Evaluation of Industrial Biocides on a Novel Aspergillus versicolor TANCK-1 and Elucidation of Their Probable Biocidal Mechanism.

Abstract: In the present investigation, a novel fungus was isolated from leather watch strap and identified as Aspergillus versicolor TANCK-1 by 18 s rRNA sequencing. The isolated fungus was evaluated against three structurally different fungicides such as 2-(thiocyanomethylthio)benzothiazole (TCMTB), potassium dimethyldithiocarbamate (KDDC) and 2,2-dibromo-3-nitrilopropionamide (DBNP) to control the fungal growth. Among these, TCMTB was found to effectively inhibit the growth at a minimum concentration of 31.2 µg/mL as compared to 1250 and 625 µg/mL for KDDC and DBNP respectively. Increased membrane permeability in the fungicide treated samples was evident from cellular release and decrease in cellular ergosterol content. Nevertheless, SEM analysis revealed a considerable change in fungicide treated mycelium with the collapse of hyphae structure and shrunken spores, which was observed to be very pronounced in KDDC and DBNP. Results indicated that all three biocides bring about inhibition through membrane damage with almost negligible effect on the cell wall.

Graphical Abstract: Schematic diagram explaining the fungicidal action on Aspergillus versicolor TANCK-1.