Cellulase Production Under Solid-State Fermentation by Trichoderma reesei RUT C30: Statistical Optimization of Process Parameters

Investigating process parameters to enhance (hemi)cellulolytic enzymes activity produced by Trichoderma reesei RUT-C30 using deoiled oil palm mesocarp fiber in solid-state fermentation

This study investigates the synthesis of (hemi)cellulolytic enzymes, including endoglucanase (CMCase), xylanase, and β-glucosidase, employing Trichoderma reesei RUT-C30 and deoiled oil palm mesocarp fiber (OPMF) through solid-state fermentation (SSF). The objective was to determine the optimal process conditions for achieving high enzyme activities through a one-factor-at-a-time approach. The study primarily focused on the impact of the solid-to-liquid ratio, incubation period, initial pH, and temperature on enzyme activity. The effects of OPMF pretreatment, particularly deoiling and fortification, were explored. This approach significantly improved enzyme activity levels compared to the initial conditions, with CMCase increasing by 111.6 %, xylanase by 665.2 %, and β-Glucosidase by 1678.1 %. Xylanase and β-glucosidase activities, peaking at 1346.75 and 9.89 IU per gram dry substrate (GDS), respectively, under optimized conditions (1:4 ratio, pH 7.5, 20 °C, 9-day incubation). With lower moisture levels, CMCase reached its maximum activity of 227.84 IU/GDS. The study highlights how important it is for agro-industrial byproducts to support environmentally sustainable practices in the palm oil industry. It also emphasizes how differently each enzyme reacts to changes in process parameters.

Improved consolidated bioprocessing for itaconic acid production by simultaneous optimization of cellulase and metabolic pathway of Neurospora crassa

Lignocellulose was directly used in itaconic acid production by a model filamentous fungus Neurospora crassa. The promoters of two clock control genes and cellobiohydrolase 1 gene were selected for heterologous genes expression by evaluating different types of promoters. The effect of overexpression of different cellulase was compared, and it was found that expression of cellobiohydrolase 2 from Trichoderma reesei increased the filter paper activity by 2 times, the cellobiohydrolase activity by 4.5 times, and that the itaconic acid titer was also significantly improved. A bidirectional cis-aconitic acid accumulation strategy was established by constructing the reverse glyoxylate shunt and expressing the transporter MTTA, which increased itaconic acid production to 637.2 mg/L. The simultaneous optimization of cellulase and metabolic pathway was more conducive to the improvement of cellulase activity than that of cellulase alone, so as to further increase itaconic acid production. Finally, through the combination of fermentation by optimized strains and medium optimization, the titers of itaconic acid using Avicel and corn stover as substrate were 1165.1 mg/L and 871.3 mg/L, respectively. The results prove the potential of the consolidated bioprocessing that directly converts lignocellulose to itaconic acid by a model cellulase synthesizing strain.

Consolidated bioprocessing of lignocellulosic biomass: Technological advances and challenges

Consolidated bioprocessing (CBP) is characterized by a single-step production of value-added compounds directly from biomass in a single vessel. This strategy has the capacity to revolutionize the whole biorefinery concept as it can significantly reduce the infrastructure input and use of chemicals for various processing steps which can make it economically and environmentally benign. Although the proof of concept has been firmly established in the past, commercialization has been limited due to the low conversion efficiency of the technology. Either a native single microbe, genetically modified microbe or a consortium can be employed. The major challenge in developing a cost-effective and feasible CBP process is the recognition of bifunctional catalysts combining the capability to use the substrates and transform them into value-added products with high efficiency. This article presents an in-depth analysis of the current developments in CBP around the globe and the possibilities of advancements in the future.

Whole-Genome Sequence and Comparative Analysis of Trichoderma asperellum ND-1 Reveal Its Unique Enzymatic System for Efficient Biomass Degradation

