Recent innovations in fertilization with treated digestate from food waste to recover nutrients for arid agricultural fields.

This study aims to explore the development of sustainable fertilizers from waste materials of a biogas plant and a brewery. These wastes, rich in organic carbon and nitrogen, were processed with sulfuric(VI) and phosphoric(V) acid mixture, facilitating the production of free amino acids and achieving waste sanitization. This treatment produced by-products, which extended the range of possible applications. The highest concentration of free amino acids (360 mg/l) was achieved through hydrolyzing with a 40% concentration medium over 24 h. In this case, the maximum levels were recorded for beta-alanine (69.3 mg/l), glycine (46.8 mg/l), isoleucine (43.5 mg/l), proline (36.2 mg/l), and valine (31.5 mg/l). The study presents two fertilizer technologies, with and without micronutrients, that satisfy European Parliament Regulation 2019/1009 (Ntot > 2%, Norg > 0.5%, Corg > 3%). Bioavailability of nutrients in the formulations ranged from 60 to 100%. The efficacies of these fertilizers were evaluated in 30-day pot trials with various plant species, with both single application and fertigation tested. Multielement analysis confirmed high nutrient transfer in the soil-plant system, and the inclusion of micronutrients led to biofortification of plant biomass in Cu (48.3 ± 7.2 mg/kg), Mn (249 ± 37 mg/kg), Zn (164 ± 25 mg/kg), and Fe (211 ± 32 mg/kg). These sustainable fertilizers present an alternative to traditional, non-renewable fertilizers and offer promising solutions for precision agriculture and environmentally conscious production.

Maximizing the potential of leachate from sewage sludge as a sustainable nutrients source to alleviate the fertilizer crisis.

Leachate from separate digesters in biological wastewater treatment plants contains valuable biogenic compounds that can serve as fertilizer nutrients. In this study, a method was developed to utilize leachate from sewage sludge dewatering as a raw material for the preparation of a plant conditioner, providing water, nutrients, and growth-stimulating amino acids. A chemical conditioning procedure (65% HNO3) was used to prepare the leachate solution for fertilization. The feasibility of producing an amino acid-based fertilizer using shrimp shells and inorganic acids (96% H2SO4 and 85% H3PO4) was also demonstrated. Microbiological analysis confirmed the safety of the formulations, and chelation of micronutrients with available amino acids was proven (up to 100% chelating degree). The bioavailability of all nutrients was confirmed through extraction tests (extraction in neutral ammonium citrate). Germination tests showed similar fresh plant masses to those with commercial preparations, demonstrating the effectiveness of the developed technology. This approach aligns with circular economy principles and sustainable development and contributes to mitigating the impacts of climate change.

Insights into the Genomic and Phenotypic Landscape of the Oleaginous Yeast Yarrowia lipolytica.

Although Yarrowia lipolytica is a model yeast for the study of lipid metabolism, its diversity is poorly known, as studies generally consider only a few standard laboratory strains. To extend our knowledge of this biotechnological workhorse, we investigated the genomic and phenotypic diversity of 56 natural isolates. Y. lipolytica is classified into five clades with no correlation between clade membership and geographic or ecological origin. A low genetic diversity (π = 0.0017) and a pan-genome (6528 genes) barely different from the core genome (6315 genes) suggest Y. lipolytica is a recently evolving species. Large segmental duplications were detected, totaling 892 genes. With three new LTR-retrotransposons of the Gypsy family (Tyl4, Tyl9, and Tyl10), the transposable element content of genomes appeared diversified but still low (from 0.36% to 3.62%). We quantified 34 traits with substantial phenotypic diversity, but genome-wide association studies failed to evidence any associations. Instead, we investigated known genes and found four mutational events leading to XPR2 protease inactivation. Regarding lipid metabolism, most high-impact mutations were found in family-belonging genes, such as ALK or LIP, and therefore had a low phenotypic impact, suggesting that the huge diversity of lipid synthesis and accumulation is multifactorial or due to complex regulations.

The Role of Plasma Membrane Pleiotropic Drug Resistance Transporters in the Killer Activity of Debaryomyces hansenii and Wickerhamomyces anomalus Toxins.

The killer strains of Debaryomyces hansenii and Wickerhamomyces anomalus species secrete antimicrobial proteins called killer toxins which are active against selected fungal phytopathogens. In our research, we attempted to investigate the role of plasma membrane pleiotropic drug resistance (PDR) transporters (Pdr5p and Snq2p) in the mechanism of defense against killer toxins. Saccharomyces cerevisiae mutant strains with strengthened or weakened pleiotropic drug resistance due to increased or reduced number of mentioned PDR efflux pumps were tested for killer toxin susceptibility. The present study demonstrates the influence of the Snq2p efflux pump in immunity to W.anomalus BS91 killer toxin. It was also shown that the activity of killer toxins of D. hansenii AII4b, KI2a, MI1a and CBS767 strains is regulated by other transporters than those influencing W. anomalus killer toxin activity. In turn, this might be related to the functioning of the Pdr5p transporter and a complex cross-talk between several regulatory multidrug resistance networks. To the best of our knowledge, this is the first study that reports the involvement of PDR transporters in the cell membrane of susceptible microorganisms in resistance to killer yeasts' toxins.

