Influence of initial L-asparagine and glycerol concentrations on the batch growth kinetics of Mycobacterium bovis BCG

Estudou-se a influência das concentrações iniciais, no meio de Sauton, de asparagina e glicerol sobre as produtividades, expressas em unidades formadoras de colônias e biomassa microbiana, referentes aos cultivos submersos do Mycobacterium bovis, em biorreator de 20 mL. As concentrações iniciais de 2,27 e 25 mL/L de asparagina e glicerol, respectivamente, conduziram à maior produtividade, em unidades formadoras de colônias, a saber 2,7.106 colônias/mg.dia. Por outro lado, as concentrações de 4,54 e 25 mL/L dos mesmos componentes, corresponderam à melhor produtividade em biomassa, a saber: 2,5 g/dia. Através das análises dos consumos relativos de asparagina e glicerol (50 e 26 per center respectivamente), verificou-se também que as concentrações destes componentes podem ser reduzidas na composição original do meio de Sauton, com o objetivo de obter uma produção otimizada de vacina BCG em bioreator.

Nitrogen consumption during batch cultivation of Neisseria meningitidis (serogroup c) in Frantz medium

Capsular polysaccharide, extracted from microorganism cultivations, is the principal antigen for elaboration of vaccine against the disease caused by Neisseria meningitidis serogroup C. The final protein content allowed in this vaccine is 1 (per cent). In order to find a relationship between nitrogen consumption and cell growth, including polysaccharide production, and cell nitrogen content, cultivations were carried out in an 80 liters bioreactor (total capacity), under the following conditions: Frantz medium; temperature of 35ºC; air flow of 5L/min (0.125vvm); agitation frequency of 120 rpm and vessel pressure of 6 psi (k(L)a=0.07min(-1).Concentrations of biomass, total polysaccharide, cellular nitrogen, residual organic and inorganic nitrogen in the medium were measured during cultivation. From five cultivations carried out under the same conditions, a mean cell nitrogen percentage of 12.6(per cent)(w/w) in respect to the dry biomass was found. The inorganic nitrogen in the medium did not change significantly along the cultivation time, whereas the organic nitrogen consuption was linearly related to cell growth, with constant yeield factors (average of 8.44). Polysaccharide production kinetics followed the cell growth kinetics until the beginning of the stationary growth phase. A supplemental polysaccharide production was observed until the end of cultivation, but without cell nitrogen absorption. Thus, the results indicate that polysaccharide is produced in two phases, being the first one biomass formation followed by non-associated to growth. /