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Volume 2 Number 1 2008 
CONTENTS AND ABSTRACTS
Buddolla Viswanath (South Africa/India), M. Subhosh Chandra (South Korea/India), K. Praveen Kumar, H. Pallavi, B. Rajasekhar Reddy (India) Fungal Laccases and Their Biotechnological Applications with Special Reference to Bioremediation (pp 1-13)
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ABSTRACT
Invited Mini-Review: The exploration for efficient and green oxidation technologies has increased the interest in the use of enzymes to replace conventional non-biological methods. Among the different existing oxidant enzymes, laccases have been the subject of study due to their importance in environment protection, where enzymatic catalysis could serve as a more environmentally benign alternative than the currently used chemical processes. Fungal laccases are extracellular multi-copper oxidases mainly secreted by filamentous fungi. They have been attracting the attention of environmental scientists because of their ability to oxidise a wide variety of aromatic compounds. Though the laccases are demonstrated to have a range of promising applications, they are used in bioremediation of soils, water and the development of environmentally friendly processes in the pulp and paper industry. This paper reviews the potential applications of laccase enzymes with special reference to bioremediation.
Dariush Norouzian (Iran) Effect of Different Factors on Fermentative Production of Enzymes by Fungi (pp 14-18)
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Invited Mini-Review: Fungi are exploited to produce extracellular enzymes which are of prime importance in academia, industrial biotechnology and ultimately commerce. To produce and exploit enzymes during the fermentation processes by fungi, various factors can affect productivity. The environment provided to the fungi for such tasks should be friendly, and henceforth, the environment where the fungi are to be cultivated must provide uniform distribution of nutrients, maintenance of optima hydrogen ion concentration, temperature, oxygen through agitation where the last mechanical factor could cause the fragmentation and breakage of the fungal mycelia thus influencing the yield.
Buddolla Viswanath, M. Subhosh Chandra, K. Praveen Kumar, B. Rajasekhar Reddy (India) Production and Purification of Laccase from Stereum ostrea and its Ability to Decolorize Textile Dyes (pp 19-25)
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Original Research Paper: Because of its broader specificity to oxidise both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant pollutants, laccase was optimally produced on medium with 0.02% guaiacol by growth of Stereum ostrea for 4 days in submerged culture. Inclusion of guaiacol in the medium enhanced laccase production by 7-fold. Extracellular laccase was purified up to 70-fold from the culture filtrate by a two-step protocol ? ammonium sulphate (80% w/v) and Sephadex G-100 column chromatography. The purified enzyme, which was characterized for its kinetic properties, had an apparent molecular mass of 66 kDa. The optimal pH and temperature were found to be 6.0 and 40°C, respectively. The Km and Vmax values for the substrate guaiacol were found to be 13.25 mM and 255 nkat/mg of protein, respectively. The effect of inhibitory compounds, EDTA, SDS and arginine on laccase activity was determined. With SDS, the percentage inhibition increased as the concentration of SDS decreased from 5 to 0.5%. The purified enzyme decolourized textile dyes up to 90%. The decolourization ability of S. ostrea laccase suggests that this enzyme could be used for decolourization of industrial textile dyes.
Dariush Norouzian, Azim Akbarzadeh, Seyed Mohammad Atyabi, Ali Farhangi (Iran) Kinetic Characteristics of Immobilized Tyrosinase of Edible Mushroom in Synthesizing L-3, 4-Dihydroxyphenylalanine (L-Dopa) (pp 26-29)
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ABSTRACT
Original Research Paper: Tyrosinase (EC 1.14.18.1) from edible mushroom was immobilized onto agar particles activated by various concentrations of sodium periodate solution. It was found that agar activated with 200 and 300 mM periodate solution could adsorb the highest amount of tyrosinase. The progress of the reactions of two forms of tyrosinases (soluble tyrosinase and tyrosinase covalently bound to activated agar particles) were linear up to 50 and 120 min, respectively. The Michaelis-Menten constant (Km) values of free and immobilized tyrosinases were determined as 0.8 and 0.9 mM, respectively by Lineweaver-Burk plots. The optimum temperature of the immobilized tyrosinase increased from 25 to 35°C while the optimum pH of the immobilized form remained unchanged relative to free tyrosinase. The immobilized tyrosinase on agar was recycled 6 times maintaining 50% of its original activity at the end of the last cycle.
