Which is not a typical mechanism of action of obligate anaerobes for producing energy?
Produce energy by exploiting cytochrome system
Absence of air enhancing their growth potential
Lack of enzyme catalase
Devoid of superoxide dismutase
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
Bacteria