Abstract
Three non-flocculating mutant strains were derived from the flocculating parent Flavobacterium strain B. And then flocculating revertant was isolated from one of the mutants. Guanidine hydrochloride-extracted cells were prepared from the parent, mutant and revertant cells, and their capacity to form aggregates was examined in the presence of the partially purified aggregation factor from the parent. The extracted cells from the parent, revertant and two mutants formed aggregates in the reconstitution system, indicating that these two mutants did not flocculate because of their inabilities to form a functional aggregation factor. The extracted cells of another mutant failed to form aggregates even in the presence of the aggregation factor, indicating that some other component(s), different from the aggregation factor, is involved in the flocculation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the envelope proteins revealed that the envelopes from cells whose extracted cells formed aggregates in the presence of aggregation factor contained two dense protein bands, and the envelopes from cells whose extracted cells did not form aggregate with aggregation factor contained smaller amounts of these bands. It was also noted that the calcium-binding activity of the envelopes was generally higher in the former than the latter. The results appear to indicate that one or both of these proteins might be involved in flocculation.
