Some Rhodotorula spp. have been characterized as oleaginous yeasts. Under certain culture conditions they can accumulate neutral lipids, which are mainly triglycerides (TAG). Microbial TAG that can be used as raw material for biodiesel synthesis are attractive for the biofuel industry. In this study, the ability to synthesize lipids of Rhodotorula glutinis R4, isolated in Antarctica, was compared with eight strains belonging to the genera Rhodotorula and Yarrowia with the aim of proposing a novel source of oils for biodiesel synthesis. All strains were cultured under nitrogen (N) limiting conditions and an excess of carbon (C) in the culture medium. We found that yeasts accumulated between 9-48.9 % (w/w) of lipids. Among them, R. glutinis R4 showed the highest growth (14 g L-1, μmax 0,092 h-1) and lipid production (7 g L-1; 47 % w/w). Microbial oils produced by R. glutinis R4 are similar to vegetable oils, with 61 % of oleic acid, indicating that it is adequate for biodiesel synthesis. Our results demonstrate that biodiesel derived from R. glutinis R4 complies with international fuel standards ASTM D6751 and EN 14214. Therefore, this work demonstrates that Rhodotorula glutinis R4 is a novel and valuable source of microbial oils for biodiesel synthesis.

The growing global population, along with evolving dietary trends and increasing concerns about health and the environment, underscores the urgent need to transform current food systems to minimize their environmental footprint and enhance global food security. This transformation has driven the development and demand for alternative food sources. In this context, alternative proteins emerge as promising options due to their production from plants, microorganisms, and insects, which potentially reduces the environmental impact of food production while supporting global food security. Nevertheless, the transition toward alternative proteins presents significant challenges related to the presence of antinutritional compounds, poor amino acid composition, lower digestibility, and undesirable organoleptic characteristics. Moreover, these new generations of alternative foods are highly processed, raising concerns about their nutritional adequacy compared to traditional products. In this context, fermentation technologies have emerged as promising tools to overcome these limitations. Traditional fermentation can degrade antinutritional factors, improve digestibility, and release bioactive compounds, allowing the production of new products with health-promoting properties. Beyond traditional fermentation, biomass fermentation to single-cell protein or microbial protein production represents a sustainable alternative, promoting a climate-friendly approach aligned with circular bioeconomy principles by upcycling various agro-industrial streams. Thus, this review discusses how microbial strategies (from traditional fermentation to cutting-edge microbial protein production) can enhance the nutritional properties of alternative protein-based foods. Emphasis is placed on the capacity of traditional fermentation to improve nutritional quality and bioactivity, mitigate undesirable sensory traits, and preserve or enhance micronutrient content. Additionally, integrating biomass fermentation and emerging precision fermentation positions microorganisms as valuable contributors to more nutritious and sustainable food systems.

Single-cell oils (SCOs) offer a promising alternative to conventional biodiesel feedstocks. The main objective of this work was to obtain SCOs suitable for biodiesel production from the oleaginous yeast Rhodotorula glutinis R4 using sugarcane vinasse from a local sugar-derived alcohol industry as the substrate. Additionally, crude glycerol from the local biodiesel industry was evaluated as a low-cost carbon source to replace expensive glucose and as a strategy for integrating the bioethanol and biodiesel industries for the valorization of both agro-industrial wastes. R4 achieved a high lipid accumulation of 88% and 60% (w/w) in vinasse-based culture media, containing 10% and 25% vinasse with glucose (40 g L⁻¹), respectively. When glucose was replaced with crude glycerol, R4 showed remarkable lipid accumulation (40%) and growth (12.58 g L⁻¹). The fatty acids profile of SCOs showed a prevalence of oleic acid (C18:1), making them suitable for biodiesel synthesis. Biodiesel derived from R4 oils exhibits favorable characteristics, including a high cetane number (CN = 55) and high oxidative stability (OS = 13 h), meeting international biodiesel standards (ASTMD6751 and EN14214) and ensuring its compatibility with diesel engines. R. glutinis R4 produces SCOs from vinasse and crude glycerol, contributing to the circular economy for sustainable biodiesel production.

Among microbials, Trichoderma spp. have been the focus of significant research due to their capacity to promote plant growth and suppress a wide range of phytopathogens. A total of 27 native isolates of Trichoderma spp. were obtained from diverse agroecological regions of the province of Tucumán, Argentina, and were characterized by their antagonistic activity and phytostimulant potential. In vitro assays revealed the ability of the isolates to combat fungal phytopathogens that affect various economically important crops, such as Penicillium digitatum, Alternaria alternata, Botrytis cinerea, Phytophthora capsici, and Fusarium oxysporum. Furthermore, it was determined that diffusible compounds secreted by Trichoderma isolates did not induce the elongation of the primary root of Arabidopsis thaliana in vitro; however, volatile compounds released by certain isolates not only induced this process but also increased the area occupied by the lateral roots of the plant. Based on this screening, five isolates were selected for further analyses: T. longibrachiatum (CP-1), T. breve (HM-1), T. scalesiae (L1-03), T. yunnanense (M4Ar-05), and T. atrobrunneum (M5Ar-03). The strains were evaluated for their ability to promote the growth of A. thaliana under greenhouse conditions and modulate the expression of growth and defense-related genes. All treated plants exhibited increased biomass and leaf area, accompanied by isolate-dependent changes in the expression of genes involved in plant development and immune responses. These results suggest that the selected Trichoderma spp. possess multiple beneficial traits, with valuable agricultural properties, and provide a basis for the development of bioformulations adapted to local production systems.