Fluorescent Fingerprints of Endolithic Phototrophic Cyanobacteria Living within Halite Rocks in the Atacama Desert

Roldán, Mónica; Ascaso, Carmen; Wierzchos, Jacek

doi:10.1128/aem.03428-13

Cited by 41 publications

(33 citation statements)

References 55 publications

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“…Fluorescence of these two components occurs in different cells within the filament, with no spatial overlap seen. This result indicates pigment partitioning or compartmentalized expression in HT-58-2Cyano, which has been observed in cyanobacteria within halite rocks (41). Further study is required to identify the pigment(s) producing the autofluorescence in the 513-to 616-nm wavelengths.…”

Section: Discussionmentioning

confidence: 80%

Genome Sequence and Composition of a Tolyporphin-Producing Cyanobacterium-Microbial Community

Hughes

Zhang

et al. 2017

Appl Environ Microbiol

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The cyanobacterial culture HT-58-2 was originally described as a strain of with the ability to produce tolyporphins, which comprise a family of distinct tetrapyrrole macrocycles with reported efflux pump inhibition properties. Upon reviving the culture from what was thought to be a nonextant collection, studies of culture conditions, strain characterization, phylogeny, and genomics have been undertaken. Here, HT-58-2 was shown by 16S rRNA analysis to closely align with strains and not with isolates. Light, fluorescence, and scanning electron microscopy revealed cyanobacterium filaments that are decorated with attached bacteria and associated with free bacteria. Metagenomic surveys of HT-58-2 cultures revealed a diversity of bacteria dominated by, 97% of which are species. A dimethyl sulfoxide washing procedure was found to yield enriched cyanobacterial DNA (presumably by removing community bacteria) and sequence data sufficient for genome assembly. The finished, closed HT-58-2Cyano genome consists of 7.85 Mbp (42.6% G+C) and contains 6,581 genes. All genes for biosynthesis of tetrapyrroles (e.g., heme, chlorophyll, and phycocyanobilin) and almost all for cobalamin were identified dispersed throughout the chromosome. Among the 6,177 protein-encoding genes, coding sequences (CDSs) for all but two of the eight enzymes for conversion of glutamic acid to protoporphyrinogen IX also were found within one major gene cluster. The cluster also includes 10 putative genes (and one hypothetical gene) encoding proteins with domains for a glycosyltransferase, two cytochrome P450 enzymes, and a flavin adenine dinucleotide (FAD)-binding protein. The composition of the gene cluster suggests a possible role in tolyporphin biosynthesis. A worldwide search more than 25 years ago for cyanobacterial natural products with anticancer activity identified a culture (HT-58-2) from Micronesia that produces tolyporphins. Tolyporphins are tetrapyrroles, like chlorophylls, but have several profound structural differences that reside outside the bounds of known biosynthetic pathways. To begin probing the biosynthetic origin and biological function of tolyporphins, our research has focused on studying the cyanobacterial strain, about which almost nothing has been previously reported. We find that the HT-58-2 culture is composed of the cyanobacterium and a community of associated bacteria, complicating the question of which organisms make tolyporphins. Elucidation of the cyanobacterial genome revealed an intriguing gene cluster that contains tetrapyrrole biosynthesis genes and a collection of unknown genes, suggesting that the cluster may be responsible for tolyporphin production. Knowledge of the genome and the gene cluster sharply focuses research to identify related cyanobacterial producers of tolyporphins and delineate the tolyporphin biosynthetic pathway.

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Section: Discussionmentioning

confidence: 80%

Genome Sequence and Composition of a Tolyporphin-Producing Cyanobacterium-Microbial Community

Hughes

Zhang

et al. 2017

Appl Environ Microbiol

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“…b) when observed by FM. This signal can be ascribed to the autofluorescence of chlorophyll a and phycobiliproteins, which are the components of phycobilisomes – light‐harvesting antennae of photosystem II in Cyanobacteria (Roldán et al ., ). The autofluorescence emission of intact phycobilisomes mainly arises from the red‐emitting allophycocyanin (APC) forms, with a peak between 670 and 675 nm (Gantt et al ., ), along with the red fluorescence of chlorophyll a , which is mostly in the 675–695 nm range (Brown, ; Mimuro et al ., ; Roldán et al ., ).…”

