Chapter 3: Microbial Ecology Flashcards
During trophic transfer, what happens with the energy/biomass lost?
- Most parts are respired and remineralized (recycled) to inorganic forms of C,N,P
- this source of energy and nutrients is what allows new production
how does remineralization occur?
- breakdown of OM by decomposers
- decomposers produce CO2 ammonium and phospate
describe decomposition
the conversion of insoluble OM into smaller molecules by enzymatic reactions of digestion, and subsequent metabolism
marine detritus
- consists partly of the leftovers from feeding
- varies in biological dynamics
- low quality food source for lager organisms, but utilized by microorganisms
the difference between DOM and POM
DOM:
-0.2-1um
-DOC(dissolved organic carbon) larges pool of OM in the sea, large fraction resistant to decay.
POM:
-larger than 1um
-consists of living and non-living material
-marine snow caused by collisions of transparent exopolymer particles
how does detritus recycling compare to primary producers?
- recycling OM can be taken up several times by the same food web
- OM utilized by the food web is larger than what is produced by the primary producers
how much OM is recycled each cycle?
~50%
the microbial food web consists of which types of organisms?
virus, bacteria, algae, protozoa, and small larval zooplankton
why aren’t virus classified as living?
- lack a cell wall
- incapable of reproduction w/o the aid of host DNA
what are the two particular groups of interest of bacteria?
Organotrophs: heterotrophs that utilize OM, organic detritus, and breaking down all natural materials.
Chaemoautotrophic nitrifying bacteria: use CO2 and inorganic nutrients. some oxidizes ammonia to nitrite and some nitrite to nitrite.
what type of ‘troph is algae classified?
photoautotroph
what are the two main types of protozoa, and what classifies them?
Heterotrophic nanoflagellates
-bacterivores
-2-20um
-flagellated for movement and food capture
-autotrophic, mixotrophic, heterotrophic.
Microzooplankton protists
-20-200um
-include ciliates and larger dinoflagellates
-mostly heterotrophs that prey on phytoplanktons and bacteria
As bacteria are quick-growing, but also quick to be eaten, what are the two methods to obtain field estimates of bacterial growth?
- DNA method
- Protein method
describe the ‘DNA’ method of estimating microbial growth
- measures the rate of thymidine infused seawater are incorporated into bacterial DNA
- incubation, filtered samples, DNA extracted, radioactivity measured. able to estimate thymidine content.
describe the protein method of estimating microbial growth
- measures leucine in synthesized protein.
- measures production of biomass directly, while DNA method measures the rate at which cells are produced.
what are the key growth regulating mechanisms for micro-organisms?
grazing, resource limitation, virus attacks
what is the relationship between bacteria and predatory protozoans?
predators populations have growth rates relatively close to that of bacteria, so they are able to respond to the numerically fluctuations of their prey. They are more capable of controlling prey populations than in the phytoplankton/mesozooplankton relationship
what percentage of bacterial mortality is due to viruses? protozoans?
V: 5-40%
P: 5-65%
photosynthesis and ________ are linked processes in the ecosystem
respiration
Photosynthesis provides ___________ for respiration
organic material
respiration reduces organic material into ____________ required for _________.
inorganic nutrients
photosynthesis
P and R are not necessarily in phase with each other, and the difference (P-R) si the ______
net community production (NCP)
the NCP rate is perhaps the most important measure of plankton systems as it is the basis for ________________
interpreting the dynamics of such systems
describe the basic seasonal cycle of the plankton
spring: development of spring phytoplankton bloom
late spring/early summer: demise of the phytoplankton bloom
summer: recycling
autumn/winter: regenerative period
describe the spring phase
- stratification begins (shallowing of mixed layer, deepening of critical depth)
- explosive growth phase of phytoplankton
- release of organic detritus, results in bacterial growth and energy flux in microbes
- net community production
describe late spring/early summer phase
- grazer community established, more growth in heterotroph community
- main players are bacteria, heterotroph nanoflagellates, and microzooplankton
- net community production falls, becomes negative
- limited nutrient availability due to grazers
describe summer phase
- importance of recycled nutrients increase
- system more balanced w/ P and R as dominant groups
- predators better control their prey
- prey pops reduced, growth in predators
- similar to tropic plankton communities
describe autumn/winter period
- thermal strat weakens, decreased phytoplankton activity
- heterotrophs consume OM available as detritus
- nutrients recycle to inorganic forms
- dominated by heterotroph activity, negative NCP
what endows microorganisms with extrodinarily high metabolic rates?
small size and large surface-to-volume ratio
the utilization of ‘waste’ organic detritus by the micro-organisms provides the basis of a ______________ that originates from __________
second food chain
marine bacteria
what is a common nitrogenous waste product of heterotrophic metabolism?
ammonium
