9/1/2009

GROWTH MEDIUM- selective media growth -

- -2nd Group:

à Erwin A. P. (10) à Masrifa I. I. (12)

à Rio H. D. C. (24) à Shinta K. (26)

à Trimah W. (30) à Yeni A. (34)

SMK NEGERI 1 (STM PEMBANGUNAN) TEMANGGUNGPROGRAM KEAHLIAN TEKNIK KIMIA

Jl. Kadar Maron, Kotak Pos 104, Phone (0293)4901639 Temanggung 56221

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CONTENTS

COVER PAGE …………………………………………………………………… i

CONTENTS ………………………………………………………………………ii

I. GROWTH MEDIA …………………………………………………………1

1. The Meaning of a Growth Media ………………………………………………1

2. The Types Growth Media………………………………………………………2

3. The Table of Growth Media ……………………………………………………3

II. SELECTIVE MEDIA GROWTH …………………………………………4

1. The Definition …………………………………………………………………4

2. The Funtion of Selective Medium……………………………………………...4

3. Some Examples of Selective Media ……………………………………………5

4. Some Pictures of Selective Media ……………………………………………7

SOURCE …………………………………………………………………………8

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GROWTH MEDIA

1. The Meaning of a Growth Media

A growth medium or culture medium is

a liquid or gel designed to support the growth of microorganisms or cells, or small

plants like the moss Physcomitrella patens

a mixture of nutrients, moisture and other chemicals that bacteria need for growth

in a laboratory environment.

An Agar Plate -- an example of a bacterial growth

medium. Specifically, it is a streak plate; the orange lines

and dots are formed by bacterial colonies.

This invention relates to media which support the

growth of some microbes but are designed to inhibit the growth of other types of microbes

for culturing microbes in a sample containing a mixture of species. Such media are termed

selective media. This invention comprises a novel type of selective media. The preferred

embodiment provides a selective media for the detection of target Salmonella species,

which allows Salmonella species to survive and grow whilst inhibiting the growth of many

other commensal bacteria.

Media can be solid, such as Jell-o-like agar that is poured into the bottom half of a

Petri dish, or media can be liquid to allow for bacterial growth suspended in test tubes.

Media aren’t used to examine individual bacteria, but rather to grow bacterial colonies

There are two major types of growth media: those used for cell culture, which use

specific cell types derived from plants or animals, and microbiological culture, which are

used for growing microorganisms, such as bacteria or yeast. The most common growth

media for microorganisms are nutrient broths and agar plates; specialized media are

sometimes required for microorganism and cell culture growth. Some organisms, termed

fastidious organisms, require specialized environments due to complex nutritional

requirements. Viruses, for example, are obligate intracellular parasites and require a

growth medium composed of living cells.

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2. The Types Growth Media

The most common growth media for microorganisms are nutrient broths (liquid

nutrient medium) or Luria Bertani medium (LB medium or Lysogeny Broth). Liquid media

are often mixed with agar and poured into petri dishes to solidify. These agar plates

provide a solid medium on which microbes may be cultured. They remain solid, as very

few bacteria are able to decompose agar. Bacteria grown in liquid cultures often form

colloidal suspensions.

The differences between growth media used for cell culture and those used for

microbiological culture are because cells derived from whole organisms and grown in

culture often cannot grow without the addition of, for instance, hormones or growth factors

which usually occur in vivo.[4] In the case of animal cells, this difficulty is often addressed

by the addition of blood serum to the medium. In the case of microorganisms, there are no

such limitations, as they are often unicellular organisms. One other major difference is that

animal cells in culture are often grown on a flat surface to which they attach, and the

medium is provided in a liquid form, which covers the cells. In contrast, bacteria such as

Escherichia coli may be grown on solid media or in liquid media.

An important distinction between growth media types is that of defined versus

undefined media. A defined medium will have known quantities of all ingredients. For

microorganisms, they consist of providing trace elements and vitamins required by the

microbe and especially a defined carbon source and nitrogen source. Glucose or glycerol

are often used as carbon sources, and ammonium salts or nitrates as inorganic nitrogen

sources. An undefined medium has some complex ingredients, such as yeast extract or

casein hydrolysate, which consist of a mixture of many, many chemical species in

unknown proportions. Undefined media are sometimes chosen based on price and

sometimes by necessity - some microorganisms have never been cultured on defined

media.

A good example of a growth medium is the wort used to make beer. The wort contains

all the nutrients required for yeast growth, and under anaerobic conditions, alcohol is

produced. When the fermentation process is complete, the combination of medium and

dormant microbes, now beer, is ready for consumption.

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3. The Table of Growth Media

GROWTH MEDIA / AGAR PLATES

Selective media

Gram

positive

ActinobacteriaMycobacterium tuberculosis (Lowenstein-Jensen medium) ·

Mycoplasma pneumoniae (Eaton's agar)

Firmicutes

Corynebacterium diphtheriae (Hoyle's agar) · Enterococcus (Bile

esculin agar) · Lactobacillus (MRS agar) · Staphylococcus

(Mannitol salt agar)

Gram

negative

Alphaproteobacteria Brucella abortus (Brucella agar)

Betaproteobacteria Neisseria (Thayer-Martin agar)

Gammaproteobacteria

Bordetella (Bordet-Gengou agar) · Enterobacteriaceae (VRBD

agar) · Haemophilus influenzae/Legionella pneumophila

(Buffered charcoal yeast extract agar) · Pseudomonas aeruginosa

(Cetrimide agar) · Salmonella (XLT agar) · DCA agar ·

Salmonella/Shigella (XLD agar)

Differential media

Lactose fermenting gram negative (MacConkey agar/Sorbitol-MacConkey agar, Eosin methylene blue) ·

Hektoen enteric agar · sulfur (Bismuth sulfite agar)

Fungal media

Dermatophyte test medium · Potato dextrose agar · Sabouraud agar

Nonselective media

Chocolate agar · Nutrient agar · Plate count agar

Other/ un-grouped media

Cysteine lactose electrolyte deficient agar · Cystine tryptic agar · Endo agar · Müller-Hinton agar/PNP

agar · R2a agar · Simmons' citrate agar · Trypticase soy agar · TSI agar

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SELECTIVE MEDIA GROWTH

1. The Definition

A growth medium is selective if it allows only certain types of bacteria to grow, while

inhibiting the growth of others.

For example, if a microorganism is resistant to a certain antibiotic, such as ampicillin

or tetracycline, then that antibiotic can be added to the medium in order to prevent other

cells, which do not possess the resistance, from growing. Media lacking an amino acid

such as proline in conjunction with E. coli unable to synthesize it were commonly used by

geneticists before the emergence of genomics to map bacterial chromosomes.

2. The Funtion of Selective Medium

Selective media are used for:

support the growth of some microbes but are designed to inhibit the growth of other

types of microbes for culturing microbes in a sample containing a mixture of species.

providing general information regarding the bacteria that are able to grow on these

specialized types of agar.

For example, organisms that can utilize a given sugar are easily screened by making

that sugar the only carbon source in the medium. On the other hand, selective inhibition of

some types of microorganisms can be achieved by adding dyes, antibiotics, salts or specific

inhibitors which affect the metabolism or enzyme systems of the organisms.

Another example, media containing potassium tellurite, sodium azide or thallium

acetate (at concentrations of 0.1 - 0.5 g/l) will inhibit the growth of Gram-negative

bacteria. Media supplemented with penicillin (5-50 units/ml) or crystal violet (2 mg/l) will

inhibit the growth of Gram-positive bacteria. Tellurite agar, therefore, is used to select for

Gram-positive organisms, and nutrient agar supplemented with penicillin can be used to

select for Gram-negative organisms.

Selective growth media are also used in cell culture to ensure the survival or

proliferation of cells with certain properties, such as antibiotic resistance or the ability to

synthesize a certain metabolite. Normally, the presence of a specific gene or an allele of a

gene confers upon the cell the ability to grow in the selective medium. In such cases, the

gene is termed a marker.

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Selective growth media for eukaryotic cells commonly contain neomycin to select

cells that have been successfully transfected with a plasmid carrying the neomycin

resistance gene as a marker. Gancyclovir is an exception to the rule as it is used to

specifically kill cells that carry its respective marker, the Herpes simplex virus thymidine

kinase (HSV TK).

3. Some Examples of Selective Media

Some examples of selective media include:

a) Eosin-Methylene Blue Agar (EMB)

This agar medium is both selective and differential. The combination of the two dyes

eosin and methylene blue inhibits most Gram positive bacteria but allows many Gram

negative organisms to grow.

