Which is not a typical mechanism of action of obligate anaerobes for producing energy?
Answer: a) Produce energy by exploiting cytochrome system (JAWETZ 27(tm) EDITION P-74)Oxygen requirements* Obligate aerobes> Require oxygen for growth> Contain superoxide dismutase, which protects them from the toxic 02'* Obligate anaerobes> Grow in the absence of Oxygen; may even die on oxygen exposure> Grow maximally at a p02 concentration of less than 0.5% to 3%.> Lack superoxide dismutase; catalase, and cytochrome-C oxidase (enzymes that destroy toxic products of oxygen metabolism)> Instead of oxygen, they require another substance such as a hydrogen acceptor during the generation of metabolic energy and utilize fermentation pathways (not cytochrome system) with distinctive metabolic products> Outnumber aerobes 1000:1 in the gut and 100:1 in the mouth.> Comprise 99% of the total fecal flora (10n/g of stool in the large bowel).> Usually cause polymicrobial infections, those involving more than one genus or species.> Are foul smelling.* Facultative anaerobes> Grow in the presence or absence of oxygen.> Shift from a fermentative to a respiratory metabolism in the presence of air> Energy needs are met by consuming less glucose under a respiratory metabolism than under a fermentative metabolism (Pasteur effect).> Most pathogenic bacteria are facultative anaerobes.* Aerotolerant anaerobes> Resemble facultative bacteria but have a fermentative metabolism both with and without an oxygen environment* Microaerophilic> Best grow at low oxygen tension (< 5%)> Example: Campylobacter, Helicobacter
Produce energy by exploiting cytochrome system
Absence of air enhancing their growth potential
Lack of enzyme catalase
Devoid of superoxide dismutase
Bacteria