Search

Lactobacillus paracasei FT700 was tested for its survival in simulated gastrointestinal conditions ( in vitro ) and for its sensitivity to antibiotics. The strain was used to produce fermented milk and the cell-free supernatant was freeze-dried and applied in cell cultures (monocytes and macrophages) to evaluate its cytotoxicity and immunomodulatory effects. After 180 min at pH 2.0 or in simulated gastric juice, L. paracasei FT700 concentrations were reduced by 4 and 3 log cfu/mL, respectively. Moreover, the strain was susceptible to the majority of antibiotics tested. Freeze dried cell-free fermented milk supernatant (FMS) was toxic to monocytes after 72 h of exposure at 10 mg/mL inducing their apoptosis. However, at concentrations below toxic level, FMS stimulated the differentiation of monocytes into macrophages, as observed by the increased expression of CD71 marker. This immune stimulation was not inflammatory since low production of TNF-α was observed. Overall, L. paracasei FT700 has potential to be used as probiotic in functional fermented milk. [ABSTRACT FROM AUTHOR]

Summary: A strain of an unidentified strictly anoxic, Gram-postive, non-motile Ruminococcus-like bacterium was isolated from a human faecal sample. The organism used carbohydrates as fermentable substrates, produced acetate, succinate, and hydrogen as the major products of glucose metabolism, and possessed a G + C content of 43.3 mol%. The morphological and biochemical characteristics of the organism were consistent with its assignment to the genus Ruminococcus but it did not correspond to any recognized species of this genus. Comparative 16S rRNA gene sequencing showed the unidentified bacterium represents a previously unrecognised sub-line within the Clostridium coccoides rRNA group of organisms. The nearest relative of the unknown bacterium corresponded to Ruminococcus obeum but a 16S rRNA sequence divergence value of >3% demonstrated it represents a different species. Based on the presented findings a new species, Ruminococcus luti, is described. The type strain of Ruminococcus luti is BInIXT (DSM 14534T, CCUG 45635T). [Copyright &y& Elsevier]