Suspension Cultures - Use of liquid medium in suspension cultures allows easy and extensive scaling up by employing bioreactors, although a limited scaling up can be achieved by using larger culture flasks usually 250 ml flasks having 50 ml medium are used). A bioreactor is a culture vessel, generally of a large volume, e.g., I I to over 1000 I, which has provisions for
(i) aeration,
(ii) stirring to achieve medium and cell mixing,
(iii) contamination control and
(iv) replacement of used medium and/or used medium plus cells. The bioreactors used for culture of plant cells may be of following four types:
(1) batch bioreactors,
(2) continuous bioreactors,
(3) multistage bioreactors and
(4) immobilized cell bioreactors; all bioreactors, except the last one are commonly called stirred tank reactors since the vessel has a device for stirring.