Virulence profile of Candida spp. isolated from an anaerobic biodigester supplied with dairy cattle waste.

Anaerobic biodigesters play a crucial role in enhancing animal waste management. However, the presence of pathogens in the biodigestion process poses a significant concern. Candida spp., a widespread fungus known for its opportunistic nature and adaptability to diverse environmental conditions, including reciprocal transmission between humans and animals, is one such pathogen of concern. Therefore, it is imperative to assess the virulence profile of Candida spp. originating from anaerobic biodigestion processes. Here we demonstrate that strains isolated from the biodigestion process of dairy cattle waste exhibit noteworthy virulence mechanisms, surpassing the virulence of clinical control strains. After we identified strains from affluent, effluent, and biofertilizer, we observed that all analyzed isolates produced biofilm. Additionally, a substantial proportion of these isolates demonstrated phospholipase production, while only a few strains exhibited protease production. Furthermore, all strains exhibited resistance or dose-dependent responses to amphotericin B and itraconazole, with the majority displaying resistance to fluconazole. In the in vivo test, we observed a significant correlation (p < 0.05) between the LT50 and biofilm formation as well as hyphae/pseudohyphae production. Additionally, some isolates demonstrated a quicker nematode-killing capacity compared to clinical controls. Our findings underscore the considerable pathogenic potential of certain Candida species present in the dynamics of anaerobic biodigestion. Importantly, the anaerobic biodigester system did not eliminate Candida strains from dairy cattle waste, highlighting the need for caution in utilizing biodigester products. We advocate for further studies to explore the virulence of other microorganisms in various animal production contexts. Furthermore, our results emphasize the urgency of enhancing waste treatment methods to effectively eliminate pathogens and curb their potential dissemination.

Resveratrol-coated gold nanorods produced by green synthesis with activity against Candida albicans.

Candida albicans is an opportunistic yeast capable of causing a wide range of mucosal, cutaneous, and systemic infections. However, therapeutic strategies are limited to a few antifungal agents. Inorganic nanoparticles have been investigated as carrier systems for antifungals as potential new treatments. In this study, we focused on the antifungal activity of gold nanorods, a specific rod-shaped gold nanoparticle, produced by green synthesis using resveratrol as a metal-reducing agent. The synthesis method resulted in stable control nanoparticles (AuNp) and resveratrol-coated gold nanoparticles (AuNpRSV) with medium sizes of 32.4 × 15.9 nm for AuNp, and 33.5 × 15.3 nm for AuNpRSV. Both AuNp and AuNpRSV inhibited the C. albicans grown at 2.46 µg/mL, exhibited fungicidal effects at 4.92 µg/mL, and significantly decreased filamentation, biofilm viability, reactive oxygen species production and ergosterol levels of C. albicans. In addition, exposure to AuNpRSV reduced the ability of C. albicans to grow in the presence of cell membrane stressors. Transmission electron microscopy revealed enlargement of the cell wall and retraction of the cell membrane after treatment with AuNp and AuNpRSV. Promisingly, in vivo toxicity analysis demonstrated that both nanoparticles maintained the full viability of Galleria mellonella larvae at 49.20 µg/mL. In conclusion, both gold nanoparticles exhibited antifungal activity; however, these effects were enhanced by AuNpRSV. Altogether, AuNps and AuNpRSVs are potential antifungal agents for the treatment of C. albicans infections.

Silver Nanoparticle-Embedded Carbon Nitride: Antifungal Activity on Candida albicans and Toxicity toward Animal Cells.

The development of engineered nanomaterials has been considered a promising strategy to control oral infections. In this study, silver-embedded carbon nitrides (Ag@g-CN) were synthesized and tested against Candida albicans, investigating their antifungal action and biocompatibility in animal cells. Ag@g-CN was synthesized by a simple one-pot thermal polymerization technique and characterized by various analytical techniques. X-ray diffraction (XRD) analysis revealed slight alterations in the crystal structure of g-CN upon the incorporation of Ag. Fourier transform infrared (FT-IR) spectroscopy confirmed the presence of Ag-N bonds, indicating successful silver incorporation and potential interactions with g-CN's amino groups. UV-vis spectroscopy demonstrated a red shift in the absorption edge of Ag@g-CN compared with g-CN, attributed to the surface plasmon resonance effect of silver nanoparticles. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) confirmed the 2D layered sheet like morphology of both materials. The Ag 3d peaks found in X-ray photoelectron spectroscopy (XPS) confirmed the presence of metallic Ag0 nanoparticles in Ag@g-CN. The Ag@g-CN materials exhibited high antifungal activity against reference and oral clinical strains of C. albicans, with minimal inhibitory concentration (MIC) ranges between 16-256 µg/mL. The mechanism of Ag@g-CN on C. albicans was attributed to the disruption of the membrane integrity and disturbance of the biofilm. In addition, the Ag@g-CN material showed good biocompatibility in the fibroblastic cell line and in Galleria mellonella, with no apparent cytotoxicity observed at a concentration up to 1000 µg/mL. These findings demonstrate the potential of the Ag@g-CN material as an effective and safe antifungal agent for the treatment of oral fungal infections.