micro lab exam 3

Aspergillus niger (Mold)

Candida albicans (Yeast)

Saccharomyces cervisiae (Yeast)

Methylene blue stain

Rhizopus stolonifor (Mold)

Penicillium chrysogenum (Mold)

Lactophenol Cotton Blue Stain

MSA Analysis

Yellow- Halophile/ Ferments Mannitol

Hot Pink- Halophile/ Does not ferment mannitol

MSA

both a selective medium and a differential medium

MSA selects for organisms that tolerate the 7.5% NaCl (Halotolerant)

MSA differentiates organisms on their ability to ferment the sugar mannitol.

pH indicator phenol red.

Scolex

suckers and hooks for attachment.

Proglottids

reproductive segments that make up the body

Protozoa Classification

Protozoa are organized based on locomotion (motility)

• Amoeba - move via pseudopods

• Flagellates - move via flagella

• Ciliates - move via cilia

• Apicomplexans/sporozoa - do not move or may have an undulating membrane, glide, or attach

Obligate or strict aerobes

require O₂ to make ATP through aerobic cellular respiration and will only grow in the O₂-rich layer at the surface of the broth.

Obligate anaerobes

obtain energy through anaerobic respiration or fermentation, will be killed by O₂

will only grow below the pink band, where there is no O₂.  

Facultative anaerobes

thrive in the presence of O₂, but also grow in its absence by relying on fermentation or anaerobic respiration,

will grow throughout but better on top

Microaerophiles

require minimal amounts of O₂ for growth

will grow in a thin layer just below the pink band.

Aerotolerant anaerobe

do not use O₂ - usually have a fermentative metabolism, are not harmed by the presence of O_2,

will grow evenly all throughout the medium.

(a) Obligate or strict aerobes

(b) Obligate anaerobes

(c) Facultative anaerobes

(d) Microaerophiles

(e) Aerotolerant anaerobes

Acidophiles

prefer a pH less than 5.5

Neutrophiles

grow best in a pH between 5.5-8.5

Alkaliphiles 

thrive in a pH above 8.5

KB Test

diameter of the inhibition zone (in millimeters) around each individual antibiotic to determine the species susceptibility or resistance.

MAC

both selective and differential.

selects for Gram-negative bacteria.

differentiaties based on their ability to ferment the sugar lactose

contains crystal violet and bile salts,

MAC Analysis

Growth: Gram-negative

No Growth: Gram-positive

Pink/ Red- Lactose Fermenter

Yellow- Non Lactose Fermenter

Oxidase Test

detect for enzyme cytochrome c oxidase

reangant- -tetramethyl-p-phenylenediamine dihydrochlorid

oxidation- purple

Catalase Test

tests for catalase enzyme

reangent- hydrogen peroxcide

bubbles- catalase enzyme is present

Phenol Red Test

determines if a microorganism can ferment a specific carbohydrate ( lactose, sucrose, or glucose) to produce acid or acid and gas

pH indicator phenol red

Phenol Red Test Analysis

• A⁺ for acid production (yellow) 

• Weak A+ for small acid production (bright orange)

• A^– if no acid was produced (red, red orange) 

• G⁺ for gas production

• G^- if no gas was produced

• P⁺ for peptonization (bright pink color)

Nitrate Reduction Test

tests for ability to produce nitrate reductase

reangants Sulfanilic acid, -dimethyl-1-naphthylamine, and zinc

Gas in Durnham tube and if the bacterium is a non-fermenter, this indicates denitrification

• Immediatly Red : Positive for Nitrate Reductase (Nitrate reduced to Nitrite).

• No Color Change : Preliminary negative or further reduction.

