Effect of altitude on microbial succession during traditional enset fermentation, Tariku Hunduma and Mogessie Ashenafi
Abstract: Effect of altitude on microbial succession during traditional enset fermentation was determined at enset culture sites, 2908 (high altitude) and 2252 (mid-altitude) meters above sea level. Counts of aerobic mesophilic bacteria and lactic acid bacteria showed differences between the study sites. The warmer temperature of the fermenting mass at the mid-altitude site contributed to the rapid proliferation of microorganisms and rapid fermentation process and hence shorter fermentation time (112 days) than at the high altitude site (142 days). The microorganisms isolated from traditional enset fermentation process, at both sites were similar. Bacillus spp. and Lactic acid bacteria dominated the fermentative microflora at the initial and later stages of the fermentation, respectively. The coliforms and other members of Enterobacteriaceae contributed to initial lowering of the pH of the fermenting mass. At about day 15, the homofermentative lactobacilli took over the process and dominated the flora till the end of fermentation. Following the proliferation of the lactobacilli, the pH decreased and titratable acidity increased. Count of yeasts remained low throughout the fermentation process. The coliforms and enterobacteriaceae were undetectable following domination of the microflora by LAB. The decline in moisture content of the fermenting mass was relatively faster at the mid altitude than at the high altitude site. Some Gram-negative rods and other Gram-positive cocci were occasionally encountered at lower levels. Almost all isolates were amylolytic than proteolytic and lipolytic due to high carbohydrate content of the substrate. This study showed there could be differences in microbial succession from place to place depending on various factors.
Keywords: Ensete ventricosum, Fermentation, LAB, Altitude