Cristina Giatti Marques de Souza

Effect of easily metabolizable sugars in the production of xylanase by Aspergillus tamarii in solid-state fermentation

Abstract The effect of easily metabolizable sugars (glucose, xylose, fructose, maltose, cellobiose and lactose) on xylanase production by Aspergillus tamarii in solid-state fermentation (SSF) was studied using wheat bran, corn cob and sugar cane bagasse as substrate. The addition of different sugars at a concentration of 1% to sugar cane bagasse or corn cob media caused severe catabolic repression. In contrast, wheat bran systems were resistant to catabolic repression even at high concentrations of glucose (10%). In wheat bran cultures, glucose uptake was very efficient and less than 5% of initial glucose concentration was present in the culture medium after 4 days of cultivation. In corn cob and sugar cane bagasse cultures, glucose uptake was slower and more than 60% of the initial glucose concentration was present in the culture medium after 4 days of cultivation. These results demonstrate the importance of the nature of the substrate used in solid state cultures to obtain a system resistant to catabolic repression.

Decolourisation of industrial dyes by solid-state cultures of Pleurotus pulmonarius

A solid-state system to obtain rapid in vivo industrial dye decolourisation by the white-rot fungus Pleurotus pulmonarius is proposed. When cultivated on glucose\ammonium tartrate–corncob solid-state medium, P. pulmonarius decolourised structurally different synthetic dyes (including azo, triphenylmethane, heterocyclic and polymeric dyes). Amido black, congo red, trypan blue, methyl green, remazol brilliant blue R (RBB), methyl violet, ethyl violet and brilliant cresyl blue were completely decolourised after 6 days of cultivation, while methylene blue and Poly R-478 were partially decolourised. The capability of fungal culture to decolourise industrial dyes appears to be due to high titres of laccase (480 U/ml) produced in response to the presence of soluble phenolics.

Decolorization of Industrial Dyes by a Brazilian Strain of Pleurotus pulmonarius Producing Laccase As the Sole Phenol-Oxidizing Enzyme

The ability of a Brazilian strain ofPleurotus pulmonarius to decolorize structurally different synthetic dyes (including azo, triphenylmethane, heterocyclic and polymeric dyes) was investigated in solid and submerged cultures. Both were able to decolorize completely or partially 8 of 10 dyes (Amido Black, Congo Red, Trypan Blue, Methyl Green, Remazol Brilliant Blue R, Methyl Violet, Ethyl Violet, Brilliant Cresyl Blue). No decolorization of Methylene Blue and Poly R 478 was observed. Of the four phenol-oxidizing enzymes tested in culture filtrates (lignin peroxidase, manganese peroxidase, aryl alcohol oxidase, laccase),P. pulmonarius produced only laccase. Both laccase activity and dye decolorization were related to glucose and ammonium starvation or to induction by ferulic acid. The decolorizationin vivo was tested using three dyes — Remazol Brilliant Blue R, Trypan Blue and Methyl Green. All of them were completely decolorized by crude extracellular extracts. Decolorization and laccase activity were equally affected by pH and temperature. Laccase can thus be considered to be the major enzyme involved in the ability ofP. pulmonarius to decolorize industrial dyes.

Hepatoprotective Effects of Mushrooms

The particular characteristics of growth and development of mushrooms in nature result in the accumulation of a variety of secondary metabolites such as phenolic compounds, terpenes and steroids and essential cell wall components such as polysaccharides, β-glucans and proteins, several of them with biological activities. The present article outlines and discusses the available information about the protective effects of mushroom extracts against liver damage induced by exogenous compounds. Among mushrooms, Ganoderma lucidum is indubitably the most widely studied species. In this review, however, emphasis was given to studies using other mushrooms, especially those presenting efforts of attributing hepatoprotective activities to specific chemical components usually present in the mushroom extracts.

Copper improves the production of laccase by the white-rot fungus Pleurotus pulmonarius in solid state fermentation

Pleurotus pulmonarius (Fr) Quelet, um basidiomiceto causador da podridao branca da madeira produz lacase como principal enzima ligninolitica quando cultivado em meio em estado solido utilizando sabugo de milho como substrato. O ion cobre tem grande efeito na producao da enzima. Os melhores resultados foram obtidos pela adicao de 25.0 mM de CuSO4 que causou uma elevacao dos niveis enzimaticos de 270 U.L-1 para 1.420 U.L-1 O fungo mostrou uma alta resistencia ao ion cobre nas condicoes de cultivo utilizadas neste trabalho.

