Characteristics and role of the exocellular polysaccharides produced by five cyanobacteria isolated from phototrophic biofilms growing on stone monuments.
TL;DR: The secretion of protective pigments in the polysaccharide layers, namely mycosporine amino acid-like substances (MAAs) and scytonemins, under exposure to UV radiation showed how the acclimation response contributes to the persistence of cyanobacteria on exposed lithoid surfaces in tropical areas.
Abstract: Three coccoid and two filamentous cyanobacterial strains were isolated from phototrophic biofilms exposed to intense solar radiation on lithic surfaces of the Parasurameswar Temple and Khandagiri caves, located in Orissa State, India. Based on to their morphological features, the three coccoid strains were assigned to the genera Gloeocapsosis and Gloeocapsa, while the two filamentous strains were assigned to the genera Leptolyngbya and Plectonema. Eleven to 12 neutral and acidic sugars were detected in the slime secreted by the five strains. The secretions showed a high affinity for bivalent metal cations, suggesting their ability to actively contribute to weakening the mineral substrata. The secretion of protective pigments in the polysaccharide layers, namely mycosporine amino acid-like substances (MAAs) and scytonemins, under exposure to UV radiation showed how the acclimation response contributes to the persistence of cyanobacteria on exposed lithoid surfaces in tropical areas.
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470 citations
TL;DR: The aim of this survey is to outline the state-of-the-art of the importance of the cyanobacterial EPS excretion, both for the producing cells and for the microbial associations in which cyanobacteria are a key component.
Abstract: Exopolysaccharides (EPSs) are an important class of biopolymers with great ecological importance. In natural environments, they are a common feature of microbial biofilms, where they play key protective and structural roles. As the primary colonizers of constrained environments, such as desert soils and lithic and exposed substrates, cyanobacteria are the first contributors to the synthesis of the EPSs constituting the extracellular polymeric matrix that favors the formation of microbial associations with varying levels of complexity called biofilms. Cyanobacterial colonization represents the first step for the formation of biofilms with different levels of complexity. In all of the possible systems in which cyanobacteria are involved, the synthesis of EPSs contributes a structurally-stable and hydrated microenvironment, as well as chemical/physical protection against biotic and abiotic stress factors. Notwithstanding the important roles of cyanobacterial EPSs, many aspects related to their roles and the relative elicited biotic and abiotic factors have still to be clarified. The aim of this survey is to outline the state-of-the-art of the importance of the cyanobacterial EPS excretion, both for the producing cells and for the microbial associations in which cyanobacteria are a key component.
268 citations
Cites background from "Characteristics and role of the exo..."
...The synthesis of these pigments is elicited by UV exposure, as well [38,71]....
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...Phototrophic biofilms can be found growing on exposed lithic substrates, and cyanobacterial EPSs play key roles in protecting from UV irradiation and drought [38]....
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..., metal removed per gram of cell dry weight) being somewhat correlated to the anionic density of the capsulated or sheathed cells [38]....
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TL;DR: The use of cyanobacteria as soil conditioners has been studied intermittently for many decades Some of the documented direct effects of the cyanobacterial inoculation are related to soil stabilization and improvement, enrichment in nutrients and increase in moisture content.
144 citations
01 Dec 2020
TL;DR: In this article, the role of microbes in the deterioration processes, the biochemical mechanisms involved and possible strategies for sustainable conservation of stone monuments and buildings are discussed, as well as how microbes contribute to the biodeterioration processes through their activities and biogeochemical cycles of elements.
Abstract: Geomicrobially induced deterioration of stone monuments and buildings contributes to a considerable loss of world cultural heritage, especially when exposed to a changing climate or environment. The active biodeterioration processes typically involve biochemical activities and cooperation among functional microorganisms in epilithic biofilms, which assimilate mineral nutrients and metabolize anthropogenic pollutants through biogeochemical cycles. Development of any effective mitigation strategies requires the comprehensive understanding of such processes. We focus on how microbes contribute to the biodeterioration processes through their activities and biogeochemical cycles of elements, discuss biochemical mechanisms involved and provide innovative strategies for sustainable conservation of stone monuments and buildings. Biodeterioration of stone monuments and buildings can lead to a loss of world cultural heritage. This Review discusses the role of microbes in the deterioration processes, the biochemical mechanisms involved and possible strategies for sustainable conservation of stone monuments and buildings.
118 citations
01 Jan 2016
TL;DR: In this chapter, the current knowledge regarding the structure and composition of EPSs, the factors eliciting their synthesis, and the related codifying genes involved is reviewed and it is underlined and discussed how, notwithstanding the huge number of studies available, different aspects still need to be clarified.
Abstract: Extracellular polysaccharides (EPSs) produced by microalgae and cyanobacteria are molecules with a great ecological significance for the producing organisms, serving in a wide array of biological processes and increasing the organism tolerance to environmental stresses. In addition, due to their distinctive chemical, rheological properties and the biological activity of some of them, these macromolecules could find application in industrial, pharmaceutical and medical fields. In this chapter, the current knowledge regarding the structure and composition of EPSs, the factors eliciting their synthesis, and the related codifying genes involved is reviewed. It is also underlined and discussed how, notwithstanding the huge number of studies available, different aspects still need to be clarified. For example, there are limited informations concerning EPS synthetic pathways, and how these processes are influenced by environmental factors. Expand the knowledge on these aspects could help elaborating biotechnological strategies to increase the yields and direct the synthesis to polymers with desired characteristics.
