Increase In Laccase Production Research Articles

Assessing the impact of corn steep liquor as an inducer on enhancing laccase production and laccase gene (Lac1) transcription in Pleurotus pulmonarius during solid-state fermentation

Laccases are crucial for agro-waste delignification in sustainable practices. Considering the necessity for cost-effective laccase pretreatments in industrial applications, numerous efforts have been directed towards identifying potential enzyme inducers for increasing laccase production. This study explored corn steep liquor as a cost-effective laccase inducer in Pleurotus pulmonarius solid substrate fermentation of tender coconut fiber. Utilizing tender coconut fiber for laccase production offers dual benefits of fiber valorisation and enzyme synthesis sustainably. We investigated the impact of corn steep liquor on transcription of Lac1 gene in P. pulmonarius and on extracellular laccase activity. Adding 2 % CSL notably boosted laccase production (314.62 + 5.93 IU/ml) and increased Lac1 transcript levels by 5.6-fold compared to non-induced cultures. SEM analysis revealed improved delignification as a result of increased laccase production. Our findings suggest that corn steep liquor serves as an inducer for regulating laccase gene expression in P. pulmonarius, leading to increased extracellular laccase production.

An apoptosis-inducing factor controls programmed cell death and laccase expression during fungal interactions

Apoptotic-like programmed cell death (PCD) is one of the main strategies for fungi to resist environmental stresses and maintain homeostasis. The apoptosis-inducing factor (AIF) has been shown in different fungi to trigger PCD through upregulating reactive oxygen species (ROS). This study identified a mitochondrial localized AIF homolog, CcAIF1, from Coprinopsis cinerea monokaryon Okayama 7. Heterologous overexpression of CcAIF1 in Saccharomyces cerevisiae caused apoptotic-like PCD of the yeast cells. Ccaif1 was increased in transcription when C. cinerea interacted with Gongronella sp. w5, accompanied by typical apoptotic-like PCD in C. cinerea, including phosphatidylserine externalization and DNA fragmentation. Decreased mycelial ROS levels were observed in Ccaif1 silenced C. cinerea transformants during cocultivation, as well as reduction of the apoptotic levels, mycelial growth, and asexual sporulation. By comparison, Ccaif1 overexpression led to the opposite phenotypes. Moreover, the transcription and expression levels of laccase Lcc9 decreased by Ccaif1 silencing but increased firmly in Ccaif1 overexpression C. cinerea transformants in coculture. Thus, in conjunction with our previous report that intracellular ROS act as signal molecules to stimulate defense responses, we conclude that CcAIF1 is a regulator of ROS to promote apoptotic-like PCD and laccase expression in fungal-fungal interactions. In an axenic culture of C. cinerea, CcAIF1 overexpression and H2O2 stimulation together increased laccase secretion with multiplied production yield. The expression of two other normally silent isozymes, Lcc8 and Lcc13, was unexpectedly triggered along with Lcc9.Key points• Mitochondrial CcAIF1 induces PCD during fungal-fungal interactions• CcAIF1 is a regulator of ROS to trigger the expression of Lcc9 for defense• CcAIF1 overexpression and H2O2 stimulation dramatically increase laccase production

Zinc’s impact on the growth and laccase activity of Trametes pubescens and an equilibrium study of zinc adsorption

ABSTRACT Due to the influence of some ions on laccase production by Trametes pubescens, the impact of different concentrations of zinc (Zn) on fungus growth and laccase production was investigated. The removal kinetics and adsorption isotherm of Zn by T. pubescens from an aqueous solution were evaluated. The results demonstrated the growth inhibition of fungus by an increase in Zn concentration. Zn concentrations of 10 and 20 mg L−1 in the medium caused an increase in the growth of fungus. Laccase production reduced at 100 and 200 mg L−1 of Zn. The kinetic parameters of Zn adsorption onto the biomass of fungus from aqueous solutions (containing 200 mg L−1 Zn) obtained by experiments at different contact times. The results indicated a trend of increasing Zn removal by fungus with the contact time, and it was well-described by the Intra-particle diffusion and Elovich models. The maximum removal of Zn was 67.1% at 7200 min, with a maximum sorption capacity of 44.7 mg g−1. The adsorption of Zn was well-fitted to the Freundlich and Langmuir sorption models. This study indicated an impact of a low concentration of Zn to increase laccase production and the feasibility of this fungus to remove Zn from aqueous solutions.

