Microbiology lab 1

Question 1

safety instructions

Answer 1

• Know the locations of emergency exit, fire extinguisher, full body shower, eye shower
• Biological samples = possibly pathogenic: work clean (e.g. when you spill something clean it up with Ethanol (EtOH))
• Flame and EtOH: ALWAYS keep the EtOH away from flames, e.g. flame of the Bunsen burner.
• In the lab: don’t eat, drink, smoke, put make-up on, don’t put anything in your mouth.
• Gloves: wear gloves when you handle biological samples and chemical samples, change gloves if you spill on them, don’t smear contaminated substances all over the lab just because you wear gloves
• When leaving the lab: wash your hands thoroughly
• Lab coat: wear inside the lab at all times, not outside
• Please let me know if you break something/ something is not working properly so we can fix it

Question 2

waste disposal

Answer 2

Categories of waste:
1) broken glassware
2) Liquid chemical waste: solutions that do not contain cells
3) Solid waste on bench top: contaminated gloves, tubes, pipette tips etc.
4) Liquid biological waste + antibiotics: anything that came in contact with microorgansims and
contains antibiotics
5) Liquid biological waste liquid: anything that came in contact with microorganisms
6) cardboard

Question 3

working sterile

Answer 3

• Use gloves to protect your samples (and yourself) and EtOH
• If you contaminated your gloves change them!
• Stay away from the flame with your gloves!
• Keep in mind that anything that is not sterilized by EtOH, autoclaved or flamed is not sterile and must not come into contact with your sterile sample
• Minimize contact with air (close caps quickly, work with bunsenburner if instructed, keep samples away from your face (various reasons: contamination, safety)

Question 4

LB

Answer 4

LB = Luria Broth, is a rich medium used to grow different kinds of bacteria.

Question 5

Rich medium

Answer 5

Rich medium = medium that contains an undefined and complex source of energy, e.g. yeast extract, which is just ground up yeast and contains a wide range of sugars, lipids, proteins etc.

Question 6

Minimal medium

Answer 6

Minimal medium = medium that is defined. You know exactly what components are in the medium and their concentrations. An example for minimal medium is the medium we use to grow yeast in a bioreactor during experiment 9.

Question 7

culture

Answer 7

You call a collection of microorganisms in liquid medium a culture.

Question 8

colony

Answer 8

A collection of microorganisms on a plate originating from a single cell is called a colony.

Question 9

pure culture

Answer 9

A culture is pure if it only contains one kind of strain, meaning ideally all individual cells in the culture share the same genotype.

Question 10

MacConkey

Answer 10

MacConkey = special medium that contains neutral red as pH marker

Question 11

Macrococcus carousellicus

Answer 11

Macrococcus carousellicus: gram positive

Question 12

Escherichia coli

Answer 12

Escherichia coli: gram negative

Question 13

Gram positive / negative

Answer 13

Gramnegativa bakterier är bakterier som inte färgas i ett gramfärgningstest. Motsatsen är grampositiva bakterier. Skillnaden mellan gramnegativa och grampositiva bakterier är hur deras cellväggar är uppbyggda.

Question 14

lab 1

Answer 14

BACTERIA IN OUR ENVIRONMENT

Question 15

lab 2

Answer 15

OBTAINING PURE CULTURES USING SMEARS

Question 16

lab 4

Answer 16

GRAM STAIN

Question 17

lab 5

Answer 17

DETERMINATION OF CELL NUMBERS IN A YEAST CULTURE

Question 18

lab 6

Answer 18

EVALUATION OF MICROORGANISMS IN A SAMPLE

Question 19

lab 7

Answer 19

ANTIBIOTIC RESISTANCE

Question 20

Methylene blue

Answer 20

Methylene blue binds to negatively charged cell components, thus staining these parts of the cell dark blue.

Question 21

dH2O

Answer 21

dH2O = deionized water, can be refilled from the tap labelled with “WDC”