Purification and characterization of a novel extracellular halophilic and organic solvent-tolerant amylopullulanase from the haloarchaeon, Halorubrum sp. strain Ha25

Extremophiles. 2014 Jan;18(1):25-33. doi: 10.1007/s00792-013-0589-6.

Abstract

A halophilic archaeon, Halorubrum sp. strain Ha25, produced extracellular halophilic organic solvent-tolerant amylopullulanase. The maximum enzyme production was at high salt concentration, 3-4 M NaCl. Optimum pH and temperature for enzyme production were 7.0 and 40 °C, respectively. Molecular mass of purified enzyme was estimated to be about 140 kDa by SDS-PAGE. This enzyme was active on pullulan and starch as substrates. The apparent Km for the enzyme activity on pullulan was 4 mg/ml and for soluble starch was 1.8 mg/ml. Optimum temperature for amylolytic and pullulytic activities was 50 °C. Optimum pH for amylolytic activity was 7 and for pullulytic activity was 7.5. This enzyme was active over a wide range of concentrations (0-4.5 M) of NaCl. The effect of organic solvents on the enzyme activities showed that this enzyme was more stable in the presence of non-polar organic solvents than polar solvents. This study is the first report on amylopullulanase production in halophilic bacteria and archaea.

MeSH terms

  • Archaeal Proteins / chemistry*
  • Archaeal Proteins / isolation & purification
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / isolation & purification
  • Glycoside Hydrolases / chemistry*
  • Glycoside Hydrolases / isolation & purification
  • Halorubrum / enzymology*
  • Hot Temperature
  • Osmolar Concentration
  • Solvents

Substances

  • Archaeal Proteins
  • Bacterial Proteins
  • Solvents
  • Glycoside Hydrolases
  • amylopullulanase