Production and properties of polygalacturonate lyase by an alkalophilic microorganism Bacillus sp. RK9

Bacillus sp. RK9 was isolated from soil and produced a constitutive polygalacturonate lyase. Production of the enzyme required the presence of complex nitrogen (peptone and yeast extract). Highest activity was obtained with an initial pH of 9.7. The organism was alkalophilic. No growth occurred below pH 7.5. The enzyme was purified by salt precipitation and diethylaminoethyl (DEAE) cellulose ion-exchange chromatography. The pH optimum for activity was 10.0 in 0.01 M glycine-NaOH buffer. Calcium alone, of divalent cations, activated the enzyme by 2.9-fold. Complete inhibition of enzyme activity was achieved by 1 mM ethylenediaminetetraacetic acid (EDTA). Hydrolysis of substrate occurred in a random fashion and the enzyme was 50% more active towards acid soluble pectic acid (ASPA) than towards sodium polypectate.