Section: Resultsmentioning

confidence: 97%

Distribution of scytonemin in endolithic microbial communities from halite crusts in the hyperarid zone of the Atacama Desert, Chile

Vítek

Jehlička

Ascaso

et al. 2014

FEMS Microbiol Ecol

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Scytonemin, a UV-screening molecule produced by certain Cyanobacteria to protect against harmful UV radiation, was studied in endolithic cyanobacterial colonies in the halite crust from one of the driest places on Earth - the hyperarid zone of the Atacama Desert. The distribution of the pigment within the evaporitic crust was studied in detail by various independent analytical methods: Raman spectroscopy (including Raman imaging); advanced microscopic observations (fluorescence microscopy, confocal laser scanning microscopy, low-temperature scanning electron microscopy); and spectrophotometric analyses. The differences in scytonemin biosynthesis were mapped within the colonized interior layers, which can be divided into scytonemin-rich and scytonemin-poor zones. A 532 nm laser for excitation proved to be an ideal excitation source with which to observe the relative content of scytonemin within a particular cell aggregate, as well as between different cell aggregates; based on the scytonemin/carotenoid Raman signal intensity ratio of selected corroborative bands for these two compounds. Significantly, scytonemin was found to accumulate within a decayed biomass in the surface portions of the halite crust. These were found to be highly enriched in both the absolute scytonemin content (as documented by UV/VIS spectrophotometry) and its content relative to other pigments associated with the cyanobacterial cells (e.g. carotenoids and chlorophyll).

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“…Microbial communities dominated by Chroococcidiposis strains inhabit halite deposits in the hyperarid core of the Atacama Desert (Wierzchos et al ). It has also been shown that cyanobacteria and associated heterotrophic bacteria reside within pore spaces in nodule‐shaped halite crusts (Ríos et al ; Roldán et al ). These lithic microbial communities have developed adaptive strategies to withstand the extreme environmental conditions that prevail in the Atacama Desert (Gómez‐Silva ), as is the case with similar communities in the Namib Desert (Stomeo et al ).…”

Section: Desertsmentioning

confidence: 99%

Extreme environments: microbiology leading to specialized metabolites

et al. 2019

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Summary The prevalence of multidrug‐resistant microbial pathogens due to the continued misuse and overuse of antibiotics in agriculture and medicine is raising the prospect of a return to the preantibiotic days of medicine at the time of diminishing numbers of drug leads. The good news is that an increased understanding of the nature and extent of microbial diversity in natural habitats coupled with the application of new technologies in microbiology and chemistry is opening up new strategies in the search for new specialized products with therapeutic properties. This review explores the premise that harsh environmental conditions in extreme biomes, notably in deserts, permafrost soils and deep‐sea sediments select for micro‐organisms, especially actinobacteria, cyanobacteria and fungi, with the potential to synthesize new druggable molecules. There is evidence over the past decade that micro‐organisms adapted to life in extreme habitats are a rich source of new specialized metabolites. Extreme habitats by their very nature tend to be fragile hence there is a need to conserve those known to be hot‐spots of novel gifted micro‐organisms needed to drive drug discovery campaigns and innovative biotechnology. This review also provides an overview of microbial‐derived molecules and their biological activities focusing on the period from 2010 until 2018, over this time 186 novel structures were isolated from 129 representatives of microbial taxa recovered from extreme habitats.

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Fluorescent Fingerprints of Endolithic Phototrophic Cyanobacteria Living within Halite Rocks in the Atacama Desert

Cited by 41 publications

References 55 publications

Genome Sequence and Composition of a Tolyporphin-Producing Cyanobacterium-Microbial Community

Genome Sequence and Composition of a Tolyporphin-Producing Cyanobacterium-Microbial Community

Distribution of scytonemin in endolithic microbial communities from halite crusts in the hyperarid zone of the Atacama Desert, Chile

Extreme environments: microbiology leading to specialized metabolites

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