A Murashige and Skoog medium (MS) was used. It is a plant
growth medium used in the laboratories for plant tissue cultures. This
culture medium contains macro-elements, microelements, vitamins,
organic components, plant growth regulators, gelling agents (agar)
and sucrose.
In order to study the ability of membranes to perform the complete
elimination of bacterial cells, a typical solution was prepared.
100 ml of a mineral medium gelled with agar and thermally sterilized
at the temperature 121 °C for 20 min. Subsequently, a nonsterile
organic medium containing some vitamins (Glycine(C2H5NO2), Nicotinic
acid (C6H5NO2), Pyridoxine hydrochloride (C8H12CINO3) and
Thiamine hydrochloride (C12H18Cl2N4OS)) was passed through a prepared
MF membrane (sterilized at the temperature 121 °C for 20 min)
down to the bottle containing the mineral medium. After that, the
sterilized medium was poured into a sterile petri dish. The petri dish
was tightly closed to prevent any contamination by micro-organisms.
All operations were carried out in a filtered-air environment with a
laminar air-flow cabinet around the Bunsen burner. The unit operation
diagram is shown in Fig. 1c.