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1.
Carbohydr Polym ; 229: 115525, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31826510

RESUMO

The extracellular polysaccharides produced by cyanobacteria have distinctive characteristics that make them promising for applications ranging from bioremediation to biomedicine. In this study, a sulfated polysaccharide produced by a marine cyanobacterial strain and named cyanoflan was characterized in terms of morphology, chemical composition, and rheological and emulsifying properties. Cyanoflan has a 71 % carbohydrate content, with 11 % of sulfated residues, while the protein account for 4 % of dