Production of peptide antifungal antibiotic and biocontrol activity of Bacillus subtilis.

Among different bacterial cultures, a potent Bacillus subtilis MTCC-8114 was isolated from garden soil samples which showed 16 and 14 mm inhibition zones by spot inoculation method and 24 and 22 mm inhibition zones by well agar diffusion method against test fungi i.e. Microsporum fulvum and Trichophyton species. Among four media tested, the maximum growth and antibiotic production was found in trypticase soya broth (TSB) medium at 37 degrees C, pH-7 and 48 h of incubation. The Rf value (0.64) by Thin Layer Chromatography (TLC) technique and UV and FTIR spectral data of the active antifungal compound, indicated that the isolated compound belongs to peptide antifungal antibiotic group. MIC value of antifungal antibiotic was 135 and 145 microg/ml.

Isolation, characterization and antifungal activity of Streptomyces sampsonii GS 1322.

For new antifungal antibiotics from actinomycetes, a strain of Streptomyces GS 1322 was isolated from a sample of garden soil. The strain was found to possess antagonistic activity against four fungi i.e., Candida albicans, Aspergillus niger, Microsporum gypseum and Trichophyton sp. The strain was identified as Streptomyces sampsonii and the antifungal compound produced by it was found to be the heptaene group of polyene antibiotics.

Production of industrially important enzymes by some actinomycetes producing antifungal compounds.

Seventeen strains of actinomycetes antagonistic to yeast and moulds have been tested for their ability to produce amylase, lipase, gelatinase and caseinase using solid media containing starch, Tween-20, gelatin and skimmed milk, respectively, Enzyme producing potential of test strains is expressed in ternis of relative enzyme activity (REA). Actinomycetes strain Streptomyces somaliensis GS 1242 and Streptomyces sampsonii GS 1322 showed higher amylase production (REA 6.5) while maximum lipase activity was noted in Streptomyces strain SAP 1089 (REA 7.0). Gelatinase activity was noted higher is S. sampsonii GS 1322 (REA 9.6) and S. somaliensis GS 1242 (REA 8.8). Enzyme producing potential of these strains has been discussed in terms of their industrial significance.

Optimisation of nutritional requirements and process control parameters for the production of HA-2-91, a new tetraene polyene antibiotic.

HA-2-91, a new tetraene polyene antibiotic produced during submerged fermentation of Streptomyces arenae var ukrainiana. Optimisation of nutritional requirements and process control parameters were studied for higher productivity of HA-2-91 during fermentative production in shaken flasks using complex media. Experimental findings indicate that jowar starch (Sorghum vulgare) is the best carbon source while cornsteep liquor in combination with peanut meal are the best nitrogen sources. Exogenous addition of amino acids, divalent cations and fatty acids suppressed the productivity of HA-2-91. Incorporation of glucose into the production medium above 5% (w/v) results in inhibition of productivity of HA-2-91 which may be due to catabolite regulation. The concentration of phosphate ions above 10 ppm also showed similar suppression effect on the productivity of HA-2-91. However, ferrous ions at 100 ppm showed slight stimulatory effect on the production of HA-2-91. The optimum process control parameters for the production of HA-2-91 were found to be temperature, 28 degrees C; inoculum concentration from seed to production medium, 1% (v/v); pH and volume of production medium 6.5 and 100 ml respectively; and fermentation cycle time, 120 hours.

Optimisation of cultural conditions for antifungal antibiotic accumulation by Streptomyces rochei G164.

To induce higher amount of antifungal antibiotic production by variation of cultural parameters has been studied. The maximum effectivity was found in sucrose as carbon source, peptone as nitrogen source and at pH 7.0. The effect of other selected factors were also evaluated in order to judge the variables that influenced antibiotic production.

Effect of dissolved oxygen levels on biosynthesis of aureofungin by Streptoverticillium cinnamoneum var. terricola.

Biosynthesis of aureofungin by Streptoverticillium cinnamoneum var, terricola was found to be an oxygen dependent reaction. An accelerated rate of aureofungin production, along with a better yield coefficient were obtained under conditions of enhanced aeration during fermentation. A higher oxygen transfer rate was found to stimulate aureofungin A, and suppresses aureofungin B formation.