Lignocellulose degradation by Penicillium janthinellum enzymes is influenced by its variable secretome and a unique set of feedstock characteristics

Substrate characteristics and proteins that affect lignocellulose-hydrolysis by the hypercellulolytic fungus Penicillium janthinellum NCIM 1366 (PJ-1366) were investigated. The hydrolysis rate of PJ-1366 enzymes was very high, with upto 75 % of the reaction being completed in initial 4 h. Comparison of the hydrolytic efficiencies on differently pretreated biomass indicated that the greatest (negative) effect was imparted by lignin, suggesting that improving ligninase activity of the PJ-1366 enzymes may help to improve hydrolysis. Larger pore sizes and higher crystallinity of substrates, which favor enzyme penetration and processive hydrolysis, positively influenced hydrolysis efficiency. For alkali-pretreated substrates, 16 FPU/g of PJ-1366 cellulases released the sugar-equivalent of using 10 FPU/g of a commercial biomass hydrolyzing enzyme. By correlation analysis, 41 proteins, including 20 CAZymes were identified, whose abundance in the secretome positively correlated with the cellulase activities of the culture filtrate. These proteins may be considered as the primary drivers of FPase/CMCase/pNPGase/xylanase activity in PJ-1366.

Improving saccharification of ramie stalks by synergistic effect of in-house cellulolytic enzymes consortium

The high cost of cellulase is one of the main obstacles hindering the large-scale biorefining of lignocellulosic biomass. Therefore, developing efficient method for preparation of cellulase is promising. In the present study, the production of cellulase by Trichoderma reesei, Trichoderma harzianum, and Aspergillus niger was optimized, and the synergistic effect of these cellulase on enzymatic hydrolysis of pretreated ramie stalks was also evaluated. The maximum CMCase (Carboxymethyl Cellulase) and filter paper activity (FPA) produced by T. reesei reached to 3.12 IU/mL and 0.13 IU/mL, respectively. The maximum activities of CMCase (3.68 IU/mL), FPA (0.04 IU/mL) and β-glucosidase (8.44 IU/mL) were obtained from A. niger. The results also showed that under the premise of the same FPA activity, the contribution of β-glucosidase activity to yield of reducing sugar was greater than that of CMCase. Besides, cellulase produced by T. reesei and A. niger had the best synergistic effect on enzymatic hydrolysis of pretreated ramie stalks. The highest reducing sugars yield (417 mg/g dry substrate) was achieved when enzyme cocktail was prepared at the ratio of 1:1, which was 1.36–3.35 folds higher than that of different single enzymes. The present research has provided a novel method for efficient preparation of enzymes consortium for enzymatic hydrolysis of ramie stalks.

Morphologically favorable mutant of Trichoderma reesei for low viscosity cellulase production

Metabolite production by filamentous fungi hampered because of high viscosity generated during growth. Low viscosity fermentation by mold is one of the preferred ways of large scale enzymes production. Cellulolytic enzymes play a key role during the process of lignocellulosic biomass conversion. In this study a mutant RC-23-1 was isolated through mutagenesis (diethyl sulfate followed by UV) of T. reesei RUT-C30. RC-23-1 not only gave higher cellulase production but also generated lower viscosity during enzyme production. Viscosity of mutant growth was more than three times lower than parent strain. RC-23-1 shows unique, yeast like colony morphology on solid media and small pellet like growth in liquid media. This mutant did not spread like mold on solid media. This mutant produces cellulases constitutively when grown in sugars. Using only glucose, the cellulase production was 4.1 FPU/ml. Among polysaccharides (avicel, xylan and pectin), avicel gave maximum of 6.2 FPU/ml and pretreated biomass (rice straw, wheat straw and sugarcane bagasse) produced 5.1-5.8 FPU/ml. At 7L scale reactor, fed-batch process was designed for cellulase production using different carbon and nitrogen sources. Maximum yield of cellulases was 182 FPU/g of lactose consumed was observed in fed-batch process. The produced enzyme used for hydrolysis of acid pretreated rice straw (20% solid loading) and maximum of 60 % glucan conversion was observed. RC-23-1 mutant is good candidate for large scale cellulase production and could be a model strain to study mold to yeast-like transformation. This article is protected by copyright. All rights reserved.

