Addition of the biosurfactant-producing strain in its spent broth
will result in a higher concentration of organic carbon in the
nutrient solution. This could possibly result in increased survival of
the added bacterial strain. In the treatment receiving KB cell culture
this was not the case and there was no increase in the amount of
fluorescent pseudomonads after six days compared with the
control. However, for the treatment receiving the biosurfactantproducing
strain cultivated in a broth based on nutrient solution
and with rapeseed oil as a carbon source, an increased amount of
fluorescent pseudomonads was observed compared with the
control. As no selective method was used to trace the added strain,
this could have been due to either an increase in the added strain or
a general increase in fluorescent pseudomonads. However, the
potential of using this in practise is less since even this minor
addition of oil (less than 0.2% w/w) was observed to be toxic to the
plants, causing a large reduction in plant weight.