title: Kinetics of Bacillus thuringiensis var. israelensis growth on high glucose concentrations.
abstract: The kinetic and general growth features of Bacillus thuringiensis var. israelensis were evaluated. Initial glucose concentration (S0) in fermentation media varied from 10 to 152 g/l. The results afforded to characterize four morphologically and physiologically well-defined culture phases, independent of S0 values: Phase I, vegetative growth; Phase II, transition to sporulation; Phase III, sporulation; and Phase IV, spores maturation and cell lysis. Important process parameters were also determined. The maximum specific growth rates (microX,m) were not affected with S0 up to 75 g/l (1.0-1.1 per hour), but higher glucose concentrations resulted in growth inhibition by substrate, revealed by a reduction in microX,m values. These higher S0 values led to longer Phases III and IV and delayed sporulation. Similar biomass concentrations (Xm=15.2-15.9 g/l) were achieved with S0 over 30.8 g/l, with increasing residual substrate, suggesting a limitation in some other nutrients and the use of glucose to form other metabolites. In this case, with S0 from 30.8 to 152 g/l, cell yield (YX/S) decreased from 0.58 to 0.41 g/g. On the other hand, with S0=10 g/l growth was limited by substrate, and YX/S has shown its maximum value (0.83 g/g).
authors: Laboratório de Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, CEP 28013-602, RJ, Brazil. mberbert@uenf.br
authors: M A
authors: MA
authors: Berbert-Molina
authors: A M R
authors: AM
authors: Prata
authors: L G
authors: LG
authors: Pessanha
authors: M M
authors: MM
authors: Silveira
mesh_terms: D001413:Bacillus thuringiensis / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism; D018533:Biomass; D005285:Fermentation; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics
chemical_list: D005947:Glucose