Résumé
An amylolytic lactic acid bacterium, identified as Lactobacillus plantarum, was isolated from cassava roots (Manihot esculenta var. Ngansa) during retting. Cultured on starch, the strain displayed a growth rate of 0.43 per hour, a biomass yield of 0.19 g/g, and a lactate yield of 0.81 g/g. The growth kinetics were similar on starch and glucose. Enough enzyme was synthesized, and starch hydrolysis was not a limiting factor for growth. The synthesized amylolytic enzyme was purified by fractionated precipitation with ammonium sulfate and by anion exchange chromatography. It was identified as an alfa-amylase with an optimal pH of 5.5 and an optimal temperature of 65 degrees C. The use of such a strain as a cassava fermentation starter for gari production had the following effects: a change from a heterofermentative pattern observed in natural fermentation to a homofermentation one, a lower final pH, a faster pH decline rate, and a greater production of lactic acid (50 g/kg of dry matter).