Production of crude cellulase and xylanase from Trichoderma harzianum PPDDN10 NFCCI-2925 and its application in photocopier waste paper recycling

Optimization of enzymatic saccharification of industrial wastes using a thermostable and halotolerant endoglucanase through Box-Behnken experimental design

This study describes the production, characterization and application of an endoglucanase from Penicillium roqueforti using lignocellulosic agro-industrial wastes as the substrate during solid-state fermentation. The endoglucanase was generated after culturing with different agro-industrial wastes for 96 h without any pretreatment. The highest activity was obtained at 50 °C and pH 4.0. Additionally, the enzyme showed stability in the temperature and pH ranges of 40-80 °C and 4.0-5.0, respectively. The addition of Ca2+, Zn2+, Mg2+, and Cu2+ increased enzymatic activity. Halotolerance as a characteristic of the enzyme was confirmed when its activity increased by 35% on addition of 2 M NaCl. The endoglucanase saccharified sugarcane bagasse, coconut shell, wheat bran, cocoa fruit shell, and cocoa seed husk. The Box-Behnken design was employed to optimize fermentable sugar production by evaluating the following parameters: time, substrate, and enzyme concentration. Under ideal conditions, 253.19 mg/g of fermentable sugars were obtained following the saccharification of wheat bran, which is 41.5 times higher than that obtained without optimizing. This study presents a thermostable, halotolerant endoglucanase that is resistant to metal ions and organic solvents with the potential to be applied in producing fermentable sugars for manufacturing biofuels from agro-industrial wastes.

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.

Isolation, morphological identification, and xylanase characteristics of anaerobic gut fungi Neocallimastix from Anatolian wild goat

This study shows the morphological identification of anaerobic fungal strains isolated from fecal samples of goats inhabiting Turkey and the effects of various metal ions and chemicals on extracellular xylanase production. Three different anaerobic gut fungi isolated from wild goats in Turkey were identified as Neocallimastix spp. xylanase, cellulase, and lichenase production were tested in culture supernatants, and the maximum-specific activities were found as 560.42 ± 9.39, 159.70 ± 3.88, and 157.36 ± 3.83 (μmol/min/mg protein), respectively. While the optimum temperature range of exo-xylanases was found as 40-50°C, their optimum pH range was determined as 6.0-6.5. Xylanase activity decreased in metal ions and other chemical reactants based on dose. The metal ion that significantly inhibited xylanase activity was Fe⁺³ . It was found that the ferric ions inhibited xylanase activity in all three anaerobic gut fungi by 30%-90% depending on molarity. On the contrary, the 1 mM concentrations of the Mn⁺² , Ba⁺² , Co⁺² , Cu⁺² , Sn⁺² , and Mg⁺² metal ions and the ethylenediaminetetraacetic acid and β-mercaptoethanol reagents had a positive effect at rates in the range of 3%-92%. In conclusion, these findings demonstrate that anaerobic gut fungus has very stable fibrolytic enzymes that need to be separated, as well and the existence of a unique resource for industrial applications.

Multi-efficient endoglucanase from Aspergillus niger MPS25 and its potential applications in saccharification of wheat straw and waste paper deinking

The deinking in the paper industry is in great demand, and microbial enzymes are key players. In the present study, the endoglucanase production from newly isolated fungi Aspergillus niger MPS25 is reported. The optimization of endoglucanase production was carried out using one factor at a time approach resulting in endoglucanase activity (2.37 IU/ml) at 45 °C and pH 8 in submerged fermentation (SmF), which shows optimum enzyme activity at 60 °C. Interestingly, the metal ions viz. Co²⁺ stimulated the endoglucanase activity, whereas Mn²⁺ reduced the enzyme activity, which shows that this enzyme can be used for effluent treatment released through deinking. The enzymatic hydrolysis of wheat straw produced 26.96 ± 0.108 mg/g of reducing sugars, indicating its potential in saccharification and the biofuel industry. Furthermore, the validation of the deinking efficiency of this enzyme resulted in improved deinking of mixed office waste and old newspapers by 31.5% and 20.4%, respectively. The strength properties, viz. burst factor and tear index, breaking length, and tensile index of the handmade paper sheets, were also improved which were analyzed by the scanning electron micrographs. The FTIR and XRD analysis of pulp provided insights into the changes in functional groups and cellulose crystallinity, respectively. These results indicate that multi-efficient endoglucanase from Aspergillus niger MPS25 is suitable for enzyme-based eco-friendly deinking for waste paper recycling and lignocellulosic biomass saccharification.

Pretreatment of lignocellulosic biogas substrates by filamentous fungi

Decomposition of lignocellulosic plant biomass by four filamentous fungi was carried out to facilitate subsequent anaerobic degradation and biogas formation. Agricultural side products, wheat straw and corn stover and forestry energy plant willow chips were selected as plant biomass sources. The substrates were confronted by pure cultures of Penicillium aurantiogriseum (new isolate from rumen), Trichoderma reesei (DSM768), Gilbertella persicaria (SZMC11086) and Rhizomucor miehei (SZMC11005). In addition to total cellulolytic filter paper degradation activity, the production of endoglucanase, cellobiohydrolase, β-glucosidase enzymes were followed during the pretreatment period, which lasted for 10 days at 37 °C. The products of pretreatments were subsequently tested for mesophilic biogas production in batch reactors. All 4 strains effectively pretreated the lignocellulosic substrates albeit in varying degrees, which was related to the level of the tested hydrolytic enzyme activities. Penicillium aurantiogriseum showed outstanding hydrolytic enzyme production and highest biogas yield from the partially degraded substrates. Corn stover was the best substrate for biomass decomposition and biogas production. Scanning electron microscopy confirmed the deep penetration of fungal hyphae into the lignocellulosic substrate in all cases.

