Evolutionary adaptation of Kluyveromyces marxianus strain for efficient conversion of whey lactose to bioethanol |
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Institution: | 1. Graduate Institute of Food Science Technology, National Taiwan University, Taipei 10617, Taiwan;2. Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan;3. Department of Agricultural Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan;4. Department of Food Science, Tunghai University, Taichung, Taiwan;5. Institute of Biotechnology, National Taiwan University, Taipei 10617, Taiwan;1. Biotechnology & Biochemical Engineering Laboratory (BiotecLab), Federal University of Rio Grande do Sul, Av. Bento Gonçalves, 9500, PO Box 15090, ZC 91501-970 Porto Alegre, RS, Brazil;2. Food Science and Technology Institute, Federal University of Rio Grande do Sul, Av. Bento Gonçalves, 9500, PO Box 15090, ZC 91501-970 Porto Alegre, RS, Brazil;3. Biological Science Institute, Federal University of Minas Gerais, Brazil;1. Chemical Engineering Department, Jadavpur University, Kolkata - 700032, India;2. Chemical Engineering Department, Heritage Institute of Technology, Kolkata – 700107, India |
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Abstract: | The aim of the present work is to develop an osmotolerant yeast strain with high lactose utilization and further use it to ferment lactose rich whey permeate for high ethanol titer and to reduce energy consumption. Ethanol production and growth rate of selected MTCC 1389 strain were quite high in whey containing lactose up to 150 g/L but it remains constant in lactose concentration (200 g/L) as cells encountered osmotic stress. Thus, strain MTCC 1389 was used for an adaptation to lactose concentration 200 g/L for 65 days and used further for fermentation of lactose rich whey. Fermentation with an adapted K. marxianus MTCC 1389 strain in laboratory fermenter resulted in ethanol titer of 79.33 g/L which is nearly 17.5% higher than the parental strain (66.75 g/L). Expression analysis of GPD1, TPS1and TPS2 found upregulated in lactose adapted K. marxianus strain as compared to the parental strain. These results suggest that an adapted K. marxianus strain accumulates glycerol and trehalose in response to lactose stress and improve osmotolerance in K. marxianus cells. Thus, the study illustrates that evolutionary engineering is an efficient strategy to obtain a superior biofuel yeast strain, which efficiently ferments four-fold concentrated cheese whey. |
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Keywords: | Fermentation Ethanol Lactose Whey Adaptation |
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