Antifungal Activities of Chitosan and Nanoparticle Derivatives under Various pH Conditions (original) (raw)

The reuse of treated wastewater effluent is receiving considerable attention for possible applications in agriculture and as supplement for drinking water shortages, however acceptable quality must be maintained to ensure that no negative environmental and health effects will transpire. The need to avoid synthetic chemicals is paramount and has led to the development of natural antimicrobial compounds for the removal of harmful microorganisms found in wastewater. This study is aimed at evaluating the effect of chitosan of various molecular weights as possible antifungal agent against fungi likely to occur in wastewater sources, namely Aspergillus fumigatus, Aspergillus ochraceus, and Penicillium chrysogenum. The study will also include the antifungal evaluation of silver nanoparticles that have been immobilized on chitosan films. Chitosan of various concentrations has indicated strong inhibitory activity against A. fumigatus, A. ochraceus, and P. chrysogenum (MICHMW = 37.5-75 µg/mL, MICMMW = 75-150 µg/mL, MICLMW = 37.5-150 µg/mL). The combination of chitosan with silver nanoparticles has exhibited the strongest antifungal effects with MICs reduced to a range of 18.75-37.5 µg/mL against the Aspergillus species while pristine silver nanoparticles having higher overall MIC values between 50 µg/mL and 100 µg/mL with maximum inhibitory zones of 12.79±1.52 mm for A. fumigatus, 14.25±0.98 mm for A. ochraceus, and 14.71±0.51 mm for P. chrysogenum. Lower pH values also influenced the complex efficacy with significant increase of inhibition at pH 5.