Assessment of drying conditions for storage of a yeast-based decolorization solution for application in textile industrial wastewater treatment plants.

The textile industry produces harmful effluents that are discharged into the environment, damaging the aquatic and other ecosystems. A yeast-based solution for decolorization of textile industrial wastewater was produced and evaluated. Three yeast strains, Candida parapsilosis (HOMOGS20B), Yarrowia lipolytica (HOMOGST27AB) and Candida pseudoglaebosa (LIIIS36B), isolated from a textile wastewater treatment plant and previously selected for their dye decolorization capacity, were freeze-dried. Additionally, Yarrowia lipolytica (HOMOGST27AB) was also spray-dried. Skim milk powder and maltodextrin were used as cell protectors, and the freeze-dried products were stored at cold (4 °C) and room temperature for 210 days. The viability of the yeast cells and their decolorization capacity over time were assessed. Dried yeast cells maintained their viability, and decolorization capacity for at least 90 days of storage after spray- and freeze-drying with both cell-protecting agents. The dried yeast-based solution for decolorizing textile industrial wastewater combines stability, efficiency, and convenience of production for application in real industrial facilities.

Screening for a more sustainable solution for decolorization of dyes and textile effluents using Candida and Yarrowia spp.

Dyed effluents from textile industry are toxic and difficult to treat by conventional methods and biotechnological approaches are generally considered more environmentally friendly. In this work, yeast strains Candida parapsilosis, Yarrowia lipolytica and Candida pseudoglaebosa, isolated from wastewater treatment plants, were tested for their ability to decolorize textile dyes. Both commercial textile synthetic dyes (reactive, disperse, direct, acid and basic) and simulated textile effluents (a total of 32 solutions) were added to a Normal Decolorization Medium along with the yeast (single strains and consortia) and the decolorization was evaluated spectrophotometrically for 48-72 h. Yeasts were able to perform decolorization through adsorption and biodegradation for 28 of the dyes and simulated effluents by more than 50%. Y. lipolytica and C. pseudoglaebosa presented the best results with a true decolorization of reactive dyes, above 90% at 100 mg l-1, and simulated effluents at 5 g l-1 of concentration. Enzyme production was evaluated: oxidoreductase was found in the three yeasts, whereas tyrosinase was only found in Y. lipolytica and C. pseudoglaebosa. Y. lipolytica and C. pseudoglaebosa are a potential biotechnological tool for dye degradation in textile wastewaters, especially those containing reactive dyes and a promising tool to integrate in bioremediation solutions, contributing to circular economy and eco sustainability in the water sector since the treated water could possibly be reused for irrigation.

Variation in ectomycorrhizal fungal communities associated with Silver linden (Tilia tomentosa) within and across urban areas.

Trees in urban areas face harsh environmental conditions. Ectomycorrhizal fungi (EcM) form a symbiosis with many tree species and provide a range of benefits to their host through their extraradical hyphal network. Although our understanding of the environmental drivers and large scale geographical variation of EcM communities in natural ecosystems is growing, our knowledge of EcM communities within and across urban areas is still limited. Here, we characterized EcM communities using Illumina miseq sequencing on 175 root samples of the urban tree Tilia tomentosa from three European cities, namely Leuven (Belgium), Strasbourg (France) and Porto (Portugal). We found strong differences in EcM richness and community composition between cities. Soil acidity, organic matter and moisture content were significantly associated with EcM community composition. In agreement, the explained variability in EcM communities was mostly attributed to general soil characteristics, whereas very little variation was explained by city and heavy metal pollution. Overall, our results suggest that EcM communities in urban areas are significantly associated with soil characteristics, while heavy metal pollution and biogeography had little or no impact. These findings deliver new insights into EcM distribution patterns in urban areas and contribute to specific inoculation strategies to improve urban tree vitality.

Characterization and antimicrobial properties of food packaging methylcellulose films containing stem extract of Ginja cherry.

BACKGROUND: Food contamination and spoilage is a problem causing growing concern. To avoid it, the use of food packaging with appropriate characteristics is essential; ideally, the packaging should protect food from external contamination and exhibit antibacterial properties. With this aim, methylcellulose (MC) films containing natural extracts from the stems of Ginja cherry, an agricultural by-product, were developed and characterized. RESULTS: The antibacterial activity of films was screened by the disc diffusion method and quantified using the viable cell count assay. The films inhibited the growth of both Gram-positive and Gram-negative strains (Listeria innocua, methicillin-sensitive Staphylococcus aureus, methicillin-resistant S. aureus, Salmonella Enteritidis, Escherichia coli). For the films with lower extract content, effectiveness against the microorganisms depended on the inoculum concentration. Scanning electron microscope images of the films showed that those containing the extracts had a smooth and continuous structure. UV-visible spectroscopy showed that these materials do not transmit light in the UV. CONCLUSION: This study shows that MC films containing agricultural by-products, in this case Ginja cherry stem extract, could be used to prevent food contamination by relevant bacterial strains and degradation by UV light. Using such materials in food packaging, the shelf life of food products could be extended while utilizing an otherwise wasted by-product.