Differential morphogenesis of the extraradical mycelium of an arbuscular mycorrhizal fungus grown monoxenically on spatially heterogeneous culture media.

A new in vitro experimental system was developed to study the morphogenesis of discrete regions of a single extraradical mycelium of the arbuscular mycorrhizal (AM) fungus Glomus intraradices, growing simultaneously in six different agar-based media. The media were (i) unamended water agar (WA), (ii) WA+PO(4)(3-) (PO(4)(3-)), (iii) WA+NO(3)(-) (NO(3)(-)), (iv) WA+NH(4)(+) (NH(4)(+)), (v) WA+NH(4)(+)+MES (NH(4)(+)+MES) and (vi) minimal medium (M, complete nutrients). Each medium was amended with the pH indicator bromocresol purple. The extraradical mycelium of the fungus showed between-treatment differences in morphogenesis, architecture, formation of branched absorbing structures (BAS) and sporulation. Extraradical hyphae that developed in WA or PO(4)(3-) compartments exhibited an economic development pattern, in which runner hyphae radially extended the external colony. Extraradical hyphal growth in the NO(3)(-) compartments was characterized by increased formation of runner hyphae, BAS and spores and an alkalinization of the medium. In the two NH(4)(+)-amended media (NH(4)(+), NH(4)(+)+MES), sporulation was suppressed and considerable morphological changes were noted. These results show the plasticity of G. intraradices that lets it efficiently exploit an heterogeneous substrate.

Stereoselective reduction of ketones by Daucus carota hairy root cultures.

Reduction of acetophenone by Daucus carota hairy root cultures afforded (S)-phenylethanol in high yield (96%) and excellent enantiomeric excess (ee>or=98%). Aromatic ketones, keto esters, and a simple aliphatic ketone were reduced with good stereoselectivity (ee=62-98%) and moderate to high chemical yields (25-90%).