Copper (Cu) was used in antiquity to prevent waterborne and food diseases because, as a broad-spectrum antimicrobial agent, it generates reactive oxygen species, ROS.

Microbiology has long been a keystone in fermentation, and innovative yeast molecular biotechnology continues to represent a fruitful frontier in brewing science. Consequently, modern understanding of brewer’s yeast has undergone significant refinement over the last few decades. This publication presents a condensed summation of Saccharomyces species dynamics with an emphasis on the relationship between; traditional Saccharomyces cerevisiae ale yeast, S. pastorianus interspecific hybrids used in lager production, and novel hybrid yeast progress. Moreover, introgression from other Saccharomyces species is briefly addressed. The unique history of Saccharomyces cerevisiae and Saccharomyces hybrids is exemplified by recent genomic sequencing studies aimed at categorizing brewing strains through phylogeny and redefining Saccharomyces species boundaries. Phylogenetic investigations highlight the genomic diversity of Saccharomyces cerevisiae ale strains long known to brewers for their fermentation characteristics and phenotypes. The discovery of genomic contributions from interspecific Saccharomyces species into the genome of S. cerevisiae strains is ever more apparent with increasing research investigating the hybrid nature of modern industrial and historical fermentation yeast.

Nanotechnology is a promising new technology, of which antimicrobial metal nanocomposites are predicted to become valuable in medical and food packaging applications. Copper is a redox-active antimicrobial metal that can become increasingly toxic depending on the target biomolecule’s donor atom selectivity and the chemical species of copper present. Mass is the traditional measurement of the intrinsic elemental chemistry, but this practice fails to reflect the morphology and surface area reactivity of nanotechnology. The carboxymethyl cellulose copper nanoparticles (CMC-Cu) investigated in this study have unique and undefined toxicity to Saccharomyces cerevisiae that is different from CuSO4. Cellular surface damage was found in scanning electron micrographs upon CMC-Cu exposure. Further investigation into the lipids revealed altered phosphatidylcholine and phosphatidylethanolamine membrane composition, as well as depleted triacylglycerols, suggesting an impact on the Kennedy lipid pathway. High levels of reactive oxygen species were measured which likely played a role in the lipid peroxidation detected with CMC-Cu treatment. Metal homeostasis was affected by CMC-Cu treatment. The copper sensitive yeast strain, YJM789, significantly decreased cellular zinc concentrations while the copper concentrations increased, suggesting a possible ionic mimicry relationship. In contrast to other compounds that generate ROS, no evidence of genotoxicity was found. As commonplace objects become more integrated with nanotechnology, humanity must look forward past traditional measurements of toxicity.

The use of interspecific hybrids during the industrial fermentation process has been well established, positioning the frontier of advancement in brewing to capitalize on the potential of Saccharomyces hybridization. Interspecific yeast hybrids used in modern monoculture inoculations benefit from a wide range of volatile metabolites that broaden the organoleptic complexity. This is the first report of sake brewing by Saccharomyces arboricola and its hybrids. S. arboricola x S. cerevisiae direct-mating generated cryotolerant interspecific hybrids which increased yields of ethanol and ethyl hexanoate compared to parental strains, important flavor attributes of fine Japanese ginjo sake rice wine. Hierarchical clustering heatmapping with principal component analysis for metabolic profiling was used in finding low levels of endogenous amino/organic acids clustered S. arboricola apart from the S. cerevisiae industrial strains. In sake fermentations, hybrid strains showed a mosaic profile of parental strains, while metabolic analysis suggested S. arboricola had a lower amino acid net uptake than S. cerevisiae. Additionally, this research found an increase in ethanolic fermentation from pyruvate and increased sulfur metabolism. Together, these results suggest S. arboricola is poised for in-depth metabolomic exploration in sake fermentation.

Glyphosate and copper-based herbicides/fungicides affect non-target organisms, and these incidental exposures can impact microbial populations. In this study, glyphosate resistance was found in the historical collection of S. cerevisiae, which was collected over the last century, but only in yeast isolated after the introduction of glyphosate. Although herbicide application was not recorded, the highest glyphosate-resistant S. cerevisiae were isolated from agricultural sites. In an effort to assess glyphosate resistance and impact on non-target microorganisms, different yeast species were harvested from 15 areas with known herbicidal histories, including an organic farm, conventional farm, remediated coal mine, suburban locations, state park, and a national forest. Yeast representing 23 genera were isolated from 237 samples of plant, soil, spontaneous fermentation, nut, flower, fruit, feces, and tree material samples. Saccharomyces, Candida, Metschnikowia, Kluyveromyces, Hanseniaspora, and Pichia were other genera commonly found across our sampled environments. Managed areas had less species diversity, and at the brewery only Saccharomyces and Pichia were isolated. A conventional farm growing RoundUp Ready™ corn had the lowest phylogenetic diversity and the highest glyphosate resistance. The mine was sprayed with multiple herbicides including a commercial formulation of glyphosate; however, the S. cerevisiae did not have elevated glyphosate resistance. In contrast to the conventional farm, the mine was exposed to glyphosate only one year prior to sample isolation. Glyphosate resistance is an example of the anthropogenic selection of nontarget organisms.

Saccharomyces cerevisiae are a phenotypically diverse species that adapt to a wide variety of environments by exploiting standing genetic diversity and selecting for advantageous mutations. Glyphosate and copper-based herbicides/ fungicides affect non-target organisms, these incidental exposures can impact microbial populations. In this study, glyphosate resistance was found in the historical collection of yeast which was collected over the last century, but only in yeast isolated after the introduction of glyphosate. The highest glyphosate-resistant yeasts were isolated from agricultural sites. However, herbicide application at these sites was not recorded. In an effort to assess glyphosate resistance and impact on non-target microorganisms, yeast were harvested from 15 areas with known herbicidal histories, including an organic farm, conventional farm, remediated coal mine, suburban locations, state park, and a national forest. Yeast representing 23 genera were isolated from 237 samples of plant, soil, spontaneous fermentation, nut, flower, fruit, feces, and tree material samples. Saccharomyces, Candida, Metschnikowia, Klyveromyces, Hanseniaspora, and Pichia were other genera commonly found across our sampled environments. Managed areas had less species diversity and at the brewery, only Saccharomyces and Pichia were isolated. A conventional farm growing RoundUp Ready™ corn had the lowest phylogenetic diversity and the highest glyphosate resistance. The mine was sprayed with multiple herbicides including a commercial formulation of glyphosate; however, the yeast did not have elevated glyphosate resistance. In contrast to the conventional farm, the mine was exposed to glyphosate only one year prior to sample isolation. Glyphosate resistance is an example of the anthropogenic selection of nontarget organisms.