Xylanase production byAspergillus tamarii

Aspergillus tamarii has been found to grow well and to produce high cellulase-free xylanase activity when growing on corn cob powder as the principal substrate. Maximum xylanase production (285-350 U/mL) was obtained when the strain was grown in media supplemented with high corn cob concentration (5-8%, w/v) for 5 d. The presence of constitutive levels of xylanase was detected in cultures with glucose as the carbon source. Zymogram analysis for detection of xylanase activity after electrophoresis in polyacrylamide gels has shown thatA. tamarii produces at least two xylanases under the conditions utilized. The hydrolysis patterns of xylan demonstrated that the xylanases were endoenzymes, yielding mainly xylobiose, xylotriose, and higher xylooligosaccharides with traces of xylose.

Production of laccase as the sole phenoloxidase by a Brazilian strain of Pleurotus pulmonarius in solid state fermentation.

The production of laccase by a Brazilian strain of Pleurotus pulmonarius was studied in solid state fermentation using wheat bran as substrate. Among oxidative and hydrolytic enzymes tested (laccase, aryl alcohol oxidase, lignin peroxidase, Mn peroxidase, xylanase and cellulase), laccase was the main enzyme produced by P. pulmonarius. The most suitable condition for maximum production of laccase (8,600 U/g substrate) was initial moisture content of 75% and 5 days of cultivation at 30 °C. The optimum pH and temperature for laccase activity were found to be 6.5 and 50 °C, respectively. P. pulmonarius laccase was stable at 50 °C for more than 6 hours, and it retained about 73% and 18% of its activity when heated for 1 h at 55 and 60 °C, respectively. The enzyme was greatly stable at alkaline pH, but not at acidic pH. The laccase activity appear to be correlated with the ability of crude extract to decolourize several industrial dyes.

Solid-State Bioconversion of Passion Fruit Waste by White-Rot Fungi for Production of Oxidative and Hydrolytic Enzymes

Yellow passion fruit waste (YPFW) is an abundant food waste in Brazil, rich in carbohydrates. The aim of the present work was to obtain useful oxidative and hydrolytic enzymes. YPFW solid-state cultures were done using the food-grade white-rot fungi Pleurotus ostreatus, Pleurotus pulmonarius, Macrocybe titans, Ganoderma lucidum, and Grifola frondosa. Under the conditions used in this work, the main enzymes produced by the fungi were laccases, pectinases, and aryl-β-d-glycosidases (β-glucosidases, β-xylosidases, and β-galactosidases). Laccases were produced by all fungi, and in this respect, the YPFW was as good as substrate as wheat bran, the most commonly substrate used for white-rot fungi cultivation. M. titans was the best producer of pectinase in YPFW cultures, while P. ostreatus and P. pulmonarius were the best producers of aryl-β-glycosidases in both YPFW and wheat bran cultures.

Production of amylases by Aspergillus tamarii

A strain of Aspergillus tamarii, a filamentous fungus isolated from soil, was able to produce both a-amylase and glucoamylase activities in mineral media supplemented with 1% (w/v) starch or maltose as the carbon source. Static cultivation led to significantly higher yields than those obtained using shaking culture. The production of amylases was tolerant to a wide range of initial culture pH values (from 4 to 10) and temperature (from 25 to 42oC). Two amylases, one a-amylase and one glucoamylase, were separated by ion exchange chromatography. Both partially purified enzymes had optimal activities at pH values between 4.5 and 6.0 and were stable under acid conditions (pH 4.0-7.0). The enzymes exhibited optimal activities at temperatures between 50o and 60o C and were stable for more than ten hours at 55oC.

Endophytic fungi: expanding the arsenal of industrial enzyme producers

Endophytic fungi, mostly belonging to the Ascomycota, are found in the intercellular spaces of the aerial plant parts, particularly in leaf sheaths, sometimes even within the bark and root system without inducing any visual symptoms of their presence. These fungi appear to have a capacity to produce a wide range of enzymes and secondary metabolites exhibiting a variety of biological activities. However, they have been only barely exploited as sources of enzymes of industrial interest. This review emphasizes the suitability and possible advantages of including the endophytic fungi in the screening of new enzyme producing organisms as well as in studies aiming to optimize the production of enzymes through well-known culture processes. Apparently endophytic fungi possess the two types of extracellular enzymatic systems necessary to degrade the vegetal biomass: (1) the hydrolytic system responsible for polysaccharide degradation consisting mainly in xylanases and cellulases; and (2) the unique oxidative ligninolytic system, which degrades lignin and opens phenyl rings, comprises mainly laccases, ligninases and peroxidases. The obvious ability of endophytic fungi to degrade the complex structure of lignocellulose makes them useful in the exploration of the lignocellulosic biomass for the production of fuel ethanol and other value-added commodity chemicals. In addition to this, endophytic fungi may become new sources of industrially useful enzymes such as lipases, amylases and proteases.