Overview of lignocellulolytic enzyme systems with special reference to valorization of lignocellulosic biomass

Lignocellulosic biomass, one of the most valuable natural resources, is abundantly present on earth. Being a renewable feedstock, it harbors a great potential to be exploited as a raw material, to produce various value-added products. Lignocellulolytic microorganisms hold a unique position regarding the valorization of lignocellulosic biomass as they contain efficient enzyme systems capable of degrading this biomass. The ubiquitous nature of these microorganisms and their survival under extreme conditions have enabled their use as an effective producer of lignocellulolytic enzymes with improved biochemical features crucial to industrial bioconversion processes. These enzymes can prove to be an exquisite tool when it comes to the eco-friendly manufacturing of value-added products using waste material. This review focuses on highlighting the significance of lignocellulosic biomass, microbial sources of lignocellulolytic enzymes and their use in the formation of useful products.

Partial purification of bacterial cellulo-xylanolytic enzymes and their application in deinking of photocopier waste paper

The potential of alkaline cellulo-xylanolytic enzymes from non-pathogenic Bacillus subtilis strain was tested for deinking of photocopier waste paper. Cellulase and xylanase play a crucial role in deinking of different types of waste paper. Partial purification of cellulo-xylanolytic enzymes was carried out using ultrafiltration followed by ammonium sulfate precipitation. The ultrafiltered enzyme was used for deinking the photocopier waste paper along with chemical deinking. An enzyme dose of 0.6 IU/g and reaction time of 60 min for ultrafiltered cellulo-xylanolytic enzyme significantly increased deinking efficiency, tear index (9.52%) and folding endurance (5±2%) as compared to chemical deinking. There was improvement in strength properties such as tear index and double-fold along with freeness of pulp (18%). There was slight decrease in tensile index (0.6%) and burst index (16%) while ISO brightness remained unaffected. Enzymatic deinking (74.3%) by ultrafiltered cellulo-xylanolytic from Bacillus subtilis was found significant over conventional chemical deinking.

Xylanolytic Enzymes in Pulp and Paper Industry: New Technologies and Perspectives

The pulp and paper industry discharges massive amount of wastewater containing hazardous organochlorine compounds released during different processing stages. Therefore, some cost-effective and nonpolluting practices such as enzymatic treatments are required for the potential mitigation of effluents released in the environment. Various xylanolytic enzymes such as xylanases, laccases, cellulases and hemicellulases are used to hydrolyse raw materials in the paper manufacturing industry. These enzymes are used either individually or in combination, which has the efficient potential to be considered for bio-deinking and bio-bleaching components. They are highly dynamic, renewable, and high in specificity for enhancing paper quality. The xylanase act on the xylan and cellulases act on the cellulose fibers, and thus increase the bleaching efficacy of paper. Similarly, hemicellulase enzyme like endo-xylanases, arabinofuranosidase and β-D-xylosidases have been described as functional properties towards the biodegradation of biomass. In contrast, laccase enzymes act as multi-copper oxidoreductases, bleaching the paper by the oxidation and reduction process. Laccases possess low redox potential compared to other enzymes, which need some redox mediators to catalyze. The enzymatic process can be affected by various factors such as pH, temperature, metal ions, incubation periods, etc. These factors can either increase or decrease the efficiency of the enzymes. This review draws attention to the xylanolytic enzyme-based advanced technologies for pulp bleaching in the paper industry.

Application of surfactants in papermaking industry and future development trend of green surfactants

In this work, the application of chemical surfactants, including cooking aids, detergents, surface sizing agents, and deinking agents as core components, is introduced in the wet end of pulping and papermaking. This method for the combined application of enzymes and surfactants has expanded, promoting technological updates and improving the effect of surfactants in practical applications. Finally, the potential substitution of green surfactants for chemical surfactants is discussed. The source, classification, and natural functions of green surfactants are introduced, including plant extracts, biobased surfactants, fermentation products, and woody biomass. These green surfactants have advantages over their chemically synthesized counterparts, such as their low toxicity and biodegradability. This article reviews the latest developments in the application of surfactants in different paper industry processes and extends the methods of use. Additionally, the application potential of green surfactants in the field of papermaking is discussed. KEY POINTS: • Surfactants as important chemical additives in papermaking process are reviewed. • Deinking technologies by combined of surfactants and enzymes are reviewed. • Applications of green surfactant in papermaking industry are prospected.

Optimization of Culture Conditions and Production of Bio-Fungicides from Trichoderma Species under Solid-State Fermentation Using Mathematical Modeling

Agro-industrial wastes suitable for economical and high mass production of novel Trichoderma species under solid-state fermentation were identified by optimizing the culture conditions using a mathematical model and evaluating the viability of the formulated bio-product. Fourteen inexpensive, locally available, organic substrates and cereals were examined using a one-factor-at-a-time experiment. The fungus colonized nearly all substrates after 21 days of incubation, although the degree of colonization and conidiation varied among the substrates. A mixture of wheat bran and white rice (2:1 w/w) was found to support maximum growth of T. asperellum AU131 (3.2 × 107 spores/g dry substrate) and T. longibrachiatum AU158 (3.5 × 107 spores/g dry substrate). Using a fractional factorial design, the most significant growth factors influencing biomass production were found to be temperature, moisture content, inoculum concentration, and incubation period (p ≤ 0.05). Analysis of variance of a Box-Behnken design showed that the regression model was highly significant (p ≤ 0.05) with F-values of 10.38 (P = 0.0027, T. asperellum AU131) and 12.01 (p < 0.0017, T. longibrachiatum AU158). Under optimal conditions, maximum conidia yield of log10 (8.6) (T. asperellum AU131) and log10(9.18) (T. longibrachiatum) were obtained. For wettable powder Trichoderma species formulations, it was possible to maintain conidial viability at room temperature (25 °C) for eight months at concentrations above 106 CFU/g.

