Deoxyribonucleic acid base composition of some members of the Micrococcaceae

Comparison of methods for routine separation of coagulase-negative staphylococci from micrococci isolated from sheep

A total of 176 Gram-positive, catalase positive cocci strains, isolated from sheep were studied by different routine tests for the differentiation of staphylococci and micrococci, comparing their validity and usefulness. By glucose fermentation and growth in the anaerobic portion of thioglycolate 85 and 73.6% respectively of coagulase negative staphylococci were misclassified as Micrococcus spp. Susceptibility to lysostaphin was an adequate test for the differentiation of the strains. Atypical results in the production of acid from glycerol/erythromycin were obtained in 11.8% of the coagulase negative strains and 16.7% of micrococci. The combined use of the selective media furazolidone agar and Schleifer and Krämer medium resulted in a fast and useful separation of ovine staphylococci and micrococci. The bacteriolytic activity misclassified 32.2% of the coagulase negative strains.

Rapid distinction between micrococci and staphylococci with furazolidone agars

Furazolidone agar proved to be a suitable medium for separating strains of the genera Micrococcus and Staphylococcus. 720 isolates (including 24 type strains) of gram- and catalase-positive cocci were tested for growth on tryptone soya and peptone agar with the addition of 50 microgram/ml furazolidone. The results were compared with the classification obtained by the standard-O/F-test and by the test system of Schleifer and Kloos. For routine identification and separation of staphylococci from micrococci a peptone agar with 20 microgram furazolidone/ml is recommended.

Bacteriolytic activity in staphylococci

The bacteriolytic activity of Staphylococcus aureus and Staphylococcus albus strains was tested with various media. Whereas S. aureus strains were found to be active under all conditions, the percentage of active S. albus strains was significantly influenced by the composition of the medium. Ionic strength and concentration of the organic nitrogen source were found to be the main factors affecting the expression of bacteriolytic activity of straphylococci. Virtually all of 318 S. aureus and 603 S. albus strains were active on a medium containing 3% peptone, 0.3% glucose, 0.2% yeast extract, 0.1% disodium phosphate, 2.2% sodium chloride and 0.9% agar. The optimal conditions for the bacteriolytic activity of S. aureus strains were different from those of most S. albus strains. Within S. albus, optimal conditions differed also from strain to strain. It is suggested that further studies on this subject may prove useful for the identification and taxonomy of staphylococci. A possible relationship between the production of extracellular bacteriolytic enzymes and pathogenic properties of staphylococci is also considered.

The identification of staphylococci in clinical and food microbiology laboratories

A comprehensive review of the methods which have been utilized for the identification of staphylococci is presented. Biochemical characteristics which have assisted in the primary isolation of staphylococci, such as pigmentation, hemolytic activity, the egg yolk phenomenon, and deoxyribonuclease and coagulase production, are also analyzed. The potential applicability of advanced techniques to identify staphylococci, such as the detection of enterotoxin production, base ratio analysis, cell wall analysis, phage typing, and serology, is discussed. The following procedures are recommended for routine use: Idnetification of Staphylococcus sp. (clinical laboratories): microscopic observation, catalase activity, coagulase production, lysostaphin sensitivity, and (optional) facultative growth in thioglycolate medium. Identification of Staphylococcus aureus (food laboratories): microscopic observation, catalase activity, coagulase production, thermonuclease production, and (optional) lysostaphin sensitivity.

Deoxyribonucleic acid base composition and biochemical properties of certain coagulase-negative enterotoxigenic cocci

Eight coagulase-negative, enterotoxigenic strains of cocci and one weakly coagulase-positive strain isolated from a number of different sources, including cases of food poisoning incidents, were evaluated for their relationship to Staphylococcus aureus on the basis of deoxyribonucleic acid (DNA) buoyant density and physiological studies. One strain of cocci produced enterotoxins A and C, two strains produced types B and C, four strains produced only type C, and one strain only type D. The enterotoxin produced by one strain of cocci was serologically untypable. None of the test organisms produced detectable amounts of enterotoxin in broth cultures. The test strains of cocci exhibited the following profile: all produced catalase; all grew anaerobically and fermented glucse; five were sensitive to lysostaphin; the percentage of guanine plus cytosine content of their DNA varied from 32.7 to 37.6; five produced acid from mannitol both aerobically and anaerobically; two formed delta-hemolysin; five produced phosphatase and acetoin; and all produced heat-stable nuclease. None of the organisms exhibited typical characteristics of S. aureus, S. epidermidis, or S. saprophyticus. On the basis of the present data and data reported elsewhere, these organisms should be considered as variants or mutants of S. aureus.

