CARACTERIZACIÓN MORFOLÓGICA Y MOLECULAR DE CIANOBACTERIAS FILAMENTOSAS AISLADAS DE FLORECIMIENTOS DE TRES LAGOS URBANOS EUTRÓFICOS DE LA CIUDAD DE MÉXICO

Abstract

Cyanobacteria are traditionally classified
based on morphological and ecological
traits, which can result in incorrect identifications due to phenotypic plasticity,
and in the case of isolated strains, due to
morphological changes provoked by the
culture conditions. The gene 16S rRNA is
useful for taxonomic identification, helping
to overcome the aforementioned problems.
Using morphological and molecular characteristics, we isolated and identified filamentous cyanobacteria present in blooms
in three eutrophic urban lakes in Mexico
City with the aim of recognizing genera of
cyanobacteria other than Microcystis that
may be present. Water samples were collected during March 2007, and through micromanipulation we obtained monospecific
cultures that were preliminarily identified
using morphological traits. In addition,
total DNA was extracted, and a partial region of the 16S rRNA gene was amplified
to corroborate the taxonomic identifications; these were confirmed through their
phylogenetic positioning. In this way most
of the isolated strains identified by their
morphological traits could be confirmed at
the generic level. We identified strains of
Anabaenopsis, Arthrospira, Leptolyngbya,
Limnothrix, Geitlerinema, Phormidium,
Planktolyngbya, Planktothrix, Pseudanabaena and Spirulina, showing the diversity
of cyanobacteria that could be recorded
in blooms even though the dominant taxa
could be Microcystis spp. To accurately
determine taxonomic identity we strongly
recommend the use of both techniques in
order to avoid errors due to phenotypic
variation provoked by environmental factors or culture conditions.