Enhanced laccase activity in Trametes versicolor (L.: Fr.) Pilát by host substrate and copper.

Laccases are appealing biocatalysts for various industrial utilizations. The fungus Trametes versicolor (L.: Fr.) Pilát causes white rot in wood and has been identified as an important fungal laccase producer. To investigate laccase production and activity in T. versicolor, the native isolate was collected from the host (Quercus castaneifolia) in the forests of Guilan province, northern Iran, and then purified and identified using the molecular marker. Its ability to produce laccase enzyme in the presence of different plant substrates including sawdust and wood chips of oak, poplar, and pine was evaluated. Also, the effect of copper as an enzyme inducer was investigated in vitro. The results showed that adding the wood to the culture medium increased laccase production, and among these, oak sawdust had the greatest effect, a 1.7-fold increase from that in the control (4.8 u/l vs. 2.8 u/l). Also, the enzyme extraction time effect on the optimal recovery yield showed that the 5-h enzyme extraction cycle resulted in the highest yield of the enzyme (18.97 u/l). Moreover, adding different concentrations of copper to the fungal culture medium increased the production of laccase, and the highest amount of enzyme (92.04 u/l) was obtained with 3.5 mM of CuSO4 along with oak sawdust. Based on the results, the addition of host wood sawdust ("oak" in this work) and copper particles together stimulates the fungal growth and the laccase production during submerged cultivation of T. versicolor. Therefore, it would be a safe and cheap strategy for the commercial production of laccase by filamentous fungi.

Enhanced laccase production by mutagenized Myrothecium verrucaria using corn stover as a carbon source and its potential in the degradation of 2-chlorophen.

Chlorophenols are widely used in industry and are known environmental pollutants. The degradation of chlorophenols is important for environmental remediation. In this study, we evaluated the biodegradation of 2-chlorophenol using crude laccase produced by Myrothecium verrucaria. Atmospheric and room temperature plasma technology was used to increase laccase production. The culture conditions of the M-6 mutant were optimized. Our results showed that corn stover could replace glucose as a carbon source and promote laccase production. The maximum laccase activity of 30.08U/mL was achieved after optimization, which was a 19.04-fold increase. The biodegradation rate of 2-chlorophenol using crude laccase was 97.13%, a positive correlation was determined between laccase activity and degradation rate. The toxicity of 2-CP was substantially reduced after degradation by laccase solution. Our findings show the feasibility of the use of corn stover in laccase production by M. verrucaria mutant and the subsequent biodegradation of 2-chlorophenol using crude laccase.

Characterization of Laccase from the Fungi Fusarium Isolated from Potato Peels Using Carbon and Nitrogen Sources

Laccases (E.C. 1.10.3.2 benzenediol: oxygen oxidoreductase) are an interesting group of N glycosylated multicopper blue oxidase enzymes. They are widely found in fungi, bacteria plants, insects, and lichen. They catalyze the oxidation of various phenolic and non-phenolic compounds, with the concomitant reduction of molecular oxygen to water. Laccase has various applications in industries such as textile dye bleaching, paper, and pulp bleaching, food processing, bioremediation, biodegradation, wood processing, and pharmaceuticals. However, the high cost of production has been a major hindrance to its commercial usage. This study was carried out to investigate the extraction, purification, and characterization of laccase from fungi isolated from potato peels using three different substrates. Extraction was carried out using submerged fermentation, with glucose, lactose, and maltose as the carbon sources and varying nitrogen sources; yeast and ammonium chloride (NH4Cl) Laccase was also characterized by assessing parameters such as pH, temperature, and protein concentration. Enzyme activity for maltose (yeast), glucose (yeast), glucose (NH4Cl) and lactose (NH4Cl) increased from 25oC -45 oC with optimum pH of 6,6,8 and 5 respectively while activity for maltose (NH4Cl) and lactose(yeast) increased from 25oC-65oC with optimum pH at 5 and 8 respectively. This study suggests that increased laccase production from potato peels can be achieved by using maltose, glucose and lactose as carbon sources with NH4Cl as nitrogen source.