A non-waste strategy for enzymatic hydrolysis of cellulose recovered from domestic wastewater

Cellulose is a potential resource to be recovered from wastewater treatment plants (WWTP). Enzyme formulations can be employed to hydrolyze cellulose into fermentable sugars, to be further used as biochemical building blocks or reducing its recalcitrance to further treatment processes. This study proposed the production, recovery and formulation of cellulase using domestic wastewater as culture medium and its application for the hydrolysis of cellulosic residues recovered from WWTPs. Cellulose was recovered from raw sanitary wastewater using a fine-mesh sieve (0.35 mm) and quantified through enzymatic hydrolysis and thermogravimetric analysis. The production, concentration and formulation of cellulase enzyme resulted in an enzymatic blend of endoglucanases (7.3 U_FP/mL), cellobiohydrolases (7.4 U_CMC/mL) and beta-glucosidases (4.4 U_BGL/mL). The content of the recovered cellulosic material was 21.3% according to enzymatic hydrolysis and 27.7 for thermogravimetric results. The enzymatic hydrolysis of the WWTP residue using the produced cellulase (107.6 ± 10.2 mg_reduc/g_residue) showed better results than using the commercial cellulase complex (66.4 ± 2.5 mg_reduc/g_residue). This fact showed the potential of application of the produced enzyme for the hydrolysis of cellulosic residues recovered from WWTP processes. In a non-waste biorefinery approach, the generated hydrolysate can be further used for producing added-value biomolecules including biofuels and biochemicals.

Evaluation of Blend Production of Cellulases and Xylanases Using Pretreated and Recycled Carnauba Straw

Carnauba (Copernicia prunifera) is a Brazilian palm tree used for wax production, which usually generates a large amount of waste. This work evaluated the carnauba waste for cellulase and xylanase production using Trichoderma reesei CCT2768 through a solid-state fermentation (SSF). Carnauba waste was used in its crude form (C-IN), pretreated (C-P) with alkaline hydrogen peroxide (AHP), and also recycled after the SSF process (C-PR). C-IN, C-P, and C-PR were characterized by XRD, FTIR, and SEM. Cellulase and xylanase production was performed by SSF for 72 h, and the enzymatic extracts obtained were mixed each other in different concentrations. FPase, CMCase, and xylanase activities were determined. Trichoderma reesei CCT-2768 has shown high performance to produce cellulases and xylanases. Total cellulase, CMCase, and β-glycosidase presented a highest activity when C-PPR1 (25% of C-PR and 75% of C-P) was used as a carbon source, with yield of 2.85 U/g, 41.21 U/g, and 2.80 U/g, respectively. The highest xylanase production was achieved when only the pretreated carnauba waste (C-P) was used, with an enzyme activity of 224.93 U/g. Carnauba has shown a promising carbon source capacity to induce the production of cellulolytic and xylanolytic enzymes by using T. reesei CCT2768, promoting the circular and ecofriendly economy, as well as a cost reduction, of the production process of these enzymes.

Enzymatic Hydrolysis of Lignocellulosic Biomass Using an Optimized Enzymatic Cocktail Prepared from Secretomes of Filamentous Fungi Isolated from Amazonian Biodiversity