The lignocellulosic enzymes of Trichoderma asperellum have been intensely investigated toward efficient conversion of biomass into high-value chemicals/industrial products. However, lack of genome data is a remarkable hurdle for hydrolase systems studies. The secretory enzymes of newly isolated T. asperellum ND-1 during lignocellulose degradation are currently poorly known. Herein, a high-quality genomic sequence of ND-1, obtained by both Illumina HiSeq 2000 sequencing platforms and PacBio single-molecule real-time, has an assembly size of 35.75 Mb comprising 10,541 predicted genes. Secretome analysis showed that 895 proteins were detected, with 211 proteins associated with carbohydrate-active enzymes (CAZymes) responsible for biomass hydrolysis. Additionally, T. asperellum ND-1, T. atroviride IMI 206040, and T. virens Gv-298 shared 801 orthologues that were not identified in T. reesei QM6a, indicating that ND-1 may play critical roles in biological-control. In-depth analysis suggested that, compared with QM6a, the genome of ND-1 encoded a unique enzymatic system, especially hemicellulases and chitinases. Moreover, after comparative analysis of lignocellulase activities of ND-1 and other fungi, we found that ND-1 displayed higher hemicellulases (particularly xylanases) and comparable cellulases activities. Our analysis, combined with the whole-genome sequence information, offers a platform for designing advanced T. asperellum ND-1 strains for industrial utilizations, such as bioenergy production.

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.

Microbial cellulases - An update towards its surface chemistry, genetic engineering and recovery for its biotechnological potential

The inherent resistance of lignocellulosic biomass makes it impervious for industrially important enzymes such as cellulases to hydrolyze cellulose. Further, the competitive absorption behavior of lignin and hemicellulose for cellulases, due to their electron-rich surfaces augments the inappropriate utilization of these enzymes. Hence, modification of the surface charge of the cellulases to reduce its non-specific binding to lignin and enhance its affinity for cellulose is an urgent necessity. Further, maintaining the stability of cellulases by the preservation of their secondary structures using immobilization techniques will also play an integral role in its industrial production. In silico approaches for increasing the catalytic activity of cellulase enzymes is also significant along with a range of substrate specificity. In addition, enhanced productivity of cellulases by tailoring the related genes through the process of genetic engineering and higher cellulase recovery after saccharification seems to be promising areas for efficient and large-scale enzyme production concepts.

Sequential process of solid-state cultivation with fungal consortium and ethanol fermentation by Saccharomyces cerevisiae from sugarcane bagasse

Solid-state cultivation (SSC) is the microbial growth on solid supports, producing a nutrient-rich solution by cell enzymes that may be further used as a generic microbial medium. "Second-generation" ethanol is obtained by fermentation from mainly the acid hydrolysates of lignocellulosic wastes, generating several microbial growth inhibitors. Thus, this research aimed at evaluating the feasibility of ethanol fermentation from sugarcane bagasse hydrolysate after SSC with vinasse as the impregnating solution by a consortium of A. niger and T. reesei as opposed to the conventional method of acid hydrolysis. Fermentation of the hydrolysate from SSC leading to the yield of 0.40 g g^-1, i.e., about 78% of maximum stoichiometric indicating that the nonconventional process allowed the use of two by-products from sugarcane processing in addition to ethanol production from glucose release.

Recent developments on solid-state fermentation for production of microbial secondary metabolites: Challenges and solutions

Microbial secondary metabolites (SMs) are the intermediate or the product of metabolism produced during fermentation process. SMs are produced during stationary phase and play a major role in competition, antagonism and self defence mechanisms. These metabolites finds application in the pharmaceuticals, food, cosmetics etc. These are produced besides primary key metabolites (e.g., amino acids, lipids, carbohydrates etc.). Growth condition in solid-state fermentation (SSF) resembles microorganism's own native environment allowing the microorganisms to adapt best. Recent developments in bioprocessing has identified specific SSF practices that have a significant impact on SMs production. The practice of SSF, representing new opportunities to design better bioprocessing with potential genetic development goals for expanding the list of exciting SMs. Current updates cover advanced techniques on SSF to improve microbial SMs production and their ease of operation and cost-effective production strategies. Various factors affecting the SSF have been discussed with respect to sustainable development of novel SSF strategies for SMs production.

