B. Sikyta

A device for cultivation of plant and animal cells

SummaryA device is described for cultivation of suspension cultures of plant and animal cells in plastic bags placed on carrier plates in a thermostat box. Pendular motion of these plates ensures mixing of the fluid and aids in transfer of oxygen pumped above the fluid surface.

Population changes in a culture of Escherichia coli K12 1EA growing in a ribitol-limited chemostat

SummaryThe growth of the strain Escherichia coli K12 1EA in a chemostat was limited by ribitol as the source of carbon and energy. Specific activities of ribitol dehydrogenase and D-arabinitol dehydrogenase were assayed to measure expression of the two closely linked catabolic operons rbt and dal. Population changes occuring in a chemostat were analyzed by testing single colony isolates in batch cultures: double constitutive mutant 1EA-A was first selected while later hyperproducing strains of the type 11EA and 111EA synthesizing constitutively 4 times and 8 times more ribitol dehydrogenase, respectively, prevail in the chemostat.

Selection of constitutive tryptophanase hyperproducing mutants of Escherichia coli

SummaryConstitutive tryptophanase hyperproducing mutants of Escherichia coli were isolated. The specific enzyme activities of these mutants are 3–5 times higher than those of the fully induced wild-type strain and the enzyme synthesis is more resistant to catabolite repression.

Selection aid properties of hyperproducing D-serine deaminase mutants of Escherichia coli

SummaryHyperproducing constitutive D-serine deaminase mutant E. coli were selected by a chemostat method. The specific activity of the enzyme in these mutants is 25fold higher in comparison with the fully induced parental strain.

Cultivation and properties of ice-nucleation active bacteriaPseudomonas syringae CCM 4073

SummaryAn ice-nucleating bacteriumPseudomonassyringae CCM 4073 selected from 30 ice-nucleating bacteria was cultivated in pilot-plant bioreactors at 28°C; the cells showed a high ice-nucleation activity even in dry state, sublimation activity and activation after imposition into refrigenator.

Stability and storage ofEscherichia coli mutants hyperproducing β-galactosidase

SummaryEnzyme activity of the hyperproducing mutants isolated from a chemostat decreases by passaging under nonselective conditions to about one half of the original value, and then remains stable. High activity can be quickly restored by transfer to chemostat selective conditions. The elaborated storage method prevents the decrease of enzyme activity after 2–3 years.

Continuous cultivation of microorganisms

This review presents selected studies on continuous cultivation including the genetics and selection of microorganisms, production of biomass, liquid fuels and other products, published in 1982-1984 and bearing a relationship to biotechnology.

Linear growth in microbial cultures limited by accumulated substrate

SummaryThe “linear” growth phase in cultures limited by intracellular (conservative) substrate is represented by a flat exponential curve. Within the range of experimental errors, the presented model fits well the data from both batch and continuous cultures ofEscherichia coli, whose growth is limited in that way.

Stability of hyperproduction of D-serine deaminase and tryptophanase inEscherichia coli

SummaryD-Serine deaminase hyperproducing mutants ofE. coli lose about one half of their original activity during passaging. On the other hand, the mutant hyperproducing tryptophanase is completely stable.

Strains of Escherichia coli with simultaneous elevated synthesis of three catabolic enzymes

SummaryEscherichia coli strains producing simultaneously three enzymes (tryptophanase, D-serine deaminase and β-galactosidase) in elevated amounts, and with increased resistance to catabolite repression were isolated by a multistep chemostat selection procedure.