Fermentation technologies for the production of exopolysaccharide-synthesizing Lactobacillus rhamnosus concentrated cultures

Abstract

Abbreviations:AS The exopolysaccharide (EPS)-producing cultures such as Lactobacillus rhamnosus RW-9595M present a challenge for the culture producers because the high viscosity of the fermented growth medium makes it difficult to recover the cells by centrifugation or filtration. This study examined four approaches to reduce viscosity of the medium while producing high cell densities: incubation temperature, extended incubation in the stationary growth phase, production in alginate gel beads and fed-batch fermentation technology. Automated spectrophotometry (AS) was used to study the effects of temperature, pH and lactate level on growth of the strain. In AS assays, there was no significant difference in final maximal biomass *Corresponding author production at temperatures ranging between 34ºC to 44ºC, but lower yields were noted at 46ºC. A pH below 6.0 and a lactate concentration higher than 4% almost completely prevented growth. Under batch fermentation conditions, the viscosity of the medium obtained at 37ºC was two fold higher than for 44ºC. For cultures produced at 37ºC, centrifugation at 10000 g during 5 min did not allow complete recovery of cells, in contrast to cultures grown at 44ºC. An extended period of incubation (5 hrs) in the stationary growth phase did not reduce the final viscosity of the growth medium. For similar biomass levels, the glucose-based fed-batch fermentation allowed a 40% reduction in viscosity of the fermented medium in comparison to traditional batch

Novel Techniques in the Production of Industrially Imperative Products

“…The exopolysaccharide (EPS)-producing cultures such as Lactobacillus rhamnosus RW-9595M present a challenge for the culture producers because the high viscosity of the fermented growth medium make it difficult to recover the cells by centrifugation or filtration [62]. Study has been carried out in order to make it feasible for separation of cells from the culture.…”

“…In addition to their technological benefits, LAB EPS have been recognized to have antitumor, antiulcer and blood cholesterol lowering activities, as well as the capability to enhance the immune system. Therefore EPS- producing strains are of commercial value for both their technological and putative probiotic properties [62] (Figure 5).…”

Structural characterization and biological activity of exopolysaccharide from Lysinibacillus fusiformis

“…This can be solved by optimising the inoculation methodology and the fermentation conditions. A high EPS production could result in the formation of a highly viscous fermentation broth, making the recovery of cells and further downstream processing difficult (Champagne et al, 2007).…”

The growth and recovery of an exopolysaccharide-producing Lactobacillus rhamnosus culture on growth media containing apple juice or molasses

“…Analyses: Viscosity, ease of recovery to centrifugation and bacterial counts of the fermented broths were measured as described by Champagne et al (2007). OD measurements were done at 600 nm using a Beckman (Fullerton, CA, USA) DU-7400 instrument.…”

“…Recovery of growth media on viscosity: Lactobacillus rhamnosus RW-9595M is a very high exopolysaccharide (EPS) producer (Macedo et al, 2002). The EPS increases the viscosity of the medium and makes it difficult to recover the cells by centrifugation (Champagne et al, 2007). This was the case since centrifugation at 4,000 g for 5 min only removed half the biomass.…”