Use of the Gen 18S, as a genetic marker for the molecular identification of epilithic dietoms

Abstract

The task presented was based on evaluating the potential use of the 18SV4 gene as a DNA barcode in the epilithic diatoms of Ecuador, evaluating and verifying its ability to differentiate between species and the feasibility of using universal primers. For this it was necessary to analyze the sequences of epilithic diatoms of different origins, by analyzing their alignment, which determined the regions that presented interspecific variability, and the flanking zones that allow their amplification in all species. Diatomaceous cultures were established in the CHU # 10 culture medium, in order to perform the molecular analyzes, DNA extraction and PCR amplification. A pure culture could not be obtained, so the work was carried out with a mixed culture of green algae and diatoms in which four species of diatoms were observed under a microscope, which were then identified with the use of taxonomic guides. The DNA of the specific culture was extracted by two methods: The process using the Powersoil DNA isolation kit and the extraction buffer method. The conditions were established for the amplification by PCR and finally a DGGE was made that allowed the separation of the DNA bands of 3 of the 4 species present in the crop: Gomphonema langenula, Gomphonema parvulum, Navicula cataracta-rheni and Nitzchia acidoclinata.