AbstractA strainof Bacillus subtilis(IMD198) isolated from peat degraded starch to maltose with little production of glucose and other products. Highest levels of enzyme were achieved in a salts medium containing soya bean meal and starch. The enzyme was purified by precipitation with isopropanol, adsorption on calcium phosphate gel and fractionation on DEAE‐and CM‐cellulose ion‐exchange resins. The latter chromatographic procedure removed a contaminating activity that produced dextrins as end‐products from starch or amylose. The action pattern of the purified, major enzyme activity indicates that it may be β