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

CommunicationProbiotics can be defined as "Live microorganisms which, when administered in adequate amounts, confer a health benefit on the host" (Araya et al., 2002).Of the various lactobacilli being used as probiotics, Lactobacillus acidophilus has been the most widely studied (Champagne et al., 2005).Less is known, however, on the production and use of Lactobacillus rhamnosus in foods, even though some strains, particularly GG and R0011, have been shown to be valuable probiotics (Ouwehand et al., 2003).Strain L. rhamnosus RW-9595M is a very high exopolysaccharide (EPS) producer (Macedo et al., 2002) which is of interest to the food industry because of beneficial effects on texture and yields (Broadbent et al., 2001;De Vuyst et al., 2001) as well as for potential EPS-linked health benefits (Ruas-Madiedo et al., 2002).Additionally, the RW-9595M strain used in this study shows potential for the enhancement of the immune system (Chabot et al., 2001).Culture manufacturers must propagate the strains in appropriate media, recover the cells and freeze or dry them.Commercial media such as Lactobacilli MRS are expensive to use at the industrial scale (Garcia et al., 2006).Furthermore some consumers ask for products that do not contain meat or dairy ingredients as well as have Kosher certification.In response to these demands, producers of probiotic cultures are constantly challenged to develop novel growth media, particularly fruit or vegetable-based.In this study, we examined apple juice and molasses for this purpose and if it is possible to recover this EPS-producing culture by centrifugation.Culture and media: Lactobacillus rhamnosus RW-9595M was obtained from the Agriculture and Agri-Food Canadaʼs Food R & D Centre.Cultures were prepared as described by Champagne et al. (2007).For the screening of growth media, three commercial substrates were used: molasses (65% total solids; Gramma, St-John, NB, Canada), apple juice concentrate (40% total solids; McCain, Florenceville, NB, Canada), and Lactobacilli MRS medium (Difco; Becton Dickinson, Sparks, MD, USA).Bakerʼs yeast extracts (YE) were FNI-100 (Lallemand, Montréal, QC, Canada) and Difco (Becton-Dickinson), while FNI-200 (Lallemand) was a brewerʼs YE.Three peptones from Organotechnie (La Courneuve, France) were also assayed: N1 tryptone, E1 wheat and A3 soy peptone. 1)

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