Continuous culture of ruminal microorganisms in chemically defined medium. II. Culture medium studies

Ruminal ciliates have been grown in continuous culture in chemically defined media and in the absence of viable bacteria. Oligotrichic ruminal ciliates seem to require insoluble carbohydrates for growth; the holotrichic ciliates require soluble carbohydrates, but at low concentrations. Both groups of ciliates utilize amino acids as their principal nitrogen source when these are supplied in micromolar concentrations; at millimolar concentrations, amino acids are toxic, possibly from excessive ammonia formation arising from ciliate deaminase activity. Holotrichic ruminal ciliates are destroyed by overdeposition of amylopectin when glucose is present above 0.1% concentration in the medium. Ecological requirements of ruminal ciliates are also described.

Procedure for cleaning of Clostridium botulinum spores

Grecz, N. (Quartermaster Food and Container Institute, Chicago, Ill.), A. Anellis, and M. D. Schneider. Procedure for cleaning of Clostridium botulinum spores. J. Bacteriol. 84:552-558. 1962.-Liberation of clean spores from vegetative sporangia of Clostridium botulinum strains was accomplished by the use of lytic enzymes and sonic oscillation. Suspensions of crude spores in phosphate buffer (pH 7) were digested with lysozyme (200 mug/ml) and trypsin (100 mug/ml). Rapid lysis of sporangia was induced by ultrasonic oscillation of the reacting mixture at 10 kc for 5 min at 0, 0.5, 1, 2, 4, and 6 hr of incubation at 45 C. Intermittent washing of the reacting spore suspension with a solution of lysozyme and trypsin hastened purification of the spore crop. The cleaning procedure was completed by repeated washing of the spores with distilled water. The spores produced by this procedure were clean, as judged by their microscopic appearance, refractility to staining, loss of heat-sensitive toxin, and partition behavior in a two-phase system composed of polyethylene glycol and 3 m potassium phosphate buffer (pH 7.1). The cleaning procedure appeared not to affect the viability, resistance to heat and gamma radiation, or the toxic nature of C. botulinum spores.

Continuous culture of ruminal microorganisms in chemically defined medium. I. Design of continuous-culture apparatus

An apparatus is described which has been used for successful continuous culture of the ciliates from the rumen of cattle. Automatic control of feeding rate, pH, oxidation-reduction potential, temperature, stirring rate, aeration rate, salinity, and volume of the culture is provided for, using standard commercial equipment, whenever possible. The operation of this apparatus is described.

Techniques for the rapid and sensitive detection of penicillinase

Practical problems in the detection of penicillinase are discussed. A membrane technique for this purpose is described, with various modifications, suitable for screening large numbers of organisms and yet more sensitive than most methods.A one-stage membrane technique is adequate for detecting hydrolysis of penicillin G but a two-stage technique is required to demonstrate hydrolysis of some other penicillins. A gradient adaptation can be used for quantitative purposes.Staphylococci, coliforms, Proteus, and other organisms can be tested in this way for penicillinase formation; the method is also suitable for testing lysates, filtrates, and dialysates, provided independent provision is made for enzyme inducement.

Maintenance of the rumen microbial population in continuous culture

The design and use of an apparatus for continuous in vitro cultivation of the mixed bovine rumen microbial population are described. Data relative to the concentrations and proportions of volatile fatty acids produced, methanogenesis, carbon dioxide production, and survival of bacteria and protozoa indicated that an essentially normal in vivo fermentation pattern was maintained in vitro for experimental periods of from 3 to 10 days. The continuous cultures were responsive to major changes in type of feed intake. A change from grain to hay resulted in increased acetate and decreased propionate production, whereas decreased acetate and increased propionate resulted when feed intake was changed from hay to grain. Methanogenesis, volatile fatty acid production, and the numbers of microorganisms in the cultures were proportional to the amount of feed materials added up to levels calculated to approximate the in vivo maintenance requirement of the adult bovine.

Statistical study of the spot-plate technique for viable-cell counts

A statistical study of the spot-plate technique was made for the purpose of establishing an acceptable counting range. The organism used in these studies was Micrococcus lysodeikticus. Standard deviations and coefficients of variation were computed for counts ranging from 20 to 440. The lower and upper limits for acceptable counts, based on coefficients of variation of 10 and 5.8, respectively, were chosen as 100 and 300.

