact factors. Recently, whole-cell directed evolution, employing iterative rounds of genome-wide diversity generation and high-throughput screening (HTS), has been considered to be a promising strategy in strain improvement at the genome level.

Results

In this study, whole-cell directed evolution of P. pastoris, employing atmospheric and room temperature plasma (ARTP) mutagenesis and droplet-based microfluidic HTS, was developed to improve heterogenous cellulase production. The droplet-based microfluidic platform based on a cellulase-catalyzed reaction of releasing fluorescence was established to be suitable for methanol-grown P. pastoris. The validation experiment showed a positive sorting efficiency of 94.4% at a sorting rate of 300 droplets per second. After five rounds of iterative ARTP mutagenesis and microfluidic screening, the best mutant strain was obtained and exhibited the cellulase activity of 11,110 ± 523 U/mL, an approximately twofold increase compared to the starting strain. Whole-genome resequencing analysis further uncovered three accumulated genomic alterations in coding region. The effects of point mutations and mutant genes on cellulase production were verified using reconstruction of point mutations and gene deletions. Intriguingly, the point mutation Rsc1G22V was observed in all the top-performing producers selected from each round, and gene deletion analysis confirmed that Rsc1, a component of the RSC chromatin remodeling complex, might play an important role in cellulase production.

Conclusions

We established a droplet-based microfluidic HTS system, thereby facilitating whole-cell directed evolution of P. pastoris for enhancing cellulase production, and meanwhile identified genomic alterations by whole-genome resequencing and genetic validation. Our approaches and findings would provide guides to accelerate whole-cell directed evolution of host strains and enzymes of high industrial interest.