Extracellular proteases and laccases produced by Pleurotus ostreatus PoB: the effects of proteases on laccase activity.

Laccases are enzymes produced by plants and white rot fungi, such as Pleurotus ostreatus, with industrial applications. Fungal laccases have been widely studied, and investigations, such as those involving recombinant DNA technology or adding inducers, have been made to increase laccase production. On the other hand, it has been proposed that extracellular proteases could decrease laccase activity when both types of enzymes are produced by P. ostreatus. The aim of this work was to evaluate the effects of proteases on the activity of extracellular laccases produced by P. ostreatus PoB in submerged culture. Results showed that P. ostreatus PoB produced alkaline, acidic, and neutral proteases. Protease activity was quantified, and the highest activity at alkaline pH (9.0) was 5.63 IU/L (192 h), that at acidic pH (2.0) was 3.38 IU/L (192 h), and that at neutral pH (7.0) was 6.20 IU/L (312 h). The protease activity decreased in the presence of different protease inhibitors, as phenylmethylsulfonyl fluoride (PMSF), EDTA, pepstatin A, and a cocktail of protease inhibitors. Laccase activity was determined in cultures with and without protease inhibitors. In the control culture (without inhibitor), the highest laccase specific activity was 99.88 IU/mg protein. In cultures with PMSF, pepstatin A, or a cocktail of protease inhibitors, laccase activity increased by approximately 1.35-fold (138 IU/mg protein) with respect to the control culture. The inhibitor EDTA did not produce a positive effect on extracellular laccase activity. These results suggest that laccase activity is affected by the actions of acidic and neutral extracellular proteases.

The Role of Laccase from Zygomycetous Fungus Mortierella elasson in Humic Acids Degradation

Biochemical stability of soil humus is an important factor affecting soil quality. Fungi are among the most efficient decomposers of humic matter due to presence of oxidative enzymes, including phenoloxidase laccase. Production of laccase by zygomycetes, a group of cellulolytic fungi widespread in soil, is poorly studied. The potential role of laccase from zygomycetes in humus turnover is unknown. Here, we show for the first time that laccase of zygomycetous fungus Mortierella elasson can effectively depolymerize humic acids in vitro. The fungus produced laccase extracellularly in a liquid culture medium. Unlike in case of laccases in ligninolytic basidiomycetes, attempts to increase enzyme activity using inductors, changes in the source of nitrogen and carbon failed to lead to any increase in laccase production. Laccase was purified using ion exchange chromatography and gel filtration. The molecular weight of the laccase was 51.75 kDa. The laccase catalyzed the oxidation of ABTS and K4[Fe(CN)6], phenolic compounds, but not tyrosine. The laccase activity was inhibited by NaN3 and NaF. The pH optimum of the laccase activity was 3.0 for ABTS and 5.0 for 2,6-dimethoxy phenol. The enzyme had moderate thermal stability and was rapidly inactivated at 70 °C. Purified laccase depolymerized humic acids from retisol, compost and peat more effectively than culture liquid containing laccase. The results of the study extend our knowledge of the role of laccases from different producers in the transformation of natural organic matter.

Yarrowia lipolytica Bioprocess Development: From Flask to Bioreactor.

Yarrowia lipolytica produces a range of valuable biotechnological products from natural metabolites and enzymes to heterologous proteins. The production of these products is affected by medium composition and various environmental factors. Here we describe bioprocess development for a recombinant laccase production by Y. lipolytica. At first, response surface methodology (RSM), as a statistical technique for design of experiment (DOE), is used for the optimization of medium composition in flask level. Then, results of RSM are applied to increase laccase production in controlled conditions of the bioreactor.

