Yeasts from tropical forests: Biodiversity, ecological interactions, and as sources of bioinnovation.

Tropical rainforests and related biomes are found in Asia, Australia, Africa, Central and South America, Mexico, and many Pacific Islands. These biomes encompass less than 20% of Earth's terrestrial area, may contain about 50% of the planet's biodiversity, and are endangered regions vulnerable to deforestation. Tropical rainforests have a great diversity of substrates that can be colonized by yeasts.

Dung beetle-associated yeasts display multiple stress tolerance: a desirable trait of potential industrial strains.

Background: Stress-tolerant yeasts are highly desirable for cost-effective bioprocessing. Several strategies have been documented to develop robust yeasts, such as genetic and metabolic engineering, artificial selection, and natural selection strategies, among others. However, the significant drawbacks of such techniques have motivated the exploration of naturally occurring stress-tolerant yeasts.

Physiology of Saccharomyces cerevisiae during growth on industrial sugar cane molasses can be reproduced in a tailor-made defined synthetic medium.

Fully defined laboratory media have the advantage of allowing for reproducibility and comparability of results among different laboratories, as well as being suitable for the investigation of how different individual components affect microbial or process performance. We developed a fully defined medium that mimics sugarcane molasses, a frequently used medium in different industrial processes where yeast is cultivated. The medium, named 2SMol, builds upon a previously published semi-defined formulation and is conveniently prepared from some stock solutions: C-source, organic N, inorganic N, organic acids, trace elements, vitamins, Mg + K, and Ca.

Yeast population dynamics in Brazilian bioethanol production.

The large-scale and nonaseptic fermentation of sugarcane feedstocks into fuel ethanol in biorefineries represents a unique ecological niche, in which the yeast Saccharomyces cerevisiae is the predominant organism. Several factors, such as sugarcane variety, process design, and operating and weather conditions, make each of the ∼400 industrial units currently operating in Brazil a unique ecosystem. Here, we track yeast population dynamics in 2 different biorefineries through 2 production seasons (April to November of 2018 and 2019), using a novel statistical framework on a combination of metagenomic and clonal sequencing data.

Comparative proteome analysis of different Saccharomyces cerevisiae strains during growth on sucrose and glucose.

Both the identity and the amount of a carbon source present in laboratory or industrial cultivation media have major impacts on the growth and physiology of a microbial species. In the case of the yeast Saccharomyces cerevisiae, sucrose is arguably the most important sugar used in industrial biotechnology, whereas glucose is the most common carbon and energy source used in research, with many well-known and described regulatory effects, e.g.

Blocking Mitophagy Does Not Significantly Improve Fuel Ethanol Production in Bioethanol Yeast Saccharomyces cerevisiae.

Ethanolic fermentation is frequently performed under conditions of low nitrogen. In Saccharomyces cerevisiae, nitrogen limitation induces macroautophagy, including the selective removal of mitochondria, also called mitophagy. Previous research showed that blocking mitophagy by deletion of the mitophagy-specific gene increased the fermentation performance during the brewing of Ginjo sake.

Ethanol yield calculations in biorefineries.

The ethanol yield on sugar during alcoholic fermentation allows for diverse interpretation in academia and industry. There are several different ways to calculate this parameter, which is the most important one in this industrial bioprocess and the one that should be maximized, as reported by Pereira, Rodrigues, Sonego, Cruz and Badino (A new methodology to calculate the ethanol fermentation efficiency at bench and industrial scales. Ind Eng Chem Res 2018; 57: 16182-91).

Saccharomyces cerevisiae strains used industrially for bioethanol production.

Fuel ethanol is produced by the yeast Saccharomyces cerevisiae mainly from corn starch in the United States and from sugarcane sucrose in Brazil, which together manufacture ∼85% of a global yearly production of 109.8 million m3 (in 2019). While in North America genetically engineered (GE) strains account for ∼80% of the ethanol produced, including strains that express amylases and are engineered to produce higher ethanol yields; in South America, mostly (>90%) non-GE strains are used in ethanol production, primarily as starters in non-aseptic fermentation systems with cell recycling.

A biorefinery concept for the production of fuel ethanol, probiotic yeast, and whey protein from a by-product of the cheese industry.

