|
Title:
|
DNA-based methodologies for the quantification of live and dead cells in formulated biocontrol products based on Pantoea agglomerans CPA-2
|
|
Author:
|
Soto Muñoz, Lourdes; Torres Sanchis, Rosario; Usall i Rodié, Josep; Viñas Almenar, Inmaculada; Solsona Aixalà, Cristina; Teixidó i Espasa, Neus
|
|
Notes:
|
Pantoea agglomerans strain CPA-2 is an effective biocontrol agent (BCA) against the major postharvest pathogens present on pome and citrus fruits. Dehydration, such as freeze-drying, spray-drying and fluidized bed drying is one of the best ways to formulate BCAs. In this work, the survival of CPA-2 cells after formulation was determined by dilution plating and molecular methods as qPCR alone and combined with a sample pretreatment with a propidium monoazide dye (PMA-qPCR) and they were used to calculate treatment concentrations in efficacy trials on postharvest oranges. Furthermore, no significant differences in CPA-2 survival were observed as determined by dilution plating and PMA-qPCR after both the freeze drying and fluidized bed drying processes; however, an interesting significant difference was observed in the spray dried product comparing all quantitative methods. A difference of 0.48 and 2.17 log10 CFU or cells g/dw was observed among PMA-qPCR with qPCR and dilution plating, respectively. According to our study, dilution plating was shown to be an unreliable tool for monitoring the survival of CPA-2 after spray drying. In contrast, the combination of PMA and qPCR enabled a quick and unequivocal methodology to enumerate viable and VBNC CPA-2 cells under stress-dried conditions. Efficacy trials showed that, after 3 days, spray drying formulation rehydrated with 10% non-fat skimmed milk (NFSM) was as effective as fresh cells to control Penicillium digitatum in oranges.
The authors would like to thank Svetlana Dashevskaya for her excellent technical assistance. The authors are grateful to the Spanish Government for the financial support by the national project RTA2009-0053-00-00 (Plan Nacional de I + D + I, Ministerio de Ciencia e Innovación, Spain) and to the National Council of Science and Technology of México (CONACyT) for L. Soto PhD grant 198363. |
|
Subject(s):
|
-Bed fluidized-drying
-Dilution plating
-Freeze-drying
-PMA |
|
Rights:
|
(c) Elsevier, 2015
info:eu-repo/semantics/restrictedAccess |
|
Document type:
|
Article
Article - Published version |
|
Published by:
|
Elsevier B.V.
|
|
Share:
|
|
