The Cell Growth Environment- http://www.sigmaaldrich.com/Area_of_Interest/Life_Science/Cell_Culture/Key_Resources/ECACC_Handbook/Cell_Culture_Techniques_6.html#Environment
Cultured cells require a sterile environment and a supply of nutrients for growth. Basic Constituents of media. Sigma - [Read The Cell Growth Environment]
Can you autoclave liquid Media? FAQ- http://invitrogen.custhelp.com/cgi-bin/invitrogen.cfg/php/enduser/std_adp.php?p_sid=HczfJTng&p_lva=1&p_faqid=120