meningitidis. The DNA content of N. meningitidis was somewhat higher at the highest applied growth rate. The phospholipid and lipopolysaccharide
contents in N. meningitidis varied with growth rate but no specific trends were identified. The cellular fatty acid composition and the amino acid buy BIBW2992 composition did not vary significantly with growth rate. Additionally, the PorA content in the OMV was significantly lower at the highest growth rate. The metabolic fluxes at different growth rates were calculated using flux balance analysis. Errors in these calculations were detected using Monte Carlo Simulation. Thus the reliability of these calculated values of flux distribution could be specified, which are not reported for this type of analysis. The yield of biomass on the substrate (Y(x/s)) and the maintenance coefficient (m(s)) were determined as 0.44 (±0.04) g/g and 0.04 (±0.02) g/(g h), respectively. The growth associated energy requirement (Y(x/ATP)) GSK1120212 solubility dmso and the non-growth associated ATP requirement for maintenance (m(ATP)) were estimated 0.13 (±0.04) mol/mol and 0.43 (±0.14) mol/mol h, respectively. These authors found the split ratio between the Entner–Doudoroff and the pentose phosphate pathways. The pathways utilizing glucose alone in N. meningitidis, had a minor effect on ATP formation rate but a major effect
on the fluxes going through, for instance, the citric-acid cycle. Therefore, they presented flux values in ranges for the underdetermined parts of metabolic network
rather than presenting single values, which is the more common practice in literature. The studies aiming biomass or OMV production reported in previous literature and cited above were performed employing glucose as principal carbon source, instead lactate as in the present study. So no comparisons can be performed between them and the present one. The empirical expression proposed by Luedeking & Piret [35] was used for analysis of the main cultivation product. It relates the specific product formation rate (μP) with the specific growth rate of microorganism (μX) by the equation μP = α·μX + β. Astemizole This equation, where α and β are empirical constants, indicates the existence of two mechanisms of production of the product. The first is associated with bacterial growth (represented by α·μX) while the other is independent of the growth of microorganisms (represented by β) [36]. A computer program (Logiciel du Lissage), based on polynomial fit by the Spline method [37] was employed for OMV curve fitting and calculation of specific product formation rate. In the present study, product formation is non-growth associated. The values of β = μP obtained for each assay are presented in Table 1. Series C assays presented the highest values of β, signifying the best cultivation condition among those studied for production of OMV.