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Secondary metabolites and nitrogen fixation of benthic marine Cyanobacteria: how different from freshwater relatives?
www.ciimar.up.pt/project_details.php?ID=15

More:  Institutes 
Reference no: PTDC/MAR/102258/2008
Acronym: MARCYANO
Period: April 2010 till April 2013
Status: Completed

Institutes (3)  Top 
  • Ministério da Ciência e da Tecnologia; Foundation for Science and Technology (FCT), more, sponsor
  • University of Porto; Interdisciplinary Centre for Marine and Environmental Research (Porto) (CIIMAR), more, partner
  • University of Porto; Institute for Molecular and Cell Biology (IBMC), more, partner

Abstract:
The LEGE (CIIMAR) culture collection has 140 marine cyanobacteria strains isolated from different sites along the Portuguese coast, belonging to more than 40 different morphotypes. Some cyanobacteria are able to produce potent toxins and/or have the ability to fix atmospheric N2, properties with obvious ecological and environmental implications, and also with a biotechnological interest.
In this project the identification of cyanobacteria will be done a polyphasic approach, that will utilize light and transmission electron microscopy as well as molecular methods like the sequencing of the16S rRNA gene. To screen the capability of the isolates to fix atmospheric nitrogen, the presence of nifK, one of the genes encoding to the complex responsible for nitrogen fixation, the nitrogenase, will be assessed. Cyanobacteria may produce a large variety of secondary metabolites. Concerning their structure, the majority of bioactive metabolites isolated so far are polyketides, non-ribosomal peptides or a hybrid of the two. Polyketides (PK) are a large and diverse group of natural products that include antibacterial, antifungal, anticancer, antiparasitic, and immunosuppressant activities, among others. Like PK, non-ribosomal peptides (NRP) are a very diverse family of secondary metabolites with a broad range of biological properties. They are synthesized by non-ribosomal peptide synthases (NRPS) characterized by a modular organization in which each module is responsible for the activation, thiolation, modification and condensation of a amino acid unit. Secondary metabolism has evolved into the existence of hybrid PK/NRP structures. An example of a hybrid metabolite is the well known cyanobacterial metabolite microcystin. The presence of genes encoding cyanotoxins synthetases will be examined to ascertain the existence of potentially toxic isolates. For this task, the aminotransferase domain, which is located on the modules McyE and NdaF of the microcystin and nodularin synthetase enzyme complexes, will be used to distinguish possible hepatotoxigenic strains. Furthermore, lyophilized samples from the main different isolates will be analysed by MALDI-TOF mass spectrometry to evaluate the production of cyanotoxins – e.g. microcystins - or other secondary metabolites. Global biogeographic patterns in cyanobacteria have not yet been assessed. Therefore due to its wide distribution and its relevance for water quality and public health it is imperative to ellucidate the biogeographic dispersion patterns of cyanobacteria in temperate Altlantic areas.

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