Alanine dehydrogenase (EC 18.104.22.168), in the presence of NAD(+), catalyzes the reversible deamination of L-alanine. Screening of alanine dehydrogenase in bacillus strains was carried out to develop its utilization as an industrial and analytical catalyst. Eight bacillus strains were used, including Bacillus megaterium LA 199 which abundantly produces enzymes. Alanine dehydrogenase was purified simply from Bacillus megaterium LA 199 by heat treatment at pH 5.4, followed by DEAE-Sepharose CL-6B and Sepharose CL-2B chromotography. The enzyme consisted of six subunits with an identical molecular mass of 42.5 kDa. The Km were 1.17 x 10(-2)mM for NADH and 5.12 x 10(-2) mM for pyruvate.