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

Liliane KOUAME, Ginette DOUE, Niamke ADOM, Honore OUATTARA, Sébastien NIAMKÉ

Abstract

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.

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