Feasibility of the use of different types of enzymatically treated cellulosic fibres for polylactic acid (PLA) recycling

In the present study, the potential use of cellulosic microfibers (CMFs) extracted from hemp fiber (HF) and pulp and paper solid waste (mixed sludge (MS), deinked sludge (DS)) as a reinforcing agent in novel bio composite materials produced from recycled Polylactic acid (rPLA) was investigated. CMFs were extracted and treated using physicochemical method followed by enzymatic treatment with laccase and cellulase. The effects of CMFs concentrations (1.5, 3 and 6% w/w) and fiber size (75 μm-1.7 mm) on the mechanical properties (impact and tensile) and biodegradability of the biocomposite samples were investigated. A modified interfacial adhesion between rPLA matrix and the three fibers used, was clearly observed through mechanical tests due to alkali and enzymatic treatments. The use of different types of enzymatically treated cellulosic fibers for polylactic acid (PLA) recycling was assessed by Scaning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The combined physicochemical and enzymatic treatments led to a considerable size reduction of the cellulosic fibers (HF, MS and DS) resulting in the enhanced interfacial adhesion between rPLA matrix and fibers. The biocomposite obtained with rPLA with HF gave the most favorable values for Young's modulus (324.53 ± 3.10 MPa, p-value 0.03), impact strength (27.61 ± 2.94 kJ/m², p-value 0.01) and biodegradation rate (1.97%).

Saccharification of water hyacinth biomass by a combination of steam explosion with enzymatic technologies for bioethanol production

In the present work, bioethanol was produced by sugar fermentation obtained from water hyacinth using a novelty hybrid method composed of steam explosion and enzymatic hydrolysis, using hydrolytic enzymes produced by solid-state fermentation and water hyacinth as substrate. The highest activity, 42 U for xylanase and 2 U for cellulase per gram of dry matter, respectively, was obtained. Steam explosion pretreatment was performed at 190 ℃ for 1, 5, and 10 min, using water hyacinth sampled from the Maria Lizamba Lagoon, the Arroyo Hondo and the Amapa River. The highest amounts of reducing sugars of water hyacinth were obtained form the samples from the lagoon (5.4 g/50 g of dry matter) after 10 min of treatment. Steamed biomass was hydrolysed using the enzymes obtained by solid-state fermentation, obtained reducing sugars (maximum 15.5 g/L); the efficiency of enzymatic hydrolysis was 0.51 g of reducing sugars per gram of water hyacinth. Finally, reducing sugars were fermented using Saccharomyces cerevisiae for conversion to ethanol, with the highest ethanol concentration (7.13 g/L) and an ethanol yield of 0.23 g/g of dry matter.

Thermostable Cellulase Biosynthesis from Paenibacillus alvei and its Utilization in Lactic Acid Production by Simultaneous Saccharification and Fermentation

Cellulosic date palm wastes may have beneficial biotechnological applications for eco-friendly utilization. This study reports the isolation of thermophilic cellulase-producing bacteria and their application in lactic acid production using date palm leaves. The promising isolate was identified as Paenibacillus alvei by 16S rRNA gene sequencing. Maximum cellulase production was acquired using alkaline treated date palm leaves (ATDPL) at 48 h and yielded 4.50 U.mL-1 FPase, 8.11 U.mL-1 CMCase, and 2.74 U.mL-1 β-glucosidase. The cellulase activity was optimal at pH 5.0 and 50°C with good stability at a wide temperature (40-70°C) and pH (4.0-7.0) range, demonstrating its suitability in simultaneous saccharification and fermentation. Lactic acid fermentation was optimized at 4 days, pH 5.0, 50°C, 6.0% cellulose of ATDPL, 30 FPU/ g cellulose, 1.0 g. L-1 Tween 80, and 5.0 g. L-l yeast extract using Lactobacillus delbrueckii. The conversion efficiency of lactic acid from the cellulose of ATDPL was 98.71%, and the lactic acid productivity was 0.719 g. L-1 h-1. Alkaline treatment exhibited a valuable effect on the production of cellulases and lactic acid by reducing the lignin content and cellulose crystallinity. The results of this study offer a credible procedure for using date palm leaves for microbial industrial applications.

Transformation of Corn Stalk Residue to Humus-Like Substances during Solid-State Fermentation

Lignocellulase production from straw fermentation has been widely investigated but the research has neglected to quantify fermentation-derived residue transformation to the humus-like substance (HULIS). To investigate the conversion efficacy of corn stalk residue to HULIS, the amount of HULIS associated with chemical composition and structural changes of humic acid-like substances (HAL) was investigated in a 30 L solid-state fermentation tank during a short period of eight days. The results show that the highest decomposition rate of corn stalk and the highest activity of cellulase, xylanase, and β-glucosidase appeared at the fourth day. At the end of fermenting process, the amount of humic acid-like substances (HAL) and the percentage of HAL in humus acid (PQ value) increased 17.5% and 8.9%, respectively, indicating Trichoderma reesei facilitates the transformation of corn stalk residue to HAL. Fatty acids decreased while aromatic carbon and carboxyl content significantly increased during the ongoing fermentation, which had a positive impact on the HAL thermal stability. The FTIR spectral and thermal analysis revealed an improvement in HAL degrees of condensation, oxidation, and aromatization. The present study suggests that the residue of corn stalks fermented with T. reesei might be a good fertilizer to improve soil characteristics.

