Characterization of the Cellulase Complex ofPenicillium echinulatum

Enzymatic degradation of cellulose in soil: A review

Cellulose degradation is a critical process in soil ecosystems, playing a vital role in nutrient cycling and organic matter decomposition. Enzymatic degradation of cellulosic biomass is the most sustainable and green method of producing liquid biofuel. It has gained intensive research interest with future perspective as the majority of terrestrial lignocellulose biomass has a great potential to be used as a source of bioenergy. However, the recalcitrant nature of lignocellulose limits its use as a source of energy. Noteworthy enough, enzymatic conversion of cellulose biomass could be a leading future technology. Fungal enzymes play a central role in cellulose degradation. Our understanding of fungal cellulases has substantially redirected in the past few years with the discovery of a new class of enzymes and Cellulosome. Efforts have been made from time to time to develop an economically viable method of cellulose degradation. This review provides insights into the current state of knowledge regarding cellulose degradation in soil and identifies areas where further research is needed.

Taxonomy, comparative genomics and evolutionary insights of Penicillium ucsense: a novel species in series Oxalica

The genomes of two Penicillium strains were sequenced and studied in this study: strain 2HH was isolated from the digestive tract of Anobium punctatum beetle larva in 1979 and the cellulase hypersecretory strain S1M29, derived from strain 2HH by a long-term mutagenesis process. With these data, the strains were reclassified and insight is obtained on molecular features related to cellulase hyperproduction and the albino phenotype of the mutant. Both strains were previously identified as Penicillium echinulatum and this investigation indicated that these should be reclassified. Phylogenetic and phenotype data showed that these strains represent a new Penicillium species in series Oxalica, for which the name Penicillium ucsense is proposed here. Six additional strains (SFC101850, SFCP10873, SFCP10886, SFCP10931, SFCP10932 and SFCP10933) collected from the marine environment in the Republic of Korea were also classified as this species, indicating a worldwide distribution of this new taxon. Compared to the closely related strain Penicillium oxalicum 114-2, the composition of cell wall-associated proteins of P. ucsense 2HH shows five fewer chitinases, considerable differences in the number of proteins related to β-D-glucan metabolism. The genomic comparison of 2HH and S1M29 highlighted single amino-acid substitutions in two major proteins (BGL2 and FlbA) that can be associated with the hyperproduction of cellulases. The study of melanin pathways shows that the S1M29 albino phenotype resulted from a single amino-acid substitution in the enzyme ALB1, a precursor of the 1,8-dihydroxynaphthalene (DHN)-melanin biosynthesis. Our study provides important knowledge towards understanding species distribution, molecular mechanisms, melanin production and cell wall biosynthesis of this new Penicillium species.

Application of Enzyme-Assisted Extraction for the Recovery of Natural Bioactive Compounds for Nutraceutical and Pharmaceutical Applications

Enzyme-assisted extraction (EAE) involves the use of hydrolytic enzymes for the degradation of the cell wall or other cell components. This supports the diffusion of the solvent into the plant or fungal material, leading to easier elution of its metabolites. This technique has been gaining increasing attention, as it is considered an eco-friendly and cost-effective improvement on classical or modern extraction methods. Its promising application in improving the recovery of different classes of bioactive metabolites (e.g., polyphenols, carotenoids, polysaccharides, proteins, components of essential oil, and terpenes) has been reported by many scientific papers. This review summarises information on the theoretical aspects of EAE (e.g., the components of the cell walls and the types of enzymes used) and the most recent discoveries in the effective involvement of enzyme-assisted extraction of natural products (plants, mushrooms, and animals) for nutraceutical and pharmaceutical applications.

Gene Regulatory Networks of Penicillium echinulatum 2HH and Penicillium oxalicum 114-2 Inferred by a Computational Biology Approach

