ISOLASI DAN KARAKTERISASI YEAST AMILOLITIK DARI RAGI TAPE

Abstract

The demand of sugar increases every year caused by people growth. Indonesia has starchy materials
like tapioca and for long time used to produce food by traditional fermentation with ragi tape. Ragi tape
contains many amylolytic and fermentative microbial. The object of this study was to isolate amylolytic yeast
from ragi tape, which could be used to produce amylolytic enzymes as an alternative source of amylolytic
enzyme from microbial origin. Isolation was done by dilution and spread plate methods on peptone glucose
yeast extract soluble starch (PGYS) agar medium, incubated 30C, for 2 days and purified with same medium.
The isolates were then identified based on morphology and physiology profiles. Selection of the strongest isolate
with high amylolytic potent was done with amylolytic activity. The chosen isolate was then used to produce
amylolytic enzyme in yeast extract malt extract soluble starch (YMS) medium with variation of soluble starch
content. 15 amylolytic yeast isolates have been isolated, and then identified with taxonomic keys were suspected
as Debaryomyces vanriji (4 isolates), Saccharomycopsis fibuligera (3 isolates), and Pichia burtonii (8 isolates).
They could grow well on starch medium. The result of selection based on amylolytic activity showed that S.
fibuligera E-3 was the strongest among the others. From the fermentation, this research obtained the cells
content increased or obtained logarithmic phase in 1st day of fermentation, and after 2nd day reached stationary
phase medium. The reduction sugar content increased in 1st day of fermentation, after 2nd day was increased
slowly. The soluble starch content was decreased rapidly in 1st day, after 2nd day was decreased slowly. The
glucoamylase activity was high at 1st day, but in 2nd day was low. S. fibuligera had glucoamylase activity 44.13
mg glucose/L/min/1 ml enzyme solution.