Trichoderma-mediated rice straw compost promotes plant growth and imparts stress tolerance

Rice straw burning is causing huge economic losses and environmental hazards. Microbial mediated ex situ composting could be a viable solution which would not only reduce the straw burning but also will enrich nutrition to the soil. Strains of Trichoderma isolated from tree bark were tested to decompose rice straw efficiently, and the Trichoderma-mediated rice straw compost was used subsequently to improve rice growth. Two isolates of Trichoderma reesei (NRRIT-26 and NRRIT-27) decomposed the straw by producing higher decomposing enzymes, like total cellulase (≥ 1.87 IU mL-1), endoglucanase (≥ 0.75 IU mL-1), xylanase (≥ 163.49 nkat mL-1), and laccase (≥ 11.75 IU mL-1). Trichoderma decomposed rice straw compost had higher nutrient contents (1.97% N, 2.04% K, and 0.88% P) and optimum C/N ratio (28:2) as compared to control. The Trichoderma decomposed rice straw as a nutrient reduced the mean germination time (2.2 days as compared to 4 days in control) and enhanced the seedling vigor and total chlorophyll content in rice. Expression of defense enzymes, like catalase (≥ 200% both in shoot and root), peroxidase (≥ 180% in root and ≥ 300% in shoot), and superoxide dismutase (≥ 160% in root and ≥ 90% in shoot), were higher in treated plants as compared to control indicating higher stress tolerance ability to crops. We conclude that the Trichoderma-mediated rice straw management is a viable option and has the potential to reduce straw burning, and at the same time, the compost could enrich soil fertility and impart intrinsic stress tolerance to rice.

Seed Biopriming With Trichoderma Strains Isolated From Tree Bark Improves Plant Growth, Antioxidative Defense System in Rice and Enhance Straw Degradation Capacity

This study is a unique report of the utilization of Trichoderma strains collected from even tree barks for rice plant growth, its health management, and paddy straw degradation. Seven different spp. of Trichoderma were characterized according to morphological and molecular tools. Two of the isolated strains, namely Trichoderma hebeiensis and Trichoderma erinaceum, outperformed the other strains. Both of the strains controlled four important rice pathogens, i.e., Rhizoctonia solani (100%), Sclerotium oryzae (84.17%), Sclerotium rolfsii (66.67%), and Sclerotium delphinii (76.25%). Seed bio-priming with respective Trichoderma strains reduced the mean germination time, enhanced the seedling vigor and total chlorophyll content which could be related to the higher yield observed in two rice varieties; Annapurna and Satabdi. All the seven strains accelerated the decomposition of rice straw by producing higher straw degrading enzymes like total cellulase (0.97–2.59 IU/mL), endoglucanase (0.53–0.75 IU/mL), xylanase (145.35–201.35 nkat/mL), and laccase (2.48–12.60 IU/mL). They also produced higher quantities of indole acetic acid (19.19–46.28 μg/mL), soluble phosphate (297.49–435.42 μg/mL), and prussic acid (0.01–0.37 μg/mL) which are responsible for plant growth promotion and the inhibition of rice pathogen populations. Higher expression of defense enzymes like catalase (≥250% both in shoot and root), peroxidase (≥150% in root and ≥100% in shoot), superoxide dismutase (≥ 150% in root and ≥100% in shoot), polyphenol oxidase (≥160% in shoot and ≥120% in shoot), and total phenolics (≥200% in root and ≥250% in shoot) as compared to the control indicates stress tolerance ability to rice crop. The expression of the aforementioned enzymes were confirmed by the expression of corresponding defense genes like PAL (>3-fold), DEFENSIN (>1-fold), POX (>1.5-fold), LOX (>1-fold), and PR-3 (>2-fold) as compared to the non-treated control plants. This investigation demonstrates that Trichoderma strains obtained from tree bark could be considered to be utilized for the sustainable health management of rice crop.

Ecological Genomics and Evolution of Trichoderma reesei

The filamentous fungus Trichoderma reesei (Hypocreales, Ascomycota) is an efficient industrial cell factory for the production of cellulolytic enzymes used for biofuel and other applications. Therefore, researches addressing T. reesei are relatively advanced compared to other Trichoderma spp. because of the significant bulk of available knowledge, multiple genomic data, and gene manipulation techniques. However, the established role of T. reesei in industry has resulted in a frequently biased understanding of the biology of this fungus. Thus, the recent studies unexpectedly show that the superior cellulolytic activity of T. reesei and other Trichoderma species evolved due to multiple lateral gene transfer events, while the innate ability to parasitize other fungi (mycoparasitism) was maintained in the genus, including T. reesei. In this chapter, we will follow the concept of ecological genomics and describe the ecology, distribution, and evolution of T. reesei, as well as critically discuss several common misconceptions that originate from the success of this species in applied sciences and industry.