Roseli Garcia Medeiros, Lais Araujo Coelho, Edivaldo Ximenes Ferreira Filho (Brazil) Agricultural Residues as Source for Production of Hemicellulases from Humicola grisea var. thermoidea (pp 30-33)
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ABSTRACT
Original Research Paper: The filamentous fungus Humicola grisea var. thermoidea produces hemicellulose-degrading enzyme activities when grown in the presence of different carbon sources, including wheat bran, oat spelt xylan, cellulose (avicel), oat bran, banana stem and coffee spent-ground. The best yield of β-xylanase, β-mannanase and α-arabinofuranosidase activities was given by the crude extract sample from a medium containing coffee spent-ground as the carbon source. The previous crude extract preparation was submitted to ultrafiltration in an Amicon system fitted with a 10 kDa-cut-off membrane. A considerable amount of β-xylanase, β-mannanase and α-arabinofuranosidase activities was found in the retentate and used for subsequent characterization. β-Mannanase, β-xylanase and α-arabinofuranosidase showed highest activity at 50, 55 and 80°C, respectively. β-Mannanase and α-arabinofuranosidase activities were stable at 50°C. However, β-xylanase was less stable. A purified b-xylanase (Xyn III), obtained through growth of the filamentous fungus H. grisea var. thermoidea in liquid medium containing banana stem as carbon source, was characterized with regard to some enzymatic properties and its action on xylan. The enzyme showed best activity at pH 7.0 and 55°C and half life of 20 min at 60°C. Xyn III exhibited preferential activity towards xylan. The determination of kinetic parameters showed that the enzyme had more affinity against insoluble arabinoxylan as substrate. DTT and DTP activated Xyn III. In contrast, NBS, XIP-1, EDC and iodoacetamide inhibited the enzyme activity.
Behnam Elhami, Naser Alemzadeh Ansari, Farideh Sedighie Dehcordie (Iran) Effect of Substrate Type, Different Levels of Nitrogen and Manganese on Growth and Development of Oyster Mushroom (Pleurotus florida) (pp 34-37)
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Original Research Paper: An experiment was conducted to increase oyster mushroom production and to evaluate the effect of different treatments on the quantitative and qualitative growth of Pleurotus florida. Two substrates (sugarcane bagasse and wheat straw) were tested, supplemented with different levels of N (0, 500, 750 μg/g), and Mn (0, 100, 200 μg/g). Different levels of nitrogen and manganese significantly affected mycelia lineal growth rate, spawn running, pinhead and fruit body formation, protein content, yield and biological efficiency but there was no significant effect on ash, dry matter and manganese content of fruit bodies. Substrate type had a significantly effect on all characters with the exception of manganese content of the fruit body. The most positive effect of N and Mn on measured characters was observed at 750 and 100 μg/g, respectively. Wheat straw substrate caused an increase in yield and reduced fruiting time compared to sugarcane bagasse. Sugarcane bagasse, on the other hand, had a higher feed value (content of protein, ash, and dry matter) than wheat straw when used as a substrate.
Ikechukwuka Cyriacus Okwulehie, Ikechukwu Adiele Okwujiako (Nigeria) The Use of Local Nigerian Substrates for the Production of Pleurotus ostreatus var. Florida Eger. Sporophores (pp 38-40)
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Short Communication: Andropogon, Panicum, Pennisetum and Oryza straws used in this study all supported the fructification of Pleurotus ostreatus var. florida Among these local Nigerian substrates, Andropogon straw supported a significantly higher fruit-body yield and fresh weight than all other straws. Panicum straw yielded the lightest and shortest fruit-bodies. Pennisetum straw resulted in the widest and longest pileus.
Ikechukwuka Cyriacus Okwulehie, Ikechukwu Adiele Okwujiako (Nigeria) The Effects of Some Physical and Nutritional Factors on the Vegetative Growth of Pleurotus ostreatus var. florida Eger. under Tropical Conditions (pp 41-44)
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Original Research Paper: Pleurotus ostreatus var. florida culture was grown on different media and agricultural wastes and also subjected to a range of temperatures and pH to investigate their influence on the performance of the mycelium. The mushroom mycelium grew best between 25 and 35°C and least at 15°C. Mycelial growth sharply decreased at ?35°C. Similarly, a pH range of 6.0-8.0 produced maximum mycelial extension, 72.90?78.66% more than the control. Mycelial yield decreased at pH below 6 and above 8. Least mycelial extension was recorded at pH 3.0. However, pH values higher than 6.0?8.0 retarded the growth of the mycelium. Mushroom mycelium grew best on oat meal yeast agar (OMYA), followed by corn meal yeast agar (CMYA), then by potato dextrose yeast agar (PDYA). Poorest growth occurred on malt extract yeast agar (MEYA), although not significantly different from that on CMYA and PDYA. The density and growth (i.e. distinct mycelial masses) of the mushroom had the highest rating on OMYA followed by CMYA, PDYA and MEYA. CMYA produced the heaviest mycelial mass followed by OMYA. Similarly the mushroom mycelium grew well on Andropogon gayanus, Pennisetum purpureum and Oryza sativa straws, but very poorly on Panicum maximum straw. The fastest mycelial extension occurred on A. gayanus straw followed by P. purpureum and O. sativa straws, although not significantly so. Our results are discussed in relation to the importance of mycelia as soup ingredients, in the production of different flavours and cellulolutic enzymes in the food industry and as biological control agents to trap nematodes and other plant disease agents.