• Red Color (After Zinc Powder): Negative for Nitrate Reduction

• No Color Change (After Zinc Powder): Positive for Nitrate Reduction

Phenyl Ethyl Alcohol Agar (PEA)

undefined medium that is selective for Gram-positive bacteria

more growth than control: gram Postitive

less growth/no growth: gram negative

Blood Agar

differential

blood=extra nutrients

if an organism produces hemolysin (degrade hemoglobin) it will be able to lyse the blood cells

yellow- Beta hemolysins (completely lyse the red blood cell and degrade the hemoglobin)

green/brown- Alpha (partially degrade the hemoglobin producing biliverdin)

no change- Gamma (no hemolysin produced)

Temp effect on microbial growth

Cold temperatures slow enzymatic reactions

Excessive heat causes irreversible damage, including denaturation, cell death

UV effect

damages DNA/RNA (pyrimidine dimers) leading to mutations or cell death

pH effect

enzymes denature in very basic or acidic

membrane integrity

cell wall integrity

ATP production ( respiration)

Psychrophiles

0°C to 15°C

Cold

Psychrotrophs

4°C to 25°C

Cold/ Moderate

Food spoilage

Mesophiles

20°C to 45°C

Moderate

human pathogens

Thermophiles

50°C to 80°C

Heat

Hyperthermophiles

80°C to 110°C

Extreme heat

Halophile

love extremly salty enviornments

Pyrimidine

bonds between two cytosines

a cytosine and a thymine

or two thymines

Disinfection

eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects

Antisepsis

eliminates transient and many pathogenic microorganisms that could cause infection on animate living tissue by arresting their growth or killing

Sterilization

kills all living organisms

Sanitization

prepares surfaces or living tissue for public health or food preparation standards by lowering the number of microbes to an acceptable level

fungal spores

reproductive particles

Conidia Spores

spores are produced and freely released

Sporangia Spores

spores are contained in a sac-like head

Endospores

used for survival in extreme conditions

flatworm vs parasitic worm reproduction

flatworms can produce sexually or asexually (break into fragments)

parasitic worms require multiple hosts for dif life stages

Selective Media

suppress unwanted microbes while allowing target organisms to grow,

Differntial Media

differentiate between closely related organisms based on visual characteristics

Enriched Media

support the growth of fastidious organisms

Enzymes needed for oxygen enviornment

Catalase

Speroxide dismutase

(break down the toxic oxygen products)

Types of organisms grown in anaerobic chamber

obligate anaerobes oxygen free

aerotolerant anaerobes dont use oxygen but can survive with

some microaerophiles require low oxygen

What are the Autoclave Conditions?

121°C for 3-60 minutes

15 PSI for 15-20 minutes

what are the two oxygen indicators?

methylene blue oxygen indicator strip

resazurin

Anaerobic Chamber

used to grow bacteria that can thrive, or survive, without O₂

gas pack removes the oxygen

methylene blue oxygen indicator strip is also used to show that the oxygen has been removed

blue- presence of O₂

white- all O₂ removed

Purpose of Durham tube

detect gas production by microorganisms during fermentation

PR

NR

Serial Dilution Set Up

1. spread dilution on plate

2. incubate

3. use dilution plate which grew 30-300 colonies to calculate the CFU/mL

Bacteria Stains

Gram stains or acid-fast stains

to highlight cell wall differences (peptidoglycan)

Fungal Stains

Lactophenol Cotton Blue Stain detect chitin in cell walls

Methylene Blue Stain encourages budding and increases contrast

Dimorphic Fungi

found as a mold in the environment, but takes on yeast form in the lungs once inhaled.

Dermatophytes

fungi that cause infections of the hair, skin, and nails

Pseudohyphae

chains of elongated yeast cells formed by incomplete budding,

Halotolerant

microorganisms (bacteria, archaea, fungi) that can survive and grow in high-salt environments

Fungicide

pesticides that kill or prevent the growth of fungi

Sporocide

powerful chemical agents designed to eliminate highly resilient microbial spores

Bacteriostatic

prevent bacteria from reproducing and growing, rather than killing them outright

which temp class causes disease

mesophiles

aerotolernace of psychrophiles,

low oxygen habitats

Aerotolernace of mesophiles

obligate aerobes to anaerobes

Aerotolerance of thermophiles and hyperthermophiles

obligate aerobes or anaerobes

Protists

Eukaryotic

unicelluar

motile

heterotrophic, phototrophic, photosynthsis

protozoans, algea

Fungi

cell walls contain chitin,

multicellular

heterotroph (feed on dead)