Abstract
BackgroundIt is generally believed that there are many natural sources of as yet unknown bioactive compounds with a high biotechnological potential. However, the common method based on the use of cell extracts in the preliminary screening for particular molecules or activities is problematic as amounts of obtained compounds may be low, and such experiments are hardly reproducible. Therefore, the aim of this work was to test whether a novel strategy to search for previously unknown biological activities can be efficient. This strategy is based on construction of metagenomic libraries and employment of Escherichia coli strains as cell factories producing compounds of properties potentially useful in biotechnology.ResultsThree cyanobacterial metagenomic libraries were constructed in the fosmid system. The libraries were screened for various biological activities. Extracts from selected E. coli clones bearing constructs with fragments of cyanobacterial genomes revealed antimicrobial or anticancer activities. Interestingly, stimulation of growth of host bacteria bearing particular plasmids with certain cyanobacterial genes was detected, suggesting a potential possibility for improvement of E. coli cultivation during biotechnological production. The most interesting plasmids were sequenced, and putative mechanisms of biological effects caused by cyanobacterial gene products are discussed.ConclusionsThe strategy of exploring cyanobacteria as sources of bioactive compounds, based on E. coli cell factories producing compounds due to expression of genes from metagenomic libraries, appears to be effective.
Highlights
It is generally believed that there are many natural sources of as yet unknown bioactive compounds with a high biotechnological potential
The aim of this work was to test whether a novel strategy, based on the use fosmid metagenomic libraries to search for biological activities appearing in Escherichia coli host cells bearing plasmids with fragments of cyanobacterial genomes, can be effective in detecting biotechnologically interesting features
Construction of cyanobacterial metagenomic libraries Three fosmid-based libraries of cyanobacterial metagenomes have been constructed. They were prepared using genomic DNA, isolated according to previously published procedure [13], derived from: (a) a bloom of Nodularia sp. which occurred in Gdańsk Bay, Baltic Sea (Poland) in June 2009; library 1; (b) a bloom of Nodularia sp. and Aphanizomenon flos-aquae which occurred in Gdańsk Bay, Baltic Sea (Poland) in May 2011; library 2; and (c) cultures of 5 marine cyanobacteria, isolated from Baltic Sea and cultured in laboratory: Microcystis aeruginosa CCNP 1101, Microcystis aeruginosa CCNP 1102, Microcystis aeruginosa CCNP 1103, Anabaena sp
Summary
It is generally believed that there are many natural sources of as yet unknown bioactive compounds with a high biotechnological potential. The aim of this work was to test whether a novel strategy to search for previously unknown biological activities can be efficient This strategy is based on construction of metagenomic libraries and employment of Escherichia coli strains as cell factories producing compounds of properties potentially useful in biotechnology. Cyanobacteria, called blue-green algae, appear to be potentially rich sources of bioactive compounds [1] They are photosynthesizing prokaryotic organisms, occupying marine, freshwater and terrestrial habitats, and belong to the oldest biological groups on Earth. It appears that marine cyanobacteria may be rich in biotechnologically and pharmacologically useful molecules [2], it is considered that they are underexploited in this matter [3]. This is perhaps, at least in part, due to publication of papers reporting isolation of various compounds from cyanobacteria, including those possessing antiviral, antibacterial, antifungal and anticancer activities (summarized in ref. [5])
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