Effect of Oligosaccharide Degree of Polymerization on the Induction of Xylan-Degrading Enzymes by Fusarium oxysporum f. sp. Lycopersici

Xylan is one of the most abundant carbohydrates on Earth. Complete degradation of xylan is achieved by the collaborative action of endo-β-1,4-xylanases and β-d-xylosidases and a number of accessories enzymes. In filamentous fungi, the xylanolytic system is controlled through induction and repression. However, the exact mechanism remains unclear. Substrates containing xylan promote the induction of xylanases, which release xylooligosaccharides. These, in turn, induce expression of xylanase-encoding genes. Here, we aimed to determine which xylan degradation products acted as inducers, and whether the size of the released oligomer correlated with its induction strength. To this end, we compared xylanase production by different inducers, such as sophorose, lactose, cellooligosaccharides, and xylooligosaccharides in Fusarium oxysporum f. sp. lycopersici. Results indicate that xylooligosaccharides are more effective than other substrates at inducing endoxylanase and β-xylosidases. Moreover, we report a correlation between the degree of xylooligosaccharide polymerization and induction efficiency of each enzyme. Specifically, xylotetraose is the best inducer of endoxylanase, xylohexaose of extracellular β-xylosidase, and xylobiose of cell-bound β-xylosidase.

Enzyme-assisted pulp refining: an energy saving approach

Energy conservation has become an essential step in pulp and paper industry due to diminishing fossil reserves and high cost of energy. Refining is a mechanical treatment of pulp that modifies the structure of the fibres in order to achieve desired paper-making properties. However, it consumes considerable amount of energy. The electrical power consumption has a direct impact on paper manufacturing cost. Therefore, there is a requirement to minimize the energy cost. Enzyme-assisted refining is the environment friendly option that reduces the energy consumption for papermaking. Enzyme-assisted refining is defined as mechanical refining after pretreatment of pulp with enzymes such as cellulases and hemicellulases. It not only reduces the energy consumption but also improves the quality of finished paper. Enzymes improve the beatability of pulp at same refining degree (°SR) and desired paper properties can be achieved at decreased refining time. The selection of suitable enzyme, optimization of enzyme dose and appropriate reaction time are the key factors for energy reduction and pulp quality improvement during enzyme-assisted refining.

A pollution reducing enzymatic deinking approach for recycling of mixed office waste paper

The efficiency of xylano-pectinolytic enzymes, co-produced by a single microbial strain Bacillus pumilus, was analysed for the recycling of mixed office waste paper through deinking and compared with the alkaline chemical deinking method. Enzymes showed maximum deinking at pH 8.5, pulp consistency of 10%, xylanase-pectinase dose of 12 and 4 IU per gram pulp, respectively, after 120 min of deinking period, and temperature at 50 °C. A chemi-enzymatic approach was employed with xylano-pectinolytic enzymes and various concentrations of deinking chemicals, which showed that enzyme-treated mixed office waste pulp requires only 40% chemicals for deinking, in order to get the almost same level of various handsheets properties, as obtained by the chemical method with 100% chemicals. Similarly, the effluent load of BOD and COD contents was also decreased by 17.90 and 19.75%. This combinational approach of deinking significantly improved the various properties of the handsheets and resulted in gain of 7.5, 9.38, 6.33 and 11.65% in tear factor, burst factor, breaking length and viscosity of the handsheets, while the effective residual ink concentration analysis of deinked handsheets of mixed office waste paper showed deinking efficiency of 22.45%, which revealed the removal of ink particles during enzymatic deinking steps.

Innovations in CAZyme gene diversity and its modification for biorefinery applications

For sustainable growth, concept of biorefineries as recourse to the "fossil derived" energy source is important. Here, the Carbohydrate Active enZymes (CAZymes) play decisive role in generation of biofuels and related sugar-based products utilizing lignocellulose as a carbon source. Given their industrial significance, extensive studies on the evolution of CAZymes have been carried out. Various bacterial and fungal organisms have been scrutinized for the development of CAZymes, where advance techniques for strain enhancement such as CRISPR and analysis of specific expression systems have been deployed. Specific Omic-based techniques along with protein engineering have been adopted to unearth novel CAZymes and improve applicability of existing enzymes. In-Silico computational research and functional annotation of new CAZymes to synergy experiments are being carried out to devise cocktails of enzymes for use in biorefineries. Thus, with the establishment of these technologies, increased diversity of CAZymes with broad span of functions and applications is seen.

Biotransformation of lignocellulosic biomass into industrially relevant products with the aid of fungi-derived lignocellulolytic enzymes

Lignocellulosic material has drawn significant attention among the scientific community due to its year-round availability as a renewable resource for industrial consumption. Being an economic substrate alternative, various industries are reevaluating processes to incorporate derived compounds from these materials. Varieties of fungi and bacteria have the ability to depolymerize lignocellulosic biomass by synthesizing degrading enzymes. Owing to catalytic activity stability and high yields of conversion, lignocellulolytic enzymes derived from fungi currently have a high spectrum of industrial applications. Moreover, these materials are cost effective, eco-friendly and nontoxic while having a low energy input. Techno-economic analysis for current enzyme production technologies indicates that synthetic production is not commercially viable. Instead, the economic projection of the use of naturally-produced ligninolytic enzymes is promising. This approach may improve the economic feasibility of the process by lowering substrate expenses and increasing lignocellulosic by-product's added value. The present review will discuss the classification and enzymatic degradation pathways of lignocellulolytic biomass as well as the potential and current industrial applications of the involved fungal enzymes.

