Optimisation De La Production De L’ α-Amylase Par Les Microorganismes Isolés Des Ferments Traditionnels De Manioc Provenant De Trois Zones De Production De L’attiéké En Côte d’Ivoire

Abstract

This research work aimed at studying production kinetic of α-amylase by microbial strains isolated from three traditional cassava ferments; with a view of their potential use as starter cultures. The study was carried out on 42 amylolytic strains comprising 15 lactic acid bacteria species, 9 yeast, 9 Bacillus sp. And 9 moulds. Amyloytic activities were assessed in vitro in a broth. Independently of strains and their origin, results showed three α-amylase regulation kinetics. From the 3 species which constitutively secrete α-amylase, only Candida tropicalis LVX8 excretes a large amount of α-amylase (171.33 ± 3 EU/mL) in 24 hours. Among strains, which α-amylase excretion is regulated by a repression, the optimal duration for each one of them varied from 4 to 24 hours. Thus, Lactobacillus casei LABZ4 secretes within 4 hours of culture, 47.3 ± 1.41 EU/mL, whereas yeast (LVX1, LVZ19, LVY16 and LVZ1), moulds (MZ2, MZ1 and MY2) and Bacilli (BX5, BY4 and BZ15) strains excreted each during 12 to 20 hours α-amylase amounts ranging from 60 ± 3.7 and 106 ± 1.3 EU/mL. For strains with amylase production modulated by inactivation, maximal amounts of enzymes were very low and reached after only 4 hours. However, for yeasts LVX14, LVY3 and LVZ18, inactivation was observed from 16 hours, with activities higher than 100 EU/mL. Considering the diversity of production kinetics of α-amylase, the use of these isolates for a controlled fermentation of cassava dough would be optimal in co-culture.