Formulation development of the biocontrol agent Bacillus subtilis strain CPAâ8 by sprayâdrying
2012
YánezâMendizábal, V. | Viñas, I. | Usall, J. | Torres, R. | Solsona, C. | Abadias, M. | Teixidó, N.
Aims: To prepare commercially acceptable formulations of Bacillus subtilis CPAâ8 by sprayâdrying with long storage life and retained efficacy to control peach and nectarine brown rot caused by Monilinia spp. Methods and Results: CPAâ8 24âhâ and 72âhâold cultures were spray dried using 10% skimmed milk, 10% skimmed milk plus 10% MgSO4, 10% MgSO4 and 20% MgSO4 as carriers/protectants. All carriers/protectants gave good percentages of powder recovery (28–38%) and moisture content (7–13%). CPAâ8 survival varied considerably among sprayâdried 24âhâ and 72âhâold cultures. Seventyâtwo hours culture spray dried formulations showed the highest survival (28–32%) with final concentration products of 1·6–3·3â×â109âCFUâg−1, while viability of 24âhâold formulations was lower than 1%. Sprayâdried 72âhâold formulations were selected to subsequent evaluation. Rehydration of cells with water provided a good recovery of CPAâ8 dried cells, similar to other complex rehydration media tested. Sprayâdried formulations stored at 4â±â1 and 20â±â1°C showed good shelf life during 6âmonths, and viability was maintained or slightly decreased by 0·2–0·3âlog. CPAâ8 formulations after 4â and 6âmonths storage were effective in controlling brown rot caused by Monilinia spp. on nectarines and peaches resulting in a 90–100% reduction in disease incidence. Conclusions: Stable and effective formulations of biocontrol agent B. subtilis CPAâ8 could be obtained by sprayâdrying. Significance and Impact of the Study: New shelfâstable and effective formulations of a biocontrol agent have been obtained by sprayâdrying to control brown rot on peach.
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