Ethanol and 2-phenylethanol production by bee-isolated Meyerozyma caribbica strains.

Investigating the biotechnological potential of wild microorganisms is paramount for optimizing bioprocesses. Given this premise, we looked for yeasts in Brazilian native stingless bees, considering the recognized potential of pollinating insect-associated microorganisms for the production of volatile organic compounds (VOCs). Two yeast strains of the species Meyerozyma caribbica were isolated from bees Scaptotrigona postica and evaluated for their fermentative capacity. Both yeasts were capable of fermenting sucrose (the main sugar used in the Brazilian ethanol industry) with over 90% efficiency and yields of up to 0.504 g/g. Through an experimental design analysis (CCD), it was verified that the ethanol productivity of these yeasts can also benefit from high concentrations of sucrose and low pH values, desirable traits for microorganisms in this biofuel production. At the same time, CCD analyses also showed the great capacity of these M. caribbica strains to produce another alcohol of broad biotechnological interest, 2-phenylethanol. Interestingly, the statistical analyses demonstrated that greater production of this compound can occur at high sugar concentrations and low availability of nitrogen sources, which can be easily achieved using residual low-cost feedstocks. Thus, our results suggest that these M. caribbica strains may be efficiently used in both ethanol and 2-phenylethanol production.

Prospecting and engineering yeasts for ethanol production under inhibitory conditions: an experimental design analysis.

The recently discovered wild yeast Wickerhamomyces sp. UFFS-CE-3.1.2 was analyzed through a high-throughput experimental design to improve ethanol yields in synthetic media with glucose, xylose, and cellobiose as carbon sources and acetic acid, furfural, formic acid, and NaCl as fermentation inhibitors. After Plackett-Burman (PB) and central composite design (CCD), the optimized condition was used in a fermentation kinetic analysis to compare this yeast's performance with an industrial Saccharomyces cerevisiae strain (JDY-01) genetically engineered to achieve a higher xylose fermentation capacity and fermentation inhibitors tolerance by overexpressing the genes XYL1, XYL2, XKS1, and TAL1. Our results show that furfural and NaCl had no significant effect on sugar consumption by UFFS-CE-3.1.2. Surprisingly, acetic acid negatively affected glucose but not xylose and cellobiose consumption. In contrast, the pH positively affected all the analyzed responses, indicating a cell's preference for alkaline environments. In the CCD, sugar concentration negatively affected the yields of ethanol, xylitol, and cellular biomass. Therefore, fermentation kinetics were carried out with the average concentrations of sugars and fermentation inhibitors and the highest tested pH value (8.0). Although UFFS-CE-3.1.2 fermented glucose efficiently, xylose and cellobiose were mainly used for cellular growth. Interestingly, the genetically engineered strain JDY-01 consumed ~ 30% more xylose and produced ~ 20% more ethanol. Also, while UFFS-CE-3.1.2 only consumed 32% of the acetic acid of the medium, JDY-01 consumed > 60% of it, reducing its toxic effects. Thus, the overexpressed genes played an essential role in the inhibitors' tolerance, and the applied engineering strategy may help improve 2G ethanol production.

Biochemical and Biotechnological Insights into Fungus-Plant Interactions for Enhanced Sustainable Agricultural and Industrial Processes.

The literature is full of studies reporting environmental and health issues related to using traditional pesticides in food production and storage. Fortunately, alternatives have arisen in the last few decades, showing that organic agriculture is possible and economically feasible. And in this scenario, fungi may be helpful. In the natural environment, when associated with plants, these microorganisms offer plant-growth-promoting molecules, facilitate plant nutrient uptake, and antagonize phytopathogens. It is true that fungi can also be phytopathogenic, but even they can benefit agriculture in some way-since pathogenicity is species-specific, these fungi are shown to be useful against weeds (as bioherbicides). Finally, plant-associated yeasts and molds are natural biofactories, and the metabolites they produce while dwelling in leaves, flowers, roots, or the rhizosphere have the potential to be employed in different industrial activities. By addressing all these subjects, this manuscript comprehensively reviews the biotechnological uses of plant-associated fungi and, in addition, aims to sensitize academics, researchers, and investors to new alternatives for healthier and more environmentally friendly production processes.

Nature's Most Fruitful Threesome: The Relationship between Yeasts, Insects, and Angiosperms.

The importance of insects for angiosperm pollination is widely recognized. In fact, approximately 90% of all plant species benefit from animal-mediated pollination. However, only recently, a third part player in this story has been properly acknowledged. Microorganisms inhabiting floral nectar, among which yeasts have a prominent role, can ferment glucose, fructose, sucrose, and/or other carbon sources in this habitat. As a result of their metabolism, nectar yeasts produce diverse volatile organic compounds (VOCs) and other valuable metabolites. Notably, some VOCs of yeast origin can influence insects' foraging behavior, e.g., by attracting them to flowers (although repelling effects have also been reported). Moreover, when insects feed on nectar, they also ingest yeast cells, which provide them with nutrients and protect them from pathogenic microorganisms. In return, insects serve yeasts as transportation and a safer habitat during winter when floral nectar is absent. From the plant's point of view, the result is flowers being pollinated. From humanity's perspective, this ecological relationship may also be highly profitable. Therefore, prospecting nectar-inhabiting yeasts for VOC production is of major biotechnological interest. Substances such as acetaldehyde, ethyl acetate, ethyl butyrate, and isobutanol have been reported in yeast volatomes, and they account for a global market of approximately USD 15 billion. In this scenario, the present review addresses the ecological, environmental, and biotechnological outlooks of this three-party mutualism, aiming to encourage researchers worldwide to dig into this field.