Peptidoglycan types of bacterial cell walls and their taxonomic implications

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Neutral lipids in the study of relationships of members of the family micrococcaceae

The organisms studied were those of the family Micrococcaceae which cannot participate in genetic exchange with Micrococcus luteus and those whose biochemical and physiological characteristics appear to bridge the genera Staphylococcus and Micrococcus. The hydrocarbon compositions of M. luteus ATCC 4698 and Micrococcus sp. ATCC 398 were shown to be similar to those previously reported for many M. luteus strains, consisting of isomers of branched monoolefins in the range C25 to C31. However, Micrococcus sp. ATCC 398 differed somewhat by having almost all C29 isomers (approximately 88% of the hydrocarbon composition). Micrococcus spp. ATCC 401 and ATCC 146 and M. roseus strains ATCC 412, ATCC 416, and ATCC 516 contained the same type of hydrocarbon patterns, but the predominant hydrocarbons were within a lower distribution range (C23 to C27), similar to Micrococcus sp. ATCC 533 previously reported. The chromatographic profile and carbon range of the hydrocarbons of an atypical strain designated M. candicans ATCC 8456 differed significantly from the hydrocarbon pattern presented above. The hydrocarbons were identified as branched and normal olefins in the range C16 to C22. Studies of several different strains of staphylococci revealed that these organisms do not contain readily detectable amounts of aliphatic hydrocarbons. The members of the family Micrococcaceae have been divided into two major groups based on the presence or absence of hydrocarbons. With the exception of M. candicans ATCC 8456, this division corresponded to the separation of these organisms according to their deoxyribonucleic acid compositions.

Nuclease production and lysostaphin susceptibility of Staphylococcus aureus and other catalase-positive cocci

Some strains of Staphylococcus epidermidis and Micrococcus sp. produce nucleases. However, thermal stability was shown to be unique to the nucleases of S. aureus. In addition, two micromethods for susceptibility testing to lysostaphin were more precise and convenient than anaerobic glucose fermentation in distinguishing between the genera Staphylococcus and Micrococcus.

Use of antibody to membrane adenosine triphosphatase in the study of bacterial relatioships

An antiserum to Ca(2+)-activated adenosine triphosphatase from membranes of Micrococcus lysodeikticus cross-reacted in agar gels with membrane adenosine triphosphatases from other pigmented micrococci and related species. Species of Micrococcus and Sarcina showed different levels of inhibition of adenosine triphosphatase activities in heterologous reactions with antiserum. Inter- and intraspecific relationships based on the inhibition reaction were compared with an independent parameter, namely the quantitative and qualitative composition of the bacterial membrane phospholipids and fatty acids. The guanine plus cytosine contents in the deoxyribonucleic acid of the species studied correlated well with the serological cross-reactivity of adenosine triphosphatases from their membranes. The types of cross-bridges found in the peptidoglycans of these cocci were also compared with the other properties. The results suggest that an antiserum specific for a major membrane protein may be a reliable and most useful adjunct in studying bacterial serotaxonomy.

Amino acid sequence of the murein of Planococcus and other Micrococcaceae

The amino acid composition and amino acid sequence of the murein (peptidoglycan) of 10 strains of planococci were studied. It is shown that the peptide subunit consists of muramyl-l-alanyl-gamma-d-glutamyl-l-lysyl-d -alanine. The cross-linking of two adjacent peptide subunits is mediated by d-glutamic acid which is bound to the epsilon-amino group of lysine by its gamma-carboxyl group and to the carboxyl group of d-alanine of an adjacent peptide subunit by its amino group. About 20 to 25% of the peptide subunits are not cross-linked. The murein structure of the different species and strains of Micrococcus, Staphylococcus, and Sarcina are compared. It is evident that the murein structure is a very good criterion for grouping the micrococci. In addition, some of these groups are fairly well defined by physiological properties as well as by their guanine + cytosine content of the deoxyribonucleic acid e.g., Micrococcus, Staphylococcus, Planococcus, Sarcina ureae. Other groups, represented by a single or a few strains only, such as M. varians NTCC 7281, M. radiodurans, M. freudenreichii ATCC 407, and M. luteus ATCC 398, need further investigation.

