This relatively old technology is gradually being eliminated, but with less investment and low technical content, it can be operated with a little training.

2. Suspension culture

A culture method of non-adherent cells.

Cells are suspended in culture medium to grow or maintain. After adaptation and selection, some adherent cells can also be cultured in this way. It is relatively simple to increase the scale of suspension culture, as long as the volume is increased. When the depth exceeds 5mm, the culture medium needs to be stirred; when it exceeds 10cm, CO2 and air need to be deeply introduced to ensure sufficient gas exchange.

A culture method in which cells are always dispersed and suspended in a culture solution by oscillating or rotating devices.

The method of culturing plant tissues in vitro with solid agar medium has been widely used in plant genetic experiments. However, this method still has some shortcomings in some aspects. For example, in the process of culture, the nutrient components of plant callus and the metabolic substances produced by plant tissue are distributed in gradient, and there are some unknown substances in agar itself that may affect culture, which may lead to metabolic changes of plant tissue during growth and development. This disadvantage can be overcome by using liquid culture medium. When plant tissues grow in liquid medium, we can improve the oxygen supply in the medium by thin-layer vibration culture or aeration. Plant cell suspension culture refers to the suspension of plant cells or smaller cell clusters in liquid culture medium, which can maintain good dispersibility during the culture process. These small cell aggregates usually come from plant callus.

The general operation process is to transfer undifferentiated callus to liquid culture medium for culture. In the process of culture, continuous rotary vibration can be carried out at the speed of 100 ~ 120 r/min. Due to the rotation and vibration of the liquid medium, the divided cells on the callus are constantly free. Cultures in mixed liquid medium include free single cells, large cell clusters and dead cell residues of inoculum.

In the process of liquid suspension culture, we should pay attention to the subculture of cells in time, because when the culture grows to a certain period, it will enter the static stage of division. For most suspension cultures, the cell density reaches the maximum at 18 ~ 25 days, and the first subculture should be carried out at this time. In subculture, large cell clumps and inoculum residues should be removed. If a cell suspension culture system is established from plant organs or tissues, it includes callus induction, subculture, single cell separation and suspension culture. At present, this technology has been widely used in the study of cell morphology, physiology, heredity and apoptosis, especially providing an ideal material and approach for the operation of genetic engineering at the plant cell level. The transformed plant cells are induced to differentiate into plants, and individuals carrying the target genes are obtained.