Abstract:
The ability of the edible mushroom Pleurotus ostreatus to produce extra cellular
enzymesof industrial importance - Beta-amylase, Alpha-amylase, Protease and Cellulase
were monitored using readily available agricultural wastes namely, sawdust, rice bran,
wheat bran and palm kernel peri carp in submerged fermentation .Fresh fruiting body of
Pleurotus ostreatus was collected and identified using standard method. Tissue culture
technique was employed in obtaining active mycelium of the mushroom from its fresh
fruiting body. Proximate and mineral compositions of the agricultural wastes were
determined before and after fermentation. The composition of the wastes was observed
to affect the quantity as well as the activity of the enzyme assayed. Rice bran had the
highest beta-amylase activity of 220llmollminlml between 48 and 72hours of
fermentation and it was used for further experiment. The beta-amylase isolated from
Pleurotus ostreatus was purified by ion exchange chromatography on DEAE Sephadex
A- 50 and Gel filtration G-150. The effect of variation in pH, temperature and different
salts on the activity of the enzyme was investigated. The optimum pH was recorded to be
5.5 while optimum temperature was 55°C. Salts namely CaCI2, CUS04, NaCl, EDTA,
MgClz and HgCh was observed to have inhibitory effect on the activity of the enzymes
with the highest inhibition recorded with HgCI and EDTA while CaCh has least
inhibitory effect on the enzyme. The Michaelis-menten constant, Km, was
3.57umol/minlml while the maximum velocity Vmax, was 0.21 umole/min/ml The low
Km values, physicochemical properties and improved activities of ~-amylase from the
mushroom Pleurotus ostreatus makes it a more favoured alternative to ~-amylase from
other microorganisms for industrial scale applications.
