microbial growth

Question 1

name the essential nutrients from microorganisms

Answer 1

C,H,O,N,S,Se,P

Question 2

out of the essential nutrients which ones have simple metabolism

Answer 2

P,N,S

Question 3

sources of C

Answer 3

CO2, org compounds

Question 4

sources of N

Answer 4

NH3,NO3,N2, organic N compounds (AA,etc)

Question 5

sources of H

Answer 5

H2O, organic compounds

Question 6

sources of O

Answer 6

H2O,O2, org compounds

Question 7

sources of P

Answer 7

PO4 (3-)

Question 8

sources of S

Answer 8

H2S, SO4 (2-) ,org S compounds (cysteine), metal sulfide (FeS,CuS,ZnS, etc)

Question 9

sources of K

Answer 9

K+ in solution, K+ salts

Question 10

sources of Mg

Answer 10

Mg in solution, Mg salts

Question 11

sources of Ca

Answer 11

in solution, salts

Question 12

sources of Na

Answer 12

in solution, salts

Question 13

Sources of Fe

Answer 13

Fe2+ , Fe3+

Question 14

what are growth factors

Answer 14

vitamins, AA, purines, pyrimidines or other ORGANIC MOLECULES.
- needed for growth and NOT synthesized by the organism

Question 15

some growth factors are the. —– or —- of another micro-organism

Answer 15

by products, waste

Question 16

growth of the population = increase —- or —-

Answer 16

number of cells, biomass

Question 17

what is a septum

Answer 17

the partition created that constricts the cell into 2 daughter cells

Question 18

explain the process of septum formation

Answer 18

cell elongation –> septum formation –> completion of septum –> formation of walls –> cell separation

Question 19

each daughter cell receives one copy of the —-, sufficient —, —- and etc

Answer 19

chromosome, ribosome, macromolecules

Question 20

cell division requires —- and cell wall —– by —-

Answer 20

cell wall synthesis, destruction, autolysins

Question 21

destroying and making — is the ket to cell division

Answer 21

peptidoglycan

Question 22

• —- allows peptidoglycan to be exported across the cytoplasmic membrane.
• location?

Answer 22

bactoprenol, where the septum is being made.

- adds new peptidoglycan to initiate separation

Question 23

at the division ring (FtsZ), —- create some — in the peptidoglycan. this allows:

Answer 23

autolysins, gaps, rearrangement of the peptidoglycan and synthesis of a new cell wall

Question 24

wall bands

Answer 24

scar between old and new peptidoglycan

Question 25

why do different bacterial cultures smell different

Answer 25

they have different metabolic pathways; produces different wastes. - also depends on the characteristics of the species and the media

Question 26

name different selective mediums mentioned in the class

Answer 26

1) bile salts | 2) mannitol salt

Question 27

bile salts ---- gram + , ----- for gram - and enteric pathogens

Answer 27

inhibit, permissive

Question 28

bile salts is toxic for a lot of microorganisms but not for -----

Answer 28

enteric pathogens. like the ones in the intestine

Question 29

lactose fermenters have a --- color. lactose non fermenters are --- . this color change is indicated by a ---

Answer 29

pink, colourless, pH indicator

Question 30

mannitol salt has a high ---- concentration. ----- most gram negative and many gram positive

Answer 30

NaCl, inhibits

Question 31

mannitol salt is used for isolation and detection of ----. how does this work?

Answer 31

staphylococcus, some are mannitol negative (cannot ferment mannitol) and turn the media pink, but some are mannitol positive and produce acids that turn the media yellow

Question 32

staphylococcus, mannitol + --> | staphylococcus, mannitol negative --->

Answer 32

staphylococcus aureus | staphylococcus epidermis

Question 33

function of staphylococcus aureus

Answer 33

wound infection, has a high antibiotic resistance

Question 34

what is a viable count

Answer 34

- measured to test microbial presence - needs a permissive growth medium - results are reliable when there are between 30 - 300 colonies

Question 35

name the methods of viable count

Answer 35

1) spread plate method | 2) pour plate method

Question 36

to get a viable count of culture with ing populations, ---- are done

Answer 36

serial dilutions

Question 37

serial dilution counts -------

Answer 37

the number of cells that are able to grow | - dead cells cannot be counted

Question 38

with ----- you can also count dead cells

Answer 38

microscopic method ** know how to calculate them

Question 39

----- an be used to differential between living and non living cells

Answer 39

viability staining

Question 40

advantages and disadvantages of microscopic method

Answer 40

adv: fast non need to wait until the bacteria has grown disadvantages: small cells can be missed, motile cells are hard to count

Question 41

flow cytometry is better at counting --- cells. like:

Answer 41

big, protozoan, yeast, mammalian cells, etc

Question 42

how does flow cytometry work

Answer 42

1) aligns all cells behind each other 2) the cells go through a detection device which is a laser 3) they pass the laser 4) the light transmitted is detected by a machine - specifies which ones are dead or alive if you use the culture of microscopic counts that are already stained

Question 43

turbidimetric method

Answer 43

measures the contribution of alive and dad cells to turbidity - high optical density = high turbidity

Question 44

turbidimetric method is affected by:

Answer 44

1) clumping: form large particles --> error --> higher OD | 2) attachment to surfaces --> lower OD

Question 45

how is the turbidimetric method done

Answer 45

measured using a spectrometer, by measuring the amount of light that goes through - technically measures the OD: log I0/I

Question 46

The relationship between the number of cells and OD depends on:

Answer 46

the type of the cell: size, shape, composition, cells inclusion, mutations, etc

Question 47

generation time

Answer 47

the time needed for the population to double | - depends on the growth medium and conditions

Question 48

when the conditions are right, microorganisms can grow -----

Answer 48

exponentially , the population forms at a constant rate equation N = N02^n --> number of cells

Question 49

calculating generation time

Answer 49

g = t/n

Question 50

know the growth cycle

Answer 50

in the notes

Question 51

most natural envs are -----, they have:

Answer 51

open systems 1) constant supply of nutrients and diffusion of waste 2) predations 3) competition with other microorganisms 4) changing env conditions

Question 52

chemostats

Answer 52

notes

Question 53

factors affecting growth

Answer 53

1) temp 2) pH 3) osmolarity 4) oxygen 5) pressure 6) radiation

Question 54

extremophiles

Answer 54

microorganism that grow preferentially under extreme conditions

Question 55

membrane gelling

Answer 55

transport processes so low that growth cannot occur

Question 56

what happens above the optimum growth rate

Answer 56

thermolysis

Question 57

membrane gelling occurs at:

Answer 57

minimum temp *doesn't kill them

Question 58

the temp range for most microorganism is typically ----

Answer 58

25- 40 degrees around the optimal temp

Question 59

psychrotolerant

Answer 59

can grow at zero degrees but have a optimal range of 25-40 degrees

Question 60

psychrophile

Answer 60

notes

Question 61

mesophile

Answer 61

notes

Question 62

thermophile

Answer 62

notes

Question 63

hyperthermophile

Answer 63

notes

Question 64

barophilic

Answer 64

grow best at high pressure