Summary: The production of extracellular β-D-fructanase by several strains of was studied in continuous culture. When glucose was the limiting nutrient, K1-R and OMZ176 accumulated fructanase to maximum levels at low growth rates (dilution rate 0·05-0·10 h), due to the longer residence times of the bacteria in the culture vessel under these conditions. Extracellular fructanase activity was greater than has been previously reported for batch cultures. The rate of fructanase production for both strains K1-R and OMZ176 increased with increasing growth rate when glucose was limiting. Under conditions of glucose sufficiency, the rate of fructanase production was always lower than in cultures where glucose was limiting, irrespective of the growth rate. Cultures of Ingbritt (serotype ) grown with sorbitol- or glucose-limitation synthesized fructanase at a very low basal rate. When fructose was the limiting carbohydrate the enzyme was induced with a maximum rate of production occurring at a dilution rate of 0·40 h. Strains of from other serotypes () were either not affected by changing the limiting sugar from glucose to fructose or else fructanase activity was slightly decreased in the fructose-limited medium. Fructanases from various strains of readily hydrolysed (2 → 6)-β-D-fructans, but all possessed the ability to hydrolyse (2 → 1)-β-D-fructans to varying degrees.


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