Analysis of nucleoid morphology during germination and outgrowth of sporesof Bacillus species

After a few minutes of germination, nucleoids in the great majority of spor es of Bacillus subtilis and Bacillus megaterium were ring shaped. The major spore DNA binding proteins, the alpha/beta-type small, acid-soluble protei ns (SASP), colocalized to these nucleoid rings early in spore germination, as did the B. megaterium homolog of the major B. subtilis chromosomal prote in HBsu. The percentage of ring-shaped nucleoids was decreased in germinate d spores with lower levels of alpha/beta-type SASP. As spore outgrowth proc eeded, the ring-shaped nucleoids disappeared and the nucleoid became more c ompact. This change took place after degradation of most of the spores' poo l of major alpha/beta-type SASP and was delayed when alpha/beta-type SASP d egradation was delayed. Later in spore outgrowth, the shape of the nucleoid reverted to the diffuse lobular shape seen in growing cells.