Modified two-phase system for partition of Bacillus macerans spores.

An aqueous two-phase system made with polyethylene glycol (PEG) 1000 and potassium phosphate gives much higher recovery of Bacillus macerans spores in the upper phase (PEG rich) than does a similar system utilizing PEG 4000. The upper phase completely rejects vegetative cells, which collect at the interface. The system may be useful in purifying spores of other species. Scanning electron micrographs of B. macerans spores cleaned in this system show no obvious attached sporangial fragments. The micrographs show that the ridged coat may form polygonal structures at the poles, as previously observed in Bacillus polymyxa spores.