lab culture media

وَقُل رَّبِّ أَدْخِلْنِي مُدْخَلَ صِدْقٍ وَأَخْرِجْنِي مُخْرَجَ صِدْقٍ وَاجْعَل لِّي مِن لَّدُنكَ سُلْطَانًا نَّصِيرًاسورة الاسراءالآيات (80)

CULTURE MEDIA

Culture media are used for recognition δ identification of microorganism

Common ingredients of culture media

1. PEPTONE 2.Meat extract 3.Nacl a. Melting point 92-95 c b. solidifing point 42-45 c 4. Agar agar c. concentration 1.5-2% (solid) 0.4- 0.8% (semisolid)

e.g. nutrient broth (Fluid)media 1.Liquid

2.solid media e.g. nutrient agar ,blood agar
A. PHYSICAL STATE(CONSISTENCY)OF MEDIA
3. Semisolid Media

Solid culture medium

Fluid culture medium (nutrient broth)


2)special-purpose media
1)simple media e.g. nutrient agar and nutrient broth.

Nutrient agar Nutrient broth Simple culture media

Simple media enriched with appropriate substance ,e.g. Blood ,glucose ,serum and ascetic fluid ,most commonly used to cultivate fastidious microorganism like streptococci

Containing inhibitory substance ( e.g. bile salt ,antibiotic, dyes…etc) which favour the growth of concerned microorganism and inhibit the growth of other . e.g. Macon key's agar

Slective medium for gram negative bacilli (contains bile salts which inhibit the growth of gram positive microorganisms)


Certain species produce characteristic growth that can be easily recognized, or can produce certain effects in the media e.g. hemolytic and non-hemolytic species on blood agar ,MacConkeys agar differintiates between lactose fermenter and non lactose fermenter gram negative bacilli, nutrient agar differintiates between species of genus Staphylococcus

Non haemolytic bacteria on blood agar

Staphylococcus citreus (lemon yellow colonies) on nutrient agar

Antibiotic sensitivity test on Mueller-Hinton agar

E- Test( strip of antibiotic contains gradients of concentrations to determine the minimum inhibitory concentration MIC)


Is the destruction or removal of all living organisms in or on an object DISINFECTION Is the destruction of pathogenic microorganism only

1. PHYSICAL METHODS 2. CHEMICAL METHOD

PHYSICAL METHOD

a. At a temperature below 100 c e.g. pasteurization of milk 100 c: b. At a temperature of min. I. Boiling at 100 c for 5-10 II. steaming at 100 c e.g. Tyndallization c. At a temperature above 100 c e.g. auto clave

1)Direct sun light 2)Ultra violet light 3)Ionizing radiation

A-DISINFECTANTS e.g. acids(toxic to living tissue) B-ANTISEPTICS e.g. chlorine and iodine(safely applied to living (tissue

1.Chemical indicators control tubes brown s sterilization 2.Adhesive tape Bowie ---dick auto clave tape test