Any bacteria that incidentally find their way to the culture medium will also multiply. Colonies on culture medium may grow to several centimetres in height. Spiroplasmas are fastidious organisms, which require a rich culture medium. The swab is then streaked on a culture medium. Its effects are rapidly reversed by simply removing it from the culture medium. The hybridomas can be grown indefinitely in a suitable cell culture medium. In microbiology, agar is used as a culture medium. CP production is influenced by culture medium and growth phase. The most common cryoprotectant used for semen is glycerol (10% in culture medium). Various fertilizers are added to the culture medium to facilitate the growth of plankton. The cells are grown in a culture medium, then fixed and stained. The culture medium used to grow Raji cells is RPMI supplemented with serum. Zygomycetes grow well on most standard fungal culture medium such as Sabouraud dextrose agar. LIF is typically added to stem cell culture medium to reduce spontaneous differentiation. Extracellular enzymes are released into the culture medium, and are much simpler to separate.