Magnesium requirement of Staphylococcus aureus for repair from sublethal heat injury

1976 ◽  
Vol 22 (8) ◽  
pp. 1202-1205 ◽  
Author(s):  
Ashton Hughes ◽  
Andre Hurst
Keyword(s):  
Staphylococcus Aureus ◽  
Salt Tolerance ◽  
Ethylenediaminetetraacetic Acid ◽  
Potassium Phosphate ◽  
Optimal Conditions ◽  
Minimal Repair ◽  
Potassium Phosphate Buffer ◽  
Heat Injury ◽  
Synthetic Media ◽  
Mg Content

Heating in potassium phosphate buffer causes Staphylococcus aureus to lose its salt tolerance and 30–40% of its cellular Mg2+. Repair from injury (regain of salt tolerance) occurred when injured cells were incubated under optimal conditions in synthetic media containing penicillin to prevent growth. Cells died when phosphates or amino acids were omitted from the medium. Omission of vitamins, glucose, Na+, and K+ had no effect. Omission of Mg2+ diminished repair. In a minimal repair medium (MRM) which contained only 3 × 10−6 M Mg (as an impurity), injured cells rapidly regained their original Mg content. About 20–50% of the cells also regained their salt tolerance provided that less than 109 cells/ml were used. With 1010 cells/ml there was no repair and cellular Mg content was half that of the control. Addition of 10−3 M ethylenediaminetetraacetic acid (EDTA) to MRM also prevented repair. Addition of 10−2 M Mg to MRM + 10−3 M EDTA permitted complete repair.

Repair of salt tolerance and recovery of lost D-alanine and magnesium following sublethal heating of Staphylococcus aureus are independent events

1981 ◽  
Vol 27 (6) ◽  
pp. 627-632 ◽  
Author(s):  
A. Hurst ◽  
A. Hughes
Keyword(s):  
Staphylococcus Aureus ◽  
Salt Tolerance ◽  
Phosphate Buffer ◽  
Synthetic Medium ◽  
Potassium Phosphate ◽  
Complex Media ◽  
Rich Medium ◽  
Potassium Phosphate Buffer ◽  
Heat Damage ◽  
Independent Events

Sublethal heating of Staphylococcus aureus S6 in potassium phosphate buffer caused loss of salt tolerance, D-alanine, and magnesium. During incubation in rich complex media all three of the damaged sites were repaired. Repair occurred more slowly but went to completion in a dilute synthetic medium (DSM), free of D-ala. DSM plus penicillin or D-cycloserine allowed repair of salt tolerance but recovery of normal levels of D-ala or Mg was prevented. When DSM-repaired cells were cultured into fresh rich medium they grew rapidly after a short lag. Cells which had acquired their salt tolerance in DSM plus cycloserine and were D-ala and Mg deficient grew slowly and had a lag of 3 h. We suggest that heat damage has two separate primary targets in S. aureus cells: the membrane, which is manifested by loss of salt tolerance, and a second site, possibly teichoic acids, manifested by loss of D-ala and Mg.

Synthesis of enterotoxin B by Staphylococcus aureus strain S6 after recovery from heat injury

1973 ◽  
Vol 19 (12) ◽  
pp. 1463-1468 ◽  
Author(s):  
D. L. Collins-Thompson ◽  
A. Hurst ◽  
H. Kruse
Keyword(s):  
Heat Treatment ◽  
Staphylococcus Aureus ◽  
Salt Tolerance ◽  
Sodium Phosphate ◽  
Potassium Phosphate ◽  
Aureus Strain ◽  
Heat Injury ◽  
K Cells ◽  
Enterotoxin B ◽  
And Control

After sublethal heat treatment of Staphylococcus aureus S6 at 52C for 15 min in either 0.1 M sodium phosphate (Na cells) or 0.1 M potassium phosphate (K cells), more than 99% of the cells were unable to grow on a medium containing 7.5% NaCl. When placed in H and K medium the survivors recovered their salt tolerance and grew after a lag of 3 h (Na cells) or 5 h (K cells). In the absence of glucose, the total amount of enterotoxin B synthesized by the Na and K cells was similar to the control cells. Addition of 0.1% glucose to the medium increased the total amount of toxin formed by Na, K, and control cells.