Ikechukwuka Cyriacus Okwulehie, Ikechukwu Adiele Okwujiako (Nigeria) Effect of Hole Size and Number on the Fruit-Body Yield of P. ostreatus var. florida Eger. (pp 45-46)
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Short Communication: In this study we wished to determine the effects of plastic pail hole size (sizes 1, 2, 3 and 4 corresponding to 7, 8, 9 and 10 cm, respectively) and number (54, 63, 72 or 81) on the yield and yield characteristics of P. ostreatus var. florida. Hole size 3 resulted in significantly higher fruit-body number and fresh weight than other hole sizes. Similarly, hole size 3 had fruit-bodies with a significantly wider pileus diameter and stipe length than fruit-bodies produced in hole sizes 1, 2 and 4. The stipe length of the fruit-bodies produced in all hole sizes were not significantly different. Plastic buckets with 72 or 63 holes produced larger and heavier fruit-bodies than 54 and 81 holes. Hole number did not significantly influence the pileus diameter or the stipe length of the mushrooms. Our results are discussed in the context of using appropriate containers for the production of large quantities of sizeable mushroom fruit-bodies.
Ramesh C. Ray, Samir K. Naskar (India) Bioethanol Production from Sweet Potato (Ipomoea batatas L.) by Enzymatic Liquefaction and Simultaneous Saccharification and Fermentation (SSF) Process (pp 47-49)
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Short Communication: The starch content in sweet potato (Ipomoea batatas var. Sankar) flour and fresh tubers was liquefied by treatment with 0.08% (v/w) commercial thermostable α-amylase (TermamylR, Novozyme, Denmark) and 0.33% (v/w) amyloglucosidase (AMGR, Novozyme, Denmark). The hydrolysate was subsequently fermented with a thermotolerant strain of Saccharomyces cerevisiae into ethanol. The result showed that the final ethanol yield of 240 and 235 g.kg-1 (flour) and 96 and 93 g.kg-1 (tuber), was little influenced by liquefaction conditions i.e. 80°C for 2 h and 90°C for 1 h, respectively in conjunction with treatment of 0.33% (v/w) AMG (45°C for 24 h). Similarly, the treatment of AMG for 45°C for 48h and 45°C for 24 h had little effect on the ultimate ethanol yield, i.e. 242 and 238 g.kg-1 (flour) and 94 and 93 g.kg-1 (tuber), respectively after liquefaction (90°C for 1 h) treatment. Another experiment was designed to study simultaneous saccharification and fermentation by saccharifying the liquefied (90°C for 1 h) hydrolysate and co-fermenting with S. cerevisiae at 40°C for 96 h. The ethanol yield was 258 g.kg-1 for flour and 95 g.kg-1 for tuber, respectively.
Quancheng Zhou, Guihua Sheng (China) Application of Simple Factorial Design and Response Surface Methodology to Optimize Biodiesel and VE Production from Soybean Deodorization Distillates (pp 50-55)
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Original Research Paper: The production of fatty acid methyl esters (FAME) used as a diesel substitute (biodiesel) was studied. The reaction of soybean deodorization distillates (SDDs) and methanol was carried out in a two-step reaction, the first step being the methyl esterification of free fatty acid (FFA) and the second step being the transesterification of triglycerides. The process of biodiesel production and the process of biodiesel and VE production from esterified SDDs were optimized using a simple factorial design and response surface methodology. A second-order model was obtained to predict the optimum extraction conditions. The optimum conditions for methyl esterifications of FFA were 65°C for 3 h at a catalyst concentration of 4.2%; the optimum conditions for transesterification of triglycerides were 74.4°C for 2.1 h with a catalyst quality of 0.49%. FAME and Vitamin E (VE) were extracted with supercritical CO2 at 120 and 250 bar, respectively. Optimum conditions for the extraction of biodiesel were extraction pressure 120 bar, extraction temperature 60°C and a CO2 flow rate of 15.0 kg/h; optimum conditions for the extraction of VE were extraction pressure 250 bar, extraction temperature 40°C and a flow rate of 25.0 kg/h. Under the optimum conditions, FAME and VE were successfully extracted. FAMA concentration and yield rate in the extraction were 87 and 82%, respectively, and the VE concentration and yield rate in the extraction were 48 and 0.84%, respectively.
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