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.

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.

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.

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.

Microbiological Quality of Fresh Blue Crabmeat, Clams and Oysters

1983 ◽  
Vol 46 (11) ◽  
pp. 978-981 ◽  
Author(s):  
B. A. WENTZ ◽  
A. P. DURAN ◽  
A. SWARTZENTRUBER ◽  
A. H. SCHWAB ◽  
R. B. READ
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Microbiological Quality ◽  
Fecal Coliforms ◽  
Geometric Means ◽  
Colony Forming Units ◽  
Plate Counts ◽  
The Mean ◽  
Eastern Oysters

The microbiological quality of fresh blue crabmeat, soft- and hardshell clams and shucked Eastern oysters was determined at the retail (crabmeat, oysters) and wholesale (clams) levels. Geometric means of aerobic plate counts incubated at 35°C were: blue crabmeat 140,000 colony-forming units (CFU)/g, hardshell clams, 950 CFU/g, softshell clams 680 CFU/g and shucked Eastern oysters 390,000 CFU/g. Coliform geometric means ranged from 3,6/100 g for hardshell clams to 21/g for blue crabmeat. Means for fecal coliforms or Escherichia coli ranged from <3/100 g for clams to 27/100 g for oysters, The mean Staphylococcus aureus count in blue crabmeat was 10/g.

Growth and enterotoxin B synthesis by Staphylococcus aureus S6 in associative growth with Pseudomonas aeruginosa

1973 ◽  
Vol 19 (10) ◽  
pp. 1197-1201 ◽  
Author(s):  
D. L. Collins-Thompson ◽  
B. Aris ◽  
A. Hurst
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Sodium Chloride ◽  
Salt Tolerance ◽  
Second Growth ◽  
Growth System ◽  
Pure Cultures ◽  
Enterotoxin B ◽  
Membrane Type ◽  
And Staphylococcus Aureus

The interaction of Pseudomonas aeruginosa and Staphylococcus aureus S6 was studied in two systems. In the first system, the two organisms were grown together in a single flask. Growth of P. aeruginosa was unaffected, but growth of S. aureus was modified. After 24 h, 99.9% of the staphylococci population lost their salt tolerance when plated on media containing 7.5% sodium chloride, and enterotoxin B synthesis by S. aureus was diminished. In the second growth system, pure cultures of P. aeruginosa and S. aureus were grown in membrane-type spinner flasks. The growth and salt tolerance of S. aureus was again affected, but to a lesser degree. Cultures of S. aureus from these experiments recovered their salt tolerance in 6 h when transferred to fresh medium.Nutrient deficiency, lack of oxygen, or pigment production by the pseudomonads did not contribute significantly to loss of salt tolerance or inhibition of enterotoxin B synthesis, but a staphylolytic enzyme(s) isolated from P. aeruginosa was shown to be responsible for the loss of these properties.

scholarly journals Antimicrobial coating on quality attributes of sausage during refrigerated storage

2018 ◽  
Vol 47 ◽  
pp. 01002 ◽  
Author(s):  
R. Naufalin ◽  
R. Wicaksono ◽  
P. Arsil ◽  
M.F. Salman
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Peroxide Value ◽  
Edible Coating ◽  
Refrigerated Storage ◽  
Barrier Effect ◽  
Moisture Barrier ◽  
Barrier Coating ◽  
Plate Counts ◽  
Quality And Shelf Life

Edible coating based on carboxymethyl cellulose (CMC) environmentally friendly. Addition on Kecombrang (Nicolaia speciosa) extract used to be antimicrobial and antioxidants coating. CMC- based edible coating added with antimicrobial of kecombrang was used to reduce the oxidative and microbial degradation sausages stored at refrigerator at 10°C for 12 days. The cmc coating reduced malonaldehyde substances and peroxide value by 0.88 mg.kg and 92.29%, respectively, compared with the controls. The moisture barrier effect was significantly better for the CMC coating compared to the control. The CMC coating of sausages inhibits the growth of either the total plate counts of Bacillus cereus, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeroginosa. Data show that cmc can effectively be used as a natural antioxidative and moisture barrier coating to extend the quality and shelf life of sausages.