Repair of Heat-Injured Staphylococcus aureus 196 E on Food Substrates and Additives and at Different Temperatures

1982 ◽  
Vol 45 (5) ◽  
pp. 458-461
Author(s):  
SAMUEL A. PALUMBO ◽  
JAMES L. SMITH
Keyword(s):  
Staphylococcus Aureus ◽  
Lactic Acid ◽  
Salt Tolerance ◽  
Agar Medium ◽  
Potassium Phosphate ◽  
Ground Beef ◽  
Potassium Phosphate Buffer ◽  
Liquid Smoke ◽  
Different Temperatures ◽  
Food Substrates

Repair of heat-injured Staphylococcus aureus 196E was studied on a newly developed agar medium containing 25% ground beef. The cells were heat-injured at 50 C in 0.1 M potassium phosphate buffer (pH 7.2). After being heated, the cells were surface plated on: Tryptic soy agar (TSA); TSA + 7% NaCl (TSAS); ground beef agar (GBA) with and without various additions; and meat/food agar. Repair is defined as the number of organisms growing on GBA, GBA + addition, or meat/food agar that is greater than the number growing on TSAS by at least one log cycle. The following additives incorporated into GBA permitted repair of heat-injured S. aureus: nitrite (up to 400 ppm), ascorbate (up to 500 ppm), lactic acid (down to pH 5.5), liquid smoke preparations, and water activity-lowering substances including glycerol (10%), NaCl (2.5%), KCl (5%) and sucrose (30%). Cells regained salt tolerance on TSA when incubated at temperatures from 20 to 45 C, but not at 16 or 50 C. Repair was most rapid at 35 C. When ground beef was replaced in the plating medium, repair occurred on frankfurter and chili beef soup agars, but not on pepperoni and Lebanon bologna agars. Repair of heat-injured S. aureus can take place on meat-foods, in the presence of various meat additives, and at temperatures from 20 to 45C.

Campylobacter jejuni in Foods: Its Occurrence, Isolation from Foods, and Injury

1986 ◽  
Vol 49 (2) ◽  
pp. 161-166 ◽  
Author(s):  
SAMUEL A. PALUMBO
Keyword(s):  
Campylobacter Jejuni ◽  
Brilliant Green ◽  
Potassium Phosphate ◽  
Polymyxin B ◽  
Differential Count ◽  
Sodium Metabisulfite ◽  
Potassium Phosphate Buffer ◽  
Sodium Pyruvate ◽  
Heat Injury ◽  
Freeze Thaw

The following aspects of Campylobacter jejuni has been reviewed: characteristics of C. jejuni, its occurrence in foods, methods to quantitatively recover the organism from food, and heat injury and freeze-thaw stress of C. jejuni. C. jejuni can be heat injured in 0.1 M potassium phosphate buffer at 46°C. Heat injury can be demonstrated as the differential count between brucella agar plus ferrous sulfate, sodium metabisulfite and sodium pyruvate (FBP) and brilliant green 2% bile broth agar plus FBP. Heat-injured C. jejuni will grow on brucella agar containing either of the three antibiotic mixtures typically used to isolate C. jejuni. Heat-injured C. jejuni will repair (regain dye and bile tolerance) in brucella broth plus FBP. C. jejuni can be freeze-thaw stressed. This stress is demonstrated as a sensitivity to the antibiotic polymyxin B or incubation at 42°C. Addition of succinate and cysteine increased recovery of freeze-thaw stressed C. jejuni. Although the presence of injured/stressed C. jejuni in foods has not yet been detected, methods are now available to begin this search. The injury/stress process may explain the often encountered difficulty in isolating C. jejuni, especially low numbers, from foods.

