The electric fungus

Abstract

Fungal cells generate D.C. and A.C. (action potentials) electrical currents during their growth and differentiation. In addition, they exhibit tropic growth (galvanotropism) and tactic responses (galvanotaxis) in applied electrical fields. The natural D.C. electrical currents of fungi are due to clustering of ion channels and pumps in certain regions of the cells, mycelium or thallus. It now seems that these electrical currents per se are not essential for the process of tip growth although the local traffic of calcium ions, which are a component of the currents, may be. Instead, electrical currents and action potentials are concerned apparently with spatial control of nutrient uptake and perhaps in intramycelium communication. Studies of the phenomenon of galvanotropism have been used to explore further the mechanisms underlying apical extension of hyphae and these also implicate local calcium ion uptake as being important for this process. Motile zoospores of phytopathogenic fungi exhibit galvanotaxis in weak electrical fields of a size comparable to those generated by plant roots. This tactic behaviour predicts the sites of their accumulation in the natural electrical fields generated by roots and suggests that they may utilize the endogenous electrical currents of plants to detect potential hosts. Generating and responding to electrical currents is therefore an important and general aspect of fungal physiology.

Growth-induced mass flows in fungal networks

“…Foraging fungal mycelia continuously remodel their morphology, and as a transport network the mycelium must adapt to changing local environmental conditions and patchy resource availability (Jennings 1987;Cairney 1992;Gow & Gadd 1995;Boddy 1999;Falconer et al 2005Falconer et al , 2007Bebber et al 2007;Fricker et al 2007). Hyphae grow by tip extension and then branch subapically to form a diffuse tree-like mycelium (Howard 1981;Gooday 1995;Heath & Steinberg 1999;Money 1997Money , 2008Steinberg 2006).…”

Biofilm productivity and concomitant cell autolysis in a membrane bioreactor

“…Doplipore septa form in situations of extreme 11 cell trauma or stress or even during ageing (Alymore et al 1984). The presence of paranthesomes (Fig 6b) supports this phenomenon because they are generally considered to provide a protective or selective function by regulating the cytoplasm immediately adjacent to the septal swellings and pores (Alymore et al 1984;Gow and Gadd, 1995). Under the severe nutrient limitation conditions imposed by extended operation of the membrane gradostat reactor, it seemed plausible that the formation of dolipore septa played a role in structural support, hyphal tip growth and maintaining rigidity of the hyphae.…”

“…This coincided with a rapid decrease in the permeation rate (Fig 4a). When fresh medium was introduced, growth proceeded as the feed permeated the immobilised biofilm, until the concentration of one particular nutrient component was reduced to a level at which it limited the specific growth rate (Gow and Gadd, 1995). Increases in biomass lead to a decrease in substrate concentration and specific growth rate until balance is reached between biomass production and removal of nutrient through washout.…”

“…This is normally used to investigate growth at submaximal rates (Gow and Gadd, 1995). The advantage of controlling the specific growth rate in a MGR is that extended operation in the stationary phase could become possible.…”

“…6b). Dolipore septa are elaborate septal complexes found in most fungi but their role in fungal physiology is still not very clear (Gow and Gadd, 1995). Doplipore septa form in situations of extreme 11 cell trauma or stress or even during ageing (Alymore et al 1984).…”