ABSTRACT
The biosynthesis of a thermogelable, extracellular homo-beta-(1 leads to 3)-glucan called "curdlan," has been studied in batch and continuous cultures of Alcaligenes faecalis var. myxogenes. Curdlan production is associated with the poststationary phase of a nitrogen-depleted, aerobic batch culture. Exopolymer is not detected in single-stage, carbon-limited continuous cultures but curdlan can be isolated from the effluent of a nitrogen-limited chemostat operating at a dilution rate (D) of less than 0.1 h-1. A spontaneous variant of strain ATCC 21680 was isolated and found to be compatible with long-term, nitrogen-limited chemostat culture. The specific rate of curdlan production is approximately four times higher in poststationary batch cultures than in single-stage continuous fermentations. The product yield (Yp/S) associated with batch processing (nongrowing cultures) is approximately 0.5 g curdlan/g glucose, with CO2 being the only detectable by-product.
Subject(s)
Alcaligenes/metabolism , Glucans/biosynthesis , Polysaccharides, Bacterial/biosynthesis , beta-Glucans , Ammonia/metabolism , Culture Media , Microbiological TechniquesABSTRACT
Beef heart cytochrome oxidase (EC 1.9.3.1) prepared in this laboratory consistently presents 10 Coomassie blue staining zones on SDS-polyacrylamide gel electrophoresis. At pH 7.0 only two of these polypeptides (III and VIa) are labelled by radioactive N-ethyl maleimide (NEM). The labelling of VIa is variable and correlates with activity of particular oxidase preparations. When cytochrome oxidase is isolated from alkylated membranes, either mitochrondria or electron transport particles, polypeptide VIa is found not to be labelled; polypeptide III is more strongly labelled than when isolated oxidase is alkylated, and label now appears in polypeptide I which is not alkylated upon treatment of isolated oxidase with NEM.