Optimization of Laccase Production from <i>Penicillium</i> sp. LX/08 for Biodelignification of Ramie (<i>Boehmeria nivea</i> L. Gaud)

Ramie solid waste as chips can be used as raw material for pulp. Ligninolytic enzymes of laccase widely used for pretreatment of the pulping process of ramie chips by biodelignification using laccase produced byPenicilliumsp. LX/08 has been done. This study aims to obtain optimal concentrations of lignin and CuSO4as enzyme inducers to increase laccase production fromPenicilliumsp. LX/08 during biodelignification process and its effect on the quality of ramie pulp. The biodelignification process of ramie chips was carried out by solid state fermentation (SSF) method with six days incubation time. Two inducer type treatment factors (CuSO4and lignin), and variations in the concentration of each lignin (0.25 g/L, 0.5 g/L, 0.75 g/L) and CuSO4(0.25 mM, 0.5 mM, 0.75 mM) were investigated in this study. The pulping process was carried out by the soda process in a digester under conditions: 12% active alkaline, temperature of 165°C for 3.5 hours. The results showed that 0.75 mM and 0.5 g/L of lignin were the optimal concentrations which could increase the laccase activity ofPenicilliumsp. LX/08 by 343 U/L and 25,8 U/L, respectively. The quality of ramie pulp showed a decrease in Kappa Number of 9,34% with an increase in pulp yield to 55,43%. Based on these results, the pretreatment method using laccase produced byPenicilliumsp. LX/08 can assist the pulping process of ramie.

Orange peel as an inducer for Laccase production in a novel fungal strain peyronellaea pinodella BL-3/4 and optimization of its cultural parameters by single parameter approach

Objectives: Laccases are one of the ligninolytic enzymes with wide industrial applications hence objective of present study is to optimize laccase production in novel fungal strain Peyronellaea pinodella BL-3/4. Methodology: Fungal strains capable of oxidizing different lignin model compounds such as guaicol, syringaldazine and 2, 2\'-Azino-bis (3ethylbenzthiozoline-6-sulphonic acid) were further tested for the laccase production in liquid media. 18s rRNA gene sequencing was performed to identify isolated novel fungal strain. Extracellular laccase activity from isolated fungal strain was optimized by the conventional `single parameter at a time\' approach. Parameters used for this study included inoculum size, temperature, pH, agitation rate, lignocellulosic substrate, carbon source and nitrogen source. Findings: Among ten isolated laccase positive fungal strains, BL-3/4, exhibited maximum activity and morphological resemblance to Peyronellaea. 18s rRNA gene sequencing and phylogenetic analysis revealed that the isolated fungal strain is a novel one and identified as Peyronellaea pinodella BL-3/4. Optimization by single parameter approach leads to an 18 fold increase in laccase production by Peyronellaea pinodella BL-3/4. During the optimization of agro residues, orange peel acting as a substrate dramatically changed laccase production from 10.4 to 65.1 U/mL. Novelty: No reports are available on Peyronellaea pinodella laccase activity and optimization of various factors affecting the laccase production. Orange peelings (an agro waste)as a substrate has increased the laccase production by six-fold in P. pinodella, this makes the fungi a better candidate for large scale production of laccase as well as for bioremediation, when compared to all other reported fungi. Keywords: Ascomycetes; Optimization; Aromatic inducers; Laccase activity; Lignin model compounds

Production, Purification, Characterization and Immobilization of Laccase from Phoma betae and its Application in Synthetic Dyes Decolorization

