Green chemistry principles for the synthesis of antifungal active gum acacia-gold nanocomposite - natamycin (GA-AuNC–NT) against food spoilage fungal strain Aspergillus ochraceopealiformis
Authors: namasivayam Karthik Raja , Manohar Mohit , Knde Akil , Samrat K , Bharani RS , Jayapraksh C 
Published: March 2022

Abstract
Evaluation of potential anti fungal activity of gum acacia -gold nanocomposite fabricated with food preservative agent natamycin (GA-AuNC–NT and its noteworthy release pattern, biocompatibility was prepared in this present investigation. GA-AuNC–NT was prepared by green science principles under in vitro condition and the synthesized nanocomposite was characterized by various characterisation techniques. Green science principles that adopted in this study reveals highly stable nano dimensional composite with significant antifungal activity. The antifungal activity was investigated against the fungal strain Aspergillus ochraceopealiformis isolated from spoiled, expired bread. The well diffusion assay, fungal hyphae fragmentation assay and spore germination inhibition assay were used to determine the antifungal activity of the synthesised nanocomposite. Potential antifungal activity of the synthesised nanocomposite was confirmed by recording zone of inhibition, high rate of hyphae fragmentation and marked spore germination inhibition against the tested fungal strain. The molecular mechanism of antifungal activity was studied by measuring oxidative stress marker genes like catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) induction adopting quantitative real-time polymerase chain reaction (q RT-PCR). Among the various treatment, a notable reduction in all the tested marker genes expression was recorded in the nanocomposite treated fungal strain. Release profile studies using different solvents reveal sustained or controlled natamycin release at the increasing periods. The synthesised nanocomposite’s high safety or biocompatibility was evaluated with the Wistar animal model by determining notable changes in behavioural, biochemical, haematological and histopathological parameters. The synthesised nanocomposite did not exhibit any undesirable changes in all the tested parameters confirming the marked biosafety or biocompatibility. The nanocomposite was coated on the bread packaging material. The effect of packaging on the proximate composition, antioxidative enzymes status, and fungal growth of bread samples incubated under the incubation period were studied. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) studies reveal that the nanocomposite was effectively coated on the packaging material without changing size, shape, and functional groups. No changes in the proximate composition and antioxidative enzymes of the packaged bread samples incubated under different incubation periods reveal the nanocomposite’s marked safety. The complete absence of the fungal growth also indicates the uniqueness of the nanocomposite. The present finding implies that the synthesised nanocomposite can be used as an effective, safe food preservative agent against food spoilage fungal strains associated with a wide range of food products and suggest a green strategy for the increased shelf life of foods.