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Advisor(s)
Abstract(s)
A major hurdle in exploitation of biocontrol agents is the limited tolerance of fluctuating environmental
conditions practically and the difficulties in developing a shelf-stable formulated product as effective as
fresh cells. Most of microorganisms are very sensitive to drying processes involved in formulation and
biological control is usually limited by the narrow range of conditions below microorganisms are able
to survive, establish and effectively control pests and diseases. P. agglomerans cells grown at low water
activities using NaCl exhibited osmotic adaptation and also demonstrated thermotolerance and desiccation
tolerance after spray drying, freeze drying and fluidized bed drying. Different formulation strategies
of P. agglomerans cells were tested in order to improve survival under field conditions and efficacy in
controlling postharvest rots, including lyophilised cells, osmotic adaptation by NaCl treatments and
additives. In general, osmotic adapted and lyophilised P. agglomerans cells showed greater survival rates
than non-osmotic adapted or fresh cells when these bacterial treatments were sprayed at field conditions.
However, this superiority was only found when additive Fungicover was added to suspension treatments.
The improved formulation of P. agglomerans provided an effective control for oranges against natural
postharvest pathogens infections and P. digitatum artificial infections. These results allowed us to conclude
that it is possible to improve environmental stress tolerance and ecological competence of P. agglomerans
by integrating certain formulation strategies. Enhancing stress tolerance and formulation strategies could
be appropriate approaches to obtain consistency and broaden the spectrum of use of biocontrol agents.
Description
Proceedings of the International Conference “Environmentally friendly and safe
technologies for quality of fruit and vegetables”, held in Universidade do Algarve, Faro,
Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924.
Keywords
Biological control Citrus Fluidized bed drying Improving environmental stress resistance Pre-harvest treatments Spray drying