Agroindustrial by-products and residues can be transformed into valuable compounds in biorefineries. Here, we present a new concept: production of fuel ethanol, whey protein, and probiotic yeast from cheese whey. An initial screening under industrially relevant conditions, involving thirty Kluyveromyces marxianus strains, was carried out using spot assays to evaluate their capacity to grow on cheese whey or on whey permeate (100 g lactose/L), under aerobic or anaerobic conditions, in the absence or presence of 5% ethanol, at pH 5.

How to characterize a strain? Clonal heterogeneity in industrial Saccharomyces influences both phenotypes and heterogeneity in phenotypes.

Populations of microbes are constantly evolving heterogeneity that selection acts upon, yet heterogeneity is nontrivial to assess methodologically. The necessary practice of isolating single-cell colonies and thus subclone lineages for establishing, transferring, and using a strain results in single-cell bottlenecks with a generally neglected effect on the characteristics of the strain itself. Here, we present evidence that various subclone lineages for industrial yeasts sequenced for recent genomic studies show considerable differences, ranging from loss of heterozygosity to aneuploidies.

Aerobic growth physiology of Saccharomyces cerevisiae on sucrose is strain-dependent.

Present knowledge on the quantitative aerobic physiology of the yeast Saccharomyces cerevisiae during growth on sucrose as sole carbon and energy source is limited to either adapted cells or to the model laboratory strain CEN.PK113-7D. To broaden our understanding of this matter and open novel opportunities for sucrose-based biotechnological processes, we characterized three strains, with distinct backgrounds, during aerobic batch bioreactor cultivations.

Neither 1G nor 2G fuel ethanol: setting the ground for a sugarcane-based biorefinery using an iSUCCELL yeast platform.

First-generation (1G) fuel ethanol production in sugarcane-based biorefineries is an established economic enterprise in Brazil. Second-generation (2G) fuel ethanol from lignocellulosic materials, though extensively investigated, is currently facing severe difficulties to become economically viable. Some of the challenges inherent to these processes could be resolved by efficiently separating and partially hydrolysing the cellulosic fraction of the lignocellulosic materials into the disaccharide cellobiose.

Forever panting and forever growing: physiology of Saccharomyces cerevisiae at extremely low oxygen availability in the absence of ergosterol and unsaturated fatty acids.

We sought to investigate how far the growth of Saccharomyces cerevisiae under full anaerobiosis is dependent on the widely used anaerobic growth factors (AGF) ergosterol and oleic acid. A continuous cultivation setup was employed and, even forcing ultrapure N2 gas through an O2 trap upstream of the bioreactor, neither cells from S. cerevisiae CEN.

Laboratory evolution and physiological analysis of Saccharomyces cerevisiae strains dependent on sucrose uptake via the Phaseolus vulgaris Suf1 transporter.

Knowledge on the genetic factors important for the efficient expression of plant transporters in yeast is still very limited. Phaseolus vulgaris sucrose facilitator 1 (PvSuf1), a presumable uniporter, was an essential component in a previously published strategy aimed at increasing ATP yield in Saccharomyces cerevisiae. However, attempts to construct yeast strains in which sucrose metabolism was dependent on PvSUF1 led to slow sucrose uptake.

Correction to: Anaerobiosis revisited: growth of Saccharomyces cerevisiae under extremely low oxygen availability.

The published online version contains mistake in Figure1. In the x-axis, instead of "1000", the number should be "100".

The role of Saccharomyces cerevisiae in stabilizing emulsions of hexadecane in aqueous media.

During downstream operations involved in the purification of hydrophobic biofuels produced by microorganisms, undesired stable emulsions may be formed. Understanding the mechanisms behind this stability is a pre-requisite for designing cost-effective strategies to break these emulsions. In this work, we aimed at increasing our knowledge on the mechanisms responsible for stabilizing yeast-containing oil-in-water emulsions.

Anaerobiosis revisited: growth of Saccharomyces cerevisiae under extremely low oxygen availability.

The budding yeast Saccharomyces cerevisiae plays an important role in biotechnological applications, ranging from fuel ethanol to recombinant protein production. It is also a model organism for studies on cell physiology and genetic regulation. Its ability to grow under anaerobic conditions is of interest in many industrial applications.