LACCASE (EC 1.10.3.2, p-diphenol: dioxygen oxidoreductases) is an extracellular enzyme found mainly in bacteria, fungi and plants. It has the ability to decolorize the hazardous synthetic dyes. Our study aimed to produce, purify, characterize and immobilize laccase from the fungus Phoma betae and its application in decolorization of synthetic dyes. Laccase was produced using both submerged and solid-state fermentations. Some inducers (ferulic acid, vertyl alcohol and CuSO4) for laccase production were used singly and in mixture. Significant increase in laccase production with all tested compounds was detected. Submerged fermentation induced laccase production than solid-state fermentation. Fast protein liquid chromatography (FPLC) used for laccase purification and through Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS/PAGE) the molecular mass of the purified laccase was 37 kDa. Optimum temperature for lacasse activity was determined at 30°C using guaiacol assay. Enzyme was more stable at -4oC than at -20 and -80oC. Maximum laccase activity was found at pH 8. Effect of metal ions and inhibitors on laccase activity was studied. Ni2+ and K1+ induced laccase activity, while Na1+, Ag1+, Hg2+, Zn2+, Cu2+, EDTA and SDS decreased laccase activity with different ratios. Laccase was immobilized in alginate beads. Both free and immobilized laccase were used to decolorize five synthetic dyes (Eriochrome Cyanine R, Merantine Brilliant Yellow 8G, Rhodamine 123, Solvent Orange 20 and Solvent Yellow 47) at concentration 0.2 g dye/L. Immobilized laccase decolorized dyes with higher yields than free one in all tested dyes. Phoma betae laccase is an efficient biocatalyst for synthetic dye decolorization.

Farnesol-induced hyperbranched morphology with short hyphae and bulbous tips of Coriolus versicolor

As the first fungal quorum sensing molecule, farnesol-induced morphological transition is usually studied in dimorphic fungi, but in basidiomycetes the morphological changes regulated by farnesol are rarely investigated. In this study, we found that farnesol made the basidiomycete Coriolus versicolor develop into a hyperbranched morphology with short hyphae and bulbous tips. Farnesol treatment resulted in a significant increase of intracellular oxidative stress level, which influenced the expression of several morphogenesis-related genes, and thereby led to the morphological changes. High oxidative stress level significantly stimulated the expression of laccase genes for improving intracellular laccase biosynthesis. The resulted hyperbranched morphology further accelerated the secretion of intracellular laccase into culture medium. As a result, extracellular laccase production reached a maximum of 2189.2 ± 54.7 U/L in farnesol-induced cultures, which was 6.8-fold greater than that of control cultures. SDS-PAGE and native-PAGE showed that farnesol increased laccase production by promoting the biosynthesis of three laccase isoforms. Together these results provide new opportunities in not only understanding the farnesol-regulated mycelial morphology in basidiomycetes, but also developing novel strategies for enhancing the production of secreted enzymes of biotechnological interest.

Elevated levels of laccase synthesis by Pleurotus pulmonarius BPSM10 and its potential as a dye decolorizing agent.

Laccases (EC 1.10.3.2) are a class of multi-copper oxidases that have industrial value. In the present study, forty-five isolates of wild mushrooms were screened for laccase production. Eight of the isolates exhibited exploitable levels of substrate oxidation capacity. Isolate BPSM10 exhibited the highest laccase activity of 103.50 U/ml. Internal Transcribed Spacer (ITS) rRNA gene sequencing was used to identify BPSM10 as Pleurotus pulmonarius. The response of BPSM10 to two nutritional media supplemented with various inducers was characterized and the results indicated that Malt Extract Broth (MEB) supplemented with Xylidine increased laccase production by 2.8× (349.5 U/ml) relative to the control (122 U/ml), while Potato Dextrose Broth (PDB) supplemented with xylidine increased laccase production by 1.9× (286 U/ml). BPSM10 has the ability to decolorize seven synthetic dyes in a liquid medium. Maximum decolorization was observed of malachite green (MG); exhibiting 68.6% decolorization at 100 mg/L. Fourier-transform infrared spectroscopy (FTIR) was employed to confirm the decolorization capacity. The present study indicates that P. pulmonarius BPSM10 has the potential to be used as a potent alternative biosorbent for the removal of synthetic dyes from aqueous solutions, especially in the detoxification of polluted water.