111 citations
References
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TL;DR: Revisions are designed to permit the generic identification of cultures, often difficult through use of the field-based system of phycological classification, and are both constant and readily determinable in cultured material.
Abstract: Summary: On the basis of a comparative study of 178 strains of cyanobacteria, representative of this group of prokaryotes, revised definitions of many genera are proposed. Revisions are designed to permit the generic identification of cultures, often difficult through use of the field-based system of phycological classification. The differential characters proposed are both constant and readily determinable in cultured material. The 22 genera recognized are placed in five sections, each distinguished by a particular pattern of structure and development. Generic descriptions are accompanied by strain histories, brief accounts of strain properties, and illustrations; one or more reference strains are proposed for each genus. The collection on which this analysis was based has been deposited in the American Type Culture Collection, where strains will be listed under the generic designations proposed here.
7,107 citations
"Characteristics and role of the exo..." refers methods in this paper
...Aliquots of exponentially growing cultures were put in uncovered Petri dishes with BG-11 medium (Rippka et al. 1979) at 308C and pre-treated for 3 days under three different light conditions: (i) 2....
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...Axenic cultures of the organisms were obtained by dilution and repeated cultivation in agarized BG11 medium (Rippka et al. 1979)....
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...Aliquots of exponentially growing cultures were put in uncovered Petri dishes with BG-11 medium (Rippka et al. 1979) at 308C and pre-treated for 3 days under three different light conditions: (i) 2.18 W m72 VIS only, (ii) 2.18 W m72 VIS plus 3.20 W m72 UVA (peak at 360 nm), (iii) 2.18 W m72 VIS…...
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TL;DR: A greater understanding of biofilm processes should lead to novel, effective control strategies for biofilm control and a resulting improvement in patient management.
Abstract: Microorganisms attach to surfaces and develop biofilms. Biofilm-associated cells can be differentiated from their suspended counterparts by generation of an extracellular polymeric substance (EPS) matrix, reduced growth rates, and the up- and down- regulation of specific genes. Attachment is a complex process regulated by diverse characteristics of the growth medium, substratum, and cell surface. An established biofilm structure comprises microbial cells and EPS, has a defined architecture, and provides an optimal environment for the exchange of genetic material between cells. Cells may also communicate via quorum sensing, which may in turn affect biofilm processes such as detachment. Biofilms have great importance for public health because of their role in certain infectious diseases and importance in a variety of device-related infections. A greater understanding of biofilm processes should lead to novel, effective control strategies for biofilm control and a resulting improvement in patient management.
4,067 citations
"Characteristics and role of the exo..." refers background in this paper
...…biomass releases carbohydrates, growth factors and other nutrients, which can be used as substrates by chemoorganotrophic bacteria that may produce corrosive organic acids or oxidize metal cations, thereby causing the decay of the stones and enhancing biodeterioration (Donlan 2002; Urzı̀ 2004)....
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01 Jan 1989
1,215 citations
"Characteristics and role of the exo..." refers methods in this paper
...For morphological identification of unstained cyanobacterial strains, the diacritic traits used for description of botanical species were considered (Anagnostidis and Komarek 1990; Komárek and Anagnostidis 1989, 1999, 2005)....
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Book•
01 Jan 2000
TL;DR: This chapter discusses cyanobacteria in deserts: life at the limits?
Abstract: 1. Introduction to the cyanobacteria B.A. Whitton, M. Potts. 2. The evolutionary record: Tracing the roots of the cyanobacterial lineage J.W. Schopf. Environments: 3. Cyanobacteria in geothermal habitats D.M. Ward, R.W. Castenholz. 4. Mats and stromatolites L. Stal. 5. Marine plankton H.W. Paerl. 6. Freshwater blooms R.L. Oliver, G.G. Ganf. 7. Picoplankton and other non-blooming forming cyanobacteria in lakes J.G. Stockner, et al. 8. Soils and rice-fields B.A. Whitton. 9. Limestones A. Pentecost, B.A. Whitton. 10. Salts and brines A. Oren. 11. Oil pollution S.S. Radwan, R.H. Al-Hasan. 12. Cyanobacterial dominance in the polar regions W.F. Vincent. 13. Cyanobacteria in deserts: life at the limits? D.D. Wynn-Williams. Molecular Ecology: 14. Detecting the environment N. Mann. 15. Molecular responses to environmental stress D. Bhaya, et al. 16. Metal metabolism and metal toxicity: repetitive DNA N.J. Robinson, et al. The Organisms: 17. Nostoc M. Potts. 18. Arthrospira (Spirulina): Systematics and ecophysiology A. Vonshak, L. Tomaselli. 19. Symbiotic interactions D.G. Adams. 20. Cyanophage C. Suttle. Environmental Factors: 21. Cyanobacterial responses to UV-radiation R.W. Castenholz, F. Garcia-Pichel. Ecological Aspects of Metabolites: 22.Cyanotoxins C. Dow.
1,023 citations