In addition to peptones, EMB contains lactose (it may also contain sucrose). Gram

negative bacteria that ferment the lactose produce acid which turns the colonies dark

purple as the acid acts upon the dyes. In addition, certain lactose-fermenting bacteria

produce flat, dark colonies with a green metallic sheen. Other lactose fermenters produce

larger, mucoid colonies, often purple only in their center. Lactose non-fermenters are either

colorless or light lavender.

b) YM (Yeast And Mold)

A medium that promotes the growth of fungi (yeast and molds) which has a low pH,

deterring bacterial growth.

c) Blood Agar (Used In Strep Tests)

Which contains bouvine heart blood that becomes transparent in the presence of

hemolytic Streptococcus.

d) MacConkey’s Agar (MAC)

MacConkey's agar is a differential plating medium selective for Gram negative

organisms, used primarily for detection and isolation of enteric bacteria (dysentery,

typhoid and paratyphoid organisms). It is generally used for differentiating strains of

Salmonella typhosa from members of the coliform group; however, the medium supports

the growth of all Salmonella and Shigella strains and gives good differentiation between

these enteric pathogens and the coliform group.

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When grown on MacConkey’s medium, The growth of gram-positive organisms are

generally inhibited by crystal violet in the medium and bile salts in the medium. Isolated

colonies of lactose-fermenting bacteria are brick-red in color and are surrounded by a zone

of precipitated bile. These reactions are due to the acids, produced by the fermentation of

lactose, upon bile salts present in the medium, and subsequent absorption of neutral red.

The acid end-products act on bile salts, and neutral red is absorbed by the precipitated

salts. Dysentery, typhoid and paratyphoid bacilli do not ferment lactose but give an

alkaline reaction when grown on the medium. Colonies of these organisms are noncolored

and transparent.

e) Hektoen Enteric Agar (HE)

Which is selective for Gram-negative bacteria.

f) Mannitol Salt Agar (MSA)

This is a selective medium that favors the growth of pathogenic staphylococci and for

differentiation between pathogenic and non-pathogenic types, which is selective for gram-

positive bacteria and differential for mannitol.

The medium contains the sugar-alcohol mannitol, a phenol red indicator, and 7.5%

sodium chloride (NaCl). The staphylococci are characteristically able to tolerate this high

salt concentration. The high salt concentration inhibits the growth of most bacteria other

than staphylococci. Generally pathogenic staphylococci are able to ferment the mannitol,

lowering the pH, and thereby turning the indicator yellow. The non-pathogenic

staphylococci do not ferment mannitol and the medium remains pink in their vicinity.

On MSA, pathogenic Staphylococcus aureus produces small colonies surrounded by

yellow zones. The reason for this change in color is that S. aureus ferments the mannitol,

producing an acid, which, in turn, changes the indicator from red to yellow. The growth of

other types of bacteria is generally inhibited.

g) Terrific Broth (Tb)

Is used with glycerol in cultivating recombinant strains of Escherichia coli.

h) Xylose Lysine Desoxyscholate (XLD)

Which is selective for Gram-negative bacteria.

i) Buffered Charcoal Yeast Extract Agar

Which is selective for certain gram-negative bacteria, especially Legionella

pneumophila.

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4. Some Pictures of Selective Media

Four types of agar plates demonstrating

differential growth depending on bacterial

metabolism.

Blood-free, charcoal-based selective

medium agar (CSM) for isolation of

Campylobacter.

Blood agar plates are often used

to diagnose infection. On the

right is a positive Streptococcus

culture; on the left a positive

Staphylococcus culture.

Selective Bacterial Media Top

Two (MAC and MSA)

Mannitol Salt Agar: Yellow Side

Pathogenic Staph

Gram- Bacteria Growing on

MacConkey's Agar

Pink Lactose Fermenters on

MacConkeys

Mannitol Salt Agar with Staph

epi and aureus

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SOURCES

http://www.toodoc.com

http://www.wikipedia.com

http://fire.biol.wwu.edu/brodham/biol346_s07/labman_week6.pdf

http://www.suite101.com

http://www.googletranslator.com

http://biosci.usc.edu/courses/2002-fall/documents/bisc300-lab_media.pdf

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