Effects of T-2 toxin on ethanol production by Saccharomyces cerevisiae.
ABSTRACT A trichothecene mycotoxin, T-2 toxin, inhibits several aspects of cellular physiology in Saccharomyces cerevisiae, including protein synthesis and mitochondrial functions. We have studied growth of, glucose utilization by, and ethanol production by S. cerevisiae and show that they are inhibited by T-2 toxin between 20 and 200 micrograms/ml in a dose-dependent manner. At 200 micrograms/ml, T-2 toxin causes cell death. This apparent inhibition of ethanol production was found to be the result of growth inhibition. On the basis of biomass or glucose consumption, T-2 toxin increased the amount of ethanol present in the culture. This suggests that T-2 inhibits oxidative but not fermentative energy metabolism by inhibiting mitochondrial function and shifting glucose catabolism toward ethanol formation. As T-2 toxin does not directly inhibit ethanol production by S. cerevisiae, this system could be used for ethanol production from trichothecene-contaminated grain products.
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ABSTRACT: Fermented foods are of importance worldwide. Most are prepared under nonsterile conditions using mixed cultures, either deliberately or unavoidably. Fungal mixed cultures show interactive relations at various levels. In this paper, inhibitory effects among fungi owing to competition, formation of organic acids, toxic proteins, and mycotoxins are discussed. In addition, fungi show inhibitory effects towards bacteria and vice versa, through pH changes, and excretion of organic acids, antibiotics, peptides, etc. Stimulatory interactions among fungi and between fungi and bacteria relate mainly to carbon and nitrogen metabolism, and they play an important role in the inherent stability of mixed-culture systems maintained by enrichment techniques. Better understanding of natural mixed-culture fermentations has evolved into the development of the concept of cocultivation employing compatible microbial strains of complementary metabolic ability. Especially in the area of direct conversion of complex carbohydrates (e.g., starch, inulin, or lignocellulosic matter into ethanol), cocultivation has much to offer. Genetic modification of starter organisms offers opportunities to improve, for example, their ability to degrade substrate with a minimum of catabolite repression, and produce final products of superior quality. This is illustrated by recent recombinant DNA constructs for alcoholic fermentations. Key words: food, fungi, interaction, inhibition, stimulation, cocultivation.Canadian Journal of Botany 73, Suppl.1 (1995) S1291-S1300. 03/2011;
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ABSTRACT: Several metabolic properties of lactic acid bacteria (LAB) serve special functions, which directly or indirectly have impact on processes such as improved quality and safety and flavour devel-opment in the malting and brewing industry. LAB are widely distributed in nature and in spontaneous fermentations, often they are found to be the dominating microflora resulting in both the inhibition of spoilage bacteria and organisms. This review de-scribes the applications of LAB in malting and brewing. Myco-toxins are naturally occurring toxic secondary metabolites of fungi that may be present in cereals. Several of these mycotoxins have been associated with human and animal diseases and are known to survive the brewing process. LAB have been shown to restrict the growth of the most important toxigenic fungi thereby reducing the formation of these harmful toxins. The occurrence of mycotoxins in cereals is discussed and their effect in beer is reviewed. The main features of this review are: (I) LAB starter cultures in malting and brewing (II) production of acid malt; (III) biological acidification of mash and wort in brewing; (IV) bacteriocins produced by LAB in brewing; (V) LAB and anti-fungal activity; (VI) mycotoxins in cereals.J. Inst. Brew. 06/2004; 110(110):163-180.