2. Materials and methods
2.1. Yeast isolation
Epiphytic micro-organisms were isolated by
shaking five grape berries in 10 ml of sterile
distilled water for 1 h at 200 rpm on a rotary
shaker (Peng and Sutton, 1991). The wash was
serially diluted and 30 ml of each dilution were
spread on basal yeast agar (BYA) containing 20 g
glucose, 1 g yeast extract, 10 g protease peptone
and 15 g agar amended with 250 mg Penicillin G
(to suppress growth of bacteria) in 1 l of distilled
water. The Petri dishes were incubated at room
temperature for 4 days and yeast-like colonies
were selected randomly according to colour and
morphological characteristics, removed with a
sterile plastic loop and transferred to fresh BYA
plates to obtain pure cultures. Colonies were held