High-throughput screening of non-conventional yeasts for conversion of organic waste to microbial oils via carboxylate platform

Converting waste into high-value products promotes sustainability by reducing waste, lowering greenhouse gas emissions, and creating new revenue streams from waste materials. This study investigates the potential of diverse yeasts for microbial oil production by utilizing of short-chain fatty acids (SCFAs) that can be produced from organic waste. A collection of 1,434 yeast strains was cultivated at 15 g/L and 25 g/L total SCFAs, consisting of mixtures of acetic, propionic and butyric acids. Eleven strains emerged as candidate strains with promising growth rates and high lipid accumulation on solid SCFA-rich media. Subsequent fermentation experiments in liquid SCFA-rich media, which focused on optimizing lipid accumulation by adjusting the carbon to nitrogen (C/N) ratio, showed an increase in lipid content at a C/N ratio of 200:1, but with a concurrent reduction in biomass. Two strains in particular were characterized by their superior lipid production capabilities compared to the reference strain Yarrowia lipolytica CECT124: Y. lipolytica EXF-17398 and Pichia manshurica EXF-7849. The characterization of these two strains indicated that they exhibit a biotechnologically relevant balance between maximizing lipid yield and maintaining growth at high SCFA concentrations. These results emphasize the potential of using SCFAs as a sustainable feedstock for oleochemical production, offering a dual benefit of waste valorisation and renewable energy generation

Characterization of Aureobasidium pullulans Isolates Selected as Biocontrol Agents Against Fruit Decay Pathogens

peer reviewe

Genome reduction and relaxed selection is associated with the transition to symbiosis in the basidiomycete genus Podaxis

Insights into the genomic consequences of symbiosis for basidiomycete fungi associated with social insects remain sparse. Capitalizing on viability of spores from centuries-old herbarium specimens of free-living, facultative, and specialist termite-associated Podaxis fungi, we obtained genomes of 10 specimens, including two type species described by Linnaeus >240 years ago. We document that the transition to termite association was accompanied by significant reductions in genome size and gene content, accelerated evolution in protein-coding genes, and reduced functional capacities for oxidative stress responses and lignin degradation. Functional testing confirmed that termite specialists perform worse under oxidative stress, while all lineages retained some capacity to cleave lignin. Mitochondrial genomes of termite associates were significantly larger; possibly driven by smaller population sizes or reduced competition, supported by apparent loss of certain biosynthetic gene clusters. Our findings point to relaxed selection that mirrors genome traits observed among obligate endosymbiotic bacteria of many insects.SUPPLEMENTARY MATERIAL: DOCUMENT S1. Figures S1–S10 and Tables S1, S2, S3, and S8TABLE S4. Orthogroups which were present in at least two genomes with the lifestyles in which they were found, related to Figure 2BTABLE S5. Predicted CAZymes, EC numbers and substrates from HotPep analysis, related to Figures 3A–3ETABLE S6. Functionally-enriched GO terms based on dcGO with an adjusted p-value cutoff of padj = 0.05, related to Figure 2BTABLE S7. Growth measurements for Podaxis strains grown on YMEA enriched with 0, 5 and 20 mM H2O2, related to Figure 3FThe Danish Council for Independent Research, the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) and the Slovenian Research Agency.https://www.cell.com/iscience/homehj2021BiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant Patholog

The termite fungal cultivar Termitomyces combines diverse enzymes and oxidative reactions for plant biomass conversion

Please read abstract in the article.The Deutsche Forschungsgemeinschaft (DFG; German Research Foundation), the Danish Council for Independent Research, a European Research Council consolidator grant and the state budget of the Slovenian Research Agency.https://journals.asm.org/journal/mbiohj2021BiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant Patholog

Effects of Desiccation and Freezing on Microbial Ionizing Radiation Survivability: Considerations for Mars Sample Return

Increasingly, national space agencies are expanding their goals to include Mars exploration with sample return. To better protect Earth and its biosphere from potential extraterrestrial sources of contamination, as set forth in the Outer Space Treaty of 1967, international efforts to develop planetary protection measures strive to understand the danger of cross-contamination processes in Mars sample return missions. We aim to better understand the impact of the martian surface on microbial dormancy and survivability. Radiation resistance of microbes is a key parameter in considering survivability of microbes over geologic times on the frigid, arid surface of Mars that is bombarded by solar and galactic cosmic radiation. We tested the influence of desiccation and freezing on the ionizing radiation survival of six model microorganisms: vegetative cells of two bacteria (Deinococcus radiodurans, Escherichia coli) and a strain of budding yeast (Saccharomyces cerevisiae); and vegetative cells and endospores of three Bacillus bacteria (B. subtilis, B. megaterium, B. thuringiensis). Desiccation and freezing greatly increased radiation survival of vegetative polyploid microorganisms when applied separately, and when combined, desiccation and freezing increased radiation survival even more so. Thus, the radiation survival threshold of polyploid D. radiodurans cells can be extended from the already high value of 25 kGy in liquid culture to an astonishing 140 kGy when the cells are both desiccated and frozen. However, such synergistic radioprotective effects of desiccation and freezing were not observed in monogenomic or digenomic Bacillus cells and endospores, which are generally sterilized by 12 kGy. This difference is associated with a critical requirement for survivability under radiation, that is, repair of genome damage caused by radiation. Deinococcus radiodurans and S. cerevisiae accumulate similarly high levels of the Mn antioxidants that are required for extreme radiation resistance, as do endospores, though they greatly exceed spores in radioresistance because they contain multiple identical genome copies, which in D. radiodurans are joined by persistent Holliday junctions. We estimate ionizing radiation survival limits of polyploid DNA-based life-forms to be hundreds of millions of years of background radiation while buried in the martian subsurface. Our findings imply that forward contamination of Mars will essentially be permanent, and backward contamination is a possibility if life ever existed on Mars