Panus strigellus laccase decolorizes anthraquinone, azo, and triphenylmethane dyes

Abstract Panus strigellus is a native basidiomycete from Brazil with laccase production potential. Laccases are involved in the biodegradation of dyes and their production can be stimulated by cultivation with agro industrial by-products. This study aimed to evaluate laccase production of P. strigellus cultivated with sugarcane bagasse on dye decolorization. Culture media had different concentrations of sugarcane bagasse (SB), sources of nitrogen (urea, yeast extract, ammonium sulfate and sodium nitrate), and concentrations of copper sulfate (0, 50, 100, 200, and 300 μM). Enzymatic extract from fungal cultivation was used in the decolorization of reactive blue 220 (RB220), malachite green (MG), and remazol brilliant blue R (RBBR). Laccase production was inversely proportional to the amount of SB in cultivation medium and higher titers of enzyme were obtained when 20 g/L SB (SB20) was used. Cultivation medium with SB20 and most nitrogen sources did not have a positive effect on laccase production whereas the addition of urea or yeast-extract reduced laccase production. Most of the copper sulfate concentrations added to SB20 medium increased laccase production, and the maximum laccase production was 55,342 U/L in the SB20 medium with 200 μM copper. The crude enzymatic extract was more effective in the decolorization of azo dye (RB220), with more than 90% of decolorization in 24 h, than anthraquinone dye (RBBR), with 60% decolorization, and triphenylmethane dye (MG), with 68% decolorization, both in 72 h.

Metallic-aromatic compounds synergistically induce Lentinus crinitus laccase production

Abstract Lentinus crinitus is a basidiomycete with the ability to produce laccase and other enzymes of biotechnological interest. Laccase production depends on cultivation conditions and can be induced by metallic, phenolic or aromatic compounds. This study aimed to evaluate the laccase production of L. crinitus cultivated in sugarcane vinasse and urea with addition of laccase inducers. L. crinitus was cultivated in sugarcane vinasse with urea and supplemented with copper sulfate (0, 50, 150, 250, 350 and 450 μM) and aromatic compounds (guaiacol, veratryl alcohol, or 2,5-xylidine) added alone or combined to the cultivation medium. Cooper (150 or 250 μM) increased laccase activity in 14.5 (49,000 U/L) and 28.5% (55,000 U/L), respectively. Guaiacol had no significant effect, but veratryl alcohol (~46000 U/L) and xylidine (~75000 U/L) increased laccase activity. Copper with other inducers had the most relevant effects on laccase production. Simultaneous guaiacol addition with 150 or 250 μM copper increased 108% and 151% laccase activity, respectively, when compared with only copper addition to vinasse-urea medium. Veratryl alcohol and 150 or 250 μM copper addition increased 100% and 138% laccase activity, respectively, when compared to only copper addition. Interaction analysis of the variables guaiacol or veratryl alcohol and copper (250 µM) added to cultivation medium demonstrated synergistic effects resulting in laccase activity increase. These results highlight the importance of L. crinitus as a laccase producer and emphasize the relevance of studies using a combination of inducers to increase laccase production.

Optimized production, purification and molecular characterization of fungal laccase through Alternaria alternata

Abstract Objective Industrial effluents and agriculture biomass are main environmental hazards which are facing by developing country like Pakistan. Along with various other industrial applications, laccases are also involved in the oxidation of various industrial hazardous compounds to detoxify them. This study was designed to produce and purify laccase from ascomyceteous fungi, i.e. Alternaria alternata through solid stat fermentation. Materials and methods Abundantly available Sarkanda grass “Saccharum spontaneum” was used as agro-waste substrate for laccase production from fungus A. alternata. Previously only white rot fungi are familiar for laccase production and almost no work has been done on laccase production by A. alternata. In this research work, different physical and chemical parameters were optimized for maximum laccase production through solid state fermentation (SSF). Results Enzyme was purified and its molecular weight was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Maximum laccase activity (21.87±0.0115 unit/mL) was detected on 7th day of incubation having pH 5 of the medium at 35°C. None of the added metal ions increased laccase production. Galactose and “yeast extract” used as optimum carbon and nitrogen source for highest laccase production. Conclusion A monomeric protein (laccase) having approximately 51 kDa molecular weight obtained after SDS-PAGE.

