Deciphering the biochemical spectrum of novel cyanobacterium-based biofilms for use as inoculants

An investigation was done using cyanobacterium Anabaena torulosa as a matrix for developing novel biofilms, with anti-grazer traits against microfauna/pathogenic fungi, through co-inoculation of agriculturally important bacteria and fungi. The biofilms generated were evaluated after 4, 6 and 9 weeks of incubation for the activity of hydrolytic enzymes and fungicidal activity against phytopathogenic fungi. The activity of β-1,3-glucanase, in general, showed a gradual increasing trend up to 9 weeks, while endoglucanase activity was highest after 6 weeks of incubation, and a 40–50% reduction in chitosanase activity was recorded by the end of 9 weeks of incubation. Observations revealed that the fungus–cyanobacterium biofilms, especially Anabaena–Aspergillus awamori, exhibited the highest activity of β-1,3-glucanase and ranked second in terms of chitosanase activity. Fungicidal activity was recorded up to 9 weeks in most of the biofilms, and the highest values were recorded in cyanobacterium–Bacillus and cyanobacterium–fungus biofilms. Such biofilms were also tested against selected nematodes in microcosm experiments, which revealed no significant deleterious effects. The biocontrol activity of such biofilmed preparations against phytopathogenic fungi, but not towards selected nematodes, illustrates their promise in agriculture as potential inoculants that can effectively establish in soil.