Penicillium echinulatum 2HH and Penicillium oxalicum 114-2 are well-known cellulase fungal producers. However, few studies addressing global mechanisms for gene regulation of these two important organisms are available so far. A recent finding that the 2HH wild-type is closely related to P. oxalicum leads to a combined study of these two species. Firstly, we provide a global gene regulatory network for P. echinulatum 2HH and P. oxalicum 114-2, based on TF-TG orthology relationships, considering three related species with well-known regulatory interactions combined with TFBSs prediction. The network was then analyzed in terms of topology, identifying TFs as hubs, and modules. Based on this approach, we explore numerous identified modules, such as the expression of cellulolytic and xylanolytic systems, where XlnR plays a key role in positive regulation of the xylanolytic system. It also regulates positively the cellulolytic system by acting indirectly through the cellodextrin induction system. This remarkable finding suggests that the XlnR-dependent cellulolytic and xylanolytic regulatory systems are probably conserved in both P. echinulatum and P. oxalicum. Finally, we explore the functional congruency on the genes clustered in terms of communities, where the genes related to cellular nitrogen, compound metabolic process and macromolecule metabolic process were the most abundant. Therefore, our approach allows us to confer a degree of accuracy regarding the existence of each inferred interaction.

Heterologous expression of Neurospora crassa cbh1 gene in Pichia pastoris resulted in production of a neutral cellobiohydrolase I

The high production cost of cellulase is one of the limitations that hinder the commercialization of lignocellulose-based biorefineries. As one of the important cellulases, Neurospora crassa cellulase is not so intensively investigated as T. reesei cellulase. In this study, the cbh1gene (NCU07340) cloned from N. crassa was expressed in Pichia pastoris under the control of alcohol oxidase 1 (AOX1) promotor. Six transformants with the highest resistance to G418 were selected by two rounds of transformant screening, among which the most robust producer of the recombinant cellobiohydrolase I (CBHI) has an Avicelase activity of 0.22 U/mL. After fermentation optimization, it was improved to 0.30 U/mL. Interestingly, the optimal temperature and pH of the recombinant CBHI were 60°C and 7.2, respectively, and it was quite stable within the wide ranges of temperature and pH. This work is a good example for the future improvement and optimization of N. crassa cellulase.

A new strain of Aspergillus tubingensis for high-activity pectinase production

Pectinase is a general term for a class of enzymes that decompose pectin. To obtain a fungal strain with high-activity pectinase of potential commercial importance, we screened microorganisms from the soil of vineyards, performed mutation breeding by ultraviolet (UV) and nitrosoguanidine (NTG) mutagenesis, and performed comparisons to commercially available pectinases. We found that the derived pectinase-producing strain Rn14-88A had the highest pectinase activity of 8363.215 U/mL, and identified it using internal transcribed spacer sequence analysis as Aspergillus tubingensis. Rn14-88A was the original strain for UV mutagenesis, from which mutant strain R-7-2-4 had the highest pectinase enzyme activity (9198.68 U/mL), which was a 9.99% increase compared to that of Rn14-88A. Following NTG mutagenesis of R-7-2-4, mutant strain Y1-3-2-6 had a pectinase enzyme activity of 9843.34 U/mL, which reflects a 6.36% increase compared to the pectinase activity of R-7-2-4. Subsequently, another round of NTG mutagenesis was performed on Y1-3-2-6, and the mutagenic strain Y2-6-3-4 exhibited an improved enzyme activity of 21,864.34 U/mL, which was 161.44% higher than that of Rn14-88A. Through liquid fermentation experiments of A. tubingensis Y2-6-3-4, it was determined that pectinase activity was the highest at a fermentation time of 20 h. Therefore, we conclude that A. tubingensis Y2-6-3-4 has potential for use in commercial production.

Schizosaccharomyces pombe as an Efficient Yeast to Convert Sugarcane Bagasse Pretreated with Ionic Liquids in Ethanol

Pretreatment of lignocellulosic biomass with ionic liquids (ILs) has been extensively studied, being regarded as one of the most promising methods for obtaining fermentable sugars. In this research, it was investigated the production of ethanol from sugars released from sugarcane bagasse pretreated with the ionic liquids [C₄mim][OAc] and [C₂mim][OAc], hydrolysed with Penicillium echinulatum enzymes and using Saccharomyces cerevisiae and Schizosaccharomyces pombe. Yields of about 43 and 56% of ethanol were observed for S. cerevisiae and biomass pretreated with [C₂mim][OAc] and [C₄mim][OAc], respectively. S. pombe yielded 52 and 78% ethanol for [C₂mim][OAc] and [C₄mim][OAc], respectively. These results indicate that S. pombe showed best performance for alcoholic fermentation from sugars released from pretreated biomass by ILs.