A cleaner process of deinking waste paper pulp using Pseudomonas mendocina ED9 lipase supplemented enzyme cocktail

Lipase enzyme has a critical role in deinking process along with other lignocellulosic enzymes. In this paper, we try to demonstrate the role of lipase in the enzyme cocktail used for enzymatic deinking. For this, we identified a potential lipolytic bacterium, Pseudomonas mendocina ED9 isolated from elephant dung with a molecular weight of 35 kDa. During the Box-Benhken model optimization, a maximum lipase activity of 105.12 U/g, which was 12.36-fold higher than the initial enzyme activity and 1.3-fold higher than the activity obtained during the Plackett Burman design, was achieved. A maximum lipase activity of 105.12 U/g was obtained after optimization. Ammonium sulphate (60%) precipitation resulted in a specific activity of 68.19 U/mg with a 1.4-fold purification and yield of 64%. Lipase from P. mendocina ED9 exhibited a Km of 0.5306 mM and Vmax of 25.0237 μmol/min/mg. A Δ brightness of approximately 14.5% were achieved during the enzymatic deinking using cocktail comprised of cellulase, xylanase and lipase. This reports the significant role and efficacy of lipase in enzyme cocktails for deinking applications. This formulation will reduce the pollution and environmental toxicity of conventional chemical deinking.

From flasks to single used bioreactor: Scale-up of solid state fermentation process for metabolites and conidia production by Trichoderma asperellum

Currently, the increasing demand of biopesticides production to replace chemical pesticides which are excessively used has made solid state fermentation (SSF) technology the need of the hour. In spite of advantages, true potential of SSF process has not been fully realized at industrial scale. A fermentation process for 6-pentyl-a-pyrone (6 PP), conidia, and lytic enzymes (cellulases, lipase, amylase) production by Trichoderma asperellum TF1 was scaled-up from 250 mL flasks and glass Raimbault column packed with 20 g of solid substrates (dry weight) to 5 Kg of solid substrate by using a new plastic single used bioreactor. For column and single used bioreactor, the fermentation was done with the application of humid air during all the process however flasks are not hermetically closed that some oxygen could flow by diffusion. T. asperellum growth was investigated using a mixture of vine shoots, jatropha cake, olive pomace and olive oil as substrate in all systems in parallel at 25 °C during 7 days. Overall, the conditions applied on the single used bioreactor resulted in the optimum 6-PP production (7.36 ± 0.37 mg g DM^-1), lipases (38.73 ± 0.21U/g DM), amylases (15.22 ± 0.13 U/g DM), and conidia production (8.55 ± 0.04 × 10⁹ conidia/g DM).

Superior cellulolytic activity of Trichoderma guizhouense on raw wheat straw

Lignocellulosic plant biomass is the world's most abundant carbon source and has consequently attracted attention as a renewable resource for production of biofuels and commodity chemicals that could replace fossil resources. Due to its recalcitrant nature, it must be pretreated by chemical, physical or biological means prior to hydrolysis, introducing additional costs. In this paper, we tested the hypothesis that fungi which thrive on lignocellulosic material (straw, bark or soil) would be efficient in degrading untreated lignocellulose. Wheat straw was used as a model. We developed a fast and simple screening method for cellulase producers and tested one hundred Trichoderma strains isolated from wheat straw. The most potent strain-UB483FTG2/ TUCIM 4455, was isolated from substrate used for mushroom cultivation and was identified as T. guizhouense. After optimization of growth medium, high cellulase activity was already achieved after 72 h of fermentation on raw wheat straw, while the model cellulase overproducing strain T. reesei QM 9414 took 170 h and reached only 45% of the cellulase activity secreted by T. guizhouense. Maximum production levels were 1.1 U/mL (measured with CMC as cellulase substrate) and 0.7 U/mL (β-glucosidase assay). The T. guizhouense cellulase cocktail hydrolyzed raw wheat straw within 35 h. Our study shows that screening for fungi that successfully compete for special substrates in nature will lead to the isolation of strains with qualitatively and quantitatively superior enzymes needed for their digestion which could be used for industrial purposes.

Production of chitosan-oligosaccharides by the chitin-hydrolytic system of Trichoderma harzianum and their antimicrobial and anticancer effects

Chitosan-oligosaccharides (COS) are low-molecular weight chitosan derivatives with interesting clinical applications. The optimization of both COS production and purification is an important step in the design of an efficient production system and for the exploration of new COS applications. Trichoderma harzianum is an innocuous biocontrol agent that represents a novel biotechnological tool due to the production of extracellular enzymes, including those that produce a COS mixture. In this work, we propose different systems for the production of COS using the T. harzianum chitinolitic system. A complete qualitative and quantitative analysis of a partially purified COS mixture were performed. Also, an evaluation of the anticancer and antimicrobial effects of the COS mixture was carried out. Three chitosan variants (colloidal, solid and solution) and two fungus stages (spores and mycelia) were tested for COS production. The best system consisted of the interaction of the solid chitosan and the fungal spores, producing a COS mixture containing species from the monomer to the hexamer, in a concentration range of 7-238 mg/mL, according to chromatographic analysis. The proposed purification method isolated the monomer and the dimer from the COS mixture. Moreover, the COS mixture has an inhibitory effect on the growth of bacteria and changes the morphology of yeasts. As anticancer compounds, COS inhibited the growth of cervical cancer cells at concentration of 4 mg/mL and significantly reduced the survival rate of the cells. In conclusion, T. harzianum proved to be an efficient system for COS mixture production.

