ISOLATION, CHARACTERIZATION AND IDENTIFICATION OF ETHANOL TOLERANT YEAST FROM WATERMELON (CITRILLUS LANATUS)
Abstract
ABSTRACT
Isolation, characterization and identification of ethanol tolerant yeast from watermelon. This study aimed at determining ethanol tolerant yeast from watermelon sold within Isa Mustapha Agwai 1 Polytechnic, Lafia Mini market. A five-fold serial dilution was made for watermelon for appropriate dilution tubes.0.1ml homogenize sample was taken from 5 folds dilution and dispense in sterile petri dishes by pour plate method. then it was allowed to settle and gel afterward inoculate plate was incubated at 37c for 7days each colony was isolated in a pure form by sub culturing in a fresh PDA plate for further studies. Distinctive morphological properties of each pure culture such as colony form, elevation of colony and colony margin was observed. Lactophenol cotton blue stain was used to stain the colony on a glass slide. Then a clean cover slip was placed on top of the teased portion of the isolate. The prepared slides were then examined microscopically using X40 objectives lens. Identification of the fungal species was based on their nature of the Mycelium, the type of fruiting bodies, and spore structure and the cultural characteristic. Microscopically, yeast appeared small rounded or oval in shape, fragile (shiny) due to the cell wall which had visible buds or pseudohyphea. The yeast isolates identified were Saccharomyces cerevisea and saccharomyces carlsbegensis. The yeast isolates were inoculated unto 10ml YPG (yeast extract, peptone glucose) broth, supplemented with different concentration of ethanol (0,5,10,15,20% v/v) The tubes were incubated for 24 hours at 30℃, the tolerance levels of all the strains were found to be in the range of 10% to 15%. Even though some strains had tolerance in 20%, growth was less. Saccharomyces cerevisiae has a higher tolerance level. The use of watermelon derived yeast for commercial bioethanol production is recommended.
Keywords: Isolation, characterization, Identification, Ethanol, Yeast
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