Bacitracins sporulation

Despite the apparent connections between formation of antibiotics and spores, it has become clear that antibiotic production is not obligatory for spore formation [192]. The most damaging evidence to the antibiotic-spore obligatory hypothesis is the existence of mutants which form no antibiotic but still sporulate. Such mutants have been found in the cases of bacitracin (Bacillus licheniformis), myco-bacillin (Bacillus subtilis), linear gramicidin (B. brevis), tyrocidine (B. brevis), gramicidin S (B. brevis), oxytetracycline (Streptomyces rimosus), streptomycin (S. griseus), methylenomycin A (Streptomyces coelicolor), and patulin (Penicillium urticae). 

In 1945, a new antibiotic was reported it was produced by a grampositive sporulating bacillus of the B. subtilis group and isolated from cultures of contaminated tissue removed from a fracture of the tibia. This strain was named after the patient Tracey I and the active principle in the cell-free filtrates of broth cultures was therefore called Bacitracin . The antibiotic was first produced in surface cultures Ass a d later by submerged cultures in synthetic media A94. Later the organism was classified as a strain of B. licheniformis. In 1949 another antibiotic from a strain of B. licheniformis, originally called A-5, was described under the name ayfivin A6 . It soon became apparent that bacitracin and ayfivin were closely related in their physical, chemical and biological properties " . The name ayfivin was therefore abandoned in favour of bacitracin . 

Mn from media containing low levels of Mn was found in the mature spores. Mn is essential for the synthesis of certain antibiotics by Bacillus, including gramicidin A, bacitracin and mycobacillin. These were once thought to be involved in the transport of Mn during sporulation, but these ideas are now discounted. The role of cations in sporulation will be discussed at the end of this section. 

H.I. Haavik and S. Thomassen, A bacitracin-negative mutant of Baaittue liohenfoimis which is able to sporulate, J. Gen. Microbiol. 76, 451 (1973). 

The possibilities that bacitracin could either accumulate as a result of hydrolysis of vegetative cell wall material during the early stage of sporulation or be a constituent of spore coats have been proposed by Bernlohr and Novelli (i960, 1963)- No evidence in support of the former suggestion is available, but Bernlohr and Sievert (1962) and Bernlohr and Novelli (1963) observed that bacitracin is directly incorporated into spore coats and that, in both variety and quantity, the amino acids of bacitracin and spore coat hydrolysates are very similar. The authors found that amino acids comprise 80% of spore coats and they suggested that as much as 75% of the coats could consist of bacitracin units cross-linked by hexosamine and phosphate ion bridges. 

As is true for bacitracin synthesis, the bulk of gramicidin, tyrocidine, and gramicidin S is produced after exponential growth ceases typical data are presented in Tables 5 and 7. The formation of gramicidin and tyrocidine (Mach 6t al., 1963), as well as bacitracin (Bernlohr and Novelli, I960) precedes the period of maximal sporulation. 

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