Conditions In Presence Of Glucose Research Articles

Co-metabolic growth and microbial diversity: Keys for the depletion of the α, δ, β and γ-HCH isomers

The objective of this study was the isolation and enrichment of microbiomes capable of degrading the main hexachlorocyclohexane isomers quantified in environmental matrices, e.g.: the α, δ, β and γ-HCH isomers. Four microbiomes were isolated and enriched from an HCH-contaminated dumpsite in Italy, both in the presence of HCH isomers (1:1:1:1) as the sole carbon sources and under co-metabolic growth conditions in presence of glucose (0.1 % v/v). The microbiomes were assessed for their relevant metabolic capabilities. A quantitative metabarcoding approach was employed to analyze the compositional evolution of the four microbiomes during the enrichment phase and the phase of testing of the HCH isomers degradation kinetics. The use of a co-metabolic substrate during enrichment process was essential for selecting microbiomes with higher biodiversity. All microbiomes efficiently degraded the α, δ, and γ-HCH isomers. The highest efficiency in the β-HCH degradation capacity was positively correlated to the highest biodiversity of the microbiome, and the involvement of Chryseobacterium and Asinibacterium sps. have been proposed for a recorded increment in bacterial load during the HCH degradation process.

Stabilization of a proteolytically sensitive cytoplasmic recombinant protein during transition to downstream processing.

The influence of aeration and glucose feeding on the stability of recombinant protein A in Escherichia coli during the transition period from a fed-batch cultivation to downstream processing was studied. Neither interruption of the feeding under aerobic conditions nor anaerobic conditions in presence of glucose could stabilize protein A completely and the intracellular ATP pool did not decrease to less than 0.75-1 mM by this treatment. On the other hand, the absence of both oxygen and glucose resulted in a decrease of the ATP pool to less than 0.5 mM and almost complete stabilization of protein A. The decrease of ATP was more severe when sulfite was used instead of nitrogen gas to create anaerobic conditions in presence of glucose. This also resulted in nearly complete stabilization of protein A, which might be explained by an inhibiting effect of sodium sulfite on fermentation. Therefore, protein stabilization and decrease of the ATP pool were correlated in experiments in vivo. The concentrations of ADP and AMP increased during starvation and may also play a role in stabilization of the protein in vivo. ATP may be a limiting factor of proteolysis also during further steps of downstream processing. Its concentration decreases by 80-90% during harvesting and centrifugation of biomass and even further during disruption of cells. However, neither addition nor regeneration of ATP in cell disintegrate was enough to restore degradation of protein A, indicating that an additional factor limits proteolysis in vitro.

Effects of lipotropic agents on the metabolism of Ehrlich ascites carcinoma cells and other tissues

Lipotropic substances, such as Amytal, pentothal, tribromethanol, chloretone and indole which exercise large inhibitory effects on brain respiration have equally large inhibitory effects on the respiration of Ehrlich ascites carcinoma cells. Indole and skatole, as well as tribromethanol, choretone and pentothal, inhibit the uptake of glycine into Ehrlich ascites cells under anaerobic conditions in presence of glucose, the extent of ihibition being greater than the inhibition of anaerobic glycolysis. Results with tribromethanol show that other tissues (mouse melanoma, mouse lymphoma, mouse spleen) are affected in a similar manner to Ehrlich ascites carcinoma cells. Tribromethanol does not increase the rate of efflux of glycine from the cells, so that the inhibition of amino acid uptake is due to a suppressing effect on the mechanism responsible for the influx. Tribromethanol also inhibits anaerobic glycolysis of ascites cell suspensions at concentrations having little or no effect on the rates of glycolysis of extracts of these cells. The concentration of the lipotropic agents required to inhibit the anaerobic uptake of glycine in ascites cells is of the same order as that required to obtain inhibitory effects on brain respiration. The results indicate that the transport systems of the cell are dependent for their activities on lipid components in the membrane structure, with which the lipotropic, or neurotropic, agents become associated. As a result of this association, transport rates of amino acids are affected.