oxidative stress

(noun)

Damage caused to cells or tissue by reactive oxygen species.

Related Terms

Examples of oxidative stress in the following topics:

  • Regulation of Sigma Factor Translation

    • The RpoS is critical in the general stress responses and can either function in promoting survival during environmental stresses, but can also prepare the cell for stresses.
    • Small noncoding RNAs are able to sense environmental changes and stresses resulting in increased expression of RpoS protein.
    • These small noncoding RNAs are capable of sensing changes in temperature (DsrA), cell surface stress (RprA) and oxidative stress (OxyS).

  • The Pentose Phosphate Shunt

    • There are two distinct phases in the pathway: the oxidative phase and the non-oxidative phase .
    • The first is the oxidative phase in which glucose-6-phosphate is converted to ribulose-5-phosphate.
    • The second phase of this pathway is the non-oxidative synthesis of 5-carbon sugars.
    • Additionally, NADPH can be used by cells to prevent oxidative stress.
    • Outline the two major phases of the pentose phosphate shunt: oxidative and non-oxidative phases

  • Bacterial Differentiation

    • However, this consistency could be affected in some circumstances (such as environmental stress) and changes in bacterial shape and size.
    • For instance, rod shapes may allow bacteria to attach more readily in environments with shear stress (e.g., in flowing water).
    • Oxidative stress, nutrient limitation, DNA damage and antibiotics exposure are some stress conditions to which bacteria respond, altering their DNA replication and cell division.
    • Filamentous bacteria have been considered to be over-stressed, sick and dying members of the population.
    • Nutritional stress can change bacterial morphology.

  • Nitrification

    • Nitrobacter plays an important role in the nitrogen cycle by oxidizing nitrite into nitrate in soil.
    • Nitrification is the net result of two distinct processes: oxidation of ammonium to nitrite (NO2−) by nitrosifying or ammonia-oxidizing bacteria and oxidation of nitrite (NO2−) to nitrate (NO3−) by the nitrite-oxidizing bacteria.
    • Nitrification is a process of nitrogen compound oxidation (effectively, loss of electrons from the nitrogen atom to the oxygen atoms):
    • Biochemically, ammonium oxidation occurs by the stepwise oxidation of ammonium to hydroxylamine (NH2OH) by the enzyme ammonium monooxygenase in the cytoplasm, followed by the oxidation of hydroxylamine to nitrite by the enzyme hydroxylamine oxidoreductase in the periplasm.
    • Oxygen is required in ammonium and nitrite oxidation, meaning that both nitrosifying and nitrite-oxidizing bacteria are aerobes.

  • Oxidation of Reduced Sulfur Compounds

    • Sulfur oxidation involves the oxidation of reduced sulfur compounds, inorganic sulfur, and thiosulfate to form sulfuric acid.
    • Sulfur oxidation involves the oxidation of reduced sulfur compounds such as sulfide (H2S), inorganic sulfur (S0), and thiosulfate (S2O2−3) to form sulfuric acid (H2SO4).
    • An example of a sulfur-oxidizing bacterium is Paracoccus.
    • In addition to aerobic sulfur oxidation, some organisms (e.g.
    • Marine autotrophic Beggiatoa species are able to oxidize intracellular sulfur to sulfate.

  • Archaeoglobus

    • Archaeoglobus are sulfate-reducing archaea, coupling the reduction of sulfate to sulfide with the oxidation of many different organic carbon sources, including complex polymers.
    • They can produce biofilm to form a protective environment when subjected to environmental stresses such as extreme pH or temperature, high concentrations of metal, or the addition of antibiotics, xenobiotics, or oxygen.

  • Microbial Ore Leaching

    • Bacteria perform the key reaction of regenerating the major ore oxidizer which in most cases is ferric iron as well as further ore oxidation.
    • (2)$4 \ Fe^{\,2+} + \ O_2 + 4 \ H^+ \longrightarrow 4 \ Fe^{\,3+} + 2 \ H_2O$ (iron oxidizers)
    • (3) $S_2O_3^{\,2-} + 2 \ O_2 + H_2O \longrightarrow 2 \ SO_4^{\,2-} + 2 \ H^+$ (sulfur oxidizers)
    • The microbial oxidation process occurs at the cell membrane of the bacteria.
    • The critical reaction is the oxidation of sulfide by ferric iron.

  • Lipid Metabolism

    • Biological lipids, which are broken down and utilized though β-oxidation, represent a potent energy source.
    • In brief, the oxidation of lipids proceeds as follows: two-carbon fragments are removed sequentially from the carboxyl end of the fatty acid after dehydrogenation, hydration, and oxidation to form a keto acid, which is then cleaved by thiolysis.
    • β-oxidation can be broken down into a series of discrete steps:
    • Oxidation: The initial step of β-oxidation is catalyzed by acyl-CoA dehydrogenase, which oxidizes the fatty acyl-CoA molecule to yield enoyl-CoA.
    • Cleavage: A thiolase then cleaves off acetyl-CoA from the oxidized molecule, which also yields an acyl-CoA that is two carbons shorter than the original molecule that entered the β-oxidation pathway.

  • Anoxic Hydrocarbon Oxidation

    • Anoxic hydrocarbon oxidation can be used to degrade toxic hydrocarbons, such as crude oil, in anaerobic environments.
    • Anaerobic oxidation of methane (AOM) is a microbial process that occurs in anoxic marine sediments.
    • It is estimated that almost 90% of all the methane that arises from marine sediments is oxidized anaerobically by this process.
    • Recent investigations have shown that some syntrophic pairings are able to oxidize methane with nitrate instead of sulfate.
    • Describe the process of anoxic hydrocarbon oxidation in regards to marine environments

  • Iron Oxidation

    • There are three distinct types of ferrous iron-oxidizing microbes.
    • These microbes oxidize iron in environments that have a very low pH and are important in acid mine drainage.
    • The second type of microbes oxidizes ferrous iron at cirum-neutral pH.
    • Biochemically, aerobic iron oxidation is a very energetically poor process which therefore requires large amounts of iron to be oxidized by the enzyme rusticyanin to facilitate the formation of proton motive force.
    • Outline the purpose of iron oxidation and the three types of ferrous iron-oxidizing microbes (acidophiles, microaerophiles and anaerobic photosynthetic bacteria)