title: Impact of osmotic/matric stress and heat shock on environmental tolerance induction of bacterial biocontrol agents against Fusarium verticillioides.
abstract: Bacillus amyloliquefaciens and Microbacterium oleovorans reduced the Fusarium verticillioides count and significantly decreased fumonisin B(1) and B(2) levels in maize grains. The aim of this study was to determine the effect of water stress tolerance and heat shock survival upon cells of the biocontrol agents B. amyloliquefaciens and M. oleovorans. The a(w) of solid and liquid media and tryptic soy medium was modified to 0.99, 0.98, 0.97 and 0.96 by addition of ionic solute NaCl and non-ionic solutes such as glycerol and glucose. The non-ionic solute polyethylene glycol 600 (PEG 600) was used to modify matrically solid media. Bacterial incubation was at 30 °C. After 24, 48 and 72 h of incubation, samples from liquid media were spread-plate on nutrient agar medium and incubated for 24 h to determine the number of viable cells. The bacterial cells were harvested by centrifugation and heat treatment carried out in a water bath at 45 °C for 30 min. The viability of cells from different incubation times in liquid media showed statistically significant differences. Cells of B. amyloliquefaciens grown in liquid media amended with glycerol showed better tolerance at low a(w) and high survival under heat stress. These results could have important implications for optimizing and improving formulations.
authors.affiliation: Agencia Nacional de Promoción Científica y Tecnológica (FONCYT), Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, km 601, 5800, Río Cuarto, Córdoba, Argentina.
authors.forename: Melina
authors.initials: M
authors.lastname: Sartori
authors.forename: Andrea
authors.initials: A
authors.lastname: Nesci
authors.forename: Miriam
authors.initials: M
authors.lastname: Etcheverry
mesh_terms: D000192:Actinomycetales / Q000502:physiology*; D000898:Antibiosis; D001407:Bacillus / Q000502:physiology*; D003470:Culture Media; D005516:Food Microbiology; D005670:Fusarium / Q000502:physiology*; D005947:Glucose; D005990:Glycerol; D018869:Heat-Shock Response; D006358:Hot Temperature; D050296:Microbial Viability; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D012965:Sodium Chloride; D012988:Soil Microbiology; D013312:Stress, Physiological; D003313:Zea mays / Q000382:microbiology*
chemical_list: D003470:Culture Media; D012965:Sodium Chloride; D005947:Glucose; D005990:Glycerol