Screening of potential IL-tolerant cellulases and their efficient saccharification of IL-pretreated lignocelluloses

Lignocellulosic biomass as one of the most abundant and renewable resources has great potential for biofuel production. The complete conversion of biomass to biofuel is achieved through the effective pretreatment process and the following enzyme saccharification. Ionic liquids (ILs) are considered as a green solvent for lignocellulose pretreatment. However, ILs exhibit an inhibitory effect on cellulase activity, leading to a subsequent decrease in the efficiency of saccharification. The screening of new potential IL-tolerant cellulases is important. In the current study, a fungal strain with a relatively high cellulase production was isolated and identified as Penicillium oxalicum HC6. The culture conditions were optimized using corn stover and peptone as the carbon source and nitrogen source at pH 4.0 and 30 °C with an inoculation size of 2% (v/v) for 8 days. It was found that P. oxalicum HC6 exhibited potential salt tolerance with the increase of the enzyme production at a salt concentration of 5.0% (w/v). In addition, high enzyme activities were obtained at pH 4.0–6.0 and 50–65 °C. The crude enzyme from P. oxalicum HC6 with good thermal stability was also stable in the presence of salt and ILs. Good yields of reducing sugar were obtained by the crude enzyme from P. oxalicum HC6 after the saccharification of corn stover that was pretreated by ILs. P. oxalicum HC6 with potentially salt-tolerant and IL-tolerant enzymes has great potential application in the enzymatic saccharification of lignocellulose.

Lignocellulosic biomass as one of the most abundant and renewable resources has great potential for biofuel production.

A Newly Isolated Penicillium oxalicum 16 Cellulase with High Efficient Synergism and High Tolerance of Monosaccharide

Compared to Trichoderma reesei RUT-C30 cellulase (Trcel), Penicillium oxalicum 16 cellulase (P16cel) from the fermentation supernatant produced a 2-fold higher glucose yield when degrading microcrystalline cellulose (MCC), possessed a 10-fold higher β-glucosidase (BGL) activity, but obtained somewhat lower other cellulase component activities. The optimal temperature and pH of β-1,4-endoglucanase, cellobiohydrolase, and filter paperase from P16cel were 50-60 °C and 4-5, respectively, but those of BGL reached 70 °C and 5. The cellulase cocktail of P16cel and Trcel had a high synergism when solubilizing MCC and generated 1.7-fold and 6.2-fold higher glucose yields than P16cel and Trcel at the same filter paperase loading, respectively. Additional low concentration of fructose enhanced the glucose yield during enzymatic hydrolysis of MCC; however, additional high concentration of monosaccharide (especially glucose) reduced cellulase activities and gave a stronger monosaccharide inhibition on Trcel. These results indicate that P16cel is a more excellent cellulase than Trcel.

Ethanol production from sugars obtained during enzymatic hydrolysis of elephant grass (Pennisetum purpureum, Schum.) pretreated by steam explosion

In this work, steam explosion was used a pretreatment method to improve the conversion of elephant grass (Pennisetum purpureum) to cellulosic ethanol. This way, enzymatic hydrolysis of vaccum-drained and water-washed steam-treated substrates was carried out with Penicillium echinulatum enzymes while Saccharomyces cerevisiae CAT-1 was used for fermentation. After 48 h of hydrolysis, the highest yield of reducing sugars was obtained from vaccum-drained steam-treated substrates that were produced after 10 min at 200 °C (863.42 ± 62.52 mg/g). However, the highest glucose yield was derived from water-washed steam-treated substrates that were produced after 10 min at 190 °C (248.34 ± 6.27 mg/g) and 200 °C (246.00 ± 9.60 mg/g). Nevertheless, the highest ethanol production was obtained from water-washed steam-treated substrates that were produced after 6 min at 200 °C. These data revealed that water washing is a critical step for ethanol production from steam-treated elephant grass and that pretreatment generates a great deal of water soluble inhibitory compounds for hydrolysis and fermentation, which were partly characterized as part of this study.

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.

