Isolation and Screening of Ethanol Tolerant Yeast, for the Production of Indigenous Liquor P. Moopanar CSIR Supervisor: Sani Gumede DUT Supervisor: L. Reddy

Slide 2 © CSIR Introduction Production of traditional beer and its economical impact Figure 1: Cashew FruitFigure 2: Palm tree

Slide 3 © CSIR

Slide 4 © CSIR The focus of this research was to isolate and screen yeasts for the improvement of current production processes of indigenous liquor. Aim

Slide 5 © CSIR Objectives To isolate ethanol tolerant yeasts from traditional juices To test ethanol tolerance of the isolated yeast strains To prepare and validate a cell bank of the isolated yeasts to minimise process variation To determine the growth profile of the yeast isolates. Establishing the efficacy of combinations of selected isolates in marula juice fermentation, to produce the highest concentration of ethanol

Slide 6 © CSIR Isolation and selection of high ethanol producing yeasts from Marula, Cashew, & Palm Isolates were evaluated for ethanol tolerance at a range of concentrations Methodology Shake flask experiments were conducted in triplicate to determine growth profiles Purified isolates were cell banked for future evaluations, the cell bank was subsequently validated Combinations of the isolates were screened for ethanol productivity in marula juice

Slide 7 © CSIR Fig 1: KM01Fig 2: KM02 Fig 3: KC01 Results & Discussion

Slide 8 © CSIR Cell Growth during ethanol tolerance trial (9%)

Slide 9 © CSIR Cell Growth during ethanol tolerance trial (12%)

Slide 10 © CSIR Cryopreservation Yeast isolateAverage counts before Average counts in cryovials after cryopreservation (cfu.ml -1 ) % cell recovery cryopreservation KC * * % KM * * % KM * * %

Slide 11 © CSIR Growth curve determination

Slide 12 © CSIR Ethanol productivity rates

Slide 13 © CSIR Sugar consumption rates

Slide 14 © CSIR pH profile of yeast combinations

Slide 15 © CSIR Conclusion Successful isolation of 3 ethanol tolerant yeasts, KM01, KM02 and KC01 Combination of three isolates was most productive in terms of ethanol productivity rates, sugar utilization rates and the final ethanol concentration obtained

Slide 16 © CSIR Proposed Future Work Pathogenicity evaluation Ethanol productivity of individual isolates Lyophilisation Impact of starter culture on taste, texture and end product Final selection and identification of organism/s Productivity of starter culture in large scale application.

Slide 17 © CSIR CSIR Biosciences and the Bioprocess development Team, especially Sani Gumede, Zinhle Ngubane and Nodumo Zulu for their intellectual input and all the individuals who aided in the success of the project. Acknowledgements