Yeast, or Saccharomyces cerevisiae, has been a part of human culture and food for centuries, dating back to ancient Egypt [1], [2]. Common applications include domestic brewing, baking, alcohol fermentation, insect control, preventing food spoilage, composting, and cosmetics [3]. Some examples of biotechnical applications of yeast are metabolite and protein production, vaccine discovery, pathology research, and clinical research [4], [5].

Multiple connections exist between biotechnology and a circular economy, such as bio-based plastics, biofuels, platform chemicals, specialty chemicals, and more [6]. While the concept of a circular economy is criticised for having varied definitions, J. Kirchherr [7] concluded that “circular economy” most commonly describes an economy based on prioritising sustainable development and economic prosperity through endorsing “reduce, reuse, and recycle activities.”

The connection between yeast and economy is well highlighted by the production of bioplastics from genetically engineered yeasts [8]. Traditional, unsustainable methods of plastic production from polymers such as olefins, also known as alkenes, are non-recyclable, manufactured from materials such as petroleum, and thus reliant on fossil fuels [9]. This is not a sustainable practice, as only 15% of total plastic waste is recycled while 400 million tonnes per year of plastic are produced on a global scale [10].

Studies of organisms like S. cerevisiae provide insight into the biology of similar organisms within the same genera or family. Useful examples include research on other fungi species which have evolved to utilise synthetic chemicals such as the PHA (polyhydroxyalkanoates) and PHB (polyhydroxybutyrate) polyesters produced by bacteria [11]. This can be utilised in our global economy via the integration of these biodegradable polyesters as substitutes for petroleum-based plastics, supporting a circular culture of reducing and recycling.

Yeast is valuable due to its non-pathogenic nature, which prevents accidental contamination of experimental products and tools. This supports the generation of accurate data and faster solutions to global research challenges, potentially within medicinal and pharmaceutical research [12], [13]. Yeast’s environmental tolerance to various stressors, including ethanol inhibition, high temperatures, and osmotic pressure fluctuations, enhances its utility in biotechnological applications [14], [15]. Additionally, the majority of yeast species, including S. cerevisiae, grow rapidly, enabling faster and more accurate results within gene expression research, as many generations can be studied [16]. Yeast provides biocatalytic qualities, facilitation, rapid conclusion, and time efficiency [12-17]

Genetic modification is incredibly useful for filtering unfavourable qualities of yeast for biotechnological applications, such as the differing compound ratios between species, and property-altering compounds [18]. For example, the engineered removal of the Gly1250Ser (1250S) point mutation increases the amount of ethyl caproate, meaning that the yeast used in the production of Japanese Sake gives a pleasant apple flavour to the drink [19]. The cultural importance of biotechnology to society is dependent on public perception. Public familiarity creates acceptance and enables the integration of science with modern society [19].

Multiple methods of improving yeast strains for biotechnological experimentation exist, two of which are mutagenesis and metabolic engineering [18].

Mutagenesis is the genetic alteration of yeast to induce new mutations to original DNA [20]. Methods include mutagens like nitroguanidine, ethyl methanesulfonate, and synthetic ultraviolet radiation [21-23]. These mutations are designed to improve desirable traits such as increased productivity, higher stress tolerance, and varying speeds of metabolism [24]. It can implement a significant range of mutations within the yeast genome [24]. Weaknesses can include a low specificity of mutations induced, and therefore a high likelihood of non-beneficial mutations occurring. The challenge of site-directed mutagenesis makes studying specific genes or genetic and phenotypic traits challenging and better supported by other methods [25].

Metabolic engineering is the targeted modification of the metabolic pathways of an organism that alters its cellular metabolism and phenotypic traits, through the use of engineered enzymes, introduction of new genes, and/or altering metabolic pathways [26]. Metabolic engineering improves the qualities of differing organisms, including S. cerevisiae, which has been crucial to the scientific community's knowledge of biochemistry, physiology, and genetics [27]. In this example, altering the metabolic pathways of yeast has multiple strengths and weaknesses in its biotechnological application [28]. Strengths include the extreme accuracy of the technology, in contrast to mutagenesis [29]. In addition, the high predictability of metabolic engineering combined with the fully sequenced yeast genome allows for consistent experimental results. The predictable and specific nature of metabolic engineering allows for the industrial-scale control of bioprocesses, which would strongly support the integration of biotechnology within a modern economy [30]. However, while metabolically engineered S. cerevisiae provides a medium for further development of technical scientific methods and tools [27], some weaknesses of this method exist. Metabolic engineering requires technical skills, as well as knowledge of the metabolism, cellular genetics, and physiology of the target species. Cell survival can often limit the insertion of mutations. Finally, the challenge of human error and unintended consequences is important to account for [31].

Mutagenesis and metabolic engineering are both genetic modifications with different applications. While mutagenesis is cost-effective, covers a wide range of genes, and successfully creates genetic diversity, it cannot provide the precision of metabolic engineering, which allows for highly technical alterations of yeast for biotechnological purposes. The decision to use one over the other comes down to the desired outcome, financial ability, and logistical constraints.

Yeast’s multifaceted applications in biotechnology, including metabolic engineering and mutagenesis, contribute to a significantly more sustainable economy. By leveraging yeast’s adaptability, we can enhance innovation and support a shift towards more environmentally friendly practices.