johnsonii only at the strain level. tRFLP analysis of a narrow spectrum of fecal LAB populations demonstrated host specificity of L. intestinalis and the E. faecium cluster at the species level of bacteria. Both observations suggest co-evolution of the bacteria,
either at the species or the strain level, with distinct animal species. The identified bacterial host specificity may be further applied to utilization of health-promoting specific strains based on the bacterium and the Ku-0059436 clinical trial host’s genetics, as part of the personalized medicine approach. Methods Isolation procedure and growth conditions A total of 104 samples were collected from a wide variety of animal hosts, originated in 58 animal species. Samples were collected in Israel during a 1.5 year
period (January 2009 – June 2010). 102 samples were feces samples, and 2 were bird pellets, i.e the materials regurgitated by the birds (see Additional file 1: Origin of samples collected from 104 animal hosts). Each sample, obtained from individual host, was treated and analyzed separately. Samples were kept at 4°C in 0.1 M sodium phosphate buffer pH 7 until arrival to the lab (up to 4 h from the collection time) and processed immediately. 0.1 M sodium phosphate buffer pH 7 was added to a final concentration of 10% (w/v), to equally normalize the growth of this website fecal bacteria from all samples (see below) according the feces weight. Samples were homogenized by vigorous vortexing,
followed by centrifugation at 1500 × g, at 4°C for 5 min. The supernatant containing the bacterial suspension was transferred to a clean tube. A 100 μ l aliquot of bacterial suspension was spread on either MRS agar (de Man, Rogosa, Sharpe; Oxoid, UK) or DIFCO m-Enterococcus agar plates (BD, Maryland, USA), and grown under both aerobic and anaerobic conditions at 37°C for 48 h. mEnterococcus agar was used to isolate L. johnsonii based on our previous study [8]. Total DNA was extracted from samples of the bacterial populations grown on the anaerobically incubated Isotretinoin mEnterococcus agar plates and terminal restriction fragment length polymorphism (tRFLP) was performed, in order to assess the presence of L. johnsonii within the total bacterial population that grew on the plate. tRFLP was conducted only for plates that presented massive bacterial growth, estimated at few dozen colonies and more (plates from 62 samples). These samples belong to hosts from six taxonomic classes, in which Mammalia (34 samples) and Aves (18 samples) were the most abundant. The mammalian hosts belonged to eight different orders, most from Rodentia (15 samples) and Carnivora (9 samples). Totally, the 62 samples belong to 50 different animal species. To isolate L. johnsonii, aerobically and anaerobically incubated mEnterococcus and MRS agar plates were screened for L.