Extracellular accumulation of pyrroles in bacterial cultures

Aerobacter aerogenes, Paracolobactrum aerogenoides, Spirillum serpens, and gelatinous strains of Chromobacterium violaceum produced an extracellular, ether-soluble, Ehrlich-positive substance when grown in media prepared with gelatin hydrolysate. The substance has been tentatively identified as pyrrole-2-carboxylic acid. Both hydroxy-l-proline and allo-d-hydroxyproline have been shown to be precursors of the material. Gelatinous strains of Chromobacterium violaceum, but not the other positive cultures, produced two ether-insoluble pyrroles as well, the precursors of which occur in gelatin hydrolysate but have not yet been identified. The property of pyrrole formation in bacteria and its possible use as an aid in identification of bacteria was discussed.

EFFECT OF AMINO ACIDS ON STEADY-STATE GROWTH OF A GROUP A HEMOLYTIC STREPTOCOCCUS

Davies, Helen C. (University of Pennsylvania, Philadelphia), Fred Karush, and Joanne H. Rudd. Effect of amino acids on steady-state growth of a group A hemolytic streptococcus. J. Bacteriol. 89:421-427. 1965.-A study has been made of amino acid utilization by a strain of type 4, group A streptococcus growing under steady-state conditions in a continuous-culture device and supplied with a completely synthetic medium. At a fixed growth rate, corresponding to a generation of time of 84 min, and with the pH maintained constant at 7.4, the bacterial turbidity was made dependent on the concentration of one of the amino acids of the defined medium. Under these conditions, the extracellular concentration of the limiting amino acid is fixed by the preset growth rate. The steady-state concentration of each of 14 essential l-amino acids was measured by means of C(14)-labeled amino acids in such limited cultures. At approximately equal turbidities, these concentrations ranged from 1.6 x 10(-6)m for methionine to 4.3 x 10(-4)m for glutamic acid. The rates of utilization of the amino acids ranged from 26 mmumoles per mg (dry weight) of bacteria per hr for histidine to 310 mmumoles per mg (dry weight) of bacteria per hr for glutamic acid. The percentage of the limiting amino acid used varied from 95% for threonine and methionine to 43% for gluamic acid. The rate of utilization of the limiting amino acid at unit concentration (tmoles per gram per hour per m) differed by a factor of 27 between extremes. These observations reflect the variation in the capacity of this streptococcal cell to take up and use different amino acids.

COOLING DEVICE FOR USE WITH A SONIC OSCILLATOR

A cooling cell is described that facilitates maintenance of biological materials at low temperatures during prolonged sonic treatment. Using this cell and a Branson S-75 Sonifier, I examined temperatures and the release of protein and enzyme activity from suspensions of Saccharomyces cerevisiae. With the Sonifier at full power, it was possible to maintain cell temperature within 9 C of the cooling-bath temperature, and to disrupt 10% (w/v) suspensions of S. cerevisiae in 10 min.

DENSITY-GRADIENT PATTERNS OF STAPHYLOCOCCUS AUREUS CELLS AND CELL WALLS DURING GROWTH AND MECHANICAL DISRUPTION

Huff, Eskin (National Institute of Allergy and Infectious Diseases, Bethesda, Md.), Harriet Oxley, and Carol S. Silverman. Density-gradient patterns of Staphylococcus aureus cells and cell walls during growth and mechanical disruption. J. Bacteriol. 88:1155-1162. 1964.-Procedures capable of rapid disruption of Staphylococcus aureus cells with optimal release of intact cell walls were investigated. This search was implemented by observation of the flotation patterns of cells and subcellular particulate matter after centrifugation in a cesium chloride density gradient. A quantitative evaluation of the light-scatter throughtout the gradient was achieved by transfer of the entire density gradient into an optical cell with wedge-shaped cross section. When this cell was photographed under indirect illumination, each band of light-scattering material appeared on the negative as a shaded curve, with an area proportional to amount of that material present. A series of photographs of known amounts of cells and cell walls was used to estimate the amounts of these materials in mixtures of the two occurring during mechanical disruption. With the methods employed, time studies established the optimal time for release of cell walls as 5 min in a Braun shaker. The use of sucrose gradients in the further purification of cell walls, and chemical analysis of the isolated walls, are described.

