BIOCHEMICAL CHARACTERIZATION OF MICROBIAL POPULATIONS INVOLVED IN LOH-DJIBOUA COCOA’S FERMENTATION IN COTE D’IVOIRE

摘要

Comprehensive report on biochemistry characteristics of microorganisms involved in Loh-Djiboua cocoa fermentation is made in order to highlight diversities that occur among them. Microbial growth monitored showed that Yeasts, LAB and Bacillus were initially present, while AAB emerged after 12 h. Throughout the process the AAB population load was higher than other microorganisms with rates between (7.76 - 7.39) log CFU / g of beans while yeast, LAB, AAB and Bacillus reached a maximum of load (7.28 - 8.82) log CFU/g of beans, under fermentative conditions of temperature (28 – 36 °C) with a peak at 45 °C (24 - 60 h) and pH ranged between 4.5 – 8. The 24 best producing yeasts pectolytic enzymes resulting from 267 isolates presented four fermentatives profiles. Among the 173 Bacillus isolates were obtained 45.08% pectinolytic activity streams with high, medium and low production level, 37.05% citrate lyase activity strains and 70.02% power acidifying strains. Homofermentative type (92.83%) largely dominated the heterofermentative type (7.72%) among the 210 strains of LAB isolated. All LAB isolated showed ability to ferment glucose while only 2 not ferment fructose and 9 not ferment sucrose. 76.19% proved to be able to assimilate citrate. The 166 isolates of AAB with clear acidifying power were constituted into 2 genera mainly Acetobacter (80.76%) and Gluconobacter (19.24%). This study emphasized the clear dominance of AAB population mainly constituted of Acetobacter during the growth dynamic of microbial groups involved in Loh-Djiboua cocoa fermentation and showed the wide variety in activities and population among these different groups.