Accumulation of organic acids in cultivations of Neisseria meningitidis C

Aiming at the industrial production of serogroup C meningococcal vaccine, different experimental protocols were tested to cultivate Neisseria meningitidis C and to investigate the related organic acid release. Correlations were established between specific rates of acetic acid and lactic acid accumulation and specific growth rate, during cultivations carried out on the Frantz medium in a 13 l bioreactor at 35°C, 0.5 atm, 400 rpm and air flowrate of 2 l min-1. A first set of nine batch runs was carried out: (1) with control of dissolved oxygen (O2) at 10% of its saturation point, (2) with control of pH at 6.5, and (3) without any control, respectively. Additional fed-batch or partial fed-batch cultivations were performed without dissolved O2 control, varying glucose concentration from 1.0 to 3.0 g l -1, nine of which without pH control and other two with pH control at 6.5. No significant organic acid level was detected with dissolved O 2 control, whereas acetic acid formation appeared to depend on biomass growth either in the absence of any pH and dissolved O2 control or when the pH was kept at 6.5. Under these last conditions, lactic acid was released as well, but it did not seem to be associated to biomass growth. A survey of possible metabolic causes of this behavior suggested that N. meningitidis may employ different metabolic pathways for the carbon source uptake depending on the cultivation conditions.

Polysaccharide production of Neisseria meningitidis (Serogroup C) in batch and fed-batch cultivations

Serogroup C polysaccharide from Neisseria. meningitidis constitutes the antigen for the vaccine against the disease caused by this bacterium. Aiming at enhancing the final polysaccharide concentration as well as the overall yield factor (polysaccharide/biomass), 20 cultivations were carried out in Frantz medium in a 13 L bioreactor at 35°C, 0.5 atm, 400 rpm and air flowrate of 2 L/min. A series of nine batch experiments was carried out under three different conditions (with control of dissolved oxygen at 10%, with control of pH at 6.5 and without dissolved oxygen and pH controls). Another set of runs consisted of 11 fed-batch cultivations without dissolved oxygen control, varying glucose concentration from less than 1.0-3.0 g/L, four of which performed controlling the pH at 6.5, and four under partial fed-batch conditions. The highest polysaccharide concentration (0.26 g/L) and the overall yield (0.16 g/g), were obtained in batch and partial fed-batch experiments when glucose concentration was maintained below 1.0 g/L. An empirical relation is proposed to relate the specific production rate of polysaccharide to glucose concentration during the stationary growth phase of the fed-batch runs. The obtained polysaccharide satisfies the molecular weight criterion, being a suitable antigen for vaccine production.

Combination of behaviour therapy with fluvoxamine in comparison with behaviour therapy and placebo. Results of a multicentre study.

BACKGROUND: We investigated whether the combination of multi-modal behaviour therapy (BT) with fluvoxamine is superior to BT and placebo in the acute treatment of severely ill in-patients with obsessive-compulsive disorder (OCD). METHOD: In a randomised, double-blind design, 30 patients were treated for nine weeks with BT plus placebo and 30 patients with BT plus fluvoxamine (maximum dosage 300 mg, mean dose 288.1 mg). BT included exposure with response prevention, cognitive restructuring and development of alternative behaviours. RESULTS: Both groups showed a highly significant symptom reduction after treatment. There were no significant differences between the groups concerning compulsions. Obsessions were significantly more reduced in the fluvoxamine and BT group than in the placebo and BT group. Furthermore, the group BT plus fluvoxamine showed a significantly higher response rate (87.5 v. 60%) according to a previously defined response criterion. Severely depressed patients with OCD receiving BT plus placebo presented a significantly worse treatment outcome (Y-BOCS scores) than all other groups. CONCLUSIONS: The results suggest that BT should be combined with fluvoxamine when obsessions dominate the clinical picture and when a secondary depression is present.

Relapse prevention program for treatment of obsessive-compulsive disorder.

Eighteen participants with obsessive-compulsive disorder received 3 weeks of intensive treatment by exposure and response prevention, which were followed by either a relapse prevention (RP) program or associative therapy (AT; an attention-control program). Independent evaluators conducted assessments of obsessive-compulsive symptoms, anxiety, and depression, before and after intensive behavior therapy, after the week of intensive RP or AT and at a 6-month follow-up. Results indicated that the RP program was effective in preventing relapse: Both treatment groups improved immediately after the intensive treatment, but the RP group remained improved at follow-up, whereas the AT group showed some return of symptoms.

A generalized kinetic model for the study of microbial growth.

The following general equation is proposed to represent the kinetics of microbial growth \documentclass{article}\pagestyle{empty}\begin{document}$$\phi (dR/dt) + \psi R + X = 0$$\end{document}, where phi and psi depend on several parameters of the fermenting system. The values of phi and psi were calculated based on results obtained in a batch lactic acid fermentation, a batch cultivation of yeast on diesel oil, and a continuous cultivation of yeast on sugarcane molasses.