Lecture 6

Question 1

In a microbial ecosystem individual cells grow to form

Answer 1

populations

Question 2

Metabolically related populations constitute groupings called

Answer 2

guilds

Question 3

Sets of guilds conducting complementary physiological processes interact to for

Answer 3

microbial communities

Question 4

Microbial communities then interact with communities of macro-organisms to define the entire

Answer 4

ecosystem

Question 5

Put the following in order that they occur in: guild, ecosystem, community, population, individual

Answer 5

individual, population, guild, community, ecosystem

Question 6

what is the source of energy and carbon for growth for Photlithotroph’s and photoorganotroph’s

Answer 6

Photlithotroph’s - energy - light, CO2 (autotroph)

photoorganotroph’s - energy - light, carbon - organic compound (heterotroph)

Question 7

what is the source of energy and carbon for growth for chemolithotroph’s and chemoorganotroph

Answer 7

chemolithotrophs - energy - oxidation of inorganic compound. Carbon - CO2 (autotroph)
chemoorganotrophs - oxidation of organic compound. Carbon - organic compound (heterotroph)

Question 8

Fill in the blanks:
Positive interactions 
Commensalism _ _
Synergism _ _
Mutualism _ _
3] Negative interactions 
Competition _ _
Amensalism _ _ _
Predation _ _
Parasitism _ _

Answer 8

Positive interactions 
Commensalism 0 + 
Synergism + + 
Mutualism + + 
Negative interactions 
Competition - -
Amensalism 0 or +, -
Predation + -
Parasitism + -

Question 9

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 :

Answer 9

• 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

Question 10

Microenvironments, occur in what habitat?

Answer 10

surfaces and biofilms

Question 11

Aquatic environments, occur in what habitat?

Answer 11

freshwater, lake ecosystems, marine environments

Question 12

Terrestrial environments occur in what habitat?

Answer 12

Soils Sediments

Question 13

Microorganisms frequently reach large numbers in such habitats playin what 2 types of roles?

Answer 13

beneficial, detrimental (pathogenic)

Question 14

What is Ecological Theory?

Answer 14

for every organism there exists at least one niche, in which that organism is most successful.

Question 15

Microorganisms inhabit in microenvironments Microorganism ___ Its habitat ___

Answer 15

3 um and 3mm

Question 16

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

Answer 16

adsorption effects

Question 17

Biofilms - how do microbes attach themselves to surfaces?

Answer 17

adhesive polysaccharide excreted by the cells

Question 18

Microorganisms in nature often face with a ____________type of existence

Answer 18

“feast-or-famine”

Question 19

__________store excess nutrients present under favorable conditions for use during periods of nutrient deprivation

Answer 19

Reserve polymers

Question 20

Define - Neutral Associations (Neutralism)

Answer 20

no competition for nutrients occupying the same environment

Question 21

Define - Positive interactions -

Answer 21

symbiotic relationship where each organism benefits

Question 22

What are 3 Positive interactions?

Answer 22

Commensalism  Synergism

Mutualism

Question 23

one population benefits while the other remains unaffected.

Answer 23

Commensalism

Question 24

two microbial populations benefit from the relationship, the association is not an obligatory one. neither organism can carry out alone

Answer 24

Synergism (Protocooperation)

Question 25

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.

Answer 25

Mutualism

Question 26

2x Examples of mutualism

Answer 26

algae or cyanobacteria and fungi that result in the formation of lichens. Endosymbioants of Protozoa

Question 27

4 x types of negative interactions

Answer 27

Competition, Antagonism (Amensalism), Parasitism, Predation

Question 28

A negative relationship between two populations in which both populations are adversely affected with respect to their survival and growth

Answer 28

Competition

Question 29

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.

Answer 29

Antagonism (Amensalism)

Question 30

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

Answer 30

Parasitism

Question 31

The killing and eating of microorganisms of one species - Ingests

Answer 31

Predation

Question 32

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

Answer 32

primary producers.

Question 33

If the deep-sea bacteria simply tolerate high pressures they are called

Answer 33

Barotolerant.

Question 34

If the deep-sea bacteria are dependent on pressure they are called

Answer 34

Barophilic

Question 35

If the deep-sea bacteria can live in very deep waters (10,000m) they are called Extreme (obligate)

Answer 35

Barophiles.

Question 36

__________ 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.

Answer 36

Terrestrial Environments

Question 37

Freshly formed spores where little or no metabolic activity occurs

Answer 37

Dormancy

Question 38

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”

Answer 38

ACTIVATION

Question 39

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

Answer 39

GERMINATION

Question 40

The process in which a vegetative cell develops from a germinated spore

Answer 40

OUTGROWTH

Question 41

Number and type of samples, locations, depths, times, intervals

Answer 41

Sampling strategies

Question 42

Specific techniques and equipment to be used

Answer 42

Sampling methods

Question 43

Types of containers, preservation methods, and maximum holding times

Answer 43

Sample storage

Question 44

they ensure that samples are taken to exactly same depth on each occasion.

Answer 44

Soil augers

Question 45

how to clean auger between samples

Answer 45

water
75% ethanol rinse
10% bleach
final rinse

Question 46

Are obtained by collecting equal amounts of soil from samples taken over a wide area and placing them in a bucket or plastic bag.

Answer 46

Composite samples

Question 47

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

Answer 47

Soil washing methodology for the isolation of fungal hyphae

Question 48

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.

Answer 48

Fungal spore isolation

Question 49

What are 2 different procedures for processing water samples for detection of viruses, bacteria and protozoa.

Answer 49

1. Membrane filtration (identification of fecal coliform bacteria from water samples) 2. Most probable number (MPN) (identification of Salmonella from sewage samples)

Question 50

What are the two approaches to the isolation of bacterial DNA from soil samples:

Answer 50

1. 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

Question 51

A major advantage of the direct lysis approach

Answer 51

Less labor intensive and faster than the bacterial fractionation method.

Question 52

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

Answer 52

Differential Centrifugation