Membrane physical state as key parameter for the resistance of the gram-negative Bradyrhizobium japonicum to hyperosmotic treatments.

The survival of Bradyrhizobium japonicum under hyperosmotic treatments achieved at various temperatures was investigated. The bacterial viability was measured at a combination of different levels of osmotic pressure (1.4-49.

Compared tolerance to osmotic stress in various microorganisms: towards a survival prediction test.

The osmotic tolerance of microbial cells of different microorganisms was investigated as a function of glycerol concentration and temperatures. Cells displayed specific sensitivity to dehydration in glycerol solutions. The viability of Gram-negative strains (Escherichia coli, Bradyrhizobium japonicum), Gram-positive strains (Lactobacillus plantarum, L.

New drying process for lactic bacteria based on their dehydration behavior in liquid medium.

This study describes the different stages of optimization in an original drying process for lactic acid bacteria that allows the retrieval of dried samples of Lactobacillus plantarum with maximum viability. The process involves the addition of casein powder to bacterial pellets, followed by mixing and then air-drying in a fluidized bed dryer. The effects on bacterial viability of the a(w) of the casein powder and the kinetics of a(w) variation in the fluidized bed dryer are considered.

Magnitude and kinetics of rehydration influence the viability of dehydrated E. coli K-12.

The influence of rehydration conditions on the recovery of Escherichia coli K-12 was studied. The results showed that the osmotic pressure gradient of rehydration shock realized before plating greatly affected cell viability. When rehydration occurred quickly from an hyperosmotic level of 133 MPa in glycerol solution before slow rehydration by plating on an agar surface to reach initial osmotic pressure (1.

Viability of Escherichia coli after combined osmotic and thermal treatment: a plasma membrane implication.

This study investigates the influence of temperature (T) and osmotic pressure (Pi) on the viability of Escherichia coli K12 during an osmotic treatment. Osmotic shock (dehydration and rehydration within 1 s) in liquid media at different temperatures (4, 10, 30 and 37 degrees C) and different levels of osmotic pressure (26, 30, 35, 40, 82 and 133 MPa) were realized. Results show that a sudden dehydration, below 40 MPa, destroyed up to 80% of the bacterial population for each tested temperature, whereas viability was greater than 90% for an osmotic pressure less than 26 MPa.