The use of lignocellulosic biomass (LCB) has emerged as one of the main strategies for generating renewable biofuels. For the efficient use of such feedstock, pre-treatments are essential. The hydrolysis of cellulose - major component of LCB - demands enzymatic cocktails with improved efficiency to generate fermentable sugars. In this scenario, lignocellulolytic fungi have enormous potential for the development of efficient enzyme platforms. In this study, two enzymatic cocktails were developed for hydrolysis of two lignocellulosic biomasses: industrial cellulose pulp and cassava peel. The solid biomass ratio in relation to the protein content of the enzyme cocktail was performed by experimental design. The optimized cocktail for the hydrolysis of cellulose pulp (AMZ 1) was composed, in protein base, by 43% of Aspergillus sp. LMI03 enzyme extract and 57% of T. reesei QM9414, while the optimal enzyme cocktail for cassava peel hydrolysis (AMZ 2) was composed by 50% of Aspergillus sp. LMI03 enzyme extract, 25% of the extract of P. citrinum LMI01 and 25% of T. reesei. The ratio between solids and protein loading for AMZ 1 cocktail performance was 52 g/L solids and 30 mg protein/g solids, resulting in a hydrolytic efficiency of 93%. For the AMZ 2 cocktail, the hydrolytic efficiency was 78% for an optimized ratio of 78 g/L solids and 19 mg protein/g solids. These results indicate that cocktails formulated with enzymatic extracts of P. citrinum LMI01, Aspergillus sp. LMI03, and T. reesei QM9414 are excellent alternatives for efficient hydrolysis of plant biomass and for other processes that depend on biocatalysis.

Composition of Synthesized Cellulolytic Enzymes Varied with the Usage of Agricultural Substrates and Microorganisms

We evaluated various agricultural lignocellulosic biomass and variety of fungi to produce cellulolytic enzymes cocktail to yield high amount of reducing sugars. Solid-state fermentation was performed using water hyacinth, paddy straw, corn straw, soybean husk/tops, wheat straw, and sugarcane bagasse using fungi like Nocardiopsis sp. KNU, Trichoderma reesei, Trichoderma viride, Aspergillus flavus, and Phanerochaete chrysosporium alone and in combination to produce cellulolytic enzymes. Water hyacinth produced (U ml^-1) endoglucanase (51.13) and filter paperase (0.55), and corn straw produced (U ml^-1) β-glucosidase (4.65), xylanase (113.32), and glucoamylase (41.27) after 7-day incubation using Nocardiopsis sp. KNU. Production of cellulolytic enzymes was altered due to addition of various nitrogen sources, metal ions, vitamins, and amino acids. The maximum cellulolytic enzymes were produced by P. chrysosporium (endoglucanase; 166.32 U ml^-1 and exoglucanase; 12.20 U ml^-1), and by T. viride (filter paperase; 1.57 U ml^-1). Among all, co-culture of T. reesei, T. viride, A. flavus, and P. chrysosporium showed highest β-glucosidase (17.05 U ml^-1). The highest xylanase (1129 U ml^-1) was observed in T. viride + P. chrysosporium co-culture. This study revealed the dependency on substrate and microorganism to produce good quality enzyme cocktail to obtain maximum reducing sugars.

Designing a cellulolytic enzyme cocktail for the efficient and economical conversion of lignocellulosic biomass to biofuels

Concerns about dwindling fossil fuels and their unfavorable environmental impacts shifted the global focus towards the development of biofuels from lignocellulosic feedstocks. The structure of this biomass is very complex due to which variety of enzymes (cellulolytic, hemicellulolytic, auxiliary/AA9) and proteins (e.g. swollenin) required for efficient deconstruction. Major impediments in large-scale commercial production of cellulosic ethanol are the cost of cellulases and inability of any single microorganism to produce all cellulolytic components in sufficient titers. In the recent past, various methods for reducing the enzyme cost during cellulosic ethanol production have been attempted. These include designing optimal synergistic enzyme blends/cocktail, having certain ratios of enzymes from different microbial sources, for efficient hydrolysis of pretreated biomass. However, the mechanisms underlying the development, strategies for production and evaluation of optimal cellulolytic cocktails still remain unclear. This article aims to explore the technical and economic benefits of using cellulolytic enzyme cocktail, basic enzymatic and non-enzymatic components required for its development and various strategies employed for efficient cellulolytic cocktail preparation. Consideration was also given to the ways of evaluation of commercially available and in-house developed cocktails. Discussion about commercially available cellulolytic cocktails, current challenges and possible avenues in the development of cellulolytic cocktails included.

