In the pioneering work on biosurfactants and interactions with
zoospore-producing plant pathogens performed by Stanghellini
and Miller (1997), a rhamnolipid-producing strain of P. aeruginosa
was used. The fluorescent pseudomonas species used in the present
study, P. koreensis, is an environmental strain not capable of growth
at 37 C (Kwon et al., 2003). This species is therefore preferable to
P. aeruginosa, which is an opportunistic human pathogen and therefore not suitable for large-scale use. In the study by
Stanghellini and Miller (1997), the biosurfactant-producing
P. aeruginosa strain was inoculated directly into the cultivation
system and a disease control effect was reported, although this was
inconsistent. To overcome this problem of inconsistency, a procedure
with repeated and dense inoculations of the biosurfactantproducing
strains into the cultivation system should be devised.
The present study had the advantage of implementation in
a greenhouse in the immediate vicinity of a laboratory. However, in
practice this is not possible and development of suitable measures
to formulate the biosurfactant-producing strains with a high
viability and a long shelf-life are key issues for further research.