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1

Statistical optimization of alpha-amylase production by Streptomyces erumpens MTCC 7317 cells in calcium alginate beads using response surface methodology

100%

Kar S. , Ray R. C.

Polish Journal of Microbiology

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2008

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tom 57

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nr 1

EN

α-Amylase has a wide range of applications in starch industries, i.e. baking, brewing, distillery, etc. The α-amylase production from Streptomyces erumpens MTCC 7317 immobilized cells was compared with that of free cells. The immobilized cells of S. erumpens in calcium alginate beads were more effective for production of α-amylase (12.2% more yield) than free cells. Response surface methodology (RSM) was used to evaluate the effect of main variables, i.e. incubation period, pH and temperature on enzyme production with immobilized cells. A full factorial Central Composite Design (CCD) was applied to study these main factors that affected α-amylase production. The experimental results showed that the optimum incubation period, pH and temperature were 36 h, 6.0 and 50°C, respectively for immobilized cells. Repeated batch fermentation of immobilized cells in shake flasks carried out in starch-beef extract medium showed that S. erumpens cells were physiologically active on the support even after four cycles of fermentation.

2

Partial characterization and optimization of production of extracellular alpha-amylase from Bacillus subtilis isolated from culturable cow dung microflora

80%

Swain M. R. , Kar S. , Padmaja G. , Ray R. C.

Polish Journal of Microbiology

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2006

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tom 55

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nr 4

EN

Studies of α-amylase production by Bacillus subtilis (CM3) isolated earlier from cow dung microflora, were carried out. The optimum temperature, pH and incubation period for amylase production were 50-70°C, 5.0-9.0 and 36 h, respectively. Enzyme secretion was very similar in the presence of any of the carbon sources tested (soluble starch, potato starch, cassava starch, wheat flour, glucose, fructose, etc.). Yeast extract and ammonium acetate (1%) as nitrogen sources gave higher yield compared to other nitrogen sources (peptone, malt extract, casein, asparagine, glycine, beef extract), whereas ammonium chloride, ammonium sulphate and urea inhibited the enzyme activity. Addition of Ca⁺² (10-40 mM) to the culture medium did not result in further improvement of enzyme production, whereas the addition of surfactants (Tween 20, Tween 40, Tween 80, and sodium lauryl sulphate) at 0.02% resulted in 2-15% increase in enzyme production. There were no significant variations in enzyme yield between shaked-flask and laboratory fermentor cultures. The purified enzyme is in two forms with molecular mass of 18.0 ± 1 and 43.0 ± 1 kDa in native SDS-PAGE.

3

Indole-3-acetic acid production and effect on sprouting of yam [Dioscorea rotundata L.] minisetts by Bacillus subtilis isolated from culturable cowdung microflora

80%

Swain M. R. , Naskar S. K. , Ray R. C.

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tom 56

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nr 2

EN

Bacillus subtilis strains (CM1-CM5) isolated from culturable (cowdung microflora were investigated for indole-3-acetic acid (IAA) production in nutrient broth (NB). All the strains tested produced IAA in NB; albeit in very low concentrations (0.09-0.37 mg/l). The addition of L-tryptophan (0.1-1.0 g/l) into NB substantially enhanced IAA production (6.1-31.5 folds) indicating that L-tryp-tophan was the precursor for IAA biosynthesis by these bacterial strains. Maximum IAA production was observed after 8 days of incubation (in late stationary phase of bacterial growth). The variation in IAA production was attributed to the genetic make up of these strains as evaluated by RAPD analysis of these isolates and B. subtilis type strain MTCC 441. Application of B. subtilis suspension (8 x 10⁹ CFU/ml) on the surface of yam (Dioscorea rotundata L.) minisetts increased the number of sprouts, roots and shoots length, root and shoot fresh weights and root: shoot ratio over those minisetts not treated with bacterial suspension. Fresh cowdung slurry treatment on yam minisetts also produced similar results as obtained with B. subtilis application.

4

Statistical optimization of alpha-amylase production by probiotic Lactobacillus plantarum MTCC 1407 in submerged fermentation

70%

Panda S. H. , Swain M. R. , Kar S. , Ray R. C. , Montet D.

Polish Journal of Microbiology

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2008

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tom 57

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nr 2

EN

Production and purification of α-amylase by probiotic Lactobacillus plantarum MTCC 1407 has been investigated under submerged fennentation using Mann Rogassa Sharpe medium containing (1%) soluble starch in lieu of glucose (2%) as carbon source. Response Surface Methodology was used to evaluate the effect of main variables, i.e. incubation period, pH and temperature on enzyme production. A full factorial Central Composite Design was applied to study these main factors that affected α-amylase production. The experimental results showed that the optimum incubation period, pH and temperature were 36 h, 7.0 and 35°C, respectively. The purified enzyme (by ammonium sulphate precipitation) had a molecular mass of 75 450 Da in SDS-PAGE.