SERS based protocol using flow glass-hemostix for detection of neuron-specific enolase in blood plasma

An inexpensive and disposable lateral flow glass-hemostix (FGH) has been developed as an immunoassay, in which surface-enhanced Raman scattering (SERS) is utilized for sensing signal transduction.

A screening approach for assessing lytic polysaccharide monooxygenase activity in fungal strains

BACKGROUND

Efforts to develop efficient lignocellulose-degrading enzymatic preparations have led to the relatively recent discovery of a new class of novel cellulase boosters, termed lytic polysaccharide monoxygenases (LPMOs). These enzymes are copper-dependent metalloenzymes that initiate the biomass deconstruction process and subsequently work together with cellulases, hemicellulases, and other accessory enzymes to enhance their hydrolytic action. Given their wide distribution and diversity, screening and isolation of potent LPMOs from natural fungal diversity may provide an important avenue for increasing the efficiency of cellulases and thereby decreasing cellulosic ethanol production costs. However, methods for quick screening and detection are still not widely available. In this article, a simple and sensitive method is described by combining nonhydrolytic activity enhancement followed by LC-MS-based quantitation of LPMOs.

RESULTS

In this study, a screening approach has been developed for the detection of nonhydrolytic cellulase-enhancing enzymes in crude fungal supernatants. With the application of a saturating benchmark cocktail of Celluclast 1.5L, fungal isolates were selected which had the capability of hydrolyzing pretreated rice straw by their synergistic enzyme fractions. Subsequently, these fungal extracts along with an LPMO-enriched commercial enzyme were investigated for their ability to produce Type I LPMO activity. An LC-MS-based methodology was applied to quantitate gluconic acid in enzymatic hydrolysates as an indirect measurement of Type I LPMO activity.

CONCLUSION

The present study describes an LC-MS-based separation method to detect and quantitate LPMO activity in a commercial enzyme. This method was also applied to screen fungal extracts. The developed screening strategy has enabled detection of LPMO activity in two industrially important Penicillium strains.

Subcritical carbon dioxide-water hydrolysis of sugarcane bagasse pith for reducing sugars production

The aim of present study was to obtain total reducing sugars (TRS) by hydrolysis in subcritical CO₂-water from sugarcane bagasse pith (SCBP), the fibrous residue remaining after papermaking from sugarcane bagasse. The optimum hydrolysis conditions were evaluated by L₁₆(4⁵) orthogonal experiments. The TRS yield achieved 45.8% at the optimal conditions: 200°C, 40min, 500rmin^-1, CO₂ initial pressure of 1MPa and liquid-to-solid ratio of 50:1. Fourier transform infrared spectrometry and two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance were used to characterize hydrolysis liquor, treated and untreated SCBP, resulting in the removal of hemicelluloses to mainly produce xylose, glucose and arabinose during hydrolysis. The severity factors had no correlation to TRS yield, indicating that the simple kinetic processes of biomass solubilisation cannot perfectly describe the SCBP hydrolysis. The first-order kinetic model based on consecutive reaction was used to obtain rate constants, activation energies and pre-exponential factors.

Cellulolytic enzyme expression and simultaneous conversion of lignocellulosic sugars into ethanol and xylitol by a new Candida tropicalis strain

BACKGROUND

Lignocellulosic ethanol production involves major steps such as thermochemical pretreatment of biomass, enzymatic hydrolysis of pre-treated biomass and the fermentation of released sugars into ethanol. At least two different organisms are conventionally utilized for producing cellulolytic enzymes and for ethanol production through fermentation, whereas in the present study a single yeast isolate with the capacity to simultaneously produce cellulases and xylanases and ferment the released sugars into ethanol and xylitol has been described.

