MicroFinalBoss

obligate aerobes

bacteria that require oxygen to live

obligate anaerobes

bacteria that are killed in the presence of oxygen

facultative anaerobes

bacteria that can use oxygen, but don't require oxygen to survive

aerotolerant anaerobes

bacteria that survive in both the presence and absence of oxygen; do not use oxygen

microaerophiles

bacteria that require oxygen to survive, but too much oxygen will kill them

capnophiles

bacteria that require extra carbon dioxide in their environment to survive

obligate aerobes

which bacteria is grown in this tube?

which bacteria is grown in this tube?

obligate anaerobes

which bacteria is grown in this tube?

facultative anaerobes

aerotolerant anaerobes

which bacteria is grown in this tube?

which bacteria is grown in this tube?

microaerophiles

which bacteria would grow best in a sealed jar with a burning candle?

capnophile

- moist heat: heat that uses water to kill bacteria

- dry heat: heat that only uses hot air to kill bacteria

what is the difference between moist heat and dry heat?

- moist heat: boiling, pasteurization, and autoclaving

- dry heat: dry oven and incineration

give examples of moist heat and dry heat

moist heat is most effective because the humidity better kills the microorganisms

which type of heat treatment is most effective (dry vs moist) and why?

- TDT: thermal death time; the lowest amount of time required to kill bacteria at a set temperature

- TDP: thermal death point: the lowest temperature required to kill bacteria in a set time

describe the difference between TDT and TDP

autoclaving: temperature of steam is raised to 121 degrees C by increasing the pressure on the steam to 15 psi and bacteria are killed in 15 minutes

what is the most effective method of moist heat sterilization? describe what happens in this procedure

UV can form pyrimidine dimers, which disrupt the DNA of bacteria

how does UV light kill bacteria?

when two thymines bind to each other in a DNA strand instead of binding to their complementary strand

*BE ABLE TO DRAW A THYMINE OR CYTOSINE DIMER!!*

describe a thymine dimer

t/f

UV light cannot penetrate surfaces, so it has to make direct contact with the microorganisms

t

what would happen if you accidentally left the lid to an agar dish while trying to kill the microorganisms with UV light?

the microorganisms would survive because the UV light can't penetrate through the lid

the minimum amount of time required to kill all bacteria of a given species with UV light

define minimum lethal dose

- disinfectants: chemical agents that KILL vegetative, pathogenic microorganisms on INANIMATE objects

- antiseptics: chemicals used on LIVING TISSUES to REDUCE the number of bacteria

describe the difference between disinfectants and antiseptics

lysol, pinsol, and chlorox

give examples of disinfectants that we used in lab

alcohol, hydrogen peroxide, and betadine

give examples of antiseptics that we used in lab

what is the difference between "static" and "cidal"

static: inhibits the growth of bacteria, cidal: kills bacteria

- antibiotics can be consumed

- antiseptics can only be used on the surface of our skin

what is the difference between antibiotics and antiseptics?

define MIC

minimum inhibitory concentration, the lowest concentration of an antibiotic that inhibits the growth of an organism

how do we determine the MIC of an organism?

testing for bacterial growth in different dilutions of the antibiotic in a liquid medium

to determine which antibiotics will be effective against a particular microorganism; if the bacteria is sensitive to a certain antibiotic, then a zone of inhibition will form

what do we use the Kirby-Bauer test for?

epidemiology

the study of the spread of disease

prevalence

the total number of people in a population who have a disease at a particular time, regardless of when they caught it or when they were diagnosed

(Total number of cases in the population)/(Total number of people in the population) x 100,000

prevalence rate

incidence

the number of new cases of disease that occur within a certain time period

(Number of new cases in the population) / (Number of people in the population) x 100,000

incidence rate

epidemic

when a disease is spreading rapidly in a particular population; it is localized

pandemic

when a disease is spreading rapidly globally or over more than one continent

endemic

when the prevalence is fairly stable in a location

sporadic disease

when a disease is spreading infrequently and in scattered locations

source case

the original patient responsible for transmitting the disease to others

why do we try to determine the source case?

to find out what is making everyone sick so that we can try to reduce the number of people getting sick

both;

- selective: chemical dyes inhibit growth of bacteria

- differential: lactose differentiates colonies of gram-negative

is EMB selective or differential? how?

is macconkey selective or differential?

both

what does a positive test look like for EMB? what about a negative test?

positive: dark green or purple color, negative: don't change color

what does a positive test look like for MacConkey? what about a negative test?

positive is pink, negative is colorless

- positive: turn yellow

- negative: stay red

- if it produces gas, then bubbles will form in the inverted tube

what does a positive test look like for Durham fermentation? what about a negative test?

what does a positive test look like for Methyl Red? what about a negative test?

positive is pink, negative stays yellow

what does a positive test look like for Voges-Proskauer? what about a negative test?

positive turns pink, negative stays yellow

what does TSIA stand for?

triple sugar iron agar

- red slant/red butt: negative for all sugars

- red slant/yellow butt: positive for Glucose only

- yellow slant/yellow butt: positive for glucose, lactose, and/or sucrose

- blackening: positive for hydrogen sulfide

tsia results

what does SIM stand for?

sulfide indole motility

- blackening: hydrogen sulfide is produced

- red ring forms at top of tube: indole is produced

- growth spreading away from injection site: motility is positive

what are the different results for a SIM test and what do they mean?

