2.6. Identification of selected bacterial isolates
Taxonomic identification of bacterial isolates showing potential for fipronil
metabolization was based upon broad morphological characteristics (shape and
arrangement of bacterial cells, grams reaction) and 16s ribosomal RNA (16s rRNA)
nucleotide sequence homology with GenBank database of NCBI (National Center for
Biotechnology Information) as described below:
Bacterial DNA isolation: A loopful of bacterial mass taken from an isolated clone on
LB-agar plate was inoculated into 3 ml of Luria Broth (LB) and allowed to grow for 48 h
at 2871 1C on an orbital shaker (150 rpm). The bacterial cell mass was harvested in
pellet by centrifugation at 10,000 rpm for 1 min. The cell mass was lyzed by
suspending in 10 mM Tris EDTA buffer (TE) containing 20 mg ml−1 lysozyme, followed
by incubation at RT for 10 min. The cellular proteins in the lysate were removed by
three extractions with phenol:chloroform (1:1 v/v) followed by chloroform:isoamyl
alcohol (25:1 v/v). The total DNA in the aqueous phase was precipitated with equal
volume of isopropanol in the presence of 0.25 M sodium acetate, pH 5.2. The bacterial
DNA was collected in pellet by centrifugation at 10,000 rpm, for 5 min. The DNA pellet
was washed once with 70% ethanol and allowed to dry at RT. The Dried DNA pellet was
dissolved in 100 μl of TE buffer and stored at −20 1C until used. The quality of DNA
isolated from bacteria was determined by horizontal agarose 0.7 per cent containing
ethidium bromide @1 mg per ml gel electrophoresis in 1 TAE (Tris Acetate EDTA)
buffer at 75 V for 1 h. The DNA bands were visualized and photographed under a UV
transilluminator in ‘UltraCam Gel documentation system’.
2.6. Identification of selected bacterial isolatesTaxonomic identification of bacterial isolates showing potential for fipronilmetabolization was based upon broad morphological characteristics (shape andarrangement of bacterial cells, grams reaction) and 16s ribosomal RNA (16s rRNA)nucleotide sequence homology with GenBank database of NCBI (National Center forBiotechnology Information) as described below:Bacterial DNA isolation: A loopful of bacterial mass taken from an isolated clone onLB-agar plate was inoculated into 3 ml of Luria Broth (LB) and allowed to grow for 48 hat 2871 1C on an orbital shaker (150 rpm). The bacterial cell mass was harvested inpellet by centrifugation at 10,000 rpm for 1 min. The cell mass was lyzed bysuspending in 10 mM Tris EDTA buffer (TE) containing 20 mg ml−1 lysozyme, followedby incubation at RT for 10 min. The cellular proteins in the lysate were removed bythree extractions with phenol:chloroform (1:1 v/v) followed by chloroform:isoamylalcohol (25:1 v/v). The total DNA in the aqueous phase was precipitated with equalvolume of isopropanol in the presence of 0.25 M sodium acetate, pH 5.2. The bacterialDNA was collected in pellet by centrifugation at 10,000 rpm, for 5 min. The DNA pelletwas washed once with 70% ethanol and allowed to dry at RT. The Dried DNA pellet wasdissolved in 100 μl of TE buffer and stored at −20 1C until used. The quality of DNAแยกต่างหากจากแบคทีเรียถูกกำหนด โดยประกอบด้วยร้อยละ 0.7 ของ agarose แนวนอนethidium โบรไมด์ @1 มก.ต่อมล.เจ electrophoresis ในเต้ 1 (ทริสเรทติ้ง Acetate EDTA)บัฟเฟอร์ที่ 75 V สำหรับ 1 h Visualized และถ่ายภาพภายใต้ UV เป็นแถบดีเอ็นเอtransilluminator 'UltraCam เจเอกสารระบบ'
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