The effect of sodium chloride on phage formation by staphylococci at elevated temperatures

In experiments with the K strain of Staphylococcus aureus and the K race of bacteriophage suspended in tryptose phosphate broth and maintained at 42 degrees C. it was found that the presence of 1 M NaCl produced certain drastic changes in the relationship between the host cells and the infecting virus: 1. Staphylococci grown at 42 degrees C. in plain broth or in NaCl-broth are "activated," i.e. when growth is stopped by lowering the temperature to 5 degrees C. and phage is added, the activity titre immediately displays a rise of 15- to 16-fold. 2. 1 M NaCl tends to prevent the sorption of phage by cocci and this effect is more pronounced at 42 degrees C. than at 5 degrees C. When the activation test is conducted at 5 degrees C. (the usual temperature) most of the phage is picked up by the cells and the described increase in activity titre follows. If the test takes place at 42 degrees C. there is little sorption and correspondingly little rise in phage titre. 3. Mixtures of staphylococci and phage incubated at 42 degrees C. in NaCl-broth fail to produce phage; the final plaque and activity titres are identical with the initial titres. Here, also, the influence of 1 M NaCl in preventing contact of phage with cocci appears to account for the results. 4. Similar mixtures held at 42 degrees C. in plain broth exhibit a drop of about 60 per cent in activity and plaque titres. The loss of phage may be due to adsorption on dead cells accumulating in the suspension or to the thermolability of the bacterium-phage complex, or to both.     

Comparative studies on the fermentative production of lantibiotics by staphylococci

Summary The production of the lanthionine-containing polypeptide antibiotics gallidermin from Staphylococcus gallinarum TÜ 3928 and pep 5 from S. epidermidis 5 is investigated with respect to regulation and stimulation of productivity by media components, optimization of both the media used and the fermentation process and is compared to the production of the lantibiotic epidermin from S. epidermidis TÜ 3298. Efficient methods for rapid quantification of lantibiotics, optimization of the media and a primary enrichment by adsorption chromatography are reported.Offprint requests to: H.-P. Fiedler     

Inhibiting action of egg albumin on the growth of coagulase-negative species of staphylococci]

The effect of various concentrations of native egg albumin on growth of three staphyloccal species was studied. It was found that addition of 25 per cent of the albumin to the medium prepared from dry nutrient agar inhibited growth of Staph. epidermidis and Staph. saprophyticus, had no effect on growth of Staph. aureus and promoted formation of a pigment by it. A mechanism of the albumin inhibitory effect is suggested. It is proposed that the albumin medium be used for differentiation of Staph. aureus and the coagulase-negative species of staphylococci.     

Enterotoxin production by staphylococci isolated from healthy goats

The ability of 342 staphylococcal isolates from different anatomical sites in healthy goats to produce staphylococcal enterotoxins (SE) was investigated. SE were produced by 74.3% of the 70 coagulase-positive strains and by 22% of the coagulase-negative strains studied. Most enterotoxigenic strains were isolated from the skin of udders and teats and from milk. SEC was the SE type most frequently produced, either alone (67.9%) or in combination with others. Five coagulase-negative species not previously reported as SE producers were identified (Staphylococcus chromogenes, S. warneri, S. sciuri, S. saprophyticus, and S. lentus). SEA, SEB, and SEC were detected in the milk of 17 of the 133 healthy goats studied. These results suggest that the goat is an important reservoir of enterotoxigenic staphylococci, most of which produce SEC.     

The protective effect of sodium chloride against thermal destruction of the phage-forming mechanism in staphylococci

Staphylococci which have been allowed to grow rapidly in a favorable environment and subsequently have been maintained in a resting state characteristically produce a sharp rise in [phage] (activity) titre when added to phage. This capacity is quickly lost when the cells are suspended in distilled water and are exposed to 44 degrees C. for a period of 15 minutes; at the same time the viable count drops to approximately 1 to 3.5 per cent of the initial value. 1 M NaCl protects "activated" cells against thermal destruction and preserves the phage-augmenting property. "Non-activated" staphylococci in distilled water suspension do not show this thermolability.     