An overview of the recent trends on the waste valorization techniques for food wastes

A critical and up-to-date review has been conducted on the latest individual valorization technologies aimed at the generation of value-added by-products from food wastes in the form of bio-fuels, bio-materials, value added components and bio-based adsorbents. The aim is to examine the associated advantages and drawbacks of each technique separately along with the assessment of process parameters affecting the efficiency of the generation of the bio-based products. Challenges faced during the processing of the wastes to each of the bio-products have been explained and future scopes stated. Among the many hurdles encountered in the successful and high yield generation of the bio-products is the complexity and variability in the composition of the food wastes along with the high inherent moisture content. Also, individual technologies have their own process configurations and operating parameters which may affect the yield and composition of the desired end product. All these require extensive study of the composition of the food wastes followed by their effective pre-treatments, judicial selection of the technological parameters and finally optimization of not only the process configurations but also in relation to the input food waste material. Attempt has also been made to address the hurdles faced during the implementation of such technologies on an industrial scale.

Optimization of cellulase production under solid-state fermentation by a new mutant strain of Trichoderma reesei

Nowadays, the use of agricultural by-products, as the cheap substrate for the production of value-added products, is of high interest for the researchers and practitioners. Cellulase is a relatively expensive and a very important industrial enzyme where in this study was produced form rice by-products under solid-state fermentation. A new mutant of Trichoderma reesei was used for cellulase production. The effective variables were initially screened by "Plackett and Burman design." Afterward, the main variables including moisture content, P source, incubation temperature, and incubation time were optimized by "one factor at a time design." Finally, the resulting variables including 74% for moisture content, 2 g/L for K2 HPO 4, 30°C of incubation temperature, and 4 days of incubation time were reported as the ultimate optimal condition for cellulase production.

Optimization of Cellulase Production by Aspergillus niger Isolated from Forest Soil

Background:

An impressive increase in the application of cellulases in various fields over the last few decades demands extensive research in improving its quality and large-scale production. Therefore, the current investigation focuses on factors relevant for optimal production of cellulase byAspergillus nigerisolated from forest soil.

Method:

Throughout this study, the fungal strainAspergillus nigerwas maintained under the submerged condition for a period of 7 days at 120 rpm rotational speed. Various physical and chemical conditions were employed in examining their influence on cellulase production by the selected fungal strain. After appropriate incubation, culture filtrates were withdrawn and checked for FPase, CMCase, and β-D-glucosidase activities.

Results:

The optimum pH and temperature for cellulase production were found to be 5.0 and 32°C, respectively. Among the various carbon sources tested in the present study, amendment of lactose in the medium yielded peak values of FPase (filter paperase) and CMCase (Carboxy-methyl cellulase) whereas fructose supported the higher titers of β-glucosidase. Among the nitrogen sources, profound FPase and CMCase activity were recorded when urea was used but higher β-glucosidase activity was noticed when yeast extract was added. Various natural lignocellulosic substrates like bagasse, coir, corncob, groundnut shells, litter, rice bran, rice husk, sawdust and wheat bran were tested to find out the induction of cellulase. Among the lignocelluloses, sawdust and litter served as good substrates for cellulase production byAspergillus niger.

Conclusion:

In gist, the outcome of this study sheds light on the cellulolytic potentiality of the fungal strainAspergillus nigerpromising in its future commercial applications which may be economically feasible.

