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l-leucine aminopeptidase production by filamentous Aspergillus fungi

K M Nampoothiri1, V Nagy, K Kovacs

  • 1Biotechnology Division, Regional Research Laboratory (CSIR), Trivandrum, Kerala, India. madhavan85@hotmail.com

Letters in Applied Microbiology
|November 25, 2005
PubMed
Abstract

Insights

Researchers screened Aspergillus fungi for leucine aminopeptidase (LAP) and methionine aminopeptidase (MAP) production. Two Aspergillus sojae and one Aspergillus oryzae strain showed high enzyme activity and thermostability, indicating potential industrial applications.

Area of Science:

  • Enzymology
  • Microbial Biotechnology
  • Industrial Microbiology

Background:

  • Filamentous fungi, particularly Aspergillus species, are known sources of valuable industrial enzymes.
  • Aminopeptidases play crucial roles in protein modification, flavor development, and biocatalysis.

Purpose of the Study:

  • To screen Aspergillus species for the production of leucine aminopeptidase (LAP) and L-methionine aminopeptidase (MAP).
  • To identify and characterize fungal strains with high aminopeptidase activity and desirable enzyme properties.

Main Methods:

  • Screening of 28 Aspergillus strains from 14 species for LAP production using shake flask fermentation.
  • Evaluation of enzyme activity under different conditions, including submerged and solid-state fermentation.
  • Determination of optimal temperature, pH, and the effect of metal ions on enzyme activity and stability.

Main Results:

  • Two Aspergillus sojae strains (NRRL 1988, NRRL 6271) and one Aspergillus oryzae strain (NRRL 6270) were identified as superior LAP producers.
  • Peak LAP activities reached 2.61 IU/ml and 13.02 IU/g dry matter (solid-state fermentation).
  • The enzymes exhibited optimal activity between 65-75°C and pH 8.0-9.0, with enhanced stability in the presence of Co(2+) and Fe(2+).

Conclusions:

  • Selected A. sojae and A. oryzae strains are efficient producers of thermostable LAP and MAP.
  • The characterized aminopeptidases are metalloenzymes with significant thermal stability.
  • These enzymes hold promise for applications in controlling hydrolysis and enhancing flavor in various substrates.

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