Production of fungal cell wall degrading enzymes by a biocontrol strain of Bacillus subtilis AF 1.

Fungal cell wall degrading chitinases and glucanases attained significance in agriculture, medicine, and environment management. The present study was conducted to describe the optimum conditions required for the production of beta-1,4-N-acetyl glucosaminidase (NAGase) and beta-1,3-glucanase by a biocontrol strain of Bacillus subtilis AF 1. B. subtilis AF 1 was grown in minimal medium with colloidal chitin (3.0%) and yeast extract (0.3% YE ) and incubated at pH 7.0 and 30 degrees C on constant shaker at 180 rpm for 6 days produced highest amounts of NAGase. Presence of 0.5 mM of phenyl methyl sulfonyl fluoride (PMSF) and 0.04% of Tween 20 further improved the enzyme production. B. subtilis AF 1 grown in minimal medium with laminarin (1%) and yeast extract (0.3%) for 3 days produced maximum amount of beta-1,3-glucanase. These conditions can be further scaled-up for large-scale production of NAGase and beta-1,3-glucanase by B. subtilis AF 1.

A phytoalexin is modified to less fungitoxic substances by crown rot pathogen in groundnut Arachis hypogaea L.

Phytoalexins from four different treatments viz. control, AF 1-treated, A. niger-treated, and dual inoculated were separated by TLC showed that one phytoalexin with an Rf value of 0.628 (P1) appeared on 2nd day only in dual-inoculated seeds of groundnut (A. hypogaea). By 3rd day three additional phytoalexins were visualized in response to A. niger-treatment with lower Rf values 0.485 (P2), 0.388 (P3) and 0.314 (P4) as compared to P1. In dual inoculated seedlings, P1 and P3 could be visualized while only P1 appeared in response to AF 1 on 3rd day. All the compounds lost fluorescence on exposure to light, got converted to pale yellow colour. In all the treatments no phytoalexin accumulation was observed after 3rd day. All the four phytoalexins had a major peak between 338 and 339.5 nm. In potato dextrose broth, the growth of A. niger showed a steady increase up to 32 hr while it was significantly inhibited with P1 in microtiter plates. P2, P3 and P4 (in the same order) had significantly less antifungal activity as compared to P1. The antifungal activity of the phytoalexins decreased with decrease in their Rf value.