STUDY ON ERGOSTEROL CONTENT AND PROTEIN PROFILE OF MEDICINAL MUSHROOM, Ganoderma lucidum
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Date
2013
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PAU Ludhiana
Abstract
Ganoderma lucidum, a specie belonging to the class basidiomycetes, family polyporaceae of the order
aphyllophorales has been widely used as a source of potent nutracuetical products. Present study was planned to
identify and characterize the role of proteins and ergosterol in the developmental process of Ganoderma lucidum.
Four strains of Ganoderma lucidum (GL I - IV) showed a gradual increase in biomass to give 25.52g to 31.72g of
biomass after three weeks of growth in mushroom complete medium broth with maximum in strain GL-III.
Ganoderma lucidum strains were grown on wheat straw supplemented with 5% wheat bran with maximum
biological efficiency for GL-I strain (31.27%) followed by GL-II (26.76%) and number of fruit bodies were 927
and 693 each weighing 33.7g and 38.6g, respectively. Ganoderma lucidum strain GL-I showed maximum
ergosterol content (4601μg/g) whereas strain GL-III showed only 32μg/g. From spawn run, maximum ergosterol
was obtained from GL-IV strain followed by strain GL-II while at pin head formation and fruit body formation
ergosterol content was better for GL-II. Ergosterol content of fruit body of GL-1 was observed maximum
(7009μg/g). Overall observation indicated that the ergosterol content increased with each stage of cultivation
process i.e. from spawn run to pinhead and finally to fruit body formation. The intracellular and extracellular
enzymatic studies have indicated enhanced activity during spawn run on solid substrate in comparison to that
grown in the broth. The esterase and peroxidase activity significantly increased during the pinning of the cultures
thus, indicating a positive role of these enzymes in fructification process. The FTIR analysis of proteins made
during different stages of cultivation namely spawn run, pin head formation and fruiting indicated that the fruiting
strains (GL-I and GL-II) have an ordered protein structure with hydrophobic amino acids. In case of GL-IV,
unordered structure was obtained that could be related to the role of hydrophobin proteins in mushroom
fructification process. Another observation on GL-IV indicated the presence of basic amino acids and aromatic
amino acids with very low amount of acidic amino acids like aspartic acid and glutamic acid. The observation
recorded during present study indicated a positive role of hydrophobic amino acids and hydrophobin proteins in
mushroom fructification process. Ganoderma lucidum strain GL-II was also grown on selenium fortified
mushroom minimal medium at different concentrations of 5ppm to 25ppm of sodium selenate. Scanning electron
micrographs exhibited gradual decrease in hyphal diameter, spore number and spore diameter with increase in
selenium concentration and the spore structures were altered. A significant decrease in spore diameter is observed
in concentration of 20ppm and 25ppm (5.60 and 1.26 μm, respectively) as compared to control (10.04 μm). The
SEM-EDS studies showed no selenium traces on the hyphal surface, however, on the contrary, SEM-EDS studies
of crushate samples revealed selenium traces indicating selenium absorption as the cytosolic moieties as
selenoproteins. Atomic absorption spectroscopy indicated an increasing trend in the uptake by the hyphal biomass
as the concentration of sodium selenate increased with maximum absorption at concentrations of 15 ppm and 25
ppm (9.9%). It was concluded that fortification till 15 ppm can be used as stress was not that prominent and culture
could grow rapidly without significant alteration in structure and morphology to enhance its biomedicinal
properties. Present study has indicated that during the mushroom development process, ergosterol content
increases with a positive role of proteins like peroxidases and hydrophobins at each stage of morphogenesis.
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