Gelling agents are used to make the media semi-solid for it to provide support to the explant without which it may submerge and deprive the growing cells of the needed oxygen. Agar (0.8–1%), agarose (0.4%), and gelrite—a bacterial polysaccharide (0.1–0.2%) are usually used as they withstand sterilization by autoclaving and are liquid while hot and semi-solid when cool.

Water-soluble antibiotics, carbenecillin (500 mg/L), cefotaxime (300 mg/L), and augmentin (250 mg/L) are included in the culture medium to prevent problems of contamination.