A novel and cost-effective methodology for enhanced production of industrially valuable alkaline xylano-pectinolytic enzymes cocktail in short solid-state fermentation cycle

The aim of this study was to enhance the production of xylano-pectinolytic enzymes concurrently and also to reduce the fermentation period. In this study, the effect of agro-residues extract-based inoculum on yield and fermentation time of xylano-pectinolytic enzymes was studied. Microbial inoculum and fermentation media were supplemented with xylan and pectin polysaccharides derived from agro-based residues. Enzymes production parameters were optimized through two-stage statistical design approach. Under optimized conditions (temperature 37°C, pH 7.2, K₂ HPO₄ 0.22%, MgSO₄ 0.1%, gram flour 5.6%, substrate: moisture ratio 1:2, inoculum size 20%, agro-based crude xylan in production media 0.45%, and agro-based crude xylan-pectin in inoculum 0.13%), nearly 28,255 ± 565 and 9,202 ± 193 IU of xylanase and pectinase, respectively, were obtained per gram of substrate in a time interval of 6 days only. The yield of both xylano-pectinolytic enzymes was enhanced along with a reduction of nearly 24 h in fermentation time in comparison with control, using polysaccharides extracted from agro-residues. The activity of different types of pectinase enzymes such as exo-polymethylgalacturonase (exo-PMG), endo-PMG, exo-polygalacturonase (exo-PG), endo-PG, pectin lyase, pectate lyase, and pectin esterase was obtained as 1,601, 12.13, 5637, 24.86, 118.62, 124.32, and 12.56 IU/g, respectively, and was nearly twofold higher than obtained for all seven types in control samples. This is the first report mentioning the methodology for enhanced production of xylano-pectinolytic enzymes in short solid-state fermentation cycle using agro-residues extract-based inoculum and production media.

Use of water hyacinth as a substrate for the production of filamentous fungal hydrolytic enzymes in solid-state fermentation

The objective of the present work was to evaluate the water hyacinth (WH) as a substrate for the production of hydrolytic enzymes (cellulases and hemicellulases) of 100 strains of filamentous fungi under conditions of solid growth. Five fungal strains, identified as Trichoderma harzianum, Trichoderma atroviride, Penicillium griseofulvum, Penicillium commune and Aspergillus versicolor, were selected and studied for their ability to grow on water hyacinth as a substrate and carbon source only, evaluating hydrolytic enzymatic activities (α-l-arabinofuranosidase, cellulase, xylanase and β-d-xylopyranosidase) and extracellular protein per g of water hyacinth dry matter (gdm). The five strains selected were able to produce the four enzymes studied; however, T. harzianum strain PBCA produces the highest xylanase (149.3 ± 14.3 IU/gdm at 108 h), cellulase (16.4 ± 0.6 IU/gdm at 84 h) and β-d-xylopyranosidase (127.7 ± 14.8 IU/gdm at 48 h). In contrast, the fungus with the highest α-l-arabinofuranosidase activity was A. versicolor, with 129.8 ± 13.3 IU/gdm after 108 h. In conclusion, T. harzianum showed the best production of the hydrolytic enzymes studied, using as a matrix and carbon source, water hyacinth. In addition, catalytic activities of arabinofuranosidase and xylopyranosidase were reported for the first time in T. versicolor and T. harzianum.

Rice straw fermentation by Schizophyllum commune ARC-11 to produce high level of xylanase for its application in pre-bleaching

Rice straw is valuable resource that has been used as substrate for cost effective production of xylanase under solid-state fermentation by a newly isolated white rot fungi, S. commune ARC-11. Out of eleven carbon sources tested, rice straw was found most effective for the induction of xylanase that produced 4288.3 IU/gds of xylanase by S. commune ARC-11. Maximum xylanase production (6721.9 IU/gds) was observed on 8th day of incubation at temperature (30 °C), initial pH (7.0) and initial moisture content (70.0%). The supplementation of ammonium sulphate (0.08% N, as available nitrogen) enhanced the xylanase production up to 8591.4 IU/gds. The xylanase production by S. commune ARC-11 was further improved by the addition of 0.10%, (w/v) of Tween-20 as surfactant. The maximum xylanase activities were found at pH 5.0 and temperature 55 °C with a longer stability (180 min) at temperature 45, 50 and 55 °C. This xylanase preparation was also evaluated for the pre-bleaching of ethanol-soda pulp from Eulaliopsis binata. An enzyme dosage of 10 IU/g of xylanase resulted maximum decrease in kappa number (14.51%) with a maximum improvement 2.9% in ISO brightness compared to control.

Solid state bioconversion of lignocellulosic residues by Inonotus obliquus for production of cellulolytic enzymes and saccharification

White rot fungi have been usually considered for lignin degradation and ligninolytic enzyme production. To understand whether the white rot fungus Inonotus obliquus was able to produce highly efficient cellulase system, the production of cellulolytic enzyme cocktails was optimized under solid state fermentation. The activities of CMCase, FPase, and β-glucosidase reached their maximum of 27.15IU/g, 3.16IU/g and 2.53IU/g using wheat bran at 40% (v/w) inoculum level, initial pH of 6.0 and substrate-moisture ratio of 1:2.5, respectively. The enzyme cocktail exhibited promising properties in terms of high catalytic activity at 40-60°C and at pH 3.0-4.5, indicating that the cellulolytic enzymes represent thermophilic and acidophilic characteristics. Saccharification of raw wheat straw and rice straw by the cellulolytic enzyme cocktail sampled on Day 12 resulted in the release of reducing sugar of 130.24mg/g and 125.36mg/g of substrate after 48h of hydrolysis, respectively.