Comparison of selective media for the enumeration of sublethally heated food-poisoning strains of Staphylococcus aureus

1974 ◽  
Vol 20 (7) ◽  
pp. 1072-1075 ◽  
Author(s):  
D. L. Collins-Thompson ◽  
A. Hurst ◽  
B. Aris
Keyword(s):  
Staphylococcus Aureus ◽  
Phosphate Buffer ◽  
Food Poisoning ◽  
Potassium Phosphate ◽  
Egg Yolk ◽  
Potassium Phosphate Buffer ◽  
Mannitol Salt Agar ◽  
Selective Media

Staphylococcus aureus strains (19 food-poisoning strains) were heated at 52C for 15 min in 100 mM potassium phosphate buffer. The sublethally heated organisms were enumerated on seven selective media commonly used for quantitating S. aureus. Compared to trypticase soy agar, Baird-Parker agar was the only medium which was satisfactory with all cultures tested. The remaining selective media gave unsatisfactory recoveries with one or more of the strains tested and are listed in the following order of decreasing acceptability: tellurite glycine agar, egg yolk azide agar, phenolphthalein phosphate agar with polymyxin, mannitol salt agar, Vogel Johnson agar.

Effect of glucose and pH on growth and enterotoxin B synthesis by Staphylococcus aureus, strain S6, after heat injury in sodium or potassium phosphate buffer

1973 ◽  
Vol 19 (7) ◽  
pp. 823-829 ◽  
Author(s):  
A. Hurst ◽  
D. L. Collins-Thompson ◽  
H. Kruse
Keyword(s):  
Phosphate Buffer ◽  
Potassium Phosphate ◽  
Aureus Strain ◽  
Lag Phase ◽  
Potassium Phosphate Buffer ◽  
Heat Injury ◽  
Glucose Levels ◽  
K Cells ◽  
Enterotoxin B ◽  
Straight Lines

Cells injured by heating at 52C for 15 min in sodium (Na cells) or potassium phosphate buffer (K cells) were allowed to grow and recover in media containing 0, 0.1%, and 1.0% glucose. Growth, acid, and enterotoxin B production was followed and compared with that of unheated control cells. Control cells growing in 0 and 0.1% glucose first lowered the pH, but injured cells did not. Straight lines were obtained from growth experiments when the ratio enterotoxin B/pH versus time was plotted. Statistical analysis of the slopes showed that Na cells differed from K cells. In 1.0% glucose, Na cells produced less acid than K cells. Na cells were 80%, control cells were 90%, and K cells were 99% repressed in their enterotoxin B synthesis. At all glucose levels, the lag phase of Na cells was about 2 h shorter than that of K cells. Heat injury caused a 30–40% loss of K+, but Na cells gained Na+ (34%) and K cells lost Na+ (28%). The K/Na ratio of Na cells was 2.75 and that of K cells was 15.75. It is argued that this difference could account for the differences observed between Na cells and K cells but cannot account for the total injury phenomenon.

Enumeration of sublethally heated staphylococci in some dried foods

1976 ◽  
Vol 22 (5) ◽  
pp. 677-683 ◽  
Author(s):  
Andre Hurst ◽  
G. S. Hendry ◽  
Ashton Hughes ◽  
Beverly Paley
Keyword(s):  
Staphylococcus Aureus ◽  
Salt Tolerance ◽  
Adenosine Triphosphate ◽  
Yeast Extract ◽  
Skim Milk ◽  
Most Probable Number ◽  
Acetyl Phosphate ◽  
Sodium Pyruvate ◽  
Probable Number ◽  
Heat Injury

The effect of 45 substances to restore the salt tolerance of sublethally heat-injured Staphylococcus aureus was tested. Sodium pyruvate, yeast extract, L-histidine, casitone (Difco), adenosine triphosphate, and acetyl phosphate were effective. For enumeration a repair medium was first used, containing sodium pyruvate and penicillin in 1% skim milk. This step was followed by counting on Baird-Parker agar with penicillinase. This method was selective; fewer than 100 staphylococci/g food could be enumerated and it gave counts about 8 times higher than the method of Giolitti and Cantoni used as a five-tube most probable number technique. Heat injury sensitized S. aureus to polymyxin.

