The remaining outer membrane fraction was sedimented by centrifugation at 15,000 g for 15 min. The outer membrane was washed with 10 mM Tris-HCl (pH 7.2) and suspended in 1 mL buffer. The lipase located in the cell fraction was detected by immunoblotting. PD0325901 ic50 The cell, culture supernatant, periplasmic, and outer membrane fractions were separated by SDS-PAGE as described by Laemmli using slab gels (24). To separate by SDS-PAGE, 50 μL of each sample prepared from the culture supernatant, periplasm, and outer membrane was solubilized with 50 μL loading solution for SDS-PAGE and a portion (10 μL) of the sample loaded onto each lane of
SDS-polyacrylamide gel. After electrophoresis, the proteins were electrophoretically transferred onto PVDF membranes (Millipore). These membranes were reacted with antiserum against the lipase, and then horseradish peroxidase-conjugated donkey anti-rabbit IgG (GE Healthcare, Little Chalfont, UK), as described by Towbin et al. (25). Two strains, A. sobria 288 (asp+, amp+) and A. sobria 288 (asp−, amp−), were pre-cultured overnight in NB (0.5) at 37°C with shaking. A portion of the overnight precultures (0.5 mL) was inoculated into 50 mL NB (0.5) and NB (3.0). The bacteria were grown at 37°C with shaking at 140 r.p.m. At 3 hrs, 6 hrs, 9 hrs, 12 hrs and 24 hrs, 10 mL of each culture was removed and
the cells harvested by centrifugation. The total RNAs of these cells were extracted, treated with DNaseI (Takara; Shiga, Japan) and purified as described previously Interleukin-3 receptor (22). The obtained
selleck products RNAs were dissolved in RNase-free water. A portion of RNA solution was mixed with an equal volume of denaturation buffer (0.18 M sodium citrate, 1.8 M sodium chloride, 14.8% formaldehyde (pH 7.0)), according to the manufacturer’s protocol for the DIG system (Roche Diagnostics, Mannheim, Germany). The RNA mixtures were spotted onto nylon membranes, which were baked for 30 min at 120°C. The probe was prepared from the DNA fragment from the 413th to the 599th amino acid residue from the amino terminal of the lipase. The DNA fragment was labeled with digoxigenin using a DIG DNA Labeling Kit (Roche Diagnostics) and used as a probe. The RNAs on the nylon membranes were hybridized with the probe and the hybridization signals detected according to the manual supplied with the DIG Nucleic Acid Detection Kit (Roche Diagnostics). Chemiluminescence was detected using LAS3000mini (Fujifilm, Tokyo, Japan). Five hundred ng of each RNA sample was reverse transcribed with random 6-mer primer using Prime Script RT reagent Kit (Takara). Reverse transcription was performed according to the manufacturer’s protocol. Part of the obtained cDNA was used as a template for quantitative real-time PCR. Real-time PCR was performed using iQ SYBR Green supermix (Bio Rad) and MiniOpticon System (Bio Rad). For this study, the mRNA of lipase gene and 16S rRNA were each detected using specific primers.