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.

Polysaccharide production in batch process of Neisseria meningitidis serogroup C comparing Frantz, modified Frantz and Cartlin 6 cultivation media

Polysaccharide of N. meningitidis serogroup C constitutes the antigen for the vaccine against meningitis. The goal of this work was to compare three cultivation media for production of this polysaccharide: Frantz, modified Frantz medium (with replacement of glucose by glycerol), and Catlin 6 (a synthetic medium with glucose). The comparative criteria were based on the final polysaccharide concentrations and the yield coefficient cell/polysaccharide (Y P/X). The kinetic parameters: pH, substrate consumption and cell growth were also determined. For this purpose, 9 cultivation runs were carried out in a 80 L New Brunswick bioreactor, under the following conditions: 42 L of culture medium, temperature 35°C, air flow 5 L/min, agitation frequency 120 rpm and vessel pressure 6 psi, without dissolved oxygen or pH controls. The cultivation runs were divided in three groups, with 3 repetitions each. The cultivation using the Frantz medium presented the best results: average of final polysaccharide concentration = 0.134 g/L and Y P/X=0.121, followed by Catlin 6 medium, with results of 0.095 g/L and 0.067 respectively. Considering the principal advantages in the use of the synthetic medium, i.e. facilitation of a cultivation and purification steps of the polysaccharide production process, there is a possibility that in the near future, Catlin 6 will replace the traditional Frantz medium.

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. /

Batch cultivation kinetics of Neisseria meningitidis (Serogroup) in Frantz medium. I. growth and polysaccharide production

Polysaccharide of N. meningitidis serogroup C constitutes the antigen for the production of the specific vaccine against this serogroup. The production kinetics of polysaccharide (serogroup C) was studies in five cultivations carried out in an 80 L fermenter (total capacity), under the following process conditions: Frantz medium; temperature 35§C; air flow 5 L.min-1 (o.125 vvm); agitation frequency 120 rpm and vessel pressure 6 psi. Global yeld factors and ield coefficients were calculated. It was observed two distinguished polysaccharide production phases: growth associated and a growth non-associated. The cell productivity was about 0.11 (g drymass. L -1.h-1) and polysaccharide productivity near 7.0 (mg polysac. L-1. h-1)(AB)