Production of 3-hydroxypropionaldehyde using a two-step process with Lactobacillus reuteri

3-Hydroxypropionaldehyde (3-HPA) produced by Lactobacillus reuteri is a broad-spectrum antimicrobial substance of glycerol conversion. The aim of the present work was to optimize 3-HPA production by Lb. reuteri ATCC 53608 using a two-step process. The first step was the production of Lb. reuteri cells in optimal conditions. Cells were then harvested by centrifugation and suspended in glycerol solution, which the resting cells bioconverted to 3-HPA. The effect of biomass concentration, temperature, glycerol concentration, anaerobic/micro-aerophilic conditions, and incubation time was studied for high 3-HPA production. 3-HPA accumulation was limited by the death of cells in contact with high concentrations of 3-HPA. However, a very high 3-HPA concentration of 235±3mM was obtained after 45min of incubation at 30°C in 400mM glycerol for an initial free-cell concentration of 1.6±0.3×1010 viablecells/ml. A high viability was maintained at low temperatures in the range 5-15°C, but with a slightly lower yield of 3-HPA at 5°C compared with higher temperatures, up to 37°C. Successive 1-h incubations of Lb. reuteri cells in 200mM glycerol at 15°C to tentatively reuse the cells resulted in decreasing 3-HPA concentrations at the end of each cycle, with two successful production cycles yielding high 3-HPA concentrations of 147±1mM and 128±2m

Production of 3-hydroxypropionaldehyde using a two-step process with Lactobacillus reuteri

ISSN:0175-7598ISSN:1432-061

Comparison of different methods for release of Bifidobacterium longum Bb46 from the poly(vinylpyrrolidone)-poly(vinylacetate-co-crotonic acid) interpolymer complex matrix, and the effect of grinding on the microparticles

Bifidobacteria have been efficiently encapsulated in poly(vinylpyrrolidone)-poly(vinylacetate-co-crotonic acid) (PVP:PVAc-CA) interpolymer complex formed in scCO2. Research indicated that this method improves the stability of encapsulated bacteria in simulated gastrointestinal fluids in vitro. However, further analysis indicated release of lower numbers of encapsulated bacteria from the encapsulating matrix. The aims of this study were to determine a method that would release high numbers of bacteria from the PVP:PVAc-CA interpolymer complex matrix microparticles, and furthermore, to determine the effects of milling on the morphological properties of the microparticles. Three release methods, namely sonication, homogenization in a stomacher and incubation in simulated intestinal fluid (SIF) were compared. Released viable bacteria were assayed using plate counts. Viable bacteria released using a stomacher were three orders of magnitude higher than those released by incubation and an order of magnitude higher than those released using sonication. SEM indicated no negative effects such as exposure of encapsulated bacteria on the matrix due to milling of product. Homogenization in a stomacher is the most efficient method for releasing bacteria from the PVP:PVAc-CA interpolymer complex matrix. Particle size of the PVP:PVAc-CA microparticles encapsulating bacteria can be reduced further by grinding, without exposing the enclosed bacteria.The authors would like to thank the National Research Foundation of South Africa for funding of the project.http://www.springer.com/chemistry/biotech/journal/1127