[27]. PCR reaction mixtures (50 μl) contained 1× PCR buffer (ThermoPol reaction buffer, New England Biolabs, Inc., Pickering, Ontario, Canada), 200 μM of each dNTPs, 0.5 μM of each forward and reverse primers, 4% (v v-1) dimethylsulfoxide (DMSO), 2.5 units of Taq polymerase (New England Biolabs, Inc.), and an appropriate amount of template DNA. The 1× Compound C order PCR buffer (pH 8.8) is composed of 10 mM KCl, 10 mM (NH4)2SO4, 20 mM Tris-HCl, 2 mM MgSO4, and 0.1% (v v-1) Triton X-100. PCR amplification program consisted of preheating at 94°C for 4 min and 30 cycles of denaturing (94°C, 30 sec), annealing (56°C, 30 sec),

and extension (72°C, 2 min) followed by final extension at 72°C for 10 min. The DGGE analysis of PCR amplicons was performed using the Bio-Rad DCode Universal Mutation Detection System (Bio-Rad Canada, Mississauga, ON, Canada). The amplicons were separated in 10% polyacrylamide (acrylamide/bisacrylamide 35.7:0.8) gels containing a 35 to 65% gradient of urea and formamide increasing screening assay in the direction of electrophoresis. A 100% denaturing solution consisted of 7 M urea and 40% (v v-1) deionized formamide. The electrophoresis was conducted in 1× TAE buffer with 100 V at 60°C for 16 hr. DNA bands in gels were visualized by silver staining [28]. The number of DNA bands, including the presence and density, were

used to determine the richness of bacterial populations. The LY2606368 nmr BioNumerics software (version 3.0, Applied Maths, Sint-Martens-Latem, Belgium) was used for similarity analyses of the profiles as described previously [29]. Extraction and quantification of DON and DOM-1 The detailed Protirelin procedures of DON extraction and quantification were described previously [20]. Briefly, DON was extracted from a bacterial culture using acetonitrile. The extracts were dissolved in methanol/water (1:1 in volume) and filtered through

a C18 SPE cartridge (Phenomenex, Torrance, CA, USA). The extracts were analyzed for DON and DOM-1 by injecting 20 μl aliquot into an Agilent Zorbax Eclipse XDB-C18 column (4.6 × 150 mm, 3.5 μm) followed by detection with a ThermoFinnigan SpectraSystem UV6000LP detector and a ThermoFinnigan LCQ Deca MS spectrometer. The MS was operated in the positive APCI mode. DON or DOM-1 were quantified on the basis of integrated peak areas using absorbance units (UV) at 218 nm or multiple ion counts (MS) at m/z 231, 249, 267, 279, and 297 for DON and m/z 215, 233, 245, 251, 263, and 281 for DOM-1. These values were compared against UV and MS values taken from calibration curves of authentic DON and DOM-1. The ratio of DON to DOM-1 transformation was calculated as: Transformation ratio = (DOM-1)/(DON + DOM-1) × 100. Selection of DON-transforming bacterial isolates An integrated approach was designed to select DON-transforming bacterial isolates from intestinal digesta samples (Fig. 2).