[Preparation of fed-batch culture of Nocardioides sp]. / Poluchenie uplotnennoi kul'tury Nocardioides sp.

A screening for carbon sources revealed ethanol to be the best substrate for condensed Nocardioides sp. culture. A strategy achieving the maximum (21 g/l) yield of biomass was developed for the control over the condensed fed-batch culture production. This control based on the algorithm ExpoDense should be predetermined in the first phase and adaptive in the second phase of two-phase process of condensed culture production.

[Biosynthesis of somatotropin in a recombinant strain of Escherichia coli]. / Biosintez somatotropina rekombinantnym shtammom Escherichia coli.

A recombinant Escherichia coli K-12 strain was grown in the regime of chemostat with glucose limitation at a different flow rate and in the regime of turbidostat. The stability of its population and the dynamics of somatotropin biosynthesis were studied. The plasmid-containing strain became less stable as the flow rate in the fermenter dropped down, which was due, apparently, to a greater limitation. The level of somatotropin biosynthesis was higher at a low dilution rate (D = 0.075, 0.17 and 0.34 h-1). Possible factors responsible for this phenomenon are discussed.

[Microbiological transformation of carbohydrates. Glucose isomerization into fructose by washed cells of Streptomyces sp. strain 29]. / Mikrobiologicheskaia transformatsiia uglevodov. Izomerizatsiia gliukozy vo fruktozu otmytymi kletkami Streptomyces sp. shtamm 29.

Glucose-fructose transformation by washed and packed cells of Streptomyces sp. 29 was studied. The cells grown on the nutrient medium containing xylose and Co and Mg salts were capable to perform glucose-fructose isomerization. The cellular activity depended in a great degree on the temperature, pH and initial glucose concentration; to a lesser extent on Co and Mg ions present in the incubation mixture, and did not depend on the age of the culture (within 8-69 hours). The activity reached its maximum at 70-80 degrees C, pH 7.0 and a low concentration of glucose (10(-3) M). Under these conditions the yield of fructose was 50% from the initial glucose concentration (or 100% from the theoretical value). Washed cells of Streptomyces sp. 29 packed into a thermally controlled column continuously transformed glucose to fructose during 24 days with a yield of 30-44%.