ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Food Microbiology
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1663736
This article is part of the Research TopicSustainable Production of Microorganism Biomass for Industrial FermentationView all 4 articles
Physiological characterization of Kluyveromyces marxianus strains for the development of a microbial platform to obtain bioethanol from cheese whey permeate
Provisionally accepted
- 1University of Bari Aldo Moro, Bari, Italy
- 2Universidad Estatal Amazonica, Puyo, Ecuador
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The increasing interest in renewable feedstocks for biochemicals production includes the valorisation of cheese whey (CW), a by-product of the dairy industry. CW contains a high concentration of lactose, accounting for most of its organic load, making it a major environmental pollutant if untreated. A valorisation approach of CW is based on the separation of valuable proteins by ultrafiltration, and the obtainment of a lactose-rich cheese whey permeate (CWP). The conversion of lactose in CWP into bioethanol is considered a sustainable solution for the valorisation of this waste. However, lactose is not metabolised by the yeast species Saccharomyces cerevisiae, namely the most industrially used microorganism, to produce bioethanol. Differently, the non-conventional yeast Kluyveromyces marxianus shows high growth rates on a broad range of industrially relevant substrates, including lactose. This study provides a comprehensive physiological characterisation of three K. marxianus strains (DSM 5422, DSM 7239, and DSM 5572) to evaluate their potential for lactose hydrolysis and fermentation in order to produce advanced bioethanol from CWP. Microplate growth tests, β-galactosidase activity assays, and flask fermentations were carried out to identify optimal strains for efficient CWP valorisation, advancing the applications of K. marxianus in industrial biotechnology. The optimal conditions for lactose utilisation and ethanol production were identified as 130 g/L of lactose at 42 °C in semi-synthetic media (SSM). Even though strain DSM 7239 showed the highest β-galactosidase activity of 27.8 ±0.9 U mg-1, strains DSM 5422 and 5572 were identified as the best performing strains at shake flask experiments in terms of ethanol yield on the substrate, with 0.48±0.03 g/g and 0.50±0.03 g/g, respectively, after 1 day of fermentation.
Keywords: Kluyveromyces marxianus, Cheese whey permeate, Ethanol, β-galactosidase, Fermentation
Received: 10 Jul 2025; Accepted: 10 Sep 2025.
Copyright: © 2025 De Micco, Radice, Fidio, Agrimi and Pisano. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Isabella Pisano, University of Bari Aldo Moro, Bari, Italy
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