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

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.