Volume 12 Part 1 Article 24: The Production of Extracellular Lipase by Mushroom Mycelia

Volume 12 Part 1 Article 24
Year 1989
Title: The Production of Extracellular Lipase by Mushroom Mycelia
Authors: C.H. Scanlon, T.R. Fermor, D.A. Wood and D.M. Lösel

Abstract:

The stimulatory effects of various lipid supplements both on sporophore yield of Agaricus bisporus in ccttinercial cultivation (SCHISLER and SINDEN 1966; SCHISLER 1967; SCHISLER and PATTON 1972) and on mycelial growth in pure culture (WARDLE and SCHISLER 196); DIJKSTRA et al. 1972; LEHRIAN et al. 1976; HOLTZ and SMITH 1978) are well documented. The mechanism of this stimulation, however, is still not well understood. HOLTZ and KMESLER (1972) and LEHRIAN et al. (1976) investigated the utilization of [14C]-labelled linoleate and acetate by mushrocm mycelium. A similar pattern of incorporation of labelled carbon was found on both substrates, indicating that linoleate is degraded to acetate, before being assimilated into other cellular ccnponents. This observation iitplies that any substrate that can be metabolized to provide an increased intracellular pool of acetate should produce the same stimulatory response. This hypothesis is supported by observations (WARDLE and SCHISLER 1969) that a wide range of lipid substrates stimulate mycelial growth in this organism. Any differences in the effects of individual supplements would therefore depend on the efficiency with which they are raetaJDolized to acetate.

Since triacylglycerol is the major class of lipid in mushroan corpost (HOLTZ et al. 1975) and since cctrposts are most ccrmonly supplanented with lipids in the form of crude or refined vegetable oil, also predccninantly ccnposed of triacyIglycerols, the ability of muslirocm mycelium to catabolize this suiDStrate is clearly inportant. The hydrolysis of triacy Iglycerols to release free fatty acids is catalyzed by lipases (E.C. 3.1,1.3). The production of an extracellular lipase by mushroan ittycelium was demonstrated by HOLTZ and SMITH (1978), using an artificial substrate, dibutyrylfluorescein to assay lipase activity. The present investigation examines in greater detail the activity of nycelial extracellular lipase against a range of natural substrates that have been previously deironstrated to stirrailate growth and includes, for the first time, a coiparative study of A. bitorquis and A. bisporus.

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