Bactericidal and bacteriolytic action of peptide antibiotic AS-48 against gram-positive and gram-negative bacteria...

A purified peptide antibiotic AS-48 from Streptococcus faecalis spp liquiefaciens S-48 exerted a bactericidal mode of action against most Gram-positive and many Gram-negative bacteria tested. In many Gram-positive bacteria and the two Myxococcus species assayed, a bacteriolytic effect, as a consequence of primary lesions, was also observed. In general, the Gram-negative bacteria were more resistant to AS-48. Escherichia coli protoplasts showed increased sensitivity and those of a resistant yeast. Saccharomyces cerevisiae 3.2, became sensitive. These data suggest that resistance is related to the cell wall structure. AS-48 adsorbed rapidly to cell walls and cytoplasmic membranes of sensitive and resistant cells. Adsorption to cytoplasmic membranes involved complete neutralization of AS-48.