Lecture 6 Flashcards
HD
In a microbial ecosystem individual cells grow to form
populations
Metabolically related populations constitute groupings called
guilds
Sets of guilds conducting complementary physiological processes interact to for
microbial communities
Microbial communities then interact with communities of macro-organisms to define the entire
ecosystem
Put the following in order that they occur in: guild, ecosystem, community, population, individual
individual, population, guild, community, ecosystem
what is the source of energy and carbon for growth for Photlithotroph’s and photoorganotroph’s
Photlithotroph’s - energy - light, CO2 (autotroph)
photoorganotroph’s - energy - light, carbon - organic compound (heterotroph)
what is the source of energy and carbon for growth for chemolithotroph’s and chemoorganotroph
chemolithotrophs - energy - oxidation of inorganic compound. Carbon - CO2 (autotroph)
chemoorganotrophs - oxidation of organic compound. Carbon - organic compound (heterotroph)
Fill in the blanks: Positive interactions Commensalism _ _ Synergism _ _ Mutualism _ _ 3] Negative interactions Competition _ _ Amensalism _ _ _ Predation _ _ Parasitism _ _
Positive interactions Commensalism 0 + Synergism + + Mutualism + + Negative interactions Competition - - Amensalism 0 or +, - Predation + - Parasitism + -
Energy enters ecosystem in the form of sunlight, organic carbon or reduced inorganic substances. Light is used by phototrophic organisms to synthesize new organic matter. The synthesized new organic matter contains :
• carbon • nitrogen • sulfur • phosphorus • iron
Don’t worry about but read:
This newly synthesized organic matter, along with organic matter that enters the ecosystem from outside and reduced inorganic substances, drives the metabolic activities of many different microorganisms
Microenvironments, occur in what habitat?
surfaces and biofilms
Aquatic environments, occur in what habitat?
freshwater, lake ecosystems, marine environments
Terrestrial environments occur in what habitat?
Soils Sediments
Microorganisms frequently reach large numbers in such habitats playin what 2 types of roles?
beneficial, detrimental (pathogenic)
What is Ecological Theory?
for every organism there exists at least one niche, in which that organism is most successful.
Microorganisms inhabit in microenvironments Microorganism ___ Its habitat ___
3 um and 3mm
Biofilms - where microbes often stick to the surfaces in masses. On surfaces microbial numbers and activity are usually much greater than in free water because of the
adsorption effects
Biofilms - how do microbes attach themselves to surfaces?
adhesive polysaccharide excreted by the cells
Microorganisms in nature often face with a ____________type of existence
“feast-or-famine”
__________store excess nutrients present under favorable conditions for use during periods of nutrient deprivation
Reserve polymers
Define - Neutral Associations (Neutralism)
no competition for nutrients occupying the same environment
Define - Positive interactions -
symbiotic relationship where each organism benefits
What are 3 Positive interactions?
Commensalism Synergism
Mutualism
one population benefits while the other remains unaffected.
Commensalism
two microbial populations benefit from the relationship, the association is not an obligatory one. neither organism can carry out alone
Synergism (Protocooperation)
a strong, specific, beneficial interaction essential for the survival of both partners. requires close physical proximity between the interacting populations. allow organisms to exist in habitats that could not be occupied by either population alone. allow the microorganisms to act as if they were a single organism with a unique identity.
Mutualism
2x Examples of mutualism
algae or cyanobacteria and fungi that result in the formation of lichens. Endosymbioants of Protozoa
4 x types of negative interactions
Competition, Antagonism (Amensalism), Parasitism, Predation
A negative relationship between two populations in which both populations are adversely affected with respect to their survival and growth
Competition
When an organism adversely affects the environment of another organism. Such organisms may be of great practical importance, since often they produce antibiotics or other inhibitory substances.
Antagonism (Amensalism)
Relationship between organisms in which one organism lives in or on another organism (of a different species). Feeds on the cells, tissues, or fluids of another organism, the host, which is commonly harmed in the process. Steal
Parasitism
The killing and eating of microorganisms of one species - Ingests
Predation
The predominant phototrophic organisms in most aquatic environments are microorganisms. Because these organisms use energy from light in the initial production of organic matter, they are called
primary producers.
If the deep-sea bacteria simply tolerate high pressures they are called
Barotolerant.
If the deep-sea bacteria are dependent on pressure they are called
Barophilic
If the deep-sea bacteria can live in very deep waters (10,000m) they are called Extreme (obligate)
Barophiles.
__________ environments are arguably the richest and most complex of all microbial environments. In surface soils culturable microorganism concentrations can reach 108 per gram of dry soil, although direct counts are generally one to two orders of magnitude larger.
Terrestrial Environments
Freshly formed spores where little or no metabolic activity occurs
Dormancy
Spores may be brought about e.g. by heating them to sublethal temperatures or by subjecting them to low pH or to certain types of chemical “ageing”
ACTIVATION
The irreversible process in which an activated spore becomes a metabolically active spore, the process is largely degradative and involves hydrolysis and depolymerization of certain spore constituents
GERMINATION
The process in which a vegetative cell develops from a germinated spore
OUTGROWTH
Number and type of samples, locations, depths, times, intervals
Sampling strategies
Specific techniques and equipment to be used
Sampling methods
Types of containers, preservation methods, and maximum holding times
Sample storage
they ensure that samples are taken to exactly same depth on each occasion.
Soil augers
how to clean auger between samples
water
75% ethanol rinse
10% bleach
final rinse
Are obtained by collecting equal amounts of soil from samples taken over a wide area and placing them in a bucket or plastic bag.
Composite samples
Saturating small volumes of soil with sterile water. Aggregates of soil are gently teased open with a fine jet of water, allowing heavier soil particles to sediment and finer particles to be decanted off. The procedure is repeated several times until only the heavier particles remain. These are then spread in a film of sterile water and examined under a dissecting microscope. Sterile needles or very fine forceps can then be used to obtain any observed fungal hyphae
Soil washing methodology for the isolation of fungal hyphae
Soil samples are placed in separate sterile boxes each containing a number of sieves of graded size. The soil samples are washed vigorously in each box and soil of defined size is retained on each sieve. Spores are determined empirically by plating successive washings (2min/wash) from each sieve. Because hyphae are retained by the sieves, any fungal colonies that arise must be from spores.
Fungal spore isolation
What are 2 different procedures for processing water samples for detection of viruses, bacteria and protozoa.
- Membrane filtration (identification of fecal coliform bacteria from water samples) 2. Most probable number (MPN) (identification of Salmonella from sewage samples)
What are the two approaches to the isolation of bacterial DNA from soil samples:
- fractionation of bacteria from soil followed by cell lysis and DNA extraction 2. in situ lysis of bacteria within the soil matrix with subsequent extraction of the DNA released from cells
A major advantage of the direct lysis approach
Less labor intensive and faster than the bacterial fractionation method.
The soil or sediment particles as well as fungal cells are removed by low-speed centrifugation step, followed by high-speed centrifugation to recover the bacterial cells. This process is called
Differential Centrifugation
