J. Basic Microbiol. 44 (2004) 1, 29 – 35 DOI: 10.1002/jobm.200310302 © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 0233-111X/04/0102-0029 (Departamento de Bioquímica, Universidade Estadual de Maringá, 87020-900, Maringá, PR. Brazil) A thermostable maltose-tolerant α-amylase from Aspergillus tamarii FABIANA GUILLEN MOREIRA, VERIDIANA LENARTOVICZ and ROSANE MARINA PERALTA* (Received 05 May 2003/Accepted 10 July 2003) An homogeneous fraction of α-amylase from Aspergillus tamarii was obtained by means of a very easy purification procedure. The enzyme is a glycoprotein containing 32% saccharide and MW of 37.5 kDa. Optimal of pH and temperature with starch as substrate were 4.5 – 6.5 and 50 – 55 °C. The enzyme was stable for several hours at temperature up to 65 °C. Starch, amylose, and amylopectin were the substrates preferentially hydrolysed and maltose and maltotriose were the main end products. The values of K M and V max for starch were 2 g/l and 880 μmoles reducing sugars/min.mg of protein, respectively. The purified enzyme was remarkably insensitive to end product inhibition, being only slightly inhibited by maltose and glucose up to 1.0 M. α-amylases (endo-1,4 α-D-glucan glucohydrolase, E.C. 3.2.1.1) are extracellular enzymes that randomly cleave the 1,4 α-D glucosidic linkages between adjacent glucose units in the linear amylose chain. α-amylases may be derived from several bacteria, yeasts and fungi. Bacterial amylase, however, is generally preferred over fungal amylase due to several char- acteristics advantages that it offers, especially its thermostability (PANDEY et al. 2000). For this reason, the majority of commercial preparations of amylases are produced by bacterial sources, especially from Bacillus species, and an extensive screening, purification, and characterisation of bacterial amylases has already been reported (PANDEY et al. 2000, GUZ- MÁN-MALDONADO and PAREDES-LÓPES 1995). In spite of among fungi the studies are more limited, attempts have been done to increase the production and to obtain homogeneous fractions of amylase among mesophilic and thermophilic fungi (GUZMÁN-MALDONADO and PAREDES-LÓPES 1995, JENSEN and OLSEN 1992, ABOUD-ZEID 1997, PARK et al. 1995, CHANG et al. 1995, PLANCHOT and COLONNA 1995, KHOO et al. 1994, SIQUEIRA et al. 1997, ODIBO and ULBRICH-HOFMANN 2001). In fungi, detailed studies on α-amylase purifi- cation have largely been limited to a few species of mesophilic fungi, particularly Aspergil- lus sp. Most purified Aspergillus sp. α-amylase presented molecular weight ranging from 50 to 75 kDa, optimum temperature of 30 – 55 °C and optimum pH of 4.0 – 7.0 (PANDEY et al. 2000). A strain of Aspergillus tamarii isolated from soil during a screening program for amylase- producing microorganisms has been described as able to produce both liquefying (α-amy- lase) and saccharifying (glucoamylase) activities. Its α-amylase was responsible by more than of 70% of total amylolytic activity found in the culture filtrates (MOREIRA et al. 1999). In this work, we described the purification and some physicochemical properties of the α-amylase from A. tamarii that showed thermostability and remarkable insensitivity to end product inhibition, glucose and maltose. * Corresponding author: Dr. R. PERALTA; e-mail: rmperalta@uem.br