TEMPERATURE-SENSITIVE MUTANTS OF BACILLUS SUBTILIS BACTERIOPHAGE SP3. II. IN VIVO COMPLEMENTATION STUDIES

Nishihara, Mutsuko (University of California, Los Angeles), and W. R. Romig. Temperature-sensitive mutants of Bacillus subtilis bacteriophage SP3. II. In vivo complementation studies. J. Bacteriol. 88:1230-1239. 1964.-A plate-spotting procedure was used in initial attempts to group the temperature-sensitive Bacillus subtilis phage SP3 mutants by complementation. The results obtained did not show any clear patterns of reactions among the mutants. Crosses were, therefore, repeated in broth at a temperature of 49 C, which greatly reduced the extent of replication of each mutant type alone. The data on mixed infections indicated that there was a minimum of six complementation groups. Of the 12 isolates, 7 did not seem to complement with each other; the rest complemented with each other and with the seven noncomplementing mutants. There was a positive correlation between the complementation reaction of a pair and the recovery of wild-phenotype phages from a 49 C broth lysate. The relative proportion of phages capable of forming wild-phenotype plaques on plates incubated at 46 C to the total number of plaque-forming units was higher in a lysate of a mixed infection with two mutants than in lysates of each mutant alone. Moreover, this frequency was higher for a mixed lysate made at 49 C than for a lysate of the same two mutants made at 37 C. These observations suggested that genetic recombination might occur at 49 C, and that the increased recovery of wild-phenotype phages in lysates made at this temperature might be due to a selective advantage for these phages. Recombination experiments at 37 C with some complementing pairs gave frequencies of 2.0 to 4.8%. The ratio of wild-phenotype revertants to total phages in the stock lysates used for these crosses at 37 C was less than 10(-6). The noncomplementing mutants were not conclusively shown to be nonidentical.

METHOD FOR THE DETECTION OF SIGNIFICANT BACTERIURIA IN LARGE GROUPS OF PATIENTS

A measured area of blotting paper was used as a vehicle for transferring a constant aliquot of urine on to the surface of a culture medium. The number of bacterial colonies growing in the inoculum area of the medium corresponded to the number of organisms in the urine. One thousand, two hundred and seventy-five urines from women attending an ante-natal clinic were tested by this method, and the results compared with the results of quantitative bacterial counting and of triphenyl tetrazolium chloride (T.T.C.) tests. The method was found to be a simple, cheap, and reliable way of screening urine specimens for significant bacteriuria.

A NEW ENRICHMENT MEDIUM FOR SALMONELLAE

A new enrichment medium for the isolation of salmonella types from faeces is described.

The inhibitory substances for coliform organisms and enterococci in this medium are magnesium chloride and sodium hydrogen selenite.

The new medium was found in routine diagnostic work to be superior to the Mueller–Kauffmann medium in the isolation ofSalmonella typhiand only a little inferior in the isolation of other salmonella types.

When used in addition to the standard media the new medium increases the number of positive results.

I am indebted to Dr Jadranka Zajc-Satler for the identification of the salmonella types isolated and to Mrs I. Mamilovič, Miss P. Ferbežar, and Mrs D. Zavodnik for technical assistance.

KINETICS OF DRY RUPTURE OF BACTERIAL SPORES IN THE PRESENCE OF SALT

Sacks, L. E. (U.S. Department of Agriculture, Albany, Calif.), Peter B. Percell, Richard S. Thomas, and Glen F. Bailey. Kinetics of dry rupture of bacterial spores in the presence of salt. J. Bacteriol. 87:952-960. 1964.-The kinetics of breaking spores in the dry state by use of an excess of sodium chloride and a steel ball in a shaking device were investigated. Under most conditions, disruption is a first-order process. The disruption-rate constant varies directly with the weight of the ball and inversely with the weight of the capsule contents (spores plus salt). Different spore batches differ somewhat in susceptibility to dry rupture. The dry-rupture process is highly reproducible and it is relatively simple to obtain preparations in which exactly 50%, or 90%, of the spores are broken. The procedure is uniquely suited to the disruption of small (5 to 20 mg) samples, but 150 mg of spores have been handled with conventional equipment. Apparently, the chief function of the salt is to separate the spores from one another with a relatively hard, energy-nonabsorbing matrix, preventing aggregation and consequent cushioning of the ball's impact. However, under certain conditions (small ball, high salt, large crystals) appreciable breakage results from collisions of spores with the salt crystals. The minimal salt-spore ratio for efficient breakage depends on the spore batch, but is usually greater than 3:1. Fine glass beads or inorganic salts other than sodium chloride will also serve as the matrix. Electron micrographs of the spores in various stages of disruption are shown, as are electron micrographs of the spore coats of Bacillus macerans, B. megaterium, B. cereus, B. coagulans, and Clostridium bifermentans. Prolonged agitation disintegrates spore coats. The spore coats of B. macerans exhibit a characteristic ribbed structure, previously detected only by carbon replicas of intact spores. Possible application to other biological materials is considered.

