Antibacterial and catalytic activity of biogenic gold nanoparticles synthesised by Trichoderma harzianum .

This study reveals the antibacterial and catalytic activity of biogenic gold nanoparicles (AuNPs) synthesised by biomass of Trichoderma harzianum . The antibacterial activity of AuNPs was analysed by the means of growth curve, well diffusion and colony forming unit (CFU) count methods. The minimum inhibitory concentration of AuNPs was 20 µg/ml. AuNPs at 60 µg/ml show effective antibacterial activity as optical absorption was insignificant. The well diffusion and CFU methods were also applied to analyse the effect of various concentration of AuNPs. Further, the catalytic activity of AuNPs was analysed against methylene blue (MB) as a model pollutant in water. MB was degraded 39% in 30 min in the presence of AuNPs and sodium borohydrate and the rate constant ( k ) was found to be 0.2 × 10-3  s-1 . This shows that the biogenic AuNP is an effective candidate for antibacterial and catalytic degradation of toxic pollutants.