New Cytoplasmic Virus-Like Elements (VLEs) in the Yeast Debaryomyces hansenii.

Yeasts can have additional genetic information in the form of cytoplasmic linear dsDNA molecules called virus-like elements (VLEs). Some of them encode killer toxins. The aim of this work was to investigate the prevalence of such elements in D. hansenii killer yeast deposited in culture collections as well as in strains freshly isolated from blue cheeses. Possible benefits to the host from harboring such VLEs were analyzed. VLEs occurred frequently among fresh D. hansenii isolates (15/60 strains), as opposed to strains obtained from culture collections (0/75 strains). Eight new different systems were identified: four composed of two elements and four of three elements. Full sequences of three new VLE systems obtained by NGS revealed extremely high conservation among the largest molecules in these systems except for one ORF, probably encoding a protein resembling immunity determinant to killer toxins of VLE origin in other yeast species. ORFs that could be potentially involved in killer activity due to similarity to genes encoding proteins with domains of chitin-binding/digesting and deoxyribonuclease NucA/NucB activity, could be distinguished in smaller molecules. However, the discovered VLEs were not involved in the biocontrol of Yarrowia lipolytica and Penicillium roqueforti present in blue cheeses.

Sustainable Surfactin Production by Bacillus subtilis Using Crude Glycerol from Different Wastes.

Most biosurfactants are obtained using costly culture media and purification processes, which limits their wider industrial use. Sustainability of their production processes can be achieved, in part, by using cheap substrates found among agricultural and food wastes or byproducts. In the present study, crude glycerol, a raw material obtained from several industrial processes, was evaluated as a potential low-cost carbon source to reduce the costs of surfactin production by Bacillus subtilis #309. The culture medium containing soap-derived waste glycerol led to the best surfactin production, reaching about 2.8 g/L. To the best of our knowledge, this is the first report describing surfactin production by B. subtilis using stearin and soap wastes as carbon sources. A complete chemical characterization of surfactin analogs produced from the different waste glycerol samples was performed by liquid chromatography-mass spectrometry (LC-MS) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the surfactin produced in the study exhibited good stability in a wide range of pH, salinity and temperatures, suggesting its potential for several applications in biotechnology.

Role of biocontrol yeasts Debaryomyces hansenii and Wickerhamomyces anomalus in plants' defence mechanisms against Monilinia fructicola in apple fruits.

The role of killer yeasts of the species Debaryomyces hansenii and Wickerhamomyces anomalus in biocontrol of Monilinia fructicola, and their involvement in plant defence mechanisms against brown rot in apple fruits, were investigated. D. hansenii KI2a and W. anomalus BS91 strains showed the highest in vitro biocontrol activity, inhibiting mycelium growth by 69.53% and 66.08% respectively, as compared to control fungal cultures. Brown rot on apple fruits was significantly reduced by BS91 and two strains of D. hansenii KI2a and AII4b by 92.46%, 85.10% and 70.02%, respectively, in comparison to infected fruits, which did not receive any pre-treatment. In enzymatic tests, the most significant changes in peroxidase (POD) and catalase (CAT) activities were observed in fruits inoculated either with BS91 followed by M. fructicola infection or with AII4b yeast strain alone, where POD activities were significantly higher by 67% and 54%, respectively, and CAT activities were significantly lower by 65% and 68%, respectively, than in untreated control fruits. These results confirmed the ability of killer yeasts to influence host-defence related enzyme activities in apple fruit tissue and may suggest that AII4b killer strain has a potential as biocontrol agent prior to infection by triggering immune response mechanisms in plant tissue, whereas BS91 strain is the most effective during pathogen infection and could be used as biocontrol agent in postharvest disease onset. Accordingly, the antagonistic strains of W. anomalus BS91 and D. hansenii KI2a and AII4b could be proposed as active ingredients for the development of biofungicide against M. fructicola.

Draft Genome Sequence of Yarrowia lipolytica Strain A-101 Isolated from Polluted Soil in Poland.

Yarrowia lipolytica is an early diverging species of the Saccharomycotina subphylum, which is recognized as a valuable host for many biotechnological applications exploiting its oleaginous capacities. The 20.5-Mb genome of the Polish Y. lipolytica strain A-101 will greatly help decipher the genetic basis of the regulation of its lipid metabolism.