Metabolic Diversity of Prokaryotes, Part I
What are the characteristics of purple bacteria?
* photosynthetic * store pigments in the cell membrane * use hydrogen sulfide
How are purple sulfur bacteria different from purple non-sulfur bacteria?
1. purple non-sulfur bacteria use a variety of organic molecules as a source of electrons, while purple sulfur bacteria use hydrogen sulfide as a source of electrons 2. purple sulfur bacteria may have gas vesicles, but purple non-sulfur bacteria do not 3. purple sulfur bacteria store sulfur in intracellular granules, while purple non-sulfur bacteria form such granules outside the cell
Cyanobacteria are a diverse group of more than _____________ genera.
60
Which streptococci are pathogens?
S. pyogenes which causes pharyngitis (strep throat) and other diseases
What genera are included under lactic acid bacteria?
Streptococcus Enterococcus Lactococcus Lactobacillus Leuconostoc
methanogens
a group of archaea that generate ATP by oxidizing hydrogen gas, using CO2 as a terminal electron acceptor
What are two types of green bacteria?
a. green sulfur bacteria b. filamentous anoxygenic phototrophic bacteria
Many cyanobacteria are able to convert nitrogen gas, N2, to _____________________________.
ammonia
anaerobic chemoorganotrophs that use fermentation
anaerobic bacteria that obtain energy by producing ATP by substrate-level phosphorylation
What were the earliest known oxygenic phototrophs?
cyanobacteria
Cyanobacteria are morphologically __________________.
diverse
heterocysts
enlarged, specialized cells that carry out only nitrogen fixation
What are oxygenic phototrophs?
photosynthetic organism that use water as source of electrons and produce O2
anoxygenic phototrophs
photosynthetic organisms that do not produce O2
cyanobacteria
photosynthetic, oxygen-producing, Gram-negative bacteria that were formerly known as blue-green algae
What are phycobiliproteins?
pigments, found in cyanobacteria, that absorb energy from wavelengths of light not well-absorbed by chlorophyll
What are the major types of anoxygenic phototrophs?
purple bacteria green bacteria genus Heliobacterium
anoxic
without oxygen
All cyanobacteria help limit atmospheric ________ buildup by using the gas as a carbon source.
CO2
Are anaerobic chemoorganotrophs that use anaerobic respiration Gram-positive or Gram-negative?
Gram-negative
purple bacteria
Gram-negative organisms that appear red, orange, or purple due to their light-harvesting pigments
green bacteria
Gram-negative organisms that are typically green or brownish in color
What are lactic acid bacteria?
Gram-positive bacteria that produce lactic acid as a major end product of their fermentative metabolism
What are clostridium?
Gram-positive rods that are obligate anaerobes that can form endospores
propionibacterium
Gram-positive, irregularly-shaped rods that produce propionic acid as their primary fermentation end product
How are anoxygenic phototrophs different from plants, algae, and cyanobacteria?
anoxygenic phototrophs have a different photosystem with a unique type of chlorophyll called bacteriochlorophyll
Why are nitrogen-fixing cyanobacteria important ecologically?
because nitrogen-fixing cyanobacteria can incorporate both N2 and CO2 into organic material, they generate a form of these nutrients that can then be used by other organisms
What are the typical habitats of anoxygenic phototrophs?
bogs lakes upper layers of mud
What groups or genera can be classified as anaerobic chemoorganotrophs that use fermentation?
clostridium lactic acid bacteria propionibacterium
Where are propionibacterium species found?
in the intestinal tract and on the skin where they cause acne
Why is S. thermophilus important to the food industry?
it is used to make yogurt
What distinguishes lactic acid bacteria from other bacteria that grow in the presence of O2?
lactic acid bacteria lack the enzyme catalase
Are all streptococci harmful?
no, many are part of the normal microbiota of the oral cavity
obligate anaerobes
organisms that carry out fermentation or anaerobic respiration and cannot survive in the presence of O2
anaerobic chemotrophs
organisms that don't need oxygen and can live in anoxic environments
chemolithotrophs
organisms that obtain energy by oxidizing chemicals such as hydrogen gas (H2)
anaerobic chemoorganotrophs that use anaerobic respiration
organisms that oxidize organic compounds such as glucose to obtain energy and often use sulfur or sulfate as a terminal electron acceptor
When vegetative clostridium develop endospores, what diseases may ensue?
tetanus, caused by C. tetani gas gangrene, caused by C. perfringens botulism, caused by C. botulinum antibiotic-associated diarrheal disease, caused by C. difficile
What are primary producers?
the first producers of energy-rich compounds that are later used by other organisms; autotrophs that can synthesize
nitrogen fixation
the process of converting nitrogen gas into nitrogen compounds, such as ammonia, that plants can absorb and use
How do methanogens get their name?
their name is derived from the process of generating ATP which also generates methane, or CH2, a colorless, odorless, flammable gas
Why are propionibacterium species valuable to the dairy industry?
they are important because their fermentation end products are important in Swiss cheese production
Where are clostridium commonly found?
they are soil inhabitants
What do anaerobic chemotrophs use instead of oxygen to harvest energy?
they oxidize chemicals