SOME PHYSIOLOGICAL CHARACTERISTICS OF NEOMYCIN AND KANAMYCIN-RESISTANT STRAINS OF STAPHYLOCOCCUS AUREUS

Five hundred and fifty-two strains of Staphylococcus aureus of hospital origin were resistant to penicillin, streptomycin, and tetracycline. Of these, 298 were also resistant to neomycin and kanamycin, and this resistance was related to pigment production on glycerol monoacetate agar, the production of beta-lysin, the absence of fibrinolytic and proteolytic activity, and to phage susceptibility. The use of physiological markers, the inadequacy of phage typing, and the possible reasons for the emergence of neomycin-resistant staphylococci are discussed.

OXYGEN INHIBITION OF GROWTH OF MYCOBACTERIUM TUBERCULOSIS

Gottlieb, S. F. (Linde Division, Union Carbide Corporation, Tonawanda, N.Y.), Noel R. Rose, Jerome Maurizi, and Edward H. Lanphier. Oxygen inhibition of growth of Mycobacterium tuberculosis. J. Bacteriol. 87:838-843. 1964.-Continuous or intermittent exposure to 3 atm of oxygen in the presence or absence of 40 mm of Hg CO(2) resulted in marked delay or inhibition of growth of Mycobacterium tuberculosis. This inhibition was more pronounced with newly inoculated cultures, as compared to young, actively growing cultures. Oxygen inhibition of growth was observed on both Lowenstein-Jensen and blood agar media. Bacteriostatic effects of oxygen are a direct function of exposure time. A more marked effect of oxygen was observed in the presence of isoniazid, streptomycin, or p-aminosalicyclic acid.

SEROLOGY OF THE MIMA-HERELLEA GROUP AND THE GENUS MORAXELLA

Mitchell, Paul D. (West Virginia University Medical Center, Morgantown), and Robert G. Burrell. Serology of the Mima-Herellea group and the genus Moraxella. J. Bacteriol. 87:900-909. 1964.-The identity of organisms which have been assigned to the Mima-Herellea group of the tribe Mimeae and their taxonomic position are uncertain. In considering the possible relationship of the Mima-Herellea group to the genus Moraxella, the approach used was the isolation and identification of representative antigenic constituents of strains designated Mima polymorpha, M. polymorpha var. oxidans, Herellea vaginicola, Moraxella lwoffi, M. liquefaciens, M. non-liquefaciens, and Bacterium anitratum. Cell-free extracts of sonically disrupted cells were used in these studies, and the precipitinogens derived by this method were considered to be of capsular and somatic origin. Identity among the strains was established by immunodiffusion, with immune sera and antigenic extracts. Heterologous and homologous reactions were performed with adsorbed and unadsorbed sera to verify the cases of identity. In every instance of homologous reaction, at least five distinct antigen-antibody systems were discernible within the Mima-Herellea group. However, as evidenced by heterologous studies, the demonstrable antigenic composition varied among the species and, in some instances, among the strains. M. polymorpha var. oxidans appeared to be serologically distinct from H. vaginicola and M. polymorpha, whereas strains of the latter two organisms were theorized to be closely related serologically. Serological cross-reactions in heterologous studies and reciprocal adsorption tests revealed the existence of a serological relationship between members of the Mima-Herellea group and the genus Moraxella. A tentative scheme of identity is postulated on the basis of these crossreactions and cultural and biochemical reactions among the designated strains of Herellea, Mima, Moraxella, and Bacterium.

SEPARATION OF TEICHOIC ACID OF STAPHYLOCOCCUS AUREUS INTO TWO IMMUNOLOGICALLY DISTINCT SPECIFIC POLYSACCHARIDES WITH ALPHA- AND BETA-N-ACETYLGLUCOSAMINYL LINKAGES RESPECTIVELY. ANTIGENICITY OF THEICHOIC ACIDS IN MAN

Human sera were found to contain antibodies precipitating with each of two samples of teichoic acid of Staphylococcus aureus prior to immunization; these antibodies were probably formed as a result of contact or infection with this microorganism. Injection of teichoic acid into two individuals resulted in a rise in circulating antibody to teichoic acid; a third subject probably had a primary response to α-teichoic acid. Quantitative precipitin and agar diffusion studies revealed the presence of two distinct antibodies in the sera and showed that each specimen of teichoic acid was a mixture of two polymers an α-linked N-acetylglucosaminyl-ribitol polymer and a β-linked N-acetylglucosaminyl-ribitol polymer, termed α- and β-teichoic acids respectively. The α-teichoic acid anti-α-teichoic acid system was inhibited best by α-linked glucosaminides and the β-anti-β-teichoic acid system was inhibited best by a β-linked glucosaminide. The α- and (β-teichoic acids could be separated from each other by specific precipitation under appropriate conditions and recovered from the washed specific precipitates. The existence of two distinct teichoic acid polymers raises important questions as to cell wall structure and the biosynthesis of the teichoic acids.