RESULTS

A yeast strain isolated from soil samples and identified as Candida tropicalis MTCC 25057 expressed cellulases and xylanases over a wide range of temperatures (32 and 42 °C) and in the presence of different cellulosic substrates [carboxymethylcellulose and wheat straw (WS)]. The studies indicated that the cultivation of yeast at 42 °C in pre-treated hydrolysate containing 0.5 % WS resulted in proportional expression of cellulases (exoglucanases and endoglucanases) at concentrations of 114.1 and 97.8 U g(-1) ds, respectively. A high xylanase activity (689.3 U g(-1) ds) was also exhibited by the yeast under similar growth conditions. Maximum expression of cellulolytic enzymes by the yeast occurred within 24 h of incubation. Of the sugars released from biomass after pretreatment, 49 g L(-1) xylose was aerobically converted into 15.8 g L(-1) of xylitol. In addition, 25.4 g L(-1) glucose released after the enzymatic hydrolysis of biomass was fermented by the same yeast to obtain an ethanol titer of 7.3 g L(-1).

CONCLUSIONS

During the present study, a new strain of C. tropicalis was isolated and found to have potential for consolidated bioprocessing (CBP) applications. The strain could grow in a wide range of process conditions (temperature, pH) and in the presence of lignocellulosic inhibitors such as furfural, HMF and acetic acid. The new yeast produced cellulolytic enzymes over a wide temperature range and in the presence of various cellulosic substrates. The cellulolytic enzymes produced by the yeast were effectively used for the hydrolysis of pretreated biomass. The released sugars, xylose and glucose were, respectively, converted into xylitol and ethanol. The potential shown by the new inhibitor tolerant cellulolytic C. tropicalis to produce ethanol or xylitol is of great industrial significance.

Hydrolysis behaviors of sugarcane bagasse pith in subcritical carbon dioxide–water

Subcritical CO₂–water exhibits a high capacity for dissolution and catalysis to promote the hydrolysis of sugarcane bagasse pith.

Untreated wheat straw: potential source for diverse cellulolytic enzyme secretion by Penicillium janthinellum EMS-UV-8 mutant

Study describes the production of cellulases by Penicillium janthinellum EMS-UV-8 using untreated wheat straw (WS), treated WS (acid, alkali, steam exploded, organo-solv) and pure cellulosic substrates (avicel, cellulose-II and carboxymethyl cellulose). Severely pretreated WS and cellulose-II produced more cellulolytic enzymes than untreated samples. XRD and FTIR analysis revels that the increase in the amorphous structure of pretreated WS/cellulose increases enzyme production. Enzyme samples prepared using different substrates were used for the hydrolysis of dilute acid treated wheat straw (DATWS), steam exploded wheat straw (SEWS) and avicel. The enzyme prepared using untreated WS gave more hydrolysis of DATWS and SEWS than the enzyme prepared using pretreated WS or pure cellulosic substrates. This revels that more diverse/potential enzymes were secreted by P. janthinellum EMS-UV-8 mutant using untreated WS. This study may contribute in production of efficient enzyme mixture/cocktail by single fungal strain for economic conversion of biomass to sugars.

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.

Improved saccharification of pilot-scale acid pretreated wheat straw by exploiting the synergistic behavior of lignocellulose degrading enzymes

Improved saccharification by exploiting the synergism between biomass degrading enzymes.

β-Amylase production from packaging-industry wastewater using a novel strain Paenibacillus chitinolyticus CKS 1

Transforming waste into valuable biotechnology products – the treatment of transport packaging wastewater withPaenibacillus chitinolyticusCKS1 for β-amylase and maltose production.

Second generation bioethanol production at high gravity of pilot-scale pretreated wheat straw employing newly isolated thermotolerant yeast Kluyveromyces marxianus DBTIOC-35

Application of thermotolerant yeast Kluyveromyces marxianus DBTIOC-35 in SSF decreases overall process time, and increases productivity and yield by allowing elimination of presaccharification step and use of high biomass concentration, respectively.

A SERS protocol as a potential tool to access 6-mercaptopurine release accelerated by glutathione-S-transferase

The developed method for monitoring GST, an important drug metabolic enzyme, could greatly facilitate researches on relative biological fields.

Evaluation of recalcitrant features impacting enzymatic saccharification of diverse agricultural residues treated by steam explosion and dilute acid

Exploring agricultural biomass for biofuel production necessitates pretreatment as a prerequisite step.