Saprolegniasis is one of the most devastating oomycete diseases in freshwater fish which is caused by species in the genus Saprolegnia including Saprolegnia parasitica. In this study, we isolated t...

Due to limited numbers of antifungal drugs and emergence of drug resistance have directed to develop nonconventional therapeutic agents against fungal pathogen Candida albicans. In this study, anticandidal activity of chitosan silver nanocomposite (CAgNC) was tested against C. albicans. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of CAgNC were determined as 25 and 100 μg/ml, respectively. Electron microscopic image results confirmed the ultrastructural cell wall deformities and injuries caused by CAgNC. Propidium iodide (PI) penetration into the CAgNC treated cells could be considered as an evidence for loss of cell membrane integrity and cell death at MFC. Level of intracellular reactive oxygen species (ROS) was increased, while cell viability was decreased with the increased of CAgNC concentrations. In our protein profile results, several induced proteins were observed under CAgNC treatment, and they could be related to multidrug and stress resistant proteins such as CDR1 (55 kDa) and CaHSP70 based on the protein band size. CAgNC mediated cell wall damage, loss of cell membrane integrity, elevated ROS level, and associated oxidative stress have been identified as the main causative factors for the anticandidal activity. Overall results from our study indicated that CAgNC could affect negatively on physiological and biochemical functions of C. albicans suggesting CAgNC as a potential alternative for antifungal chemotherapy.

A chitosan-silver nanocomposite (CAgNC) was synthesized in a green manner using low molecular weight chitosan (LMW-chitosan) and silver nitrate without applying external chemical reducing agents. The newly synthesized CAgNC was characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission electron microscopy (FE-SEM and FE-TEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), particle size and zeta potential analysis. The average sizes of LMW-chitosan and CAgNC were 1776 ± 23 nm and 240.1 ± 23.6 nm, respectively. The zeta potential of CAgNC was observed as +41.1 mV. The AgNPs that are deposited on the chitosan matrix had average size ranges between 5 and 50 nm. The Ag content of the CAgNC was determined as 0.696 ± 0.054% (w/w). The minimum inhibitory concentration (MIC) values of LMW-chitosan and CAgNC against Candida albicans were determined as 100 and 50 μg mL⁻¹, whereas the minimum fungicidal concentration (MFC) values were recorded as 400 and 150 μg mL⁻¹, respectively. Propidium iodide (PI) uptake results suggested that CAgNC affected the permeability of the cell membrane of C. albicans. Moreover, CAgNC induced the level of reactive oxygen species (ROS) at a higher level when compared to the LMW-chitosan, in a concentration-dependent manner. This report illustrates the eco-friendly approach for the reduction of silver ions using LMW-chitosan as a reducing agent to make a biologically active composite (CAgNC) and as a potential antifungal agent against C. albicans.