Enhanced production of xylanase by Fusarium sp. BVKT R2 and evaluation of its biomass saccharification efficiency

Growth of Fusarium sp. BVKT R2, a potential isolate of forest soils of Eastern Ghats on birchwood xylan in mineral salts medium (MSM) under un-optimized conditions of 30 °C, pH of 5.0, 150 rpm and inoculum size of 5 agar plugs for 7 days, yielded titer of 1290 U/mL of xylanase (EC 3.2.1.8). The effect of various operating parameters such as different substrates and their concentration, additional carbon and nitrogen sources, incubation temperature, initial pH, agitation and inoculum size on the production of xylanase by Fusarium sp. BVKT R2 was studied in shake flask culture by one factor at a time approach. The same culture exhibited higher production of xylanase (4200 U/mL) when grown on birch wood xylan in MSM under optimized conditions with an additional carbon source-sorbitol (1.5%) nitrogen source-yeast extract (1.5%) temperature of 30 °C, pH of 5.0, agitation of 200 rpm and inoculum of 6 agar plugs for only 5 days. There was enhancement in xylanase production under optimized conditions by 3.2 folds over yields under un-optimized conditions. Growth of BVKT R2 culture on locally available lignocelluloses-sawdust, rice straw and cotton stalk-in MSM for 5 days released soluble sugars to the maximum extent of 52.76% with respect to sawdust indicating its greater importance in saccharification essential for biotechnological applications.

Xylanase production from Penicillium citrinum isolate HZN13 using response surface methodology and characterization of immobilized xylanase on glutaraldehyde-activated calcium-alginate beads

The present study reports the production of high-level cellulase-free xylanase from Penicillium citrinum isolate HZN13. The variability in xylanase titers was assessed under both solid-state (SSF) and submerged (SmF) fermentation. SSF was initially optimized with different agro-waste residues, among them sweet sorghum bagasse was found to be the best substrate that favored maximum xylanase production (9643 U/g). Plackett–Burman and response surface methodology employing central composite design were used to optimize the process parameters for the production of xylanase under SSF. A second-order quadratic model and response surface method revealed the optimum conditions for xylanase production (sweet sorghum bagasse 25 g/50 ml; ammonium sulphate 0.36 %; yeast extract 0.6 %; pH 4; temperature 40 °C) yielding 30,144 U/g. Analysis of variance (ANOVA) showed a high correlation coefficient (R² = 97.63 %). Glutaraldehyde-activated calcium-alginate-immobilized purified xylanase showed recycling stability (87 %) up to seven cycles. Immobilized purified xylanase showed enhanced thermo-stability in comparison to immobilized crude xylanase. Immobilization kinetics of crude and purified xylanase revealed an increase in K_m (12.5 and 11.11 mg/ml) and V_max (12,500 and 10,000 U/mg), respectively. Immobilized (crude) enzymatic hydrolysis of sweet sorghum bagasse released 8.1 g/g (48 h) of reducing sugars. Xylose and other oligosaccharides produced during hydrolysis were detected by High-Performance Liquid Chromatography. The biomass was characterized by Scanning Electron Microscopy, Energy Dispersive X-ray and Fourier Transformation Infrared Spectroscopy. However, this is one of the few reports on high-level cellulase-free xylanase from P. citrinum isolate using sweet sorghum bagasse.

Production of crude enzyme from Aspergillus nidulans AKB-25 using black gram residue as the substrate and its industrial applications

The production of crop residues in India is estimated to be about 500-550 million tons annually. It is estimated that about 93 million tons of crop residues is burnt annually which is not only wastage of valuable biomass resources but pollution of the environment with the production of green house gases also. Among different low cost crop residues, black gram residue as the substrate produced maximal endoglucanase, FPase, and β-glucosidase activities from Aspergillus nidulans AKB-25 under solid-state fermentation. During optimisation of cultural parameters A. nidulans AKB-25 produced maximal endoglucanase (152.14 IU/gds), FPase (3.42 FPU/gds) and xylanase (2441.03 IU/gds) activities. The crude enzyme was found effective for the saccharification of pearl millet stover and bio-deinking of mixed office waste paper. The crude enzyme from A. nidulans AKB-25 produced maximum fermentable sugars of 546.91 mg/g from alkali-pretreated pearl millet stover by saccharification process at a dose of 15 FPU/g of substrate. Pulp brightness and deinking efficiency of mixed office waste paper improved by 4.6% and 25.01% respectively and mitigated dirt counts by 74.70% after bio-deinking. Physical strength properties like burst index, tensile index and double fold number were also improved during bio-deinking of mixed office waste paper.

Agave atrovirens fibers as substrate and support for solid-state fermentation for cellulase production by Trichoderma asperellum

Many efforts have been made to produce cellulase with better features and conditions, and filamentous fungi have played an important role in the bioprocess, growing in liquid and solid cultures with sugarcane bagasse, corn stover and others lignocellulosic materials. In the present study, Agave atrovirens fibers were partially characterized, thermal pretreated and used as support, substrate and inducer source for cellulolytic complex production by four strains of the genus Trichoderma, where T. asperellum was selected as the best option for this process after evaluating the enzyme activity and the invasion capacity on the pretreated Agave fibers. Fungi were able to grow on the Agave fibers secreting the complex cellulolytic enzyme. Results show Agave fibers as a good carbon source and support for T. asperellum for the production of the cellulolytic complex (endoglucanase 12,860.8 U/g; exoglucanase 3144.4 U/g; and β-glucosidase 384.4 U/g). These results show the promising potential this material could have in the production of the active enzyme cellulase complex.

