Résumé:
Subject description: Microbial enzymes are widely applied in various
biotechnological and industrial sectors. Today, amylases are one of the most requested
enzymes for their productivity and thermostability. The potential use of Geotrichum sp.
for α- amylase production was investigated for their ability to secrete extracellular
proteins.
Objectives: The purpose of this study was to determine the influence of medium
composition and growth conditions on α-amylase production in solid-state fermentation
by the thermostable Geotrichum sp. —a strain newly isolated from olive oil cake.
Methods: The production of extracellular α-amylase by Geotrichum sp. was studied
using olive oil cake as a carbon source. To maximize enzyme production, the effect on α-
amylase production of different medium ingredients and additives was examined. The
kinetics of the optimal medium for amylase production, protein estimation, sugar
concentrations, and pH were evaluated.
Results and discussion: Among the different additives tested, the greatest amylase
production was obtained with malt extract and CaCl2 moisture with citrate phosphate
buffer pH 4 at 60°C. Applying these culture conditions, α-amylase production increased
by ~1.20 fold. A study of the kinetics of extracellular amylase production revealed that
the best amylase production was achieved after 40 hours of culture. The pH varied from
6.59 to 5.33 at 5,53 and the sugar concentrations ranged from 10,87mg/ml to 6,53 in 40 h
of culture.
Conclusion: A short incubation period and cheaper substrate cost offer the
possibility of inexpensive amylase production, making the process industrially and
economically viable
