Mutanolysin

Effects of several parameters relating to dissolved oxygen(DO) on mutanolysin fermentation were studied. The experiment using shake flasks shows that the medium volume and shaker agitation speed affect the production of mutanolysin. At the same time, the agitation rate together with aeation rate has effects on DO in fermentor. Mutanolysin fermentation was affected by DO greatly. Oxygen is a key restricted factor in mutanolysin fermentation. It affects the metablism and physiological action of Streptomyces globisporus S186. Whatever the DO is excessive high or low, it won't benefit the mutanolysin production. If DO is super, S. globisporus S186 will grow luxuriantly but do not produce mutanolysin, while if DO is lower, the S. globisporus S186 won't grow well even not to produce mutanolysin. During the course of fermentation, the DO changed regularly. It is similar to many antibiotic fermentation and some amino acid fermentation. As S. globisporus S186 grow in exponential phase, DO begin to decrease rapidly from 6 h and get to the lowest point at 40 h or so. Subsequently mutanolysin starts to be produced. DO rises again from 90 h. The key technoloyg of oxygen control in the fermentation is to keep the DO at a suboptimum level. In order to get a high mutanolysin yield, during the culture in fermentor the agitation rate and aeration rate should be kept at 200 r/min and 1:0.8(V:V) respectively.

The muralytic enzyme mutanolysin can act in vivo to eliminate chronic erosive arthritis induced in rats by polymers of peptidoglycan-polysaccharide isolated from group A streptococci (PG-APS). The amounts of PG-APS in the livers and spleens of rats treated with mutanolysin were significantly reduced compared with the amounts in control rats treated with phosphate-buffered saline. However, the amounts of PG-APS in the limbs of mutanolysin- and phosphate-buffered saline-treated rats were comparable. PG-APS polymers extracted from the livers, spleens, and limbs of mutanolysin-treated rats were extensively degraded, whereas PG-APS extracted from phosphate-buffered saline-treated rats had a high molecular weight. We propose that mutanolysin abrogates arthritis in rats by degrading PG-APS polymers to a size which is no longer able to induce chronic erosive arthritis, even though the polymers are still present in the limbs.

Group B streptococci, refractory to previously tested muralysins under physiological conditions, were successfully converted to protoplasts by use of a recently describede N-acetyl muramidase, mutanolysin, derived from a streptomycete. Purified enzyme was effective, but crude preparations, although degrading cell walls, simultaneously produced peculiar effects of cytoplasmic coagulation, retention of cell shape, loss of some intracellular enzymes, and a rise in optical density. Addition of purified mutanolysin to the array of muralysins (group C streptococcal phage-associated lysin, lysozyme), previously successful in preparing protoplasts of different streptococci, now makes possible enzymatic preparation of protoplasts of streptococci of groups A, B, C. D. G, and H.