Isolation and Characterization of Yeasts from Jackfruit and Beet Root Juices

Aim: Yeasts are present as natural microflora on surface of fruits and vegetables that have eminent importance from deputing as biocontrol agents to reduce pathogens of fruits and vegetables to the health benefits of humans.

Materials and Methods: Yeasts were isolated using standard plate count technique. Colony morphology of yeasts isolates were characterized under microscope for their cell shapes and sizes. Biochemical characteristics of yeasts were characterized for presence of effervescence in catalase test and production of acid and gas in Yeast Extact Peptone Dextrose (YEPD) broth. Utilization of carbon sources were evaluated by inoculating yeast isolates in YEPD broth with specific carbon source and phenol indicator. Ethanol tolerance were evaluated inoculating yeast isolates in YEPDA broth having different concentrations of ethanol viz., 0%, 5.0%, 10.0%, 12.5% and 15.0%.

Results: Population of yeast in jackfruit juices varied from 20.5 x 103 to. 70.0 x 103cfu per millilitre. Population of yeast varied in beet root juices from 34.5 x 103 to 43.0 x 103 cfu per millilitre. Juice of Chandra variety of jackfruit recorded the highest yeast population (7.0 x 104) when compared to others. Juice of Detroit red dark variety of beetroot (4.3 x 104) recorded highest yeast population (4.3 x 104) when compared to others. Yeasts were also isolated from different fruits of which BRTY-I, JKFY-I, POMY-I, WATY-I, APLY-I, MUSKY-I and PINY-I were able to grow in jackfruit and beet root juices. The colonies of yeast varied from white to cream and few were pink. The cell shape varied from oval to ellipsoidal. All the yeast isolates were catalase positive. Most of the yeast isolates produced acid and gas. Yeast isolates were able to utilize glucose, galactose and sucrose. None of the yeast were able to utilize lactose. The highest ethanol tolerant yeasts were JCVY-I, JSVY-III, BDVY-I, PGY, Saccharomyces boulardii and Saccharomyces cerevisiae var. ellipsoideus NCIM 3207.