Bacteria oxygen-tolerant

In two sulfate-reducing bacteria we found oxygen-tolerant formate dehydrogenases with different subunit composition. The formate dehydrogenase from D. desulfuricans is an af3y protein whereas the one from D. gigas is an afi protein. Both proteins contain two MGD cofactors but the protein from D. desulfuricans contains four heme c attached to the y subunit (16 kDa). 

Methanogenic bacteria cannot tolerate oxygen and are restricted to sites that are free of it the rumen of cows provides a good example, as does the mud in rice paddies. 

Several crystal structures of [NiFe] hydrogenases have been determined from sulfate-reducing and photosynthetic bacteria [8, 84, 85], and recently also from oxygen-tolerant species [9, 10]. Two structures from the subclass [NiFeSe] hydrogenase are known [86-88] and from two [FeFe] hydrogenases [8, 89, 90],... 

Section 4.3.2), (3) in the induction of cytochrome P-450 14DHin Saccharomyces cerevisiae (Section 4.4.1.2). The oxygen tolerance among anaerobic bacteria has been discussed in Section 4.3.4. Further comments on other organisms are given here. 

In this volume not all stress types are treated. Various aspects have been reviewed recently by various authors e.g. The effects of oxygen on recombinant protein expression by Konz et al. [2]. The Mechanisms by which bacterial cells respond to pH was considered in a Symposium in 1999 [3] and solvent effects were reviewed by de Bont in the article Solvent-tolerant bacteria in biocatalysis [4]. Therefore, these aspects are not considered in this volume. Influence of fluid dynamical stresses on micro-organism, animal and plant cells are in center of interest in this volume. In chapter 2, H.-J. Henzler discusses the quantitative evaluation of fluid dynamical stresses in various type of reactors with different methods based on investigations performed on laboratory an pilot plant scales. S. S. Yim and A. Shamlou give a general review on the effects of fluid dynamical and mechanical stresses on micro-organisms and bio-polymers in chapter 3. G. Ketzmer describes the effects of shear stress on adherent cells in chapter 4. Finally, in chapter 5, P. Kieran considers the influence of stress on plant cells. 

Karnholz A, Ktlsel K, Goner A, Schramm A, Drake HL. 2002. Tolerance and metabolic response of acetogenic bacteria toward oxygen. Appl Environ Microbiol 68 1005-9. 

Some bacteria specifically utilize oxygen bound in the sulfate complex of a compound. As a result of this metabolic activity, sulfur is reduced to H2S. For this reason, these microbes are called sulfate-reducing bacteria (SRB). They can tolerate temperatures as high as 80°C (176°F) and environments from about pH 5 to pH 9. Species such as Desulfivibrio and Desulfomonas are examples of SRB. 

There are two different ways of grouping bacteria. They can be divided into three types based on their response to gaseous oxygen. Aerobic bacteria require oxygen for their health and existence and will die without it. Anerobic bacteria can t tolerate gaseous oxygen at all and die when exposed to it. Facultative... 

The microflora of the gastrointestinal tract, which develop shortly after birth, are found in the lumen, associated with remnants of food, on the mucosal surface, and in the crypts. These microorganisms, including prokaryotic and eukaryotic species, tend not to use oxygen in their energy metabolism since they exist in an environment that is essentially anaerobic. Over 99.9% of the bacterial cells are anaerobic, meaning they are unable to use oxygen even when it is provided for them. Of these bacteria, 5-20% are unable to tolerate O2 and die in its presence. 

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