Relationship between loss of magnesium and loss of salt tolerance after sublethal heating of Staphylococcus aureus

1974 ◽  
Vol 20 (8) ◽  
pp. 1153-1158 ◽  
Author(s):  
Andre Hurst ◽  
Ashton Hughes ◽  
David L. Collins-Thompson ◽  
Bhagwandas G. Shah
Keyword(s):  
Staphylococcus Aureus ◽  
Salt Tolerance ◽  
Kinetic Studies ◽  
Heat Injury ◽  
Plate Counts

The effect of sublethal heating on Staphylococcus aureus was followed by plate counting on trypticase soy agar and by calculating decimal reduction times (D52C). Pseudodecimal reduction times (D′52C) were obtained from plate counts on trypticase soy agar containing 7.5% NaCl. D52C was a measure of lethality and the ratio D′52C/D52C was used as a measure of injury. Sublethal heating was carried out in various 100 mM (pH 7.2) solutions.Orthophosphates of potassium, ammonium, and sodium were more lethal than the corresponding chlorides (average D52 values of 18.2 and 29.6 min respectively). Orthophosphates also appeared to be more injurious than chlorides (average D′52C/D52C values of 0.43 and 0.62 respectively). 'Phosphate'-heated cells lost 28.4% of their cellular Mg while 'chloride'-heated cells lost 11% of their Mg. Good correlation exists between D′52C/D52C values and the magnesium lost. Kinetic studies in potassium buffer also showed good correlation between loss of salt tolerance and loss of cellular Mg. This, and other evidence, suggests that loss of Mg is one of the primary events in the sublethal heat injury of S. aureus.

Ultrastructure of Melanin Formation in Curvularia sp., Alternaria sp., and Drechslera Sorokiniana

1977 ◽  
Vol 35 ◽  
pp. 398-399
Author(s):  
M. H. Wheeler ◽  
W. J. Tolmsoff ◽  
A. A. Bell
Keyword(s):  
Potassium Phosphate ◽  
Thielaviopsis Basicola ◽  
Wild Type ◽  
Potassium Phosphate Buffer ◽  
Transmission Microscopy ◽  
Electron Transmission ◽  
Melanin Formation ◽  
Before And After ◽  
Alternaria Sp ◽  
Electron Transmission Microscopy

(+)-Scytalone [3,4-dihydro-3,6,8-trihydroxy-l-(2Hj-naphthalenone] and 1,8-di- hydroxynaphthalene (DHN) have been proposed as intermediates of melanin synthesis in the fungi Verticillium dahliae (1, 2, 3, 4) and Thielaviopsis basicola (4, 5). Scytalone is enzymatically dehydrated by V. dahliae to 1,3,8-trihydroxynaphthalene which is then reduced to (-)-vermelone [(-)-3,4- dihydro-3,8-dihydroxy-1(2H)-naphthalenone]. Vermelone is subsequently dehydrated to DHN which is enzymatically polymerized to melanin.Melanin formation in Curvularia sp., Alternaria sp., and Drechslera soro- kiniana was examined by light and electron-transmission microscopy. Wild-type isolates of each fungus were compared with albino mutants before and after treatment with 1 mM scytalone or 0.1 mM DHN in 50 mM potassium phosphate buffer, pH 7.0. Both chemicals were converted to dark pigments in the walls of hyphae and conidia of the albino mutants. The darkened cells were similar in appearance to corresponding cells of the wild types under the light microscope.

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