Indonesia has many fermented beverages, and yeast become one of the agents in fermented process. Yeasts has a role to transform carbohydrate complex into simple compounds with release secondary metabolism to environment like amylase enzyme. This study aims to get the isolate of yeast that can potentially produce amylase enzyme. This research conducted in October 2018 until March 2019 in Microbiology Laboratory of Universitas Negeri Jakarta. The screening test of potential isolate producing amylase enzyme was performed on yeast isolate from eight source of indigenous fermented beverages that can grow in YMA medium with pH 2. Screening was carried out on YPSA medium with diffusion agar method. From 50 Isolates, 16 isolates with the codes IB4, IB15, IB20, IB21, IB26, IB36, IL78, IL80, IL81, IL86, IL88, IL97, IL113, IL136, IL146, and IL150, were able to form clear zone after 1-day incubation in room temperature. The highest amylolytic index was produced by IL86 (1,019 mm). Forming the clear zone is proof that yeast can transform starch become simpler sugar like maltose as iodine-starch reaction is resulting amylose helix and iodine become I3 − that filled main core helix. In addition to this, iodine forms complexes with starch molecules showed a dark purple colour.

Mold is one of the microorganisms that can cause damage in chocolate fruit by producing phytopathogenic toxins. Until now, pesticides have been widely used for controlling postharvest loss in fruit. Yeasts can produce secondary metabolites, which can inhibit the growth of pathogenic mold. In this study, we isolate, identify, and apply yeasts isolated from fermented cocoa beans to control the growth of pathogenic mold in chocolate fruit collected from Sentul, Indonesia. This research includes yeast isolation using the dilution method with YMA medium, mold isolation using direct planting method on PDA medium, screening ability to produce cellulase using diffusion method on CMC medium, and in-vitro antagonist testing using dual culture method on PDA medium. The results showed that 128 yeast isolates and 37 mold isolates were obtained in this study. The results of screening representative cellulase capability of 77 yeast obtained 6 positive yeast isolates produced cellulase with the highest cellulolytic index of 0.23-0.30. The 6-yeast antagonism test with the highest cellulolytic index showed that C3.3.1 isolate had the best ability to inhibit pathogenic molds with 37.36% inhibitory power.

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