Ecomycins, unique antimycotics from Pseudomonas viridiflava

Abstract

A novel family of peptide antimycotics, termed ecomycins, is described from Pseudomonas viridiflava, a plant-associated bacterium. Ecomycins B and C have molecular masses of 1153 and 1181. They contain equimolar amounts of a b hydroxyaspartic acid, homoserine, threonine, serine, alanine, glycine and one unknown amino acid. Fatty acids were detectable after hydrolysis, methylation and gas chromatography and mass spectroscopy. The ecomycins have significant bioactivities against a wide range of human and plant pathogenic fungi. The minimum inhibitory concentration values for ecomycin B were 4·0 mg ml −1 against Cryptococcus neoformans and 31 mg ml −1 against Candida albicans. Pseudomonas viridiflava also produces what appears to be syringotoxin, an antifungal lipopeptide previously described from Ps. syringae.

Coronamycins, peptide antibiotics produced by a verticillate Streptomyces sp. (MSU-2110) endophytic on Monstera sp.

“…The collective spectral and analytical data are consistent with coronamycin having a peptide core functionalized by one of a number of fatty acid moieties with varying degrees of oxidation, hydration and carbon chain length. This type of peptide antibiotic has been described by us and others, exemplified by the pseudomycins and cryptocandins (Ballio et al, 1994;Strobel et al, 1999;Miller et al, 1998). It is to be noted that other highly functionalized peptides have been virtually inseparable, as with commercially available echinomycin, which contains a family of related compounds (Waring, 1979;Castillo et al, 2003).…”

“…This results in the production of amino acid products which are readily identified but not identical to those in the native peptide. These considerations, taken together with the results of extensive prior structural analysis of antibiotics produced by endophytes (Ballio et al, 1994;Strobel et al, 1999;Miller et al, 1998), suggest that coronamycin is largely peptidyl in nature.…”

“…As an example, MS/MS of component ions 1217, 1203 and 1233 each yielded daughter ions at 435, 546, 631 and 960, suggesting the existence of a common core structure. Coronamycin evidently consists of a family of structurally related compounds; this is often the case for peptide antibiotics (Ballio et al, 1994;Strobel et al, 1999;Miller et al, 1998). These highly similar compounds are quite difficult to resolve using currently available chromatographic methods.…”

“…In addition, these compounds are released by acid hydrolysis of the parent compound and are at least partially resistant to this treatment, suggesting that they have chemical properties akin to those of amino acids. Unusual amino acids are commonly found in biologically active peptides produced by endophytes and on occasion these may have elution times close or identical to those of the standard amino acids (Ballio et al, 1994;Strobel et al, 1999;Miller et al, 1998). In addition, the hydrolysis of peptides containing unusual amino acids can cause the elimination of labile substituent groups (e.g.…”

Endophytic Detection in Selected European Herbal Plants

“…Miller et al (1998) described endophytic bacteria Pseudomonas viridiflava isolated from grasses and producing ecomycins B and C. It was investigated that these lipopeptides inhibit the human pathogens Candida albicans. Similar studies were conducted by Guan et al (2005), who reported antimicrobial agent producing strain Streptomyces griseus inhabiting Kandelia candel.…”