Effects of Potassium Sorbate on Normal Flora and on Staphylococcus aureus Added to Minced Cod

1982 ◽  
Vol 45 (9) ◽  
pp. 824-828 ◽  
Author(s):  
DONALD J. LYNCH ◽  
NORMAN N. POTTER
Keyword(s):  
Staphylococcus Aureus ◽  
Storage Period ◽  
Inhibitory Effect ◽  
Potassium Sorbate ◽  
Normal Flora ◽  
Ph Changes ◽  
Normal Microflora ◽  
Enterotoxin Production ◽  
Plate Counts ◽  
Storage Temperatures

Minced cod and pasteurized minced cod, with and without 0.5% potassium sorbate, were subjected to abusive storage temperatures of 7 and 15°C. Staphylococcus aureus FRI 100 was inoculated into the cod before storage. Total aerobic plate counts (20 and 35°C), pH changes, S. aureus counts and the presence of thermonuclease were monitored throughout the studies. With the unpasteurized minced cod, potassium sorbate caused slightly lower aerobic plate counts (at 20 and 35°C) in the 7°C study over an 11-day storage period. Psychrotrophic organisms were inhibited to a slightly greater extent than were mesophilic organisms. Inoculated S. aureus was quickly outgrown by the normal microflora without or with sorbate. Similar results were obtained at the still more abusive temperature of 15°C over a storage period of 5 d, but the inhibitory effect of sorbate was less evident. Pasteurized minced cod, inoculated with S. aureus and stored at 15°C, showed a considerable difference in growth of S. aureus with and without sorbate. Potassium sorbate resulted in a markedly slower rate of growth of the pathogen and a substantial delay of several days in production of detectable levels of thermonuclease. This delay in nuclease production is indicative of a similar delay in enterotoxin production.

Bacteriological Evaluation of Retail Ground Beef, Frozen Beef Patties, and Cooked Hamburger

1977 ◽  
Vol 40 (6) ◽  
pp. 378-381 ◽  
Author(s):  
C. L. DUITSCHAEVER ◽  
D. H. BULLOCK ◽  
D. R. ARNOTT
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Fast Food ◽  
Ground Beef ◽  
Frozen Ground ◽  
E Coli ◽  
Beef Patties ◽  
Plate Counts ◽  
Bacteriological Evaluation ◽  
G 28

A total of 108 samples of fresh refrigerated ground beef, 99 samples of frozen hamburger patties, and 107 fried hamburgers, purchased from retail stores and fast-food outlets in Ontario, were analyzed for their bacteriological quality. About 44% of non-frozen ground beef samples had aerobic plate counts exceeding 50 million/g; 50 of 108 samples (46.3%) contained Staphylococcus aureus and 46 of these 50 samples (88%) exceeded 1000 organisms/g; 43 of 108 samples were positive for Escherichia coli with 38 samples (88.4%) exceeding 500 organisms/g. About 19% of frozen hamburger patties had aerobic plate counts in excess of 10 million/g; 93 of 99 samples (93.9%) contained S. aureus with 83 of these samples (89.3%) exceeding 1000 organisms/g; 28 of 99 samples were positive for E. coli with 7 of these samples (25%) exceeding 500 organisms/g. About 96.3% of fried hamburger samples had aerobic plate counts of less than 10,000/g.

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.

Survival and Growth of Staphylococcus aureus on Temperature-Abused Beef Livers

1984 ◽  
Vol 47 (4) ◽  
pp. 260-262 ◽  
Author(s):  
B. W. BERRY ◽  
K. F. LEDDY ◽  
C. A. ROTHENBERG
Keyword(s):  
Staphylococcus Aureus ◽  
Storage Temperature ◽  
Frozen Storage ◽  
Storage Period ◽  
Developed Countries ◽  
Slow Surface ◽  
Plate Counts ◽  
Survival And Growth ◽  
High Storage ◽  
Storage Temperatures

Beef livers from freshly slaughtered cattle were inoculated with coagulase-positive Staphylococcus aureus and then placed in frozen storage. After 14 d of frozen storage, one-half of the livers were subjected to 21°C for 24 h followed by a 15-d period of storage at −1°C. The other livers were kept in frozen storage (−29°C) during this 15-d period after which all livers were subjected to either 10 or 21°C temperatures. S. aureus counts did not change during the 15-d storage period at −1°C, whereas aerobic plate counts (APC) increased by over 3 log10 cycles. The low storage temperature plus the growth of competitor bacteria most likely prevented S. aureus from proliferating. When all livers were subjected to 24 to 144 h of storage at either 10 or 21°C, those that had been subjected to 15 d of slow surface thawing displayed a lower S. aureus count and higher APC than livers subjected to rapid thawing followed by holding at the high temperatures. This may mean that if livers become contaminated with substantial numbers of S. aureus before freezing, then rapid thawing coupled with high storage temperatures (more typical of meat merchandising in less developed countries) could allow for rapid S. aureus growth before competitor organisms increase in numbers.

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