Adsorption of Bacillus subtilis bacteriophage PBS 1

Bacteriophage PBS 1 adsorbs initially on the flagella of its host, Bacillus subtilis (stage I). The phage can adsorb to both active and inactive flagella. Flagellar attachment is nonspecific as PBS 1 was shown to attach to the flagella of Bacillus species other than the normal host B. subtilis. The phage particle then quickly moves down the length of the flagellum to its base, the final adsorption site. Flagellar motion is required for flagellar base attachment (stage II). After proper attachment at the flagellar base, the phage tail sheath contracts sending the tail core through the final adsorption site (stage III). The phage DNA is then injected at this site (stage IV). Stage I adsorption does not cause loss of motility in PBS 1 -- resistant bacilli. The loss of motility observed upon infection of sensitive cells by PBS 1 may be associated with either stage II or stage III of adsorption.