Monensin A (I), a polyether antibiotic1) produced by Streptomyces cinnamonensis, is a natural ionophore specific for sodium ions2, 3). It is successfully used to control coccidiosis in poultry and to promote the growth of cattle. Studies employing 14C-labelled precursors have proved that molecule of I is assembled from five acetate, seven propionate, and one butyrate units4). According to a recent 13C NMR study5),
During cultivation in a minimal medium with glucose Alternaria tenuissima and Aspergillus vesicolor produce constitutively alpha- and beta-glucanases. Fractions of beta-1,3-glucanases exhibiting affinity for laminarin were separated by means of gel filtration chromatography. Two neutral beta-1,3-glucanases with affinity for yeast glucan were isolated by affinity chromatography and further characterized.
Phenazine-1-carboxylic acid (Ia) and 6-(3-methyl-2-butenyl)phenazine-1-carboxylic acid (IIa) were isolated from the mycelium of the strain Streptomyces cinnamonensis ATCC 15 413. Identification and structure elucidation were performed by spectroscopic methods. Both compounds weakly inhibit the growth of gram-positive bacteria.
A bubble column fitted with an ejector has been tested for its physical and biological performance. The axial diffusion coefficient of the liquid phase in the presence of electrolytes and ethanol was measured by a stimulus-response technique with subsequent evaluation by means of a diffusion model. In contrast to ordinary bubble columns, the coefficient of axial mixing is inversely dependent on the superficial air velocity. The liquid velocity acts in an opposite direction to the backmixing flow in the column. The measurement of volumetric oxygen transfer coefficient in the presence of electrolytes and ethanol was performed using a dynamic gassing-in method adapted for a column. The data were correlated with the superficial air and liquid velocities, total power input, and power for aeration and mixing; the economy coefficient of oxygen transfer was used for finding an optimum ratio of power for aeration and pumping. Growth experiments with Candida utilis on ethanol confirmed some of the above results. Biomass productivity of 2.5 g L(-1) h(-1) testifies about a good transfer capability of the column. Columns fitted with pneumatic and/or hydraulic energy input may be promising for aerobic fermentations considering their mass transfer and mixing characteristics.
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