12-D reduction

Examples of 12-D reduction in the following topics:

• Rate of Microbial Death

  • Time-temperature measurements of bacterial reduction is determined by a D-value, meaning how long it would take to reduce the bacterial population by 90% or one log10 at a given temperature.
  • The target of reduction in canning is the 12-D reduction of Clostridium botulinum, which means that processing time will reduce the amount of this bacteria by 1012 bacteria per gram or milliliter.
  • The DR for C. botulinum is 12.6 seconds.
  • A 12-D reduction will take 151 seconds .
  • This curve presents the DR value (12.6 seconds) and the 12-D reduction (151 seconds) for C. botulinum.

• Nitrate Reduction and Denitrification

  • The complete denitrification process can be expressed as a redox reaction: 2 NO3− + 10 e− + 12 H+ → N2 + 6 H2O.
  • Generally, several species of bacteria are involved in the complete reduction of nitrate to molecular nitrogen, and more than one enzymatic pathway have been identified in the reduction process.
  • The direct reduction of nitrate to ammonium (dissimilatory nitrate reduction) can be performed by organisms with the nrf-gene.
  • This is a less common method of nitrate reduction than denitrification in most ecosystems.
  • Outline the processes of nitrate reduction and denitrification and the organisms that utilize it

• Nitrogen Fixation Mechanism

  • This type of reaction results in N2 gaining electrons (see above equation) and is thus termed a reduction reaction.
  • Note this is a reduction reaction which means that electrons must be added to the N2 to reduce it to NH4.
  • ATP is not hydrolyzed to ADP until component II transfers an electron to component I (see step C and D). 21-25 ATPs are required for each N2 fixed.
  • A) Components I and II are dissociated; II is ready for reduction.
  • D) The protein complex dissociates, and nitrogenase reduces dinitrogen to ammonia and dihydrogen.

• Oxidoreductase Protein Complexes

  • In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another the oxidant, also called the electron acceptor.
  • In this example, A is the reductant (electron donor) and B is the oxidant (electron acceptor).
  • In this reaction, NAD+ is the oxidant (electron acceptor) and glyceraldehyde-3-phosphate is the reductant (electron donor).
  • Oxidoreductases can be further classified into 22 subclasses: EC 1.1 includes oxidoreductases that act on the CH-OH group of donors (alcohol oxidoreductases); EC 1.2 includes oxidoreductases that act on the aldehyde or oxo group of donors; EC 1.3 includes oxidoreductases that act on the CH-CH group of donors (CH-CH oxidoreductases); EC 1.4 includes oxidoreductases that act on the CH-NH2 group of donors (Amino acid oxidoreductases, Monoamine oxidase); EC 1.5 includes oxidoreductases that act on CH-NH group of donors; EC 1.6 includes oxidoreductases that act on NADH or NADPH; EC 1.7 includes oxidoreductases that act on other nitrogenous compounds as donors; EC 1.8 includes oxidoreductases that act on a sulfur group of donors; EC 1.9 includes oxidoreductases that act on a heme group of donors; EC 1.10 includes oxidoreductases that act on diphenols and related substances as donors; EC 1.11 includes oxidoreductases that act on peroxide as an acceptor (peroxidases); EC 1.12 includes oxidoreductases that act on hydrogen as donors; EC 1.13 includes oxidoreductases that act on single donors with incorporation of molecular oxygen (oxygenases); EC 1.14 includes oxidoreductases that act on paired donors with incorporation of molecular oxygen; EC 1.15 includes oxidoreductases that act on superoxide radicals as acceptors; EC 1.16 includes oxidoreductases that oxidize metal ions; EC 1.17 includes oxidoreductases that act on CH or CH2 groups; EC 1.18 includes oxidoreductases that act on iron-sulfur proteins as donors; EC 1.19 includes oxidoreductases that act on reduced flavodoxin as a donor; EC 1.20 includes oxidoreductases that act on phosphorus or arsenic in donors; EC 1.21 includes oxidoreductases that act on X-H and Y-H to form an X-Y bond; and EC 1.97 includes other oxidoreductases.

• Viroids

  • Trees infected with the viroid often show no symptoms other than a reduction in yield.
  • The human pathogen Hepatitis D virus is similar to viroids.
  • Trees infected with the viroid often show no symptoms other than a reduction in yield.

• Antiviral DNA Synthesis Inhibitors

  • The mechanism of hydroxycarbamide is thought to be based on the reduction of production of deoxyribonucleotides; therefore, inhibiting DNA synthesis.

• Rickettsial Diseases

  • Despite a similar name, Rickettsia bacteria do not cause rickets, which is a result of vitamin D deficiency.
  • The genomes of both Rickettsia and mitochondria are frequently said to be "small, highly derived products of several types of reductive evolution. "

• Anoxygenic Photosynthetic Bacteria

  • Photosynthesis is achieved using bacteriochlorophyll (BChl) c, d, or e, in addition to BChl a and chlorophyll a, in chlorosomes attached to the membrane.
  • When light is absorbed by the reaction center, P840 enters an excited state with a large negative reduction potential, and so readily donates the electron to bacteriochlorophyll 663 which passes it on down the electron chain.

• Paralysis-Causing Bacterial Neurotoxins

  • D. and J.
  • Honey can contain the bacteria that cause infant botulism, so children less than 12 months old should not be fed honey.

• Viral Gastroenteritis

  • The genomes of viruses in Reoviridae contains 10-12 segments which are grouped into three categories corresponding to their size: L (large), M (medium) and S (small).
  • A = rotavirus, B = adenovirus, C = norovirus and D = astrovirus.