[+l h"i't 2013, lmpact of Global Climate Change on Earth Ecosystems Editors: D.R. Khanna, A.K. Chopra, Gagan Matta, Vikas Singh & Rakesh Bhutiani Published by:BIOTECH BOOK$ NEW DELHI Poges 205-274 Chapter 26 Screening of Aspergillu.s spp. for Extra Cellular a-Amylase Activity '4shoh Ku,ma.t', Jogindu Singh Duhanl and Sunil Ku,mar Tananf 1 Dep artment of Biot echnology, Ch. Deai Lal Uniaersity, Sirsa - 125 055,Haryana 2 Dep artment of Biot echnolo gy and lr.4icr obiolo gy, Meerut Institute of Engineering and Technology, Meerut - 250 005, U.P. Nine fungal strains of, A. candidus, A. flaaus 873, A. flaaus, A. terrus, A. ocraceous, A. sulphureus, A. oryzae, A. allahabadi andA.fumigatuswere screened for alpha-amylase activity on starch agar plates.Performance of each strain was recorded in terms of hydrolysingzone formation. On the basisof the maximum halos formation and enzyme activity by solid state fermentation, A. sulphureus (956 U/ml) andA. oryme(9a0 U/ml) were selected for periodic evaluation of their dinna amylase activity. Amylasewas found to be optically activeat pH 8.0 and was acid stableat pH 4.5. Optimum activity was recorded at 50"C in caseof A. sulplureus and at 40"C in case of A. oryzae. Thermal stability was observed in the range of 30 to 70"Cfor thour. The amylase showed maximum activity at 30"C and further increase in terr[perature to 70'C for t hour reducesthe enzyme activity to 65 per cent.The amylase was slightly repressed by Na- and Mg--but not inhibited by Hg-. at 2mM concentration.Ca.-and K* enhanced the amylase activity. Keyu ords : Asper giII us, a-nntylase, Amylnse nctioity.