Growth, ethanol production, and inulinase activity on various inulin substrates by mutant kluyveromyces marxianus strains NRRL Y-50798 and NRRL Y-50799

Authors: GALINDA-LEVA, LUZ ANGELA - Cenicafe; Hughes, Stephen; LOPEZ-NUNEZ, JUAN CARLOS - Cenicafe; JARODSKY, JOSHUA - Illinois State University; ERICKSON, ADAM - Illinois State University; Lindquist, Mitchell; COX, ELBY - Green Biologics Central Mn Renewables, Llc; Bischoff, Kenneth; Hoecker, Eric; Liu, Siqing; Qureshi, Nasib; JONES, MARJORIE - Illinois State University

Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2016
Publication Date: 4/29/2016
Citation: Galinda-Leva, L.A., Hughes, S.R., Lopez-Nunez, J.C., Jarodsky, J.M., Erickson, A., Lindquist, M.R., Cox, E.J., Bischoff, K.M., Hoecker, E.C., Liu, S., Qureshi, N., Jones, M.A. 2016. Growth, ethanol production, and inulinase activity on various inulin substrates by mutant Kluyveromyces marxianus strains NRRL Y-50798 and NRRL Y-50799. Journal of Industrial Microbiology and Biotechnology. 43(7):927-939. doi: 10.1007/s10295-016-1771-5.

Interpretive Summary: The ability of Kluyveromyces marxianus mutant strains, NRRL Y-50798 (Km7) and NRRL Y-50799 (Km8) to utilize inulin was evaluated for potential use of these yeast strains in fermentation of inulin-containing food and plant waste as part of an integrated biorefinery platform. Economically important plants contain large amounts of inulin. Disposal of waste resulting from their processing presents environmental issues. Finding microorganisms capable of converting inulin waste to biofuel and valuable co-products in a biorefinery at the processing site would have significant economic and environmental impact. Our results demonstrated that in inulin medium, Km7 showed maximum growth and produced 0.35 g ethanol/g inulin at 24 h. At 24 h in inulin+glucose medium, Km7 produced 0.40 g ethanol/ g (inulin+glucose). On inulin plates Km7 was shown to exhibit inulinase activity. These K. marxianus mutant strains, especially Km7, have the potential to remediate inulin-containing fruit and vegetable processing wastes from coffee and tequila production or to be used in bioprocessing to produce valuable fuels and chemicals from renewable, inexpensive, and abundant inulin feedstocks.

Technical Abstract: Economically important plants contain large amounts of inulin. Disposal of waste resulting from their processing presents environmental issues. Finding microorganisms capable of converting inulin waste to biofuel and valuable co-products in a biorefinery at the processing site would have significant economic and environmental impact. We evaluated the ability of two mutant strains of Kluyveromyces marxianus (Km7 and Km8) to utilize inulin for ethanol production. In glucose medium, both strains consumed all glucose and produced 0.40 g ethanol/g glucose at 24 h. In inulin medium, Km7 showed maximum growth and produced 0.35 g ethanol/g inulin at 24 h, while Km8 showed maximum growth and produced 0.02 g ethanol/g inulin at 96 h. At 24 h in inulin+glucose medium, Km7 produced 0.40 g ethanol/ g (inulin+glucose) and Km8 produced 0.20 g ethanol/ g (inulin+glucose) with maximum growth of Km8 at 72 h 40% that of Km7 at 36 h. On inulin plates Km7 exhibited greater inulinase activity than Km8.