, 2008). Fucose was generally not metabolized and limited conversion was only observed in L. plantarum buy A-769662 and L. acidophilus. Fucose internalization and utilization systems have been previously identified in the anaerobic human gut bacterium Roseburia inulinivorans, and in Escherichia coli (Hacking & Lin, 1977; Scott et al., 2006), but not

in LAB. Lactobacillus reuteri, L. fermentum, L. mesenteroides subsp. cremoris and S. thermophilus hydrolysed GOS but not the more complex HMOs. GOS hydrolysis generally correlated with high activity on oNPG and pNPG, which indicated the expression of β-galactosidases. Lactobacillus reuteri expresses its LacLM β-galactosidases during growth in the presence of lactose (Nguyen et al., 2006). The role of β-galactosidases in GOS degradation was further confirmed by the release of glucose and galactose by heterologously expressed GH2 β-galactosidases of the LacLM and LacZ type. In contrast to bifidobacteria, which express both intracellular and extracellular β-galactosidases (Møller et al., 2001;

Goulas et al., 2007), β-galactosidases of strains of the genera Lactobacillus, Streptocococcus and Leuconostoc are located in the cytoplasm (Fortina et al., 2003; Nguyen et al., 2006, 2007). Transport enzymes for AP24534 price GOSs have not been identified and the lack of transport systems for GOSs explains the preference of LAB for GOSs with a low degree of polymerization (Gopal et al., 2001). GOSs synthesized by LAB β-galactosidases mainly contain di- and trisaccharides, which are dominantly β-(1–3) or β-(1–6) linked (Toba et al., 1981; Splechtna et al., 2006). Di- and trisaccharides present in GOS preparations are possibly internalized by lactose permeases of LAB. In summary, LAB are isolated from the faeces of neonates but are not able to digest complex HMOs. Therefore LAB depend on the presence of bifidobacteria

or other gut microorganisms capable of releasing monosaccharide components from HMOs. HMO components lactose, glucose, N-acetylglucosamine and fucose were fermented by strains of LAB to various extents. all β-Galactosidases contribute to GOS fermentation but do not degrade HMOs. The preference of LAB for GOS might contribute to their persistence in the faeces of infants fed with a formula containing GOS preparations. AVAC Ltd, ALIDF and Alberta Milk are acknowledged for financial support. M.G. acknowledges the Research Chairs of Canada for financial support. “
“This study investigated how quickly cells of the opportunistic pathogen Pseudomonas aeruginosa recover culturability after exposure to two of the most common environmental stressors present in drinking water, free chlorine and copper ions. Viable but nonculturable (VBNC) P. aeruginosa undetected by direct culturing following exposure to free chlorine or copper ions can survive in drinking water systems, with potential to recover, multiply, and regain infectivity.