TABLE 1.

Antibiotic-producing microorganisms used in this study

Strain	Antibiotic produced	Description	Source or reference
S. antibioticus 3720	Actinomycin	Prototrophic wild type	31
S. chattanoogensis ISP5002	Fredericamycin	Prototrophic wild type	JCM 4299 (= ATCC 19739)
S. lavendulae MA406 A-1	Formycin	Prototrophic wild type	30
B. subtilis 168	NIa	trpC2	Standard strain for studying sporulation
B. subtilis 60009	NI	strA1	From E. Freese; originally isolated by Goldthwaite et al. as str-1 (15) and now designated rpsL (39)
B. subtilis 61884	NI	aspB66 trpC2	33
B. subtilis 61883	Impaired antibiotic production	aspB66 trpC2 relA1	Isogenic relA mutant to 61884 (33)
B. subtilis 61953	Impaired antibiotic production	thr-5 trpC2 relC	34
B. cereus 2045	FR900493	Prototrophic wild type	29a
P. pyrrocinia 2327	Pyrrolnitrin	Prototrophic wild type	25

^aNI, not identified, but inhibits growth of S. aureus.