Production of Bacteriolytic Enzymes and Degradation of Bacteria by Filamentous Fungi

Abstract

Of 33 filamentous fungi, representing five taxonomic subdivisions, 3 1 were able to grow on heatkilled Bacillus subtilis cells as sole C, N and P source. Two types of decomposition were observed : cytolysis, in which the bacterial cytoplasm was rapidly degraded, leaving apparently empty cell walls, and bacteriolysis, in which the entire bacterial cell gradually disintegrated. Supernatants of cultures in which the latter type of attack occurred contained enzymes capable of dissolving bacterial cell walls. Most of these enzymes were glycosidases with pH optima of 2.0-3.9. Two were peptidases and/or amidases with pH optima of 7-8-8.3.

Basidiomycota: Homobasidiomycetes

“…However, Rayner et al (1985, p. 10) (Watling 1974 Many species of saprotrophic homobasidiomycetes are capable of lysing bacterial cells in vitro (Barron 1988;Barron and Thorn 1987;Thorn and Tsuneda 1992). In Agaricus and other filamentous fungi, this is accomplished by muramidases, which degrade bacterial cell walls (Fermor 1983;Grant et al 1986). Bacteriolytic ability has been found extensively in the polyporoid and euagarics clades, as well as in the Auriculariales and certain corticioid fungi of uncertain placement (e.g., Dendrothele; Thorn and Tsuneda 1992).…”

Cytolysis of Bacillus subtilis by Fusarium oxysporum

“…Although certain fungi also produce bacterial wall degrading hydrolases under these growth conditions (Grant et al, 1986), many do not, yet are still capable of utilizing the bacteria as their nutrient source. In these cases, the bacterial cytoplasm appears to be gradually digested away, leaving behind an apparently empty cell wall, a process which we have termed cytolysis (Grant et al, 1986).…”

“…Although certain fungi produce extracellular bacteriolytic enzymes which attack the cell walls of the bacterial substrate, many others, including some Fusarium species, apparently degrade the cytoplasm of the bacteria without affecting the wall structure (Grant et al, 1986). This process has been termed cytolysis.…”

“…A wide range of soil fungi can attack heat-killed bacterial cells, utilizing these cells as a sole source of C , N and P (Fermor & Wood, 1981;Grant et al, 1986). Although certain fungi produce extracellular bacteriolytic enzymes which attack the cell walls of the bacterial substrate, many others, including some Fusarium species, apparently degrade the cytoplasm of the bacteria without affecting the wall structure (Grant et al, 1986).…”

Bacteriolysis by Agaricus bisporus

“…The types of lytic enzymes produced by A . bisporus which are responsible for this microbial degradation have been analysed (Fermor, 1983;Grant et al, 1984Grant et al, , 1986. They include P-N-acetylmuramidases and P-N-acetylglucosaminidases.…”