FLOW SENSING IN MYCELIAL FUNGI

Hyphae of a variety of mycelial fungi were shown to reorient their dir ection of growth to grow upstream in a continuous flowing current of l iquid medium. Among those tested fungi, Aspergillus niger hyphae was m ost polarized towards the upstream. Hyphae of A. niger which had been attached to poly-l-lysine coated glass plates on the base of a continu ous-culture flow cell were exposed to a current of medium of flow rate s in the range of 0-6400 mu m s(-1) for 1-4 h. Hyphal tips quickly reo riented towards the upstream of the flowing medium and became aligned parallel to the flow axis as they grew longer. At flow rates above 160 0 mu m s(-1), however, the percentage of polarization of hyphae reache d a constant level. With other fungi, germ tube emergence was not pola rized but hyphae and branches grew towards the upstream. There was no detectable difference in the pH and oxygen concentration of the flowin g medium between inlet and outlet of the flow cell. This result sugges ts that hyphae of mycelial fungi sense transient flow of liquid medium over their surface and reorient their direction to grow upstream. (C) 1997 Elsevier Science B.V.