New anti-Pseudomonas agent isolated from a marine vibrio.

The report by R. G. Doggett et al. (Texas Rept. Biol. Med. 20:508, 1962) represented the first observation that strains of Pseudomonas aeraginosa isolated from patients with cystic fibrosis (CF) are atypical in certain physical and biochemical properties. These mucoid strains produced an unusual capsular polysaccharide when contrasted to the slime envelope of matted or smooth strains of the microorganism. V. F. lococca et al. (Am. J. Diseases Children 106: 315, 1963), in their report of bacteriology in CF, noted that the Pseudomonas cultured was frequently a very mucoid colonial variant. Physiochemical properties of this polysaccharide purified from the slime envelope of mucoid strains were reported by R. G. Doggett et al. (J. Bacteriol. 87:427, 1964; J. Bacteriol. 89: 476, 1965). A. Linker and R. S. Jones (Nature 204:187, 1964; J. Biol. Chem. 241:3845, 1966) pointed out the similarities of a capsular polysaccharide, obtained from mucoid strains of P. aeruginosa, to alginic acid. D. M. Carlson and L. W. Mathews (Biochemistry 5:2817, 1966) compared the capsular polysaccharides of mucoid strains of P. aeruginosa and found each to be polyuronic acids. Investigation of the structural characteristics of the Pseudomonas polysaccharide by alginase degradation (R. G. Doggett, unpublished data) resulted in the discovery of a substance, produced by Alginovibrio aquatilis, which inhibited growth of mucoid strains of P. aeruginosa. A preliminary classification of A. aquatilis has been made (S. M. Meland, Nytt Magasin Botanikk 10:53, 1962) in investigations of alginate-decomposing microorganisms. To determine what effect A. aquatilis would have on the intact mucoid Pseudomonas, 0.1 ml of an A. aquatilis broth culture was placed on two areas of a lawn of the mucoid organism. Figure 1 illustrates the two areas, exhibiting the depolymerization of the capsular slime. The degradation process was proportional to time as the rough areas expanded from 2 mm after 1 hr to approximately 40 mm in 12 hr. A small amount of A. aquatilis broth culture was placed on a MacConkey agar plate freshly seeded with Pseudomonas culture. After 48 hr of incubation, a small clear zone of growth inhibition was noted. This observation prompted further investigation of the properties of A. aquatilis. A. aquatilis strain 110 was used to seed 1 liter of an alginate broth (0.2%, tris(hydroxymethyl)aminomethane, 0.1 I%o KH2PO4, 0.1%O MgSO4 7H20, 0.05%c,, NH4Cl, 0.05%, peptone (Difco), 0.4c sodium alginate, 2.0c% NaCl, and 0.02C%7