Biology of the sugar-fermenting Sarcinae

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Reexamination of the association between melting point, buoyant density, and chemical base composition of deoxyribonucleic acid

The equations currently used for the calculation of the chemical base composition of deoxyribonucleic acid (DNA), expressed as moles per cent guanine plus cytosine (% GC), from either buoyant density (rho) or midpoint of thermal denaturation (T(m)) were recalculated by using only sets of data on DNA determined with the same strains. All available information from the literature was screened and supplemented by unpublished data. The results were calculated by regression and correlation analysis and treated statistically. From the data on 96 strains of bacteria, it was calculated that% GC = 2.44 (T(m) - 69.4). T(m) appears to be unaffected by the substitution of cytosine by hydroxymethylcytosine. This equation is also valid for nonbacterial DNA. From the data on 84 strains of bacteria, the relation% GC = 1038.47 (-1.6616) was calculated. The constants in this equation are slightly modified when data on nonbacterial DNA are included. Both correlations differ only slightly from those currently used, but now they lean on a statistically sound basis. As a control, the relation between rho and T(m) was calculated from data of 197 strains; it agrees excellently with the above two equations.

Deoxyribonucleic acid base composition in the taxonomy of Staphylococcus

Twenty-four strains of Staphylococcus aureus, including eight known mutants of S. aureus and strains growing under a variety of environmental conditions or exposed to a number of physical and chemical agents, maintained a remarkably narrow range of guanine plus cytosine (GC) content (32.4 to 35.1%). The wide range of GC content (30.7 to 40%) reported in the literature was due to the variety of methods and calculations used rather than to any substantial variation in base composition. The UV-2 "mutant" (ATCC 13680) with a GC content of 67.6% reported to be derived from S. aureus (ATCC 13679) was a species of Corynebacterium. The data presented were consistent with the concept that base composition changes only to a very slight degree by mutation.

Genetic relationship between Sarcina ureae and members of the genus Bacillus

Deoxyribonucleic acid-ribonucleic acid (DNA-RNA) and DNA-DNA hybridization studies were performed to determine the degree of genetic relatedness between Sarcina ureae and several members of the genus Bacillus. DNA-RNA hybridization showed a high degree of homology between S. ureae RNA and DNA from Bacillus species having a similar guanine plus cytosine content. The DNA from other genera of the family Micrococcaceae showed less homology with S. ureae RNA than did that of the Bacillus species tested; however, this homology was not found between the DNA of S. ureae and DNA from these Bacillus species or DNA from the other Micrococcaceae tested. Transformation with Bacillus DNA, infection with representatives from several major classes of Bacillus phages, and electrophoretic analysis of proteins in crude extracts of these strains were also attempted as a further test of the genetic relationship between the genera. These experiments did not support the belief that the two groups are closely related genetically.

Use of lysostaphin in the isolation of highly polymerized deoxyribonucleic acid and in the taxonomy of aerobic Micrococcaceae

By use of the staphylolytic enzyme lysostaphin, a method was devised for isolating and purifying highly polymerized deoxyribonucleic acid (DNA) from lysostaphinsusceptible Micrococcaceae. Staphylococcus aureus DNA isolated by this procedure gave an estimated molecular weight of ca. 2 x 10(8) and a residual protein content of 2.3%. The mole percentage of guanine + cytosine (GC) present in the DNA from 21 strains of aerobic Micrococceae was determined by buoyant density in cesium chloride. DNA from 12 biochemically typical members of the genus Staphylococcus gave a mean GC composition of 35.2 +/- 0.5 mole per cent. Four biochemically atypical Staphylococcus strains and one biochemically typical strain of the genus Micrococcus (M. candicans) were found to be susceptible to lysostaphin and gave typical Staphylococcus spp. GC base ratios. One biochemically atypical member of the genus Micrococcus (M. varians) was not susceptible to lysostaphin and gave a typical Micrococcus spp. GC base ratio. Lysostaphin susceptibility is an easy test to perform, and the results of this test appear to correlate with GC base ratio studies of the genera of Micrococcaceae.

Reisolation of Staphylococcus salivarius from the human oral cavity

Twenty-four strains of gram-positive facultative cocci, arranged primarily in small clusters, were isolated from the surface of the human tongue. With the exception of 14 catalase-negative isolates, these strains were identical in cultural and biochemical characteristics and in deoxyribonucleic acid base composition. All cultures produced viscous growth in both liquid and agar media. They fermented glucose anaerobically, reduced nitrate beyond nitrite, were benzidine-positive, and failed to grow in the presence of 5% NaCl or at 45 C. In addition, they exhibited guanine plus cytosine (G + C) contents of 55.4 to 58.3%. These isolates differed from strains of pediococci, aerococci, and micrococci which were included for comparison. On the basis of G + C content, these organisms appear to be intermediate between micrococci and staphylococci; however, on the basis of anaerobic glucose fermentation, it is suggested that they be placed in the genus Staphylococcus. It is proposed that they be recognized as S. salivarius.