Screening for agarolytic bacteria and development of a novel method for in situ detection of agarase

Abstract

A preliminary screening for agar-degrading bacteria from the coastal waters of India yielded two isolates, 10A and LK2, with promising agarolytic activity. Both isolates showed extensive pit formation as well as clearance zones on agar plates. Enzyme from strain LK2 was selected for further characterization. The total proteins in LK2 culture supernatant were precipitated with ammonium sulfate and dialyzed to obtain a partially purified agarase. The enzyme preparation (0.4 mg protein) could completely liquefy 0.7 percent low-melting-point agarose within 20 min at 45 degrees C. A novel procedure for in situ detection of agarase was developed using SDS-polyacrylamide gel electrophoresis followed by agarose overlay and Lugol's iodine staining of the gel. Two bands showing agarolytic activity were obtained, corresponding to molecular masses of about 25 and 28 kDa, respectively.