Filamentous cyanobacteria of the genus Lyngbya are important
contributors to coral reef ecosystems, occasionally forming dominant
cover and impacting the health of many other co-occurring
organisms. Moreover, they are extraordinarily rich sources of bioactive
secondary metabolites, with 35% of all reported cyanobacterial
natural products deriving from this single pantropical genus.
However, the true natural product potential and life strategies of
Lyngbya strains are poorly understood because of phylogenetic
ambiguity, lack of genomic information, and their close associations
with heterotrophic bacteria and other cyanobacteria. To
gauge the natural product potential of Lyngbya and gain insights
into potential microbial interactions, we sequenced the genome
of Lyngbya majuscula 3L, a Caribbean strain that produces the
tubulin polymerization inhibitor curacin A and the molluscicide
barbamide, using a combination of Sanger and 454 sequencing
approaches. Whereas ∼293,000 nucleotides of the draft genome
are putatively dedicated to secondary metabolism, this is far too
few to encode a large suite of Lyngbya metabolites, suggesting
Lyngbya metabolites are strain specific and may be useful in species
delineation. Our analysis revealed a complex gene regulatory
network, including a large number of sigma factors and other
regulatory proteins, indicating an enhanced ability for environmental
adaptation or microbial associations. Although Lyngbya
species are reported to fix nitrogen, nitrogenase genes were not
found in the genome or by PCR of genomic DNA. Subsequent
growth experiments confirmed that L. majuscula 3L is unable to
fix atmospheric nitrogen. These unanticipated life history characteristics
challenge current views of the genus Lyngbya.
Filamentous cyanobacteria of the genus Lyngbya are importantcontributors to coral reef ecosystems, occasionally forming dominantcover and impacting the health of many other co-occurringorganisms. Moreover, they are extraordinarily rich sources of bioactivesecondary metabolites, with 35% of all reported cyanobacterialnatural products deriving from this single pantropical genus.However, the true natural product potential and life strategies ofLyngbya strains are poorly understood because of phylogeneticambiguity, lack of genomic information, and their close associationswith heterotrophic bacteria and other cyanobacteria. Togauge the natural product potential of Lyngbya and gain insightsinto potential microbial interactions, we sequenced the genomeof Lyngbya majuscula 3L, a Caribbean strain that produces thetubulin polymerization inhibitor curacin A and the molluscicidebarbamide, using a combination of Sanger and 454 sequencingapproaches. Whereas ∼293,000 nucleotides of the draft genomeare putatively dedicated to secondary metabolism, this is far toofew to encode a large suite of Lyngbya metabolites, suggestingLyngbya metabolites are strain specific and may be useful in speciesdelineation. Our analysis revealed a complex gene regulatorynetwork, including a large number of sigma factors and otherregulatory proteins, indicating an enhanced ability for environmentaladaptation or microbial associations. Although Lyngbyaspecies are reported to fix nitrogen, nitrogenase genes were notfound in the genome or by PCR of genomic DNA. Subsequentgrowth experiments confirmed that L. majuscula 3L is unable tofix atmospheric nitrogen. These unanticipated life history characteristicschallenge current views of the genus Lyngbya.
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