Combined engineering of disaccharide transport and phosphorolysis for enhanced ATP yield from sucrose fermentation in Saccharomyces cerevisiae.

Anaerobic industrial fermentation processes do not require aeration and intensive mixing and the accompanying cost savings are beneficial for production of chemicals and fuels. However, the free-energy conservation of fermentative pathways is often insufficient for the production and export of the desired compounds and/or for cellular growth and maintenance. To increase free-energy conservation during fermentation of the industrially relevant disaccharide sucrose by Saccharomyces cerevisiae, we first replaced the native yeast α-glucosidases by an intracellular sucrose phosphorylase from Leuconostoc mesenteroides (LmSPase).

Erratum to: Quantitative physiology and elemental composition of Kluyveromyces lactis CBS 2359 during growth on glucose at different specific growth rates.

In the original publication of the article, the below mentioned errors have appeared. The correct text is provided in this erratum, In the abstract section, the sentence "This dataset serve" should be replaced as "This dataset serves". Also, the reference "Basso TO, Gomes FS, Lopes ML, et al (2014) Homo- and heterofermentative lactobacilli differently affect sugarcane-based fuel ethanol fermentation.

Quantitative physiology and elemental composition of Kluyveromyces lactis CBS 2359 during growth on glucose at different specific growth rates.

The yeast Kluyveromyces lactis has received attention both from academia and industry due to some important features, such as its capacity to grow in lactose-based media, its safe status, its suitability for large-scale cultivation and for heterologous protein synthesis. It has also been considered as a model organism for genomics and metabolic regulation. Despite this, very few studies were carried out hitherto under strictly controlled conditions, such as those found in a chemostat.

A simple scaled down system to mimic the industrial production of first generation fuel ethanol in Brazil.

Although first-generation fuel ethanol is produced in Brazil from sugarcane-based raw materials with high efficiency, there is still little knowledge about the microbiology, the biochemistry and the molecular mechanisms prevalent in the non-aseptic fermentation environment. Learning-by-doing has hitherto been the strategy to improve the process so far, with further improvements requiring breakthrough technologies. Performing experiments at an industrial scale are often expensive, complicated to set up and difficult to reproduce.

Elimination of sucrose transport and hydrolysis in Saccharomyces cerevisiae: a platform strain for engineering sucrose metabolism.

Many relevant options to improve efficacy and kinetics of sucrose metabolism in Saccharomyces cerevisiae and, thereby, the economics of sucrose-based processes remain to be investigated. An essential first step is to identify all native sucrose-hydrolysing enzymes and sucrose transporters in this yeast, including those that can be activated by suppressor mutations in sucrose-negative strains. A strain in which all known sucrose-transporter genes (MAL11, MAL21, MAL31, MPH2, MPH3) were deleted did not grow on sucrose after 2 months of incubation.

Physiology of Saccharomyces cerevisiae strains isolated from Brazilian biomes: new insights into biodiversity and industrial applications.

Fourteen indigenous Saccharomyces cerevisiae strains isolated from the barks of three tree species located in the Atlantic Rain Forest and Cerrado biomes in Brazil were genetically and physiologically compared to laboratory strains and to strains from the Brazilian fuel ethanol industry. Although no clear correlation could be found either between phenotype and isolation spot or between phenotype and genomic lineage, a set of indigenous strains with superior industrially relevant traits over commonly known industrial and laboratory strains was identified: strain UFMG-CM-Y257 has a very high specific growth rate on sucrose (0.57 ± 0.

Kluyveromyces marxianus as a host for heterologous protein synthesis.

The preferentially respiring and thermotolerant yeast Kluyveromyces marxianus is an emerging host for heterologous protein synthesis, surpassing the traditional preferentially fermenting yeast Saccharomyces cerevisiae in some important aspects: K . marxianus can grow at temperatures 10 °C higher than S. cerevisiae, which may result in decreased costs for cooling bioreactors and reduced contamination risk; has ability to metabolize a wider variety of sugars, such as lactose and xylose; is the fastest growing eukaryote described so far; and does not require special cultivation techniques (such as fed-batch) to avoid fermentative metabolism.