Purification and characterization of a serine protease secreted by Brevibacillus sp. KH3 for reducing waste activated sludge and biofilm formation

Bioresour Technol. 2011 Nov;102(22):10650-6. doi: 10.1016/j.biortech.2011.08.098. Epub 2011 Aug 27.

Abstract

A novel protease secreted by Brevibacillus sp. KH3 isolated from excess sludge at 50 °C and used as a sludge-lysing strain was investigated in this study. Sludge reduction was minimized by protease inhibitors and a 40-kDa protease, which significantly contributed to this sludge-reducing activity, was purified as the target protein. The final purified protease demonstrated 92-fold higher specific activity than the initial crude extracts. The sludge-reducing efficiency deteriorated relative to decreased protease activity triggered by EDTA; thus, the purified protease was a causative agent in reducing excess sludge. The 40-kDa protease was a serine metalloprotease and showed the highest activity at 50 °C and pH 8.0, and the activity was enhanced in the presence of calcium ions, indicating that the purified protease contained calcium ion. Furthermore, this 40-kDa protease inhibited biofilm formation in excess sludge. These results imply that sludge reduction is because of reduction of biofilm formation in excess sludge.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacteriolysis / drug effects
  • Biodegradation, Environmental / drug effects
  • Biofilms / drug effects
  • Biofilms / growth & development*
  • Brevibacillus / enzymology*
  • Brevibacillus / physiology*
  • Hydrogen-Ion Concentration / drug effects
  • Ions
  • Metals / pharmacology
  • Molecular Weight
  • Protease Inhibitors / pharmacology
  • Serine Proteases / isolation & purification*
  • Serine Proteases / metabolism*
  • Sewage / microbiology*
  • Temperature

Substances

  • Ions
  • Metals
  • Protease Inhibitors
  • Sewage
  • Serine Proteases