Effect of carbon and nitrogen sources in the medium on silver nano conversion and assessment of silvernano conversion principle in culture filtrate

Abstract

In order to assess the effect of carbon and nitrogen sources in the medium on nano convertibility, synthetic medium viz., Czepek Dox medium (modified) was used. Five different nitrogen sources viz., Ammonium nitrate, Casein, Glycine, Leucin and Sodium nitrate and five different carbon sources viz., Chitin, Carboxy Methyl Cellulose (CMC), Sucrose, Glucose and Lactose were assessed for their effect on the growth of Trichoderma ET-1 and the ability of culture filtrate in nano conversion. In order to have an initial idea about the principle responsible for nano conversion, three different solvents viz., diethyl ether, n-butanol and ethyl acetate and were used to extract the principle from Trichoderma ET-1 culture filtrate prepared in PDB. Silver bionano particles synthesized using diethyl ether solvent fraction at 0.0154% concentration were analysed for their stability up to 14 days in terms of absorption peaks using UV-VIS spectrophotometer. It may inferred from the experiment that cellulases play a role in nano conversion as filtrate from chitin as sole C source (and there by chitinases in culture filtrate) failed to yield satisfactory yield of bionano silver. On the other hand, addition of casein in the broth, the only protein derived N source among the different N sources evaluated, resulted in satisfactory conversion of silver in to bionano silver indicating specificity of proteins in nanoconversion. The dilution end point for converting silver in to nano silver by the solvent extracts was found to be 0.0154% dilution for diethyl ether extract and 0.0298% dilution for ethyl acetate extract. Dilutions more than that did not yield satisfactory nano conversion. The stability of biosilver nano particles was declined after 8 days due to the agglumaration of particles.