Biopolymer-based emulsions for the stabilization of Trichoderma atrobrunneum conidia for biological control.

Trichoderma spp. are ubiquitous soil-borne fungi that are widely used in biological control to promote and regulate healthy plant growth, as well as protect against plant pathogens. However, as with many biological materials, the relative instability of Trichoderma propagules limits its practical use in industrial applications. Therefore, there has been significant research interest in developing novel formulations with various carrier substances that are compatible with these fungal propagules and can enhance the shelf-life and overall efficacy of the Trichoderma. To this end, herein, we investigate the use of a variety of biopolymers and nanoparticles for the stabilization of Trichoderma atrobrunneum T720 conidia for biological control. The best-performing agents-agar and cellulose nanocrystals (CNC)-were then used in the preparation of oil-in-water emulsions to encapsulate conidia of T720. Emulsion properties including oil type, oil:water ratio, and biopolymer/particle concentration were investigated with respect to emulsion stability, droplet size, and viability of T720 conidia over time. Overall, agar-based formulations yielded highly stable emulsions with small droplet sizes, showing no evidence of drastic creaming, or phase separation after 1 month of storage. Moreover, agar-based formulations were able to maintain ~ 100% conidial viability of T720 after 3 months of storage, and over 70% viability after 6 months. We anticipate that the results demonstrated herein will lead to a new generation of significantly improved formulations for practical biological control applications. KEY POINTS: • Various biopolymers were evaluated for improving the stability of Trichoderma conidia • Oil in water emulsions was prepared using cellulose nanocrystals and agar as interface stabilizers • Agar-based emulsions showed ~ 100% viability for encapsulated conidia after 3 months of storage.

Microfibrillated cellulose as growth media for cultivation and maintenance of wood decay fungi.

Newly enforced trade restrictions on seaweed, have resulted in short supply of technical agar with potential consequences for research, public health, and clinical labs. Here we show that microfibrillated cellulose (MFC), with and without an additional carbon source, can be used as an inexpensive growth media for cultivating and maintaining wood decay fungi.

Release and environmental impact of silver nanoparticles and conventional organic biocides from coated wooden façades.

This study represents for the first time a comprehensive assessment of functionality and environmental impacts of metallic silver nanoparticles (Ag-NP) compared to conventional organic biocides. Four different transparent, hydrophobic coatings of wooden outdoor façades were tested during one year outdoor weathering. The total silver release from products with Ag-NP was proportional to the overall erosion of the coating. The results indicate that the Ag-NPs are likely transformed to silver complexes, which are considerably less toxic than ionic silver. The protective effect of the silver containing coatings against mold, blue stain and algae was insufficient, even in immaculate and non-weathered conditions. The release of organic biocides from conventional coatings was dependent on the weather conditions, the type of biocide and the use in the base or top coat. The conventional coating showed a good overall performance free from mold, blue stain and algae until the end of the test period.