Effect of different pretreatment of sugar cane bagasse on cellulase and xylanases production by the mutant Penicillium echinulatum 9A02S1 grown in submerged culture

The main limitation to the industrial scale hydrolysis of cellulose is the cost of cellulase production. This study evaluated cellulase and xylanase enzyme production by the cellulolytic mutant Penicillium echinulatum 9A02S1 using pretreated sugar cane bagasse as a carbon source. Most cultures grown with pretreated bagasse showed similar enzymatic activities to or higher enzymatic activities than cultures grown with cellulose or untreated sugar cane bagasse. Higher filter paper activity (1.253 ± 0.147 U · mL(-1)) was detected in the medium on the sixth day of cultivation when bagasse samples were pretreated with sodium hydroxide, hydrogen peroxide, and anthraquinone. Endoglucanase enzyme production was also enhanced by pretreatment of the bagasse. Nine cultures grown with bagasse possessed higher β -glucosidase activities on the sixth day than the culture grown with cellulose. The highest xylanase activity was observed in cultures with cellulose and with untreated sugar cane bagasse. These results indicate that pretreated sugar cane bagasse may be able to serve as a partial or total replacement for cellulose in submerged fermentation for cellulase production using P. echinulatum, which could potentially reduce future production costs of enzymatic complexes capable of hydrolyzing lignocellulosic residues to form fermented syrups.

Increased production of cellulases and xylanases by Penicillium echinulatum S1M29 in batch and fed-batch culture

The development of more productive strains of microorganisms and processes that increase enzyme levels can contribute to the economically efficient production of second generation ethanol. To this end, cellulases and xylanases were produced with the S1M29 mutant strain of Penicillium echinulatum, using different concentrations of cellulose (20, 40, and 60 g L(-1)) in batch and fed-batch processes. The highest activities of FPase (8.3 U mL(-1)), endoglucanases (37.3 U mL(-1)), and xylanases (177 U mL(-1)) were obtained in fed-batch cultivation with 40 g L(-1) of cellulose. The P. echinulatum enzymatic broth and the commercial enzyme Cellic CTec2 were tested for hydrolysis of pretreated sugar cane bagasse. Maximum concentrations of glucose and xylose were achieved after 72 h of hydrolysis. Glucose yields of 28.0% and 27.0% were obtained using the P. echinulatum enzymatic extract and Cellic CTec2, respectively.

Cellulase and Xylanase Production by Penicillium echinulatum in Submerged Media Containing Cellulose Amended with Sorbitol

The present work investigated the use of sorbitol as a soluble carbon source, in association with cellulose, to produce cellulases and xylanases in submerged cultures of Penicillium echinulatum 9A02S1. Because cellulose is an insoluble carbon source, in cellulase production, there are some problems with rheology and oxygen transfer. The submerged fermentations containing media composed of 0, 0.25, 0.5, 0.75, and 1% (w/v) sorbitol and cellulose that were added at different times during the cultivation; 0.2% (w/v) soy bran; 0.1% (w/v) wheat bran; and a solution of salts. The highest filter paper activity (FPA) (1.95  ±  0.04 IU·mL⁻¹) was obtained on the seventh day in the medium containing 0.5% (w/v) sorbitol and 0.5% (w/v) cellulose added 24 h after the start of cultivation. However, the CMCases showed an activity peak on the sixth day (9.99 ± 0.75 IU·mL⁻¹) in the medium containing 0.75% (w/v) sorbitol and 0.75% (w/v) cellulose added after 12 h of cultivation. The xylanases showed the highest activity in the medium with 0.75% (w/v) sorbitol and 0.25% (w/v) cellulose added 36 h after the start of cultivation. This strategy enables the reduction of the cellulose concentration, which in high concentrations can cause rheological and oxygen transfer problems.

Characterization of a novel swollenin from Penicillium oxalicum in facilitating enzymatic saccharification of cellulose

Background

Plant expansins and fungal swollenin that can disrupt crystalline cellulose have great potential for applications in conversion of biomass. Recent studies have been mainly focused on Trichoderma reesei swollenin that show relatively low activity in the promotion of cellulosic hydrolysis. Our aim was to isolate a novel swollenin with greater disruptive activity, to establish an efficient way of producing recombinant swollenin, and to optimize the procedure using swollenin in facilitation of cellulosic hydrolysis.

Results

A novel gene encoding a swollenin-like protein, POSWOI, was isolated from the filamentous fungus Penicillium oxalicum by Thermal Asymmetric Interlaced PCR (TAIL-PCR). It consisted of a family 1 carbohydrate-binding module (CBM1) followed by a linker connected to a family 45 endoglucanase-like domain. Using the cellobiohydrolase I promoter, recombinant POSWOI was efficiently produced in T. reesei with a yield of 105 mg/L, and showed significant disruptive activity on crystalline cellulose. Simultaneous reaction with both POSWOI and cellulases enhanced the hydrolysis of crystalline cellulose Avicel by approximately 50%. Using a POSWOI-pretreatment procedure, cellulases can produce nearly twice as many reducing sugars as without pretreatment. The mechanism by which POSWOI facilitates the saccharification of cellulose was also studied using a cellulase binding assay.

