Chapter 14: Functional Diversity of Bacteria

You are looking at a sample from the top green layer of a colorful bacterial mat. Using phase contrast and fluorescence microscopy, you see evenly spaced cells in he middle of a filament that are slightly smaller than the other. The smaller cells are not fluorescent, indicating they lack photosystem II, but the rest of the filament is fluorescent. What type of filamentous bacteria are you most likely looking at?

Cyanobacteria

Akinetes and hormogonia are specialized cells, found in some cyanobacteria, that facilitate nitrogen fixation, (T/F)

False

All phototrophic bacteria use monophyletic photosystem is photosynthesis, thus there is intense competition for light between different phototrophic bacteria. (T/F)

False

Although Cyanobacteria contribute more than 35% of all photosynthesis on Earth, they are not visible in the natural environment. (T/F)

False

Bacteria that produce acetate use the same metabolic pathways regardless of whether they are growing in the presence or absence of oxygen. (T/F)

False

Budding is a form of reproduction whereby prokaryotic microbes can reproduce sexually. (T/F)

False

Diazotrophs are found in all three domains of life. (T/F)

False

Diazotrophs are obligately symbiotic bacteria that fix N2 into ammonia, thus providing a critical source of nitrogen to their host. (T/F)

False

Dissimilaroy iron-oxidation is a relatively new metabolism and is restricted to one usual phylum of bacteria. (T/F)

False

Iron-reducing bacteria are obligately aerobic organisms that reduce ferric iron and oxidize hydrogen or organic compounds. (T/F)

False

Magnetosomes are specialized magnetic structures, found in iron-reducing bacteria, that aid in chemotaxis towards iron-oxides. (T/F)

False

Prosthecae are thought to be an adaptation to growth in nutrient-rich environments such as sediment sand sewage. (T/F)

False

Spirilla and spirochetes are closely related bacteria that exhibit a unique corckscrew motility. (T/F)

False

The ecological diversity of microbes is largely dependent of their complex morphological and structural diversity. (T/F)

False

There are currently no known predatory bacteria that are adapted to invade or kill nearby cells. (T/F)

False

Bioluminescent microorganisms are found in which of the following groups?

Gammaproteobacteria

A few bacteria are capable of growing on gases as the sole source of energy, carbon, and nitrogen. Which of the following combination of gases would support the growth of a bacterium in mineral media with NO other additions?

H2, O2, N2, CO2

Anoxygenic phototrophs may or may not be autotrophs. (T/F)

True

Bacteria and Archaea are general single-celled organisms, but some phyla form sheaths around multiple cells to facilitate attachment and filament formation. (T/F)

True

Bacteria the contain complex internal membrane systems are more likely to divide by budding than by binary fission. (T/F)

True

Bioluminescence is a social behavior of bacterial cells that causes luminescence to occur when a dense cell population has been attained. (T/F)

True

Budding bacteria form new cell wall material at a single point rather than throughout the whole cell. (T/F)

True

Denitrigying bacteria are often facultative anaerobes, capable of performing other forms of respiration or fermentation as well as nitrate reduction. (T/F)

True

Dissimilaroy nitrate reduction results in the production of gaseous products, while assimilaroy nitrate reduction results in the production of ammonia for biosynthesis. (T/F)

True

Nitrogenase is an oxygen-sensitive enzyme enven though many diazotrophs are aerobic microorganisms. (T/F)

True

Sulfide oxidizers are among the most ecologically diverse trophic groups because of the different strategies they employ to access sufficient amount of sulfide and oxygen simultaneously. (T/F)

True

Unicellular cyanobacteria are the most abundant phototrophs in the ocean and perform 80% of marine photosynthesis. (T/F)

True

In symbiotic associations between sulfur chemolithotrophs and eukaryotes such as tube worms and giant clams, the bacterial symbiont provides ______ while the host provides ______.

a carbon and energy source/ stable sulfide and oxygen levels

Bioluminescence is controlled by the gene regulatory mechanism called quorum sensing, wherein the

accumulation of an inducer molecule activate transcription of the lux operon

Most methanotrophs are obligate ______ because ______.

aerobes/ the initial step of methane oxidation requires O2

What growth conditions would you use to enrich for ammonia-oxidizing bacteria?

aerobic mineral media with ammonia and bicarbonate incubated in the dark

Which of the following conditions would you use to enrich purple non sulfur bacteria from lake sediments?

anoxic mineral media with an organic acid and a good light source

What form of photosynthesis evolved first on Earth?

anoxygenic

Which of the following traits do ammonia and nitrite oxidizers share?

autotrophic and aerobic

The ecological diversity of phototrophic bacteria is illustrated by the different ______ that allow them to perform photosynthesis in low light environments such as deep in the ocean, in various sediments, and in thick layered mats

bacteriochlorophyll and photosystems

Anoxygenic phototrophs

can be either autotrophic or heterotrophic and may use a variety of electron donors for photosynthesis.

