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Optimization of polysaccharides production by bacteria isolated from soil

Otimização das condições de produção de polissacarídeos por bactérias isoladas do solo

Six polysaccharide-producing bacteria, isolated from soil samples and identified as Pseudomonas and Arthrobacter (Strains 3B, 4B, 7B, 21B, 18E and 21D), were tested for the yield of polysaccharides produced during growth in two culture media: one containing glucose and the other sucrose (1, 2, 3, 4 and 5%). The yield was quantified measuring the viscosity of the broth, using the Poiscuille equation. The effect of temperature and pH of the culture media was investigated. The largest polysaccharide yield was obtained when the concentration of the carbon source was lower than 2%. Glucose and sucrose stimulated the polysaccharide production in a similar way. When the initial pH of the fermentation broth was increased from 5.0 up to 7.0, there was an increase in polysaccharide production. However, higher values (pH=8.0) caused a decrease in polysaccharide production. With regard to temperature, 30ºC was shown to be optimum, since higher or lower temperatures had a negative effect on saccharide production.

bacteria; soil; polysaccharide production; viscosity


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