A strain of the saprobic fungus Mucor ramannianus, isolated from a forest, was used to demonstrate the potential for ciprofloxacin biotransformation by zygomycetes in the environment. The fungus carried out the regioselective N-acetylation of ciprofloxacin to a single product, which was purified from culture extracts by high-performance liquid chromatography. The metabolite was identified by mass and nuclear magnetic resonance spectrometry as 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(4-acetyl-1-piperazinyl)-3-quinolinecarboxylic acid.
FEMS Microbiology Letters. 1999. V.177. N 1. P.131–135.

The ability of a nonpathogenic fungus, Pestalotiopsis guepini, to metabolize fluoroquinolone antimicrobial agents during growth on poultry litter materials was investigated. Sterilized rice hulls, ground corncobs, and pine shavings in glass jars covered with foil were moistened with sterile water and inoculated with P. guepini. The litter materials then were dosed with norfloxacin and incubated for 20 d. In rice-hull cultures, P. guepini produced 4 metabolites: 7-amino-1-ethyl- 6-fluoro-4-oxo-1,4-dihydroquinolone-3-carboxylic acid, N-formylnorfloxacin, N-acetylnorfloxacin, and desethylene-N-acetylnorfloxacin. In corncob cultures, the fungus producedN-formylnorfloxacin and N-acetylnorfloxacin. In pine-shavings cultures, there was little growth of the fungus and no metabolism of norfloxacin. The results suggest that fungi that grow on poultry litter may degrade residues of antimicrobial drugs.
J. Appl. Poult. Res. 2004. V.1.3 N2. 235-240