Effect of stirring on growth and cellulolytic enzymes production by Trichoderma harzianum in a novel bench-scale solid-state fermentation bioreactor

A novel bench-scale stirred bioreactor for solid-state fermentation was used to determine the effect of the stirring rate on growth and enzymes production by Trichoderma harzianum PBLA. Lab-scale static tubular bioreactors were first used to assess the effect of bioreactor diameter on heat accumulation, growth, and production of cellulases and xylanases. The increased diameters (1.8-4.2 cm) led to increases in temperature up to 36 °C (at a rate of 1.08 °C/cm), which negatively affected the growth and enzyme production. Afterward, in the bench-scale bioreactor operated at rates up to 3.0 rpm, maximum xylanases production (107 ± 0.3 U/g dm) was attained at rates of 0.5 and 1.0 rpm, reaching a maximum of 34 ± 0.3 °C. Cellulases production was reduced (up to 79%) due to stirring. Therefore, the production of xylanases by T. harzianum can be performed in this cross-flow stirred SSF bioreactor at rates up to 1.0 rpm, avoiding heat accumulation and damage on metabolic activity.

α-Amylase immobilization onto functionalized graphene nanosheets as scaffolds: Its characterization, kinetics and potential applications in starch based industries

α-Amylase is imperative for starch and its deriviatized industries. Functionalized graphene sheets were tailored and optimized as scaffold for α-amylase immobilization using Response Surface Methodology based on Box–Behnken design, with an overall immobilization efficiency of 85.16%. Analysis of variance provided adequacy to the mathematical model for further studies. Native and immobilized functionalized graphene were characterized using transmission and scanning electron microscopy, followed by Fourier transform infrared (FTIR) spectroscopy. Wheat α-amylase conjugated with functionalized graphene sheets were visually evident on transmission and scanning micrographs while the FTIR spectra showed interplay of various chemical interactions and bonding, during and after immobilization. Optimum pH and optimum temperature for immobilized enzyme though remained unchanged but showed broader range whereas K_m showed a slight decrease (1.32 mg/mL). It also showed enhanced thermal and storage stability and retained 73% residual activity after 10 uses. These ensemble of properties and non-toxic nature of functionalized graphene, makes it viable to be absorbed commercially in starch processing industries.

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α-Amylase was optimally anchored on functionalized graphene nanosheets using RSM.

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This multipoint attachment resulted in improved features for its industrial viability.

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With decreased K_m, bioconjugate ascertains increased affinity for substrate hydrolysis.

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Showed improved thermostability, reusability and storage stability over free enzyme.

Enhanced cellulase production by Penicillium oxalicum for bio-ethanol application

Present study was focused on cellulase production from an indigenously isolated filamentous fungal strain, identified as Penicillium oxalicum. Initially, cellulase production under submerged fermentation in shake flasks resulted in cellulase activity of 0.7 FPU/mL. Optimization of process parameters enhanced cellulase production by 1.7-fold and resulted in maximum cellulase activity of 1.2 FPU/mL in 8 days. Cellulase production was successfully scaled-up to 7 L fermenter under controlled conditions and incubation time was reduced from 8 days to 4 days for achieving similar cellulase titer. Optimum pH and temperature for activity of the crude enzyme were pH 5 and 50 °C, respectively. At 50 °C the produced cellulase retained approximately 50% and 26% of its activity at 48 h and 72 h, respectively. Hydrolytic efficiency of P. oxalicum was comparable to commercial cellulase preparations which indicate its great potential for application in the lignocellulose hydrolysis.

Influence of dilute acid and alkali pretreatment on reducing sugar production from corncobs by crude enzymatic method: a comparative study

In the present study, two commonly used catalysts in chemical pretreatment, sulfuric acid and sodium hydroxide, were tested to evaluate the effect of solid-to-liquid ratio on pretreatment and enzymatic hydrolysis. Solid to liquid ratio (S/L) was influential on sugars released with an increase in the S/L ratio between 0.03 and 0.2. Enzymatic digestibility of 0.25 M H2SO4 pretreated corncobs were released more sugars (415.12 mg/mL); whereas, corncobs pretreated with NaOH released 350.12 mg/mL of reducing sugars at S/L 0.05. Further, in comparison with NaOH pretreated corncobs, acid treated material substantially increased the accessibility and digestibility of cellulose during crude enzymatic hydrolysis (28.96 FPU) and released 398.95 mg/mL reducing sugars.