Production and Partial Characterization of an Alkaline Xylanase from a Novel Fungus Cladosporium oxysporum

A new fungus Cladosporium oxysporum GQ-3 producing extracellular xylanase was isolated from decaying agricultural waste and identified based on the morphology and comparison of internal transcribed spacer (ITS) rDNA gene sequence. C. oxysporum produced maximum xylanase activity of 55.92 U/mL with wheat bran as a substrate and NH₄Cl as a nitrogen source. Mg²⁺ improved C. oxysporum xylanase production. Partially purified xylanase exhibited maximum activity at 50°C and pH 8.0, respectively, and showed the stable activity after 2-h treatment in pH 7.0–8.5 or below 55°C. Mg²⁺ enhanced the xylanase activity by 2% while Cu²⁺ had the highest inhibition ratio of 57.9%. Furthermore, C. oxysporum xylanase was resistant to most of tested neutral and alkaline proteases. Our findings indicated that Cladosporium oxysporum GQ-3 was a novel xylanase producer, which could be used in the textile processes or paper/feed industries.

Concomitant production of xylanases and cellulases from Trichoderma longibrachiatum MDU-6 selected for the deinking of paper waste

Sixty fungal cultures were isolated from agricultural soil, industrial soil, forest canopy soil having decomposed leaf litter and compost samples collected from different regions of India. Fifteen fungal cultures were selected qualitatively for the production of xylanase and cellulases and were identified employing ITS, NS and MNS primers. The enzyme cocktail consisting of 3811 IU g(-1) of xylanase and 9.9 IU g(-1) of cellulase from Trichoderma longibrachiatum MDU-6 was selected quantitatively for the deinking of diverse paper wastes. The enzyme production increased two fold when produced at tray level in comparison with flasks. The enzyme cocktail was effective in the deinking of old newspaper samples with significant removal of chromophores, phenolics and hydrophobic compounds and less sugar loss. While in case of examination papers and laser printed papers, ink removal was not very significant. Moreover, the sugar loss was significantly high in case of examination papers. The deinking results were further confirmed with FTIR analysis. Deinked newspaper pulp sample shows brightness of 52%, which was 9.6% high than its control sample. The ERIC value for deinked newspaper pulp was found to be 655.9 ppm. Thereafter, the deinked newspaper pulp was examined under light microscope after differential staining with safranin and malachite green and also examined under scanning and transmission electron microscope, which revealed fibrillation and perforation.

Enhancement of Cellulase and Xylanase Production Using pH-Shift and Dissolved Oxygen Control Strategy with Streptomyces griseorubens JSD-1

In this study, the production of cellulase and xylanase by Streptomyces griseorubens JSD-1 was improved by integrating the pH-shift and dissolved oxygen (DO)-constant control strategies. The pH-shift control strategy was carried out by analyzing the specific cell growth rate (μ) and specific enzyme formation rate (Q p) of S. griseorubens JSD-1. The pH was controlled at 8.0 during the first 48 h to maintain high cell growth, which then shifted to 7.5 after 48 h to improve the production of cellulase and xylanase. Using this method, the maximum activities of cellulase, xylanase, and filter paper enzyme (FPase) increased by 47.9, 29.5, and 113.6 %, respectively, compared to that obtained without pH control. On the basis of pH-shift control, the influence of DO concentrations on biomass and enzyme production was further investigated. The maximum production of cellulase, xylanase, and FPase reached 114.38 ± 0.96 U mL(-1), 330.57 ± 2.54 U mL(-1), and 40.11 ± 0.38 U mL(-1), which were about 1.6-fold, 0.6-fold, and 3.2-fold higher than that of neutral pH without DO control conditions. These results supplied a functional approach for improving cellulase and xylanase production.

Fermentation Optimization and Unstructured Kinetic Model for Cellulase Production by Rhizopus stolonifer var. reflexus TP-02 on Agriculture By-Products

Agricultural by-products, rice straw, wheat bran juice, and soybean residue, were used as substrates for cellulase production using Rhizopus stolonifer var. reflexus TP-02. The culture medium was optimized though uniform design experimentation during shaking flask fermentation, and the ideal formulation obtained for filter paper enzyme (FPase) production was 10 % bran diffusion juice, 1 % rice straw, 0.17 % urea, 0.17 % soybean residue, 0.11 % KH2PO4, and 0.027 % Tween 80, and the maximal FPase activity in the culture supernatant was 13.16 U/mL at an incubation time of 3 days. A kinetic model for cellulase production in batch fermentation was subsequently developed. The unstructured kinetic model considered three responses, namely biomass, cellulase, and sugar. Models for the production of three types of cellulase components (i.e., endoglucanases, cellobiohydrolases, and β-glucosidases) were established to adequately describe the cellulase production pattern. It was found that the models fitted the experimental data well under pH 5.0 and 6.0, but only the avicelase production model predicted the experimental data under pH-uncontrolled conditions.

Biochemical evaluation of xylanases from various filamentous fungi and their application for the deinking of ozone treated newspaper pulp

Filamentous fungi, Aspergillus oryzae MDU-4 was biochemically selected among different species of Aspergillus and Trichoderma, for xylanase production. The enzyme activity and specific activity of partially purified xylanase from A. oryzae MDU-4 was 7452 IU/ml and 13,549 IU/g, respectively. Temperature and pH optima for xylanase were found to be 60°C and 6.0, respectively. The reaction kinetics of xylanase was found to be Km (3.33 mg/ml) and Vmax (18,182 μmol/mg). The implementation of ozone treatment in the deinking of newspaper pulp resulted in high crystallinity index (72.1%) and more fibrillar surface. Furthermore, the xylanase treated pulp showed significant improvement in optical properties such as brightness (57.9% ISO) and effective residual ink concentration (211 ppm). Scanning electron microscopy analysis suggests perforations in xylanase treated pulp samples. Here we report biochemical evaluation of xylanases and a combination of ozone treatment followed by catalytically efficient fungal xylanase selected for the cost competitive deinking of newspaper pulp.