Conclusion

We present a novel fungal swollenin with considerable disruptive activity on crystalline cellulose, and develop a better procedure for using swollenin in facilitating cellulosic hydrolysis. We thus provide a new approach for the effective bioconversion of cellulosic biomass.

The Penicillium echinulatum secretome on sugar cane bagasse

Plant feedstocks are at the leading front of the biofuel industry based on the potential to promote economical, social and environmental development worldwide through sustainable scenarios related to energy production. Penicillium echinulatum is a promising strain for the bioethanol industry based on its capacity to produce large amounts of cellulases at low cost. The secretome profile of P. echinulatum after grown on integral sugarcane bagasse, microcrystalline cellulose and three types of pretreated sugarcane bagasse was evaluated using shotgun proteomics. The comprehensive chemical characterization of the biomass used as the source of fungal nutrition, as well as biochemical activity assays using a collection of natural polysaccharides, were also performed. Our study revealed that the enzymatic repertoire of P. echinulatum is geared mainly toward producing enzymes from the cellulose complex (endogluganases, cellobiohydrolases and β-glucosidases). Glycoside hydrolase (GH) family members, important to biomass-to-biofuels conversion strategies, were identified, including endoglucanases GH5, 7, 6, 12, 17 and 61, β-glycosidase GH3, xylanases GH10 and GH11, as well as debranching hemicellulases from GH43, GH62 and CE2 and pectinanes from GH28. Collectively, the approach conducted in this study gave new insights on the better comprehension of the composition and degradation capability of an industrial cellulolytic strain, from which a number of applied technologies, such as biofuel production, can be generated.

Cellulases from Penicillium funiculosum: production, properties and application to cellulose hydrolysis

The objective of this work is to investigate the utilization of two abundant agricultural residues in Brazil for the production and application of cellulolytic enzymes. Different materials obtained after pretreatment of sugarcane bagasse, as well as pure synthetic substrates, were considered for cellulase production by Penicillium funiculosum. The best results for FPase (354 U L(-1)) and beta-glucosidase (1,835 U L(-1)) production were observed when sugarcane bagasse partially delignified cellulignin (PDC) was used. The crude extract obtained from PDC fermentation was then partially characterized. Optimal temperatures for cellulase action ranged from 52 to 58 degrees C and pH values of around 4.9 contributed to maximum enzyme activity. At 37 degrees C, the cellulases were highly stable, losing less than 15% of their initial activity after 23 h of incubation. There was no detection of proteases in the P. funiculosum extract, but other hydrolases, such as endoxylanases, were identified (147 U L(-1)). Finally, when compared to commercial preparations, the cellulolytic complex from P. funiculosum showed more well-balanced amounts of beta-glucosidase, endo- and exoglucanase, resulting in the desired performance in the presence of a lignocellulosic material. Cellulases from this filamentous fungus had a higher glucose production rate (470 mg L(-1) h(-1)) when incubated with corn cob than with Celluclast, GC 220 and Spezyme (312, 454 and 400 mg L(-1) h(-1), respectively).

Production of cellulases and hemicellulases by Penicillium echinulatum grown on pretreated sugar cane bagasse and wheat bran in solid-state fermentation

AIM

To evaluate the solid-state fermentation (SSF) production of cellulase and hemicellulases (xylanases), by Penicillium echinulatum 9A02S1, in experiments carried out with different concentrations of the pretreated sugar cane bagasse (PSCB) and wheat bran (WB).

METHODS AND RESULTS

This study reports the production of xylanolytic and cellulolytic enzymes by P. echinulatum 9A02S1 using a cheap medium containing PSCB and WB under SSF. The highest amounts of filter paper activity (FPA) could be measured on mixtures of PSCB and WB (32.89 +/- 1.90 U gdm(-1)). The highest beta-glucosidase activity was 58.95 +/- 2.58 U gdm(-1) on the fourth day. The highest activity for endoglucanases was 282.36 +/- 1.23 U gdm(-1) on the fourth day, and for xylanases the activity was around 10 U gdm(-1) from the second to the fourth day.

