Long-Term Production of Ergot Peptides by Immobilized Claviceps purpurea in Semicontinuous and Continuous Culture

The semicontinuous and continuous production of pharmaceutically useful ergot peptides with immobilized Claviceps purpurea could be demonstrated. A key aspect was the presence of high concentrations of CaCl₂ (96.9 mM) to give marked prolongation of the productive phase, and cultivation in a bubble column reactor became possible. Restriction of the phosphate supply avoided an otherwise problematic massive increase of outgrowing hyphae.     

Intraspecific diversity in the fungal speciesChaunopycnis alba: Implications for microbial screening programs

Intraspecific variation among 84 isolates of the anamorphic fungusChaunopycnis alba from 26 different geographical locations was analyzed by investigating optimal growth temperatures, differences in the production of secondary metabolites and presence or absence of the cyclosporin synthetase gene. The genetic diversity was assessed using random amplified polymorphic DNA (RAPD). Analysis of these data showed high genetic, metabolic and physiological diversity within this species. Isolates from the Antarctic represented the most homogeneous group withinC. alba and together with isolates from the Arctic these polar strains differed from alpine, temperate and tropical strains by low optimal growth temperatures and by low production of secondary metabolites. Isolates from tropical climes were characterized by high optimal growth temperatures and by the production of comparatively diverse metabolite spectra. Most of the isolates that were similar in the combination of their physiological and metabolic characters were also genetically related. Isolates from different geographical origins did not show many similarities, with the exception of the cyclosporin A-producing isolates, and large diversity could be observed even within a single habitat. This leads us to the suggestion that for pharmaceutical screening programs samples should be collected from a diversity of different geographical and climatic locations. For the selection of strains for screening the RAPD assay seems to be the most powerful tool. It reflected the highest intraspecific diversity and the results corresponded well with the other characteristics.     

Mineralization of 2,4,6-trinitrophenol (picric acid): Characterization and phylogenetic identification of microbial strains

Four bacterial strains that use picric acid as their sole carbon and energy source were isolated. Mineralization of¹⁴C-UL-picric acid showed that up to 65% of the radioactivity was released as¹⁴CO₂. HPLC and UV/Vis spectral analyses indicated complete degradation of picric acid by these organisms. HPLC and LC/MS analyses showed transient formation of 2,4-dinitrophenol during picric acid degradation. Degradation of picric acid was concomitant with stoichiometric release of three moles of nitrite per mole of picric acid. The four picric acid degraders were identified as close relatives ofNocardioides simplex (ATCC 6946) based on their small subunit (16S) rRNA gene sequences.This is contribution 7167 from Central Research & Development, Dupont Co, Wilmington, DE 19880, USA     

Development of a continuous system for the degradation of a cyanuric acid by adsorbed Pseudomonas sp. NRRL B-12228

Cyanuric acid in high concentrations (15.5 mm) was degraded completely by Pseudomonas sp. NRRL B-12228 independently of glucose concentration. In the batch fermentations there was a relation between the glucose concentration, on the one hand, and the liberation of ammonia or production of protein, on the other. The greater the supply of carbon, the more biomass was produced, and fewer NH _inf4 ^sup+ ions were released. Continuous fermentations using adsorbed cells could be performed to degrade cyanuric acid. In spite of different glucose feeding there was only a negligible difference in residues of s-triazine. In a one-step continuous system with dilution rates between 0.021 h^–1 and 0.035 h^–1, even a ratio of 0.65 between glucose and cyanuric acid was not sufficient to degrade the cyanuric acid supplied (320–540 mol l^–1 h^–1) completely. When a continuous two-step system was applied with dilution rates between 0.035 h^–1 and 0.056 h^–1, the consumption of carbon source could be minimized while s-triazine degradation up to 860 mol l^–1 h^–1 was complete. In this way the ratio between glucose and cyanuric acid could be increased to 0.25 (molar C:N ratio = 0.33:1). Thereby the process was made considerably more economic.     

Potential difference responses due to K+, Na+ and Cl- changes in bullfrog antrum with and without HCO3-

The effect of changing [K+], [Na+] and [Cl-] in nutrient solution was studied in bullfrog antrum with and without HCO3- in nutrient. In 25 mM HCO3- (95% O2/5% CO2) and in zero HCO3- (100% O2), nutrient pH was maintained at 7.3. Changing from 4 to 40 mM K+ or from 81 to 8.1 mM Cl- gave a decrease 10 min later in transmucosal PD (nutrient became more negative)--a normal response. These responses were less in zero than in 25 mM HCO3-. A decrease from 102 to 8 mM Na+ decreased PD (anomalous response of electrogenic NaCl symport). This effect was attenuated or eliminated in zero HCO3-. In contrast, change from 4 to 40 mM K+ gave initial anomalous PD response and change from 102 to 8 mM Na+, initial normal PD response with either zero or 25 mM HCO3-. Both responses were associated with (Na+ + K+)-ATPase pump and were greater in zero than in 25 mM HCO3-. Initial PD increases in zero HCO3- are explained as due to increase in the resistance of passive conductance and/or NaCl symport pathways. Thus, removal of HCO3- modifies conductance pathways of nutrient membrane.     

Degradation of long chain n-alkanes by Chlorococcales

Summary Four out of thirty-one algae strains belonging to the order Chlorococcales exhibited good growth on solid media containing n-alkanes. Chlorella vulgaris (397) was able to degrade n-tridecane in cooxidation. The corresponding secondary alcohols and ketones in C₂-to C₇-position could be identified in the culture broth. The same oxidation products could be found in the media of cultures grown in darkness with the addition of glucose. This demonstrates a subterminal degradation pathway of C. vulgaris.There was no indication for a mono-or diterminal oxidation of alkanes by algae.The fatty acid pattern of lipids exhibited an incease in long chain acids and a decrease in shorter chain acids. The growth rate of cells grown on alkanes increased after 72 h, but the release of autospores was retarded.     

Growth of Fusarium moniliforme on n-Alkanes: Comparison of an immobilization method with conventional processes

Summary In submerged culture there was negligible growth of Fusarium moniliforme with either n-tetradecane or gasoil (C₁₃–C₁₉) as the only carbon and energy source. In surface culture the cell yield was about 0.25 g dm^–3 dry weight after four weeks incubation. Some oxidation products, mainly isomeric tetradecanones (4-one, 5-one, 6-one and 7-one), could be identified. However the cell yield in a trickle-flow column was about 3 g dm^–3 dry weight after 7 days. Only traces of oxidation products could be detected. In a fixed-bed reactor, filled with glass rings, cell yields were similar to those in the trickle-flow column and depended on the medium flow rate.After termination of growth in the fixed-bed reactor, similar amounts of gibberellic acid were produced in a nitrogen-free medium with either gasoil or glucose.     

Ionic concentration profiles and charge distribution for the domain of a polarized spherical cell

Solutions of the Poisson-Boltzmann equation yield potential profiles and equilibrium distributions of ions on either side of a spherical shell membrane across which there exists a separation of ionic charges. For the special case in which the membrane is permeable to only one ion the total charge separation is analyzed in terms of the potential difference given by the Nernst equation. Potential profiles and ionic charge distributions are also given for situations involving a uniform distribution of fixed charges within the membrane.