Sub-Culturing

What is the defference among reference culture, Reference stock culture and working culture?
Usually it is seen that vendors provide 3-4 passage cultures, if it is the case then how further subcultures can be done?
How many times working culture can be sub-cultured from four passage subculture?
How long we can store reference stock culture at 2-8 centigrade and how many sub-culture can be produced from it?

[quote=Adnan Zahid]What is the defference among reference culture, Reference stock culture and working culture?

Reference culture also said as mother stock, the stock which we procure from national laboratories.

Reference stock culture: From the reference culture we further make reference stock “in house” to be used for one year or so.

Working culture: From the reference stocks we prepare working cultures (3-4) one each is used in the lab for one month after which we discard the working culture and use other working culture.

Usually it is seen that vendors provide 3-4 passage cultures, if it is the case then how further subcultures can be done? It is industry practice to go further for 4-5 passage, it is better to check the morphology and identification before proceeding.

How many times working culture can be sub-cultured from four passage subculture? Till there is no contamination.

How long we can store reference stock culture at 2-8 centigrade and how many sub-culture can be produced from it? It can be done for years, if there is no risk of contamination.