- positive: turns blue

- negative: stays green

what does a positive test look like for citrate utilization? what about a negative test?

what does a positive test look like for urease test? what about a negative test?

positive: turns bright pink, negative: stays orange

what does a positive test look like for oxidase test? what about a negative test?

positive- strip turns purple, negative- strip stays white

what does the oxidase test check for?

if the bacteria uses cytochrome oxidase during aerobic respiration

if the bacteria produces the enzyme urease so that urea will be broken down into ammonia

what does the urease test check for?

what does the citrate test check for?

if bacteria can use citrate alone as its carbon source

if acid is produced during glucose fermentation

what does the methyl red test check for?

for the production of 2,3-butylene glycol and acetoin from glucose

what does the Voges-Proskauer test check for?

if the bacteria can ferment the particular sugar tested and if gas is released as a byproduct

what does the durham test check for?

which test is displayed in the picture?

EMB agar

which test is displayed in the picture?

MacConkey agar

Durham fermentation tubes

which test is displayed in the picture?

Methyl Red test

which test is displayed in the picture?

which test is displayed in the picture?

Voges-Proskauer test

TSIA

which test is displayed in the picture?

SIM

which test is displayed in the picture?

which test is displayed in the picture?

Citrate utilization

which test is displayed in the picture?

urease utilization

which test is displayed in the picture?

Oxidase test

What are environmental factors that influence bacterial growth

Temperature, oxygen concentration, pH, and osmotic pressure

Oxygen serves as a _____ ______ acceptor in aerobic respiration

Terminal electron

Based on oxygen requirement, bacteria are grouped into five types:

Aerobes, microaerophiles, obligate anaerobes, aerotolerant anaerobes, facultative anaerobes, capnophiles

Aerobes

Use oxygen as their final electron acceptor in energy metabolism, must have oxygen to live

Obligate anaerobes

Use an inorganic molecule other than oxygen as their final electron acceptor, killed by the presence of oxygen

Facultative anaerobes

Can use oxygen, but does not require oxygen to grow

Microaerophiles

Require low concentrations of oxygen to grow

Aerotolerant anaerobes

Do not require oxygen, but can tolerate oxygen

Capnophiles

Require extra carbon dioxide in their environment

What are the methods to test for anaerobic growth of bacteria

Growth in thioglycolate tubes, growth in candle jars, growth in anaerogen bags, growth in incubator

What does thioglycolate do

Takes out oxygen in the agar medium

Candle jar reduced oxygen conditions

Solid sealed jar with candle in it, as candle burns it uses up some oxygen and creates co2

When happens in the candle jar when the candle flickers out

Co2 has risen from .4% to 4% and oxygen has dropped from 20% to 18%

Anaerogen system is a

Specifically designed pouch

Anaerogen system process

Place samples in the bag and insert activated anaerogen packet, anaerogen will remove all the oxygen in the bag to generate anaerobic conditions

Define and provide an example microbe: obligate anaerobe

A microbe that cannot survive in the presence of oxygen because oxygen is toxic to it. They lack enzymes that break down harmful oxygen radicals. Clostridium botulinum

Define and provide an example microbe: Obligate aerobe

A microbe that requires oxygen to survive because it uses oxygen for cellular respiration, oxygen acts as the final electron acceptor in the electron transport chain. Mycobacterium tuberculosis

Define and provide an example microbe: Facultative anaerobe

A microbe that cannot survive in grow with or without oxygen, but grows better with oxygen since aerobic respiration yields more atp. If oxygen isn’t available, it switches to fermentation or anaerobic respiration. Escherichia coli

Define and provide an example microbe: Microaerophile

A microbe that needs oxygen to survive, but only at low concentrations. High levels are toxic. Helicobacter pylori

Define and provide an example microbe: Capnophile

A microbe that thrives in environments rich in carbon dioxide, Neisseria gonorrhoeae

Why do aerobic organisms need oxygen

Aerobic organisms need oxygen because its essential for how they make energy, oxygen is the final electron acceptor, allows maximum atp yield, and cells cant survive long without it

Examples of strict aerobes

Neisseria and pseudomonas

Examples of obligate anaerobes

Clostridium and bacteroids

What do facultative anaerobes do when oxygen is present

They use aerobic respiration to break food molecules down further and obtain more ATP.

What do facultative anaerobes do when no oxygen is present

They proceed with anaerobic fermentation

Microaerophiles examples

Campylobacter and Micrococcus

Capnophile examples

Streptcoccus and hemophilus

What is a widely used method for controlling microorganisms

Heat

Moist heat examples

Boiling, pasteurization, autoclaving