Growth Inhibition of Thermotolerant Yeast, Kluyveromyces marxianus, in Hydrolysates from Cassava Pulp

• Published in: Applied biochemistry and biotechnology 2014-07, Vol.173 (5), p.1197-1208
• Main Authors: Rugthaworn, Prapassorn, Murata, Yoshinori, Machida, Masashi, Apiwatanapiwat, Waraporn, Hirooka, Akiko, Thanapase, Warunee, Dangjarean, Hatairat, Ushiwaka, Satoru, Morimitsu, Kozo, Kosugi, Akihiko, Arai, Takamitsu, Vaithanomsat, Pilanee
• Format: Article
• Language: English
• Subjects: Acetic acid; Acetic Acid - pharmacology; Acids; Biochemistry; Biological and medical sciences; Biotechnology; cassava; Chemistry; Chemistry and Materials Science; Ethanol; Ethanol - metabolism; ethanol fermentation; ethanol production; Factories; Fermentation; Fermentation - drug effects; Fundamental and applied biological sciences. Psychology; Furans - pharmacology; growth retardation; heat tolerance; high performance liquid chromatography; High temperature; hydrolysates; Hydrolysis; Kluyveromyces - drug effects; Kluyveromyces - genetics; Kluyveromyces - growth & development; Kluyveromyces - metabolism; Kluyveromyces marxianus; lactic acid; Lactic Acid - pharmacology; Liquid chromatography; Manihot - chemistry; Manihot esculenta; Mutagenesis; mutants; Mutation; Plant growth; pulp; Saccharomyces cerevisiae; Starch; Temperature; tryptophan; Tryptophan - pharmacology; wastes; Yeast; Yeasts
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/s12010-014-0906-2

In this study, we report the inhibition of Kluyveromyces marxianus TISTR5925 growth and ethanol fermentation in the presence of furan derivatives and weak acids (acetic acid and lactic acid) at high temperatures. Cassava pulp, obtained as the waste from starch processing, was collected from 14 starch factories located in several provinces of Thailand. At a high temperature (42 °C), the cassava pulp hydrolysate from some starch factories strongly inhibited growth and ethanol production of both K. marxianus (strain TISTR5925) and Saccharomyces cerevisiae (strain K3). HPLC detected high levels of lactic acid and acetic acid in the hydrolysates, suggesting that these weak acids impaired the growth of K. marxianus at high temperature. We isolated Trp-requiring mutants that had reduced tolerance to acetic acid compared to the wild-type. This sensitivity to acetic acid was suppressed by supplementation of the medium with tryptophan.