The biosynthesis of cyanobacterial sunscreen scytonemin in intertidal microbial mat communities - PubMed (original) (raw)

The biosynthesis of cyanobacterial sunscreen scytonemin in intertidal microbial mat communities

Emily P Balskus et al. FEMS Microbiol Ecol. 2011 Aug.

Abstract

We have examined the biosynthesis and accumulation of cyanobacterial sunscreening pigment scytonemin within intertidal microbial mat communities using a combination of chemical, molecular, and phylogenetic approaches. Both laminated (layered) and nonlaminated mats contained scytonemin, with morphologically distinct mats having different cyanobacterial community compositions. Within laminated microbial mats, regions with and without scytonemin had different dominant oxygenic phototrophs, with scytonemin-producing areas consisting primarily of Lyngbya aestuarii and scytonemin-deficient areas dominated by a eukaryotic alga. The nonlaminated mat was populated by a diverse group of cyanobacteria and did not contain algae. The amplification and phylogenetic assignment of scytonemin biosynthetic gene scyC from laminated mat samples confirmed that the dominant cyanobacterium in these areas, L. aestuarii, is likely responsible for sunscreen production. This study is the first to utilize an understanding of the molecular basis of scytonemin assembly to explore its synthesis and function within natural microbial communities.

© 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

PubMed Disclaimer

Figures

Figure 1

Figure 1

A) The structures of scytonemin and reduced scytonemin. B) Proposed biosynthetic pathway for scytonemin production with biochemically characterized enzymatic transformations.

Figure 2

Figure 2

Photographs of Little Sippewissett microbial mats. A) Mat 1 B) Detail of Mat 1 surface with dark green, leathery scytonemin-producing areas and lighter green, felt-like areas without scytonemin. C) Mat 5 D) Mat 6 E) Isolated scytonemin from mat samples.

Figure 3

Figure 3

Maximum likelihood phylogeny of 16S rRNA gene sequences from microbial mats. The tree was compiled by maximum likelihood using PHYML. Bootstrap confidence values >50 are indicated on the nodes. Strains are indicated after species names, followed by the accession number in parenthesis. Sequences are colored according to library (red = Mat 1A [scytonemin producing area], green = Mat 1B [scytonemin deficient area], blue = Mat 5, orange = Mat 6).

Figure 4

Figure 4

Maximum likelihood phylogeny of A) Lyngbya and B) chloroplast 16S rRNA gene sequences from microbial mats. The tree was compiled by maximum likelihood using PHYML. Bootstrap confidence values >50 are indicated on the nodes. Strains are indicated after species names, followed by the accession number in parenthesis.

Figure 4

Figure 4

Maximum likelihood phylogeny of A) Lyngbya and B) chloroplast 16S rRNA gene sequences from microbial mats. The tree was compiled by maximum likelihood using PHYML. Bootstrap confidence values >50 are indicated on the nodes. Strains are indicated after species names, followed by the accession number in parenthesis.

Figure 5

Figure 5

Richness and diversity analyses of microbial mat 16S rRNA gene clone libraries. The operational taxonomic unit definition used in all analyses corresponds to 98% DNA sequence identity (OTU0.02). A) UPGMA dendrogram of the similarity between clone libraries (including cyanobacterial and chloroplastic sequences). B) Venn diagram representing the number of OTU0.02 shared by the clone libraries (including cyanobacterial and chloroplastic sequences). The total number of OTUs in each library is shown in brackets. C) Rarefaction curves for the cyanobacterial sequences of the three largest clone libraries. Error bars represent a 95% confidence interval.

Figure 6

Figure 6

Maximum likelihood phylogenetic tree of translated ScyC amino acid sequences from sequenced cyanobacteria and Mats 1 and 5. The tree was compiled by maximum likelihood using PHYML. Bootstrap confidence values >50 are indicated on the nodes. The number in parentheses found after each taxon name is the accession number for the respective protein sequence.

Similar articles

Cited by

References

    1. Balskus EP, Walsh CT. Investigating the initial steps in the biosynthesis of cyanobacterial sunscreen scytonemin. J Am Chem Soc. 2008;130:15260–15261. - PMC - PubMed
    1. Balskus EP, Walsh CT. An enzymatic cyclopentyl[b]indole formation involved in scytonemin bisynthesis. J Am Chem Soc. 2009;131:14648–14649. - PMC - PubMed
    1. Bebout BM, Garcia-Pichel F. UV-B induced vertical migrations of cyanobacteria in a microbial mat. Appl Eviron Microbiol. 1995;61:4215–4222. - PMC - PubMed
    1. Berry JP, Gantar M, Perez MH, Berry G, Noriega FG. Cyanobacterial toxins as allelochemicals with potential applications as algaecides, herbicides, and insecticides. Mar Drugs. 2008;6:117–146. - PMC - PubMed
    1. Branowitz S, Castenholz R. Long-term effects of UV and visible irradiance on natural populations of a scytonemin-containing cyanobacteriam (Calothrix sp.) FEMS Microbiol Ecol. 1997;24:343–352.

Publication types

MeSH terms

Substances

Grants and funding

LinkOut - more resources