مجلة الاطروحة العلمية المحكمة الاطروحه للنشر العلمي
المصاحبة للفطريات الكبيرةGlobicatella sulfidifaciensوHafnia alvei الكشف جزيئياً عن بعض جينات بكتريا
علي حسين الطيف خضير
أ.د. طالب عويد الخزرجي
أ.د. محمد نظير معروف
جامعة تكريت / كلية التربية للعلوم الصرفة / قسم علوم الحياة
Abstract
The 16s rRNA gene consists of highly conserved nucleotide sequences, interspersed with variable regions that are genus or species specific. PCR primers targeting the conserved regions of rRNA amplify variable sequences of the 16s rRNA gene. Bacteria can be identified by nucleotide sequence analysis of the PCR product followed by comparison of this sequence with known sequences stored in a database . The 16s rRNA gene sequence has been determined for a large number of strains. GenBank, the largest databank of nucleotide sequences, there are many previously deposited sequences against which to compare the sequence of an unknown strain. The 16s rRNA gene is universal in bacteria, and so relationships can be measured among all bacteria . In general, the comparison of the 16s rRNA gene sequences allows differentiation between organisms at the genus level across all major phyla of bacteria, in addition to classifying strains at multiple levels, including what we now call the species and subspecies level. The occasional exceptions to the usefulness of 16s rRNA gene sequencing usually relate to more than one well known species having the same or very similar sequences . The new edition of Bergey’s Manual of Systematic Bacteriology, the most widely used and authoritativereference on bacterial taxonomy, is organized using 16s rRNAgene sequence analysis as the backbone . An important use of 16s rRNA sequencing is the identification of clinical syndromes caused by uncultivable bacteria. These relate to infections caused by bacteria that could not be cultured reliably by known methods at the time of discovery.