Glutamate from gram-positive bacteria

Virantmycin (119) isolated from S. nitrosporeus [103] exhibits an antiviral activity [104] and a weak antifungal activity. It prevents peroxidation of lipids in rat liver microsomes. In the cell assay, benzastatins C and D inhibited glutamate toxicity in N 18-RE-105 cells with EC50 values of 2.0 and 5.4 pM, respectively [105]. Pyrroxamycin (98) isolated from an unidentified streptomycete [106] was found to inhibit Gram-positive bacteria and dermatophytes. 

Under certain circumstances, many bacteria produce capsules outside their ceU envelopes. Capsules are usually made of polysaccharide however, some Bacillus capsules are composed of D-glutamic acid polypeptide. Certain Gram positive bacteria, most notably strains of Bacillus and Clostridium, produce modified ceUs (endospores) capable of surviving in adverse environments. Spore PG is found between an inner and outer membrane and differs from that in the normal vegetative cell muramic acid is mostly in the lactam form the spore PG has fewer peptide cross-links and the ceU exterior is coated with keratin. The spore also contains large quantities of calcium dipicolinate, a substance involved in microbial heat resistance. 

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