The effect of sodium intake on renal prostaglandin production

The effect of chronic alterations in dietary sodium intake on renal arachidonic acid (AA) metabolism was studied in male Wistar rats who were maintained for 14 days on a diet consisting of sodium-deficient food and either deionized water (low salt intake, LSI), 1% saline (normal salt intake, NSI), or 2% saline (high salt intake, HSI). 24 h Urinary Sodium (UNaV) and plasma renin activity (PRA) measurements were shown to validate the dietary protocol. Microsomal preparations from the cortices and medullae were incubated with radiolabeled exogenous AA, and endogenous urinary prostaglandin (PG) levels were assayed by RIA to quantify renal PG synthesis. Cortical PGF2 alpha and PGE2 synthesis was found to be the greatest following LSI. In contrast, medullary PGF2 alpha was shown to be the least following LSI and to increase with increased sodium intake. Likewise, urinary PGF2 alpha levels significantly increased with increasing sodium intake. Changes in urinary PGE2 levels showed the same trend as PGF2 alpha but did not achieve statistical significance. These data show that dietary sodium differentially affects renal cortical and medullary PG synthesis and may reflect physiological differences in the regulation of cyclooxygenase in these zones. These data further suggest that the major source of urinary PGs is the renal medulla since the relationship of urinary levels to sodium intake mimics that described for the synthesis of PGs by the medullary tissue.     

Growth-inhibitory effect of hemin on staphylococci

The antibacterial activity of hemin onStaphylococcus aureus is described. Hemin binding to bacteria was a rapid process, and each cell accumulated 5×10⁵ to 1×10⁶ molecules within 5 min. Bacterial growth was stopped completely after 30 min from addition of low concentration of hemin (3–10 g/ml). Cell viability was reduced by 99.9% in 1 h of exposure, and the effect was consistent at any stage of the growth curve whenever hemin was added. Glucose utilization was arrested immediately after hemin addition, and no CO₂ was produced. The survivors of hemin treatment regrow in a time-related kinetics depending on the dose of hemin to which the cells were exposed. The recovered bacteria were again sensitive to hemin, similar to an untreated culture. We suggested that the recovery phenomenon is a result of an on-off mechanism regulating sensitivity to hemin, rather than a selection mechanism giving rise to hemin-resistant mutants.     

Water transport by the bacterial channel alpha-hemolysin

This study is an investigation of the ability of the bacterial channel alpha-hemolysin to facilitate water permeation across biological membranes. alpha-Hemolysin channels were incorporated into rabbit erythrocyte ghosts at varying concentrations, and water permeation was induced by mixing the ghosts with hypertonic sucrose solutions. The resulting volume decrease of the ghosts was followed by time-resolved optical absorption at pH 5, 6, and 7. The average single-channel permeability coefficient of alpha-hemolysin for water ranged between 1.3x10-12 cm/s and 1.5x10-12 cm/s, depending on pH. The slightly increased single-channel permeability coefficient at lower pH-values was attributed to an increase in the effective pore size. The activation energy of water transport through the channel was low (Ea=5.4 kcal/mol), suggesting that the properties of water inside the alpha-hemolysin channel resemble those of bulk water. This conclusion was supported by calculations based on macroscopic hydrodynamic laws of laminar water flow. Using the known three-dimensional structure of the channel, the calculations accurately predicted the rate of water flow through the channel. The latter finding also indicated that water permeation data can provide a good estimate of the pore size for large channels.     

Enterotoxin production by staphylococci isolated from healthy goats.

The ability of 342 staphylococcal isolates from different anatomical sites in healthy goats to produce staphylococcal enterotoxins (SE) was investigated. SE were produced by 74.3% of the 70 coagulase-positive strains and by 22% of the coagulase-negative strains studied. Most enterotoxigenic strains were isolated from the skin of udders and teats and from milk. SEC was the SE type most frequently produced, either alone (67.9%) or in combination with others. Five coagulase-negative species not previously reported as SE producers were identified (Staphylococcus chromogenes, S. warneri, S. sciuri, S. saprophyticus, and S. lentus). SEA, SEB, and SEC were detected in the milk of 17 of the 133 healthy goats studied. These results suggest that the goat is an important reservoir of enterotoxigenic staphylococci, most of which produce SEC.     

A quantitative study of enterotoxin production by sheep milk staphylococci

Of 124 staphylococcal strains isolated from sheep milk, 78 produced enterotoxin A, B, C, or D when evaluated by an enzyme-linked immunosorbent assay. Enterotoxins A and D, elaborated by 44 and 43 strains, respectively, showed the highest incidence. Enterotoxin production by coagulase-negative strains (one Staphylococcus cohnii, three S. epidermidis, five S. haemolyticus, and four S. xylosus) was detected. Linear and logarithmic-logarithmic regressions of optical density on enterotoxin concentration yielded the best-fitting equations for enterotoxin quantitation. A significantly higher incidence of enterotoxin producers and significantly higher levels of enterotoxins produced were recorded for coagulase-positive, thermostable nuclease-positive, hemolysis-positive, or mannitol-positive strains. Mannitol utilization was the best test for discriminating between enterotoxigenic and nonenterotoxigenic staphylococci.