Microbio Chapter 11

Name two genera of endospore-forming bacteria. How do they differ?

-Bacillus and Clostridium -Clostridium species are obligate anaerobes and Bacillus species are both obligate aerobes and facultative anaerobes

Describe the family Enterobacteriaceae, and explain what distinguishes coliforms from other members of this family

-Gram-negative rods -most reside in the intestinal tract -facultative anaerobes that ferment glucose -coliforms ferment lactose

Compare and contrast the characteristics and habitats of the extreme halophiles and extreme thermophiles

-extreme halophiles are found in high numbers in salty environments (salt lakes, soda lakes, brines); they require a minimum of about 9% NaCl; can be seen as red patches -extreme halophiles are aerobic or facultative anaerobic chemoheterotrophs -extreme thermophiles are found in volcanic vents and fissures that release sulfurous gases and other hot vapors; others can be found in hydrothermal vetns in the deep sea and hot springs

What is the significance of finding coliforms in drinking water?

-it is an indicator of fecal pollution -their presence indicates a possible health risk because fecal-borne pathogens might also be present

Describe two beneficial contributions of the lactic acid bacteria

-normal microbiota of the oral cavity, intestinal tract, and vagina -important in the production of fermented foods

What metabolic process creates that rotten-egg smell characteristic of many anaerobic environments?

-sulfur- and sulfate-reducing bacteria use sulfur as terminal electron acceptors, they become reduced to form hydrogen sulfide

methanogens

archaea that obtain energy by oxidizing hydrogen gas, using CO2 as a terminal electron acceptor, thereby generating methane

The dormant forms of which of the following genera are the most resistant to environmental extremes? 1. Azotobacter 2. Bacillus 3. Clostridium 4. Myxobacteria 5. Streptomyces a. 1, 2 b. 2, 3 c. 3, 4 d. 4, 5 e. 1, 5

b

If you read that coliforms had been found in a lake, the report could have been referring to which of the following genera? a. Bcteriodes b. Bifidobacterium c. Clostridium d. Escherichia e. Streptococcus

d

sulfur-oxidizing bacteria

gram-negative bacteria that obtain energy by oxidizing elemental sulfur and reduced sulfur compounds, generating sulfuric acid

lactic acid bacteria

gram-positive bacteria that generate lactic acid as a major end product of their fermentative metabolism

Relatively little is about many obligate anaerobes. Why would this be so?

it's much harder to provide the right atmospheric environment to cultivate obligate anaerobes, so it's been harder to study them

spirochaetes

long helical bacteria that have flexible cells walls and endoflagella

chemoorganotroph

organisms that harvest energy by oxidizing organic chemicals

True or false: approximately 99% of the prokaryotes that inhabit the intestinal tract are obligate anaerobes

true