CONCLUSIONS

The present work has established the potential of P. echinulatum for FPA, endoglucanase, beta-glucosidase and xylanase productions in SSF, indicating that WB may be partially substituted by PSCB.

SIGNIFICANCE AND IMPACT OF THE STUDY

The incorporation of cheap sources, such as sugar cane bagasse, into media for the production of lignocellulose enzymes should help decrease the production costs of enzymatic complexes that can hydrolyse lignocellulose residues for the formation of fermented syrups, thus contributing to the economic production of bioethanol.

Comparison of Penicillium echinulatum and Trichoderma reesei cellulases in relation to their activity against various cellulosic substrates

Penicillium echinulatum has been identified as a potential cellulase producer for bioconversion processes but its cellulase system has never been investigated in detail. In this work, the volumetric activities of P. echinulatum cellulases were determined against filter paper (0.27 U/mL), carboxymethylcellulose (1.53 U/mL), hydroxyethylcellulose (4.68 U/mL), birchwood xylan (3.16 U/mL), oat spelt xylan (3.29 U/mL), Sigmacell type 50 (0.10 U/mL), cellobiose (0.19 U/mL), and p-nitrophenyl-glucopiranoside (0.31 U/mL). These values were then expressed in relation to the amount of protein and compared those of Trichoderma reesei cellulases (Celluclast 1.5L FG, Novozymes). Both enzyme complexes were shown to have similar total cellulase and xylanase activities. Analysis of substrate hydrolysates demonstrated that P. echinulatum enzymes have higher beta-glucosidase activity than Celluclast 1.5L FG, while the latter appears to have greater cellobiohydrolase activity. Unlike Celluclast 1.5L FG, P. echinulatum cellulases had enough beta-glucosidase activity to remove most of the cellobiose produced in hydrolysis experiments. However, Celluclast 1.5L FG became more powerful than P. echinulatum cellulases when supplemented with exogenous beta-glucosidase activity (Novozym 188). Both cellulase complexes displayed the same influence over the degree of polymerization of cellulose, revealing that hydrolyzes were carried out under the typical endo-exo synergism of fungal enzymes.

Effect of methylxanthines on production of cellulases by Penicillium echinulatum

AIM

In this work, the effect of supplementing liquid cellulase production media (CPM) with methylxanthines (aminophylline, caffeine and theophylline), with and without the addition of glucose, on the secretion of cellulases by Penicillium echinulatum strain 2HH (wild-type) and the derived mutant strain 9A02S1 was studied.

METHODS AND RESULTS

When compared with unsupplemented CPM, both strains produced higher beta-glucosidase and filter paper activities (FPAs) in CPM supplemented with 1 micromol l(-1) of caffeine but lower activities with 5 micromol l(-1) of caffeine. With theophylline only, strain 9A02S1 produced higher beta-glucosidase and FPAs, while aminophylline produced no effect on the cellulase activity of either strain. Supplementation of CPM with 0.5% (w/v) of glucose plus caffeine resulted in higher beta-glucosidase and FPAs being produced by strain 2HH, but not strain 9A02S1, than in CPM supplemented with 0.5% (w/v) of glucose only.

CONCLUSIONS

These results indicate that different concentrations of caffeine and theophylline can increase the beta-glucosidase and FPAs produced by P. echinulatum strains 2HH and 9A02S1.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results suggest that some methylxanthines, in adequate concentration, can be used as media components to increase cellulase production.

Cellulase production by Penicillium echinulatum on lactose

The inducer effect of lactose on cellulase activity in Penicillium echinulatum 9A02S1 was studied. Submerged cultivation was performed using different concentrations of lactose and cellulose, in which the pH, mycelial mass, soluble proteins, filter paper activity (FPA), and activity of beta-glucosidases were measured. The cultures containing lactose only presented low FPAs (0.1 FPU/ml). The cultures with associated cellulose and lactose and those containing cellulose only presented similar enzymatic activities (1.5 FPU/ml), suggesting the possibility of up to 75% reduction in the cellulose concentration. In relation to the beta-glucosidases, increasing the lactose/cellulose ratio results in a proportional increase of enzymatic activity. In the cultures using both inducers, there is a longer duration of the acid phase in relation to treatments using only cellulose or lactose, indicating diauxia and catabolic repression.