Optimization of amorphadiene production in engineered yeast by response surface methodology

Isoprenoids are among the most diverse bioactive compounds synthesized by biological systems. The superiority of these compounds has expanded their utility from pharmaceutical to fragrances, including biofuel industries. In the present study, an engineered yeast strain Saccharomyces cerevisiae (YCF-AD1) was optimized for production of Amorpha-4, 11-diene, a precursor of anti-malarial drug using response surface methodology. The effect of four critical parameters such as KH₂PO₄, methionine, pH and temperature were evaluated both qualitatively and quantitatively and further optimized for enhanced amorphadiene production by using a central composite design and model validation. The “goodness of fit” of the regression equation and model fit (R²) of 0.9896 demonstrate this study to be an effective model. Further, this model will be used to validate theoretically and experimentally at the higher level of amorphadiene production with the combination of the optimized values of KH₂PO₄ (4.0), methionine (1.49), pH (5.4) and temperature (33 °C).

Filamentous fungi and media for cellulase production in solid state cultures

Cellulase production was evaluated in two reference strains (T. reesei Rut-C30 and T. reesei QM9414), two strains isolated from a sugarcane cultivation area (Trichoderma sp. IPT778 and T. harzianum rifai IPT821) and one strain isolated in a program for biodiversity preservation in São Paulo state (Myceliophthora thermophila M77). Solid state cultures were performed using sugarcane bagasse (C), wheat bran (W) and/or soybean bran (S). The highest FPA was 10.6 U/gdm for M77 in SC (10:90) at 80% moisture, which was 4.4 times higher than production in pure W. C was a strong inducer of cellulase production, given that the production level of 6.1 U/gdm in WC (40:60) was 2.5 times higher than in pure W for strain M77; T. reesei Rut-C30 did not respond as strongly with about 1.6-fold surplus production. S advantageously replaced W, as the surplus production on SC (20:80) was 2.3 times relative to WC (20:80) for M77.

Use of organic waste for the production of added-value holocellulases with Cellulomonas flavigena PR-22 and Trichoderma reesei MCG 80

We evaluated the production of holocellulases from the cellulolytic microorganisms Cellulomonas flavigena PR-22 and Trichoderma reesei MCG 80 using as substrates the organic fraction of municipal solid waste (OFMSW) and digestates from a hydrogenogenic-methanogenic bioenergy production process. The first set of experiments (E1) used the mutant actinobacteria C. flavigena PR-22 whereas another set (E2) used the mutant filamentous fungi T. reesei MCG 80. In E1 with OFMSW as substrate, xylanolytic activities ranged from 1800 to 3900 international units g(holocellulose)(-1) (IU g(hol)(-1)), whereas the cellulolytic activities ranged from 220 to 420 IU g(hol)(-1). The variation of agitation speed did not have a significant effect on enzyme activity, whereas the increase of substrate concentration had a significant negative effect on both xylanolytic and cellulolytic activities on a holocellulose feed basis. Regarding E2, the OFMSW was evaluated at 1, 2 and 3 % volatile solids (VS). At 2 % VS the best filter paper activities were 1200 filter paper units (FPU) l(-1); however, in a holocellulase basis the best result was 67 FPU g(hol)(-1), corresponding to 1 % VS. Next, OFMSW was compared with OFMSW supplemented with lactose, digested solids from hydrogenogenic fermentation (D1) and digested solids from a two-stage process (D2). Against expectations, no positive effect was found in OFMSW due to lactose. The best enzymatic titres were in the order D1 > OFMSW ≈ OFMSW + lactose > D2. The use of digestates from hydrogenogenic fermentation for enzyme production holds promise for waste management. It promotes energy and added-value bioproduct generation-a green alternative to common practice of management and disposal of organic wastes.

Simultaneous pretreatment and sacchariffication of rice husk by Phanerochete chrysosporium for improved production of reducing sugars

Phanerochete chrysosporium, the white-rot fungus, (a best source for lignolytic enzymes system) was used in the biological pretreatment of rice husk for reducing sugars production. Usually reducing sugar production through biochemical process involves two steps: solid state fermentation (SSF) of fungal pretreatment for delignification, subsequently pretreated biomass subjected to enzymatic hydrolysis. During the fungal pretreatment of rice husk for reducing sugar production along with cellulase and xylanse, the activities of lignin degradation-related enzymes such as lignin peroxidases (LiP), GLOX (glyoxidase), and aryl alcohol oxidases (AAO), were observed. The fungal pretreated rice husk produced highest (895.9 mg/ml/2g of rise husk) reducing sugars on 18th day of fungal treatment. This method may be good alternative to avoid operational costs associated with washing and the removal of inhibitors during the conventional pretreatment methods.

