Cytolysis of Bacillus subtilis by Fusarium oxysporum

Abstract

Growth of Fusarium oxysporum on heat-killed Bacillus subtifis cells was accompanied by the loss of bacterial cytoplasmic contents, and this 'cytolysis' could be catalysed in heat-treated bacteria by the fungal culture fluids. In electron micrographs the bacterial walls appeared undamaged, and the absence of wall-lytic enzymes was confirmed by use of isolated bacterial walls as substrate. Appearance of cytolytic activity in cultures was paralleled by the production of proteolytic activity in the cultures. Proteolysis and cytolysis had similar pH optima at 8.8-9-0. Cultures grown on casein, but not glucose, produced high cytolytic activity. Rapid cytolysis occurred when heattreated B. subtifis cells were incubated with trypsin, subtilisin or pronase E. Viable bacteria, however, were not attacked, either by concentrated culture fluids or by the commercial protease preparations.

Glucoamylse Production in Submerged Co-Culture System of <i>Bacillus amyloliquefaciens</i> and <i>Rhizopus cohnii</i>

“…Several other reports have demonstrated that protein, peptides, and extracellular enzyme from Bacillus strains inhibit the growth of or lyse fungal cells [18,19]. Moreover, enzymes from filamentous fungi inhibit the growth of Bacillus strains [20]. These studies show that, in mixed culture systems with fungi and bacteria, each organism modulates the growth and production of metabolites of the other.…”

The use of Bacillus subtilis for screening fusaric acid production by Fusarium spp.

“…Bacillus subtilis is a common saprophytic inhabitant of soils and is thought to contribute to nutrient cycling due to the variety of proteases and other enzymes which the members of this species are capable to produce (Landa et al 2002). The formation of a transparent zone indicates the degradation of pathogenic factors of the pathogen such as toxins and it means that the whole contents of Bacillus subtilis cells are lysed, a process described by Grant et al (1991). The growth of F. oxysporum on heat-killed B. subtilis cells was accompanied by the loss of bacterial cytoplasm contents, and this 'cytolysis' could be catalysed in the heat-treated bacteria by the fluids from fungal culture.…”

“…The appearance of cytolytic activity in cultures was paralleled by the production of proteolytic activity in them. Grant et al (1991) claimed that viable bacteria, however, were not attacked by either of the concentrated culture fluids. Later, Shariffi-Tehrani and Ramezani (2003), using biochemical, physiological, and morphological tests, identified the isolates from soil as Bacillus spp.…”