- Volume 22, Issue 3, 1972

A simple diagnostic key, consisting of 13 tables, for the classification and identification of 274 named taxa included in the International Streptomyces Project (ISP) is presented. By means of the few criteria used in the ISP studies it is possible to identify organisms belonging to most of the named species included in that study. In a few cases, additional characters are required.

It is shown that the genetic determinants of type-specific antigens 1 to V of Shigella flexneri controlling similar functions are localized near the lactose-fermentation region on the chromosome; the determinant of antigen VI lies beyond it. The authors support the proposal that Shigella flexneri serotype 6 be excluded from Shigella flexneri and be considered as a subspecies in correspondence with the Soviet scheme of classification or even as a distinct species as Slopek and Mulczyk suggested. Genetic arguments based on the different behavior of S. flexneri strains in recombination with Escherichia coli K–12 Hfr are presented which support the division of S. flexneri serotype 5 into two subtypes, a and b, in correspondence with a similar division of other serotypes. The advisability of this division is confirmed by receptor analysis demonstrating differences in group-specific factors in strains of serotype 5. The antigenic formula of subtype 5b is V:7 … and of 5a, V:4 ….

Forty-seven bovine, caprine, and ovine Mycoplasma strains were studied. Fifteen of these were M. mycoides subsp. mycoides Freundt; the remaining 32 were previously designated as M. mycoides subsp. capri (Edward) Freundt, M. agalactiae (Wroblewski) Freundt, or Turkish type C. Cultures of these strains were obtained from various laboratories abroad and from the Plum Island Animal Disease Laboratory repository; they included representatives of species and serotypes previously reported. The purity of all 47 cloned strains was checked by a combination of differential inhibitory methods, cloning, characterization, and serological techniques. The strains were tested for glucose fermentation, tetrazolium reduction, arginine decarboxylation, film and spots formation, hemolysis of sheep erythrocytes, inhibitory effect of 0.02% methylene blue, and methylene blue reduction. All M. mycoides subsp. mycoides, M. mycoides subsp. capri, and related strains were biochemically and serologically compared with the other strains and with representatives of a recent classification of the entire group of caprine and ovine mycoplasmas. All of the 15 M. mycoides subsp. mycoides strains gave similar biochemical reactions. Among the 32 test Mycoplasma strains, 2 of sheep origin designated Ghaleh Morghi-16 and S-5-64 were previously misidentified as M. agalactiae; 4 other strains were identified as Turkish C type. All of these Mycoplasma strains were identified as belonging to caprine and ovine group 8. The 32 strains were divided into 2 serogroups. One group was comprised of 5 strains, including the type strain of M. mycoides subsp. capri (strain PG3), and the other group contained 27 strains, including a large number previously identified as M. mycoides subsp. capri. All of the strains in the latter group showed an antigenic relationship to M. mycoides subsp. mycoides, whereas the 5 strains of the first group were serologically distinct. The 32 strains including in these 2 groups and the 15 M. mycoides subsp. mycoides strains had no antigenic relationship to Mycoplasma agalactiae, M. arginini, Acholeplasma oculusi, or to 7 new groups of caprine and ovine Mycoplasmas. It is significant that some of the group 8 strains were isolated from goats and sheep in countries free of contagious bovine pleuropneumonia. Their antigenic identity to M. mycoides subsp. mycoides suggests that serious problems might arise if diagnosis of such cultures were made solely on a serological basis.

The viability and virulence of an 8-day-old culture of a hamster-virulent strain of Leptospira interrogans serotype canicola in Stuart’s medium were successfully preserved by the use of liquid nitrogen for freezing and storage. Glycerol was added to the culture to give a final 10% concentration. The culture was rapidly cooled at a rate of 65 C degrees per min from 0 C to -130 C and then stored in the vapor portion of the liquid-nitrogen refrigerator. Prior to freezing, the viability count and LD50 titer for hamsters were 1.2 X 108 per ml and 10-7,2 respectively. One day after freezing, the viability and virulence values were reduced 10- to 100-fold but remained essentially unchanged thereafter over a 5-year observation period. The serological properties of the strain did not appear to be altered after prolonged storage. All except 9 of 103 additional cultures of diverse L. interrogans serotypes grown in either Stuart’s medium or in a Tween-80 albumin medium were successfully preserved by liquid-nitrogen refrigeration over a 7- to 38-month observation period with glycerol as a cryoprotective agent and a controlled rate of freezing of 35 or 60 C drop per min. Failures to recover leptospiras could be attributed to either the presence of contaminating microorganisms or the sparse concentration of organisms in the original preparation. The viability of thawed cultures persisted for 7 days when held at room temperature. The feasibility of storage of stock leptospiral cultures by use of liquid-nitrogen refrigeration was demonstrated.

Eight Streptomyces species having hairy-surfaced spores were examined by transmission electron microscopy and scanning electron microscopy. On the basis of the flexibility of the spore chains and the appearance of the spores, three subgroups are proposed.

Since bacteriocins of mycobacteria could be demonstrated by our technique, bacteriocin classification of rapidly growing mycobacteria was attempted. The results coincide well with those obtained by other methods of classifying and differentiating these organisms.

A new Salmonella serotype (Salmonella sp. serotype omdurman) was isolated in the Sudan from fowls with a history of reduced egg production and general deterioration of their physical condition. A description of the new serotype, whose antigenic structure is 6,7,14: d: e,n,x, is given.

Two new Salmonella serotypes, Salmonella sp. serotype malakal and Salmonella sp. serotype khartoum, have been isolated from mesenteric lymph nodes of apparently healthy dogs in the Sudan, and they belong to Salmonella subgenus I. The antigenic formulae of these serotypes are: S. malakal = 16: e,h: 1,2; S. khartoum = (3),(15), 34: a : 1,7.