Physiological effect of multi-walled carbon nanotubes (MWCNTs) on conidia of the entomopathogenic fungus, Paecilomyces fumosoroseus (Deuteromycotina: Hyphomycetes).

The aim of the investigation was to assess the influence of commercial and carboxylated multi-walled carbon nanotubes (MWCNTs) on conidia of the entomopathogenic fungus Paecilomyces fumosoroseus. The commercial MWCNTs had an external diameter of about 40-60 nm, a length of 300-600 nm, a specific density of 140 to 300 g/dm(3) and a carbon content of above 80%. Carboxylated MWCNTs were obtained by oxidizing commercial MWCNT by heating in HNO3, filtering, washing with water and drying. Conidia after different times of contact (from 1 to 865 hours) with nanomaterials in aqueous solutions were cultured for linear and biomass growth. Growth and sporification of mycelium after culture were evaluated. MWCNTs are not greatly cytotoxic for P. fumosoroseus conidia in the applied concentrations. The linear growth of mycelium obtained from conidia after contact with nanotubes was inhibited only in 2 (out of 18) cases (ones for both kinds of nanotubes). Carboxylated nanotubes did not inhibit biomass growth at all, but commercial nanotubes inhibited biomass growth in 2 cases. Sporification was the feature most strongly modified by carbon nanotubes. The commercial nanotubes again more strongly limited sporification of mycelium than carboxylated nanotubes did. The relatively greater influence of commercial versus carboxylated nanotubes was observed in the experiments.