A R A D A AND M. RAIMBAULT. 1993. Extracellular amylase from Lactobacillus plantarum A6 was purified by fractionated precipitation with ammonium sulphate and by anion exchange chromatography. The homogeneity of the purified fraction was tested by polyacrylamide gel electrophoresis and showed multiple amylase forms. A major form had a n estimated molecular weight of 50 kDa. It was identified as an a-amylase, with an optimum pH of 5.5, an optimum temperature of 65°C a n d K,,, value of 2.38 g 1-' with soluble starch substrate. The enzyme was inhibited by N-bromosuccinimide, iodine and acetic acid. T h e enzyme activation energy was 30.9 kJ mol-'. I

Abstract:Lactobacillus p~antarum strain A 6 isolated from cassava, cultured on cellobiose MRS medium showed a growth rate of 0.41 h-l, a biomass yield of 0.22 g g-l, and produced simultaneously an intracellular linamarase (76.4 U g-' of biomass) and an extracellular amylase (36 U ml-l). The synthesis of both enzymes was repressed by glucose. The use of such a strain as a cassava fermentation starter for gari production had the following influences: a change from a heterofermentative pattern observed in natural fermentation to a homofermentation, a lower final pH, a faster pH decline rate and a greater production of lactic acid (50 g kg-' DM). However, this starter did not appear to play a significant role in cassava detoxification, since it was observed that the level of endogenous linamarase released during the grating of the roots was sufficient to permit the complete and rapid breakdown of linamarin.

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