Carboxydotrophic bacteria oxidize carbon monoxide to

carbon dioxide

The bacteria and archaea are the ONLY domains in which organisms exist that can

conserve energy from the transformation of inorganic nitrogen species

The only group of oxygenic phototrophic bacteria are the

cyanobacteria

In which of the following environments would you expect to find a high number of iron-reducing bacteria?

deep subsurface

E. coli is a chemoorganotrophic, facultative aerobe and belongs to the Proteobacteria phyum. Based on this information, which of the following function groups does E. coli most likely belong to?

denitrifying bacteria

Which of the following functional groups would you expect to find in aerobic iron-and sulfur-rich acidic mine drainage?

dissimilative iron-oxidizers

Aside from using light as a source of energy, another important part of the functional diversity of some bacterial phototrophs is their ability to

fix nitrogen gas

Nitrogenase is critical enzyme in the nitrogen cycle because it catalyzes the

fixation of nitrogen gas into ammonia

Functional traits can be shared between organisms with divergent SSU rRNA sequences because

functional traits may evolve independently, be shared through horizontal gene transfer, or be lost in divergent lineages.

Purple sulfur bacteria are

gammaproteobacteria that use hydrogen sulfide as an electon donor for photosynthesis

Green sulfur bacteria are often found at the greatest depths of all phototrophic cells in lakes, oceans, and microbial mats. This is because green sulfur bacteria

have chlorosomes that are very efficient at harvesting light, allowing them to perform photosynthesis where light intensities are very low

Typical electron donors used by dissimilative sulfate-reducers are

hydrogen, lactate, and pyruvate

Prosthecae are an adaptation for

low nutrient aquatic environmetns

Which of the following functional groups form symbiotic relationships with Eukaryotes in deep sea environments?

methanotrophs and sulfide-oxidizers

What is the difference between a methylotroph and methanotroph?

methylotrophs use organic carbon lacking C-C bonds as electron donors and carbon sources, while methanotrophs exclusively use methane as an electron donor and carbon source

Microbial diversity is though of in terms of phylogenetic diversity and functional diversity because

similar functional traits are often found in divergent phylogenetic groups

Myxobacteria display _____ behavior and form ____ that produce myxospores

swarming/ fruiting bodies

Acetogens are anaerobic organisms that produce acetate as the main product f their metabolism. They are important in

the carbohydrate metabolism of the human gut.

All microbial phototrophs

use light energy to drive electron transport to generate energy.

Nitrogen fixation is

widespread among microorganisms

Bioluminescence is catalyzed by luciferase, which creates light by

shunting electron from FMNH2 to O2, which releases energy in the form of light.

Sulfate-reducing bacteria are a _____ that are found in _____ environments.

monophyletic group/anoxic

Thioploca species contain large vacuoles that store ____, whichis used to _____ under anaerobic conditions

nitrate/ oxidize sulfide

The vacuole of the giant sulfide-oxidizing bacterium Thiomargarita namibiensis contains ____ that is used to oxidize sulfide under ____ conditions.

nitrate/anoxic

You are looking at a sample from the top green layer of a colorful bacterial mat. Using phase contrast and fluorescence microscopy, you see evenly spaced cells in he middle of a filament that are slightly smaller than the other. The smaller cells are not fluorescent, indicating they lack photosystem II, but the rest of the filament is fluorescent. What is the most likely function of the smaller cells in the filament?

nitrogen fixation

Which of the following pairs of microorganisms are NOT likely to form close associations or consortia?

nitrogen-fixing cyanobacteria and dissimilative sulfate-reducers.

The phylogenetic trees of the nifH and SSU rRNA are incongruent because

of horizontal gene transfer

Dissimilative iron-reducing bacteria couple the

oxidation of H2 or organic compounds to the reduction of ferric iron of manganese

The Cyanobacteria are united by their _____, but their _____ is very diverse.

physiology/ morphology

Bioluminescence develops when

population density is high

Dissimilitory sulfide-oxidizers use a variety of unique ecological strategies in order to

position themselves at interfaces where sulfide and oxygen meet

Bdellovibrio species are _____ cells that replicate in the ______.

predatory/ periplasmni space

Diazotrophs maximize nitrogenase activity by

producing specialized structures or fixing N2 at times when oxygen is absent to protect nitrogenase from oxygen.

Which group of bacteria would you expect t find in a shallow clear hot spring with high concentrations of geochemically produced hydrogen sulfide?

purple sulfur bacteria