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Continuous cultivation of Trichodcnna reesei M-7 mutant was performed at different temperatures (26, 30 and 34°C) with 1% lactose or glucose alone or a total of 1% mixtures of both sugars at different ratio. The secretion of individual enzymes was affected by the ratio of cellulase inducer (lactose) to the repressor (glucose). The ratio of enzyme secretions was additionally modified by the temperature of cultivations. An insignificant increase of nonspecific activity of cellulases (FPU) and significant increase of aryl-ß-glucosidase activity were observed at 26°C with lactose/glucose ratio of 3:1 and 1:1. However, when cultivated both at 30 or 34°C, the cellulolytic activities (FPU) increased significantly in the presence of 1% glucose alone. The activity of xylanases increased significantly (about 8-fold) with lactose/glucose ratio of 1:1 at 30°C. The increased synthesis of lytic enzymes (proteases, ß-1,3-glucanases) correlated with increased glucose concentration in the feeding medium and this effect potentiated at 34°C of cultivation.
The effect of the addition of detergents Tween 20, Tween 40, Tween 80 and Triton X-100 on xanthan production was investigated during batch and continuous cultivation of Xanthomonas campestris NRRL B-1459. Three of the four tested detergents: Tween 20, 40 and Triton-X 100 gave an increased xanthan production in comparison to control cultivation without detergent in the medium. The best results were achieved either with 0.05% or 0.1% concentrations of Triton-X 100. About 1.18 to 1.21 fold higher production of polymer was observed during batch cultivation in the presence of this compound in the medium. The highest xanthan concentrations were observed on day 5 and 4 of continuous cultivation in the presence of 0.05% and 0.1% of Triton X-100 (respectively 1.34 and 1.36 fold higher than control). Toxic effect of 0.1% Triton X-100 on the cells growth of the strain was observed after 5 days of continuous cultivation. In addition many examples of effect of detergents on the production of biotechnological useful compounds by various microorganisms have been presented in the work.
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