Research Article Lentinus crinitus strains respond differently to cultivation pH and temperature

Fungus ability to respond to environmental changes allows their adaptation to a wide variety of conditions such as pH, temperature, light, nutrient availability, chemicals, and competition among species. Temperature and pH can affect fungal growth as well as their metabolism. Knowing these factors on fungus species is relevant for the development of biotechnological applications and process optimization to produce biomass and enzymes. This study aimed to evaluate Lentinus crinitus mycelial growth and laccase production at different initial pH and temperatures of the cultivation medium. L. crinitus U15-9 reduced laccase production with pH increase with maximum production at pH 6 (39 U/mL) whereas L. crinitus U9-1 increased laccase production with pH increase with maximum activity at pH 7 (25.8 U/mL). Neither of the strains had mycelial growth significantly affected by initial pH in the culture medium. The greatest laccase production occurred at 28 oC for U15-9 (50 U/mL) and U9-1 (41.5 U/mL). An increase in U9-1 mycelial biomass occurred when the temperature went up from 25 to 28 oC whereas for U15-9 it was from 28 to 37 oC; at 37 oC, U15-9 produced 225% more mycelial biomass than at 28 oC, and 108% more mycelial biomass than U9-1 at 37 oC. The variation of responses to environmental stimuli between the strains makes evident that intra-specific variations are common in basidiomycetes. Our findings highlighted the best conditions of pH and temperature to produce L. crinitus laccase and make evident how different strains respond distinctly to cultivation conditions.

Evaluation of 18 isolates of basidiomycetes for Lignocellulose degrading enzymes

Since fossil fuel resources are limited there is a necessity to produce alternative types of fuel that are renewable and eco-friendly. Basidiomycetes are potential sources of enzymes that can be used for biofuel production. The current study aimed to isolate basidiomycetes from Sri Lanka, screen them for lignocellulose degrading enzymes, namely cellulase, xylanase, laccase, Mn peroxidase and lignin peroxidase and study the effect of potential inducers of laccase production. Among the eighteen basidiomycetes isolated, Pycnoporus sp. produced the highest cellulase activity (0.23 FPU/ml) whereas Phlebiopsis sp. produced the highest xylanase activity (5.4 U/ml). Earliella scabrosa produced the highest laccase (91.2 U/l) and Mn peroxidase (17.5 U/l) activities. Lignin peroxidase activity was not detected from the isolates. Effect of alkali lignin, Cu 2+ and rice bran, three potential inducers, on laccase production by E. scabrosa , Pycnoporus sp. and Trametes hirsuta (M40) was studied. Results indicated that alkali lignin (2 g/l) significantly increased laccase production from Pycnoporus sp. and T. hirsuta (M40) while Cu 2+ increased laccase production from E. scabrosa and T. hirsuta at 200 μM. Use of rice bran (10 g/l) resulted in higher laccase production from E. scabrosa and Pycnoporus sp. High laccase activity (79600 U/l) was obtained from E. scabrosa by using 50 g/l of rice bran and by extending the incubation period to 18 days. The study concluded that some of the basidiomycetes isolated can produce significant lignocellulose degrading enzyme activities.

The effect of various inducers and their combinations with copper on laccaseproduction of Trametes versicolor pellets in a repeated-batch process

The aim of this study was to increase laccase production in Trametes versicolor ATCC 200801 pellets by using various inducers and their combinations under repeated-batch conditions. Because copper is an effective inducer for laccase production, the effect of Cu on laccase production in this strain was tested first. The optimal Cu concentration for the highest laccase production was 0.5 mM. Following this preliminary study, the effect of other inducers [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), syringaldazine, guaiacol, and 2,5-xylidine] on laccase production was determined. Copper was determined to be the most efficient inducer among the inducers used. Therefore, the synergistic effect of each inducer with Cu on laccase production in this strain was investigated. While the maximum laccase activity was 0.60 U/mL in stock basal medium (SBM) alone, the highest enzyme activities detected were 4.76 and 2.87 U/mL in SBM + 0.05 mM ABTS and SBM + 1 mM 2,5-xylidine, respectively. Maximum laccase activities obtained from the combination of the inducers were 33.61 and 26.49 U/mL in SBM + 0.5 mM Cu + 0.5 mM 2,5-xylidine and SBM + 0.5 mM Cu + 0.05 mM ABTS, respectively. These were the most efficient combinations for laccase production.