SOME EFFECTS OF HYPERBARIC OXYGENATION ON BACTERIA AT INCREASED HYDROSTATIC PRESSURES

1967 ◽  
Vol 13 (10) ◽  
pp. 1311-1319 ◽  
Author(s):  
Claude E. ZoBell ◽  
Leslie L. Hittle
Keyword(s):  
Hydrostatic Pressure ◽  
Dissolved Oxygen ◽  
Partial Pressure ◽  
Oxygen Content ◽  
Hyperbaric Oxygenation ◽  
Bacterial Species ◽  
Partial Pressure Of Oxygen ◽  
Nutrient Media ◽  
Initial Oxygen Content ◽  
Initial Oxygen

The adverse effects of hyperbaric oxygenation on the reproduction and survival of bacteria are augmented by increased hydrostatic pressure. Different bacterial species differ considerably in their tolerance of increased hydrostatic pressure as well as for increased partial pressure of oxygen. Although their generation times may be lengthened and their reproduction rates retarded by increased pressures, most species of well-known bacteria are able to grow at hydrostatic pressures as high as 200–400 atm. In closed systems at 1 atm, certain aerobic bacteria grow well, or sometimes better, in nutrient media in which the partial pressure of oxygen is 5 to 10 times higher than that in the normal atmosphere (-Po2ca. 0.2 atm, equivalent to a dissolved oxygen content of ca. 7 μg/ml), but such increased concentrations of oxygen (35–70 μg/ml) are injurious at substantially increased hydrostatic pressures, for example, 5–25 atm. Escherichia coli, Bacillus subtilis, Bacillus megaterium, Pseudomonas enalia, Pseudomonas perfectomarinus, and Serratia marinorubra were sterilized within a day or two by compression to 100 atm in media having a dissolved oxygen content of 35 μg/ml. All six species thrived at 100 atm in nutrient media having an initial oxygen content of 7 μg/ml and they grew well in media with an oxygen content of 35 μg/ml at 1 atm.

Influence of Dissolved Oxygen on Acid Production in Buffalo Milk by Lactic Cultures

1983 ◽  
Vol 46 (4) ◽  
pp. 321-324 ◽  
Author(s):  
S. SHEKAR ◽  
G. S. BHAT
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Acid Production ◽  
Streptococcus Thermophilus ◽  
Buffalo Milk ◽  
Milk Samples ◽  
Streptococcus Lactis ◽  
Heated Milk ◽  
Initial Oxygen Content ◽  
Initial Oxygen

Rates of acid production in buffalo milk by lactic cultures increased with the decrease of oxygen content to 2.90 ppm. Rates of production in milk samples containing less than 2.90 ppm dissolved oxygen did not vary. Incorporating oxygen into milk to raise the initial oxygen content from 5.50 to 9.00 ppm strongly inhibited acid production by all lactic cultures. Development of acidity by lactic cultures was more rapid in milk subjected to prior heat treatment and was maximum in milk heated at 90°C for 10 min. This was attributed to a slight descrease in oxygen content and increase in free sulfhydryls in heated milk. The free sulfhydryls and dissolved oxygen content decreased considerably in milk samples inoculated with lactic cultures but not in uninoculated control samples incubated for up to 2 h. The decrease in free sulfhydryls corresponded with the decrease in dissolved oxygen in all inoculated samples. Acidification of milk with lactic acid to the same extent as that found in inoculated milk samples showed no decrease in either free sulfhydryls or dissolved oxygen content, suggesting that lactic cultures catalyze the oxidation of free sulfhydryls with dissolved oxygen thereby effecting a more rapid rate of acid production during microbial fermentation of heated milk. The rate of decrease in free sulfhydryls and dissolved oxygen content and increase in acidity corresponded well with growth of lactics, being greatest in Streptococcus lactis-and least in Streptococcus thermophilus-inoculated milk.

scholarly journals False Oxygen Consumption Effect and Factors Causing It

2011 ◽  
Vol 2011 ◽  
pp. 1-5
Author(s):  
M. V. Miniaev ◽  
M. B. Belyakova ◽  
N. V. Kostiuk ◽  
D. V. Leshchenko
Keyword(s):  
Oxygen Consumption ◽  
Low Temperature ◽  
Oxygen Content ◽  
Incubation Medium ◽  
Low Oxygen ◽  
Salting Out ◽  
Low Concentration ◽  
Initial Oxygen Content ◽  
Initial Oxygen

False oxygen consumption effect characterized by a decrease of the polarographic sensor readings by the introduction of neutral microadditives into the incubation medium was modeled and tested. These neutral microadditives neither consume oxygen nor cause its consumption by other components of the medium. It is shown that microadditives less than 3% of the volume of incubation medium can cause statistically significant effect of false oxygen consumption more than 4% of the initial oxygen content. The effect can reach more than 15% at higher volumes of additives. The most important properties of additives enhancing the effect are low oxygen content, low temperature, and low concentration of oxygen salting out components.

scholarly journals Oxygen: A Stimulus, Not “Only” a Drug

Medicina ◽  
2021 ◽  
Vol 57 (11) ◽  
pp. 1161
Author(s):  
Costantino Balestra ◽  
Jacek Kot
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Hyperbaric Oxygen ◽  
Hyperbaric Oxygenation ◽  
Extreme Environments ◽  
Hypoxia Inducible Factors ◽  
Partial Pressure Of Oxygen ◽  
New Paradigm ◽  
Simple Substance ◽  
Shock Proteins

Depending on the oxygen partial pressure in a tissue, the therapeutic effect of oxygenation can vary from simple substance substitution up to hyperbaric oxygenation when breathing hyperbaric oxygen at 2.5–3.0 ATA. Surprisingly, new data showed that it is not only the oxygen supply that matters as even a minimal increase in the partial pressure of oxygen is efficient in triggering cellular reactions by eliciting the production of hypoxia-inducible factors and heat-shock proteins. Moreover, it was shown that extreme environments could also interact with the genome; in fact, epigenetics appears to play a major role in extreme environments and exercise, especially when changes in oxygen partial pressure are involved. Hyperbaric oxygen therapy is, essentially, “intermittent oxygen” exposure. We must investigate hyperbaric oxygen with a new paradigm of treating oxygen as a potent stimulus of the molecular network of reactions.

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