The design of ligation probes was based on identification of target-specific nucleotide positions by using sequence alignments and NCBI’s Primer-BLAST. First, for those target reads that matched with at least 94% similarity to a full length 16 S rRNA gene in NCBI database, the corresponding 16 S sequences were collected and incorporated Sapanisertib into a Greengenes prokaryote 16 S reference database [38].

The minimum length cutoff in the Greengenes database was 1250 bp. A second alignment was constructed of the short pyrosequencing reads representing OTUs. For both alignments, an algorithm that screens for single nucleotide differences was implemented in R-software [39] using Biostrings package [40]. If a specific nucleotide position was identified for a given target sequence, the 3′ end of discriminating ligation probe was set to match that

position. If no such site was found, Primer-BLAST at the NCBI website was employed to find probe candidates for that target sequence. In Primer-BLAST, the nr/nt database was used as reference and primer stringency settings included at least two non-target mismatches in the last four nucleotides in the 3′ end. Finally, the Tms of selected GDC 0032 cost probes were set to 60 °C and 64 °C for the discriminating and common parts, respectively, using thermodynamic nearest neighbour calculation in Oligocalc software [41]. A schematic of the technique is presented in Figure 3. Figure 3 Schematic figure presenting the principle of the microarray technique. (1.) A linear ssDNA probe containing target recognition sequences at 5’ and 3’ termini is hybridised to environmental gDNA. The probe is ligated into a circular molecule if a complementary target sequence is present. (2.) Circular probe is PCR amplified with 5’ phosphorylated forward Bumetanide and 5’ Cy3 labeled reverse primer and

(3.) thereafter the phosphorylated strand is degraded. (4.) The Cy3-labeled products are hybridised on a microarray harbouring complementary ZipCode sequences and a common control probe sequence. Control probe carries a 6-Fam label. Probe library preparation The custom oligo library was synthesised by Agilent (Santa Clara, CA) at 10 pmol scale. The dried oligo library, containing 70 fmol of each probe, was dissolved into 70 μl of water and aliquoted to 7 X 10 μl. An aliquot was phosphorylated in a reaction containing 1X PNK buffer A (Fermentas,Lithauen), 0.5 mM ATP and 1 μl of PNK (Fermentas, Lithauen) in a 20 μl volume. The reaction was incubated at 37 °C for 45 min followed by inactivation at 65 °C for 10 min. 30 μl of 0.1X TE buffer was added for final volume of 50 μl and concentration of 400 amol/μl/probe. Template fill-in In order to validate the probes, we designed 96 oligonucleotide templates each consisting of two partially overlapping 50-mer parts. To Palbociclib ic50 produce 80-mer double stranded templates from the two oligos, a fill-in reaction containing 1X TrueStart buffer (Fermentas,Lithauen), 1.