Production of cellulases by solid state fermentation with Aspergillus terreus and enzymatic hydrolysis of mild alkali-treated rice straw

Rice straw was used as substrate for cellulase production by solid state fermentation with Aspergillus terreus. Substrate concentration, moisture ratio, inoculum size and initial pH were optimized using response surface methodology involving Box-Behnken design. The predicted filter paper activity under optimized parameters was 9.73 U/g and the validated filter paper activity was 10.96 U/g. Hydrolysis of the biomass pretreated with 0.125% to 1% NaOH for 24h at room temperature was performed using crude cellulase preparation. Treatment with 0.5% NaOH at room temperature for 24h was the most efficient treatment method for saccharification. Under the optimized conditions, rice straw yielded 676 mg reducing sugars per gram of substrate at a cellulase loading of 9 FPU g(-1) substrate. The present study establishes the possibility of using mild alkali pretreated rice straw for the production of fermentable sugars with 74.19% efficiency which can be further utilized for the production of ethanol.

Mixing of acid and base pretreated corncobs for improved production of reducing sugars and reduction in water use during neutralization

Pretreatment of biomass for bioethanol production makes it necessary to use large amounts of water for removing inhibitors and neutralization. In order to reduce water usage, separate batches of corncobs were hydrolyzed in 1M NaOH and 0.05 M H(2)SO(4), respectively, and the hydrolysis products were mixed to achieve a pH of 7. This approach lowered water usage by 10-fold compared with neutralization by distilled and recycling wash water. Mixing of the pretreated biomasses (121°C, 20 min) increased release of reducing sugars during enzymatic hydrolysis with cellulases (38.49 FPU(IU)) produced by Phanerochaete chrysosporium NCIM 1106 by 2- and 15-fold compared with the sugars released from the unmixed NaOH- and H(2)SO(4)-treated corncobs, respectively. Enzymatic hydrolysis (EH, cell free extract) of the mixed material released 395.15 mg/ml of sugars during 48 h, slightly less than what was achieved by microbial hydrolysis (whole cell hydrolysis), 424.50mg after 120 h.

Evaluation of enzyme activity and fiber content of soybean cotyledon fiber and distiller's dried grains with solubles by solid state fermentation

To increase the value of coproducts from corn ethanol fermentation and soybean aqueous processing, distiller's dried grains with solubles (DDGS) and soybean cotyledon fiber were used as the substrates for solid state fermentation (SSF) to improve feed digestibility. Aspergillus oryzae, Trichoderma reesei, and Phanerochaete chrysosporium were chosen as they produce desirable enzymes and are widely used in SSF for feed. The results showed that the cellulase and xylanase activities were significantly increased after 7 days of fermentation, and cellulose and hemicellulose degradation was also greatly increased. When soybean fiber was used as SSF substrate, the maximum activities of the cellulase and xylanase were 10.3 and 84.2 IU/g substrate (dry weight basis) after SSF treatment, respectively. However, the enzyme activities were relatively low in DDGS, and the growth of the three fungi was poor. The fungi grew better when soybean cotyledon fiber was added to DDGS, and cellulase and xylanase activity increased with the increase of soybean fiber content. Porosity was identified as an important factor for SSF because the addition of inert soybean hull alone improved the fungi growth significantly. These data suggest that the nutritional value of DDGS and soybean cotyledon fiber as monogastric animal feed could be greatly enhanced by SSF treatment.

Utilization of deoiled Jatropha curcas seed cake for production of xylanase from thermophilic Scytalidium thermophilum

Jatropha curcas is a major biodiesel crop. Large amount of deoiled cake is generated as by-product during biodiesel production from its seeds. Deoiled J. curcas seed cake was assessed as substrate for the production of xylanase from thermophilic fungus Scytalidium thermophilum by solid-state fermentation. The seed cake was efficiently utilized by S. thermophilum for its growth during which it produced good amount of heat stable extracellular xylanase. The solid-state fermentation conditions were optimized for maximum xylanase production. Under the optimized conditions viz. deoiled seed cake supplemented with 1% oat-spelt xylan, adjusted to pH 9.0, moisture content 1:3 w/v, inoculated with 1×10(6) spores per 5 g cake and incubated at 45 °C, 1455 U xylanase/g deoiled seed cake was obtained. The xylanase was useful in biobleaching of paper pulp. Solid-state fermentation of deoiled cake appears a potentially viable approach for its effective utilization.