Chocolate agar

The chocolate agar is used to grow fastidious Organisms Such as haemoglobin and neisseria which requires specially enriched culture media and micro aerophilic incubation condition.It is commonly used for primary isolation of haemophilus from clinical specimens.chocolate agar can also be made selective for haemophilus species by the addition of bacitracin.

Some haemophilus species require two special growth factor called x and v.The x factor is haemin,a heat stable derivatives of haemoglobin.The blood agar is heated untill the blood is lysed producing the characteristics brown colour of this medium.The lysed RBC release the x factor needed for haemophilus influenzae.Yeast extract in chocolate agar contain v factor which is a heat labile coenzyme nicotinamide adenine dinucleotide or NAD.

Introduction to culture method

In the field of microbiology, the growth of bacteria in laboratory is essential for many reasons.The following are the important application of the growth of bacteria in the laboratory

Identification of bacteria in the clinical sample

Preparation of pure culture

Maintenance of bacterial species for experimental studies stock culture

Testing for antibiotics sensitivity

For genetics studies

Production of bacterial vaccine and antigen

Determination of viable count

In order to grow the bacteria,we need a sample of bacteria.Tge sample of bacteria that is introduced into the growth medium is called inoculum and method is called inoculation.

The inoculation is normally done with the help of inoculation wire made of nichrome.nichrome is an alloy made of nickel and chromium.it is stable even at very High temperature.The inoculation wire is sterilized by heating to red hot.Tge inoculation wire may be in the form of loop, straight wire or aan l shaped wire.Tge loop is normally used for inoculation.Tge sterile pipette can also used for inoculation it the inoculum is a broth.

The observable growth of bacteria in the media is called culture.A pure culture is the bacterial growth that contains only one species or strain of bacteria.The pure culture is normally obtained easily by the multiplication of a single Bacterial cell when the growth in the medium contain more than one species of bacteria,it is called mixed culture.Transfer of bacteria from one medium to another medium is called subculturing.

The growth of bacteria in the culture media involves many methods the method differ based on the type of culture medium and on the purpose for which it is cultured.the following are the important method of culturing bacteria.