Purification and Partial Characterization of an Amylase from Lysobacter brunescens

SUMMARY: Four species of the genus Lysobacter, especially L. brunescens and L. gummosus, produced amylase when grown in liquid medium containing starch. The amylase was purified nearly 1200-fold with a 36% yield from the culture supernatant of L. brunescens by ammonium sulphate precipitation, CM-52 cellulose chromatography and gel filtration. An M r of 47000–49000 was estimated for the enzyme from results of SDS-PAGE and glycerol gradient centrifugation, respectively. Metal ions such as Mg2+, Ca2+, Mn2+ or Zn2+ are not required for activity. The amylase is active from pH 5.0 to 7.5, degrades starch endohydrolytically and has a K m of 2.08 mg starch ml-1. Amylopectin, amylose and glycogen were also hydrolysed. Dextran, maltose, maltotriose, maltotetraose and 4-nitrophenyl α-d-glucoside were hydrolysed very slowly, or not at all. Other enzymes capable of degrading starch, maltose or malto-oligosaccharides were not detected in the culture supernatant of L. brunescens.