Changes in acidity of plant growth media during heat sterilisation

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Journal of Applied Biosciences


Tissue culture media provide ideal conditions for growth of plant cells, but also bacteria and fungi. It is therefore necessary to sterilize media to remove these microbes prior to incubation of explants. Growth media are commonly sterilised by autoclaving at 121°C and pressure of 105 kPa for 15 minutes, or longer for larger volumes (Beyl, 2000). Some components of the growth media such as gibberellins (GA3) and capanthothenate are heat-labile and would become inactive when autoclaved (Nissen & Sutter, 1990). Such heat sensitive components are sterilised by filtering through bacteria-proof membrane (0.22μm pores) and added to the sterilised medium after it has cooled down to at least 60°C. Autoclaving the growth media at 121°C and pressure of 105 kPa for 15 - 20 minutes also breaks down sucrose into D-glucose and Dfructose, resulting in alteration in the osmotic potential of the growth media. Thus, it is important to consider these changes when performing osmotic-sensitive procedures such as protoplast culture. Moreover, the simple sugars resulting from sucrose degradation apparently have inhibitory effects on in vitro regeneration of some plant tissues (Dodds & Roberts, 1990).


Journal of Applied Biosciences (2008), Vol. 10: 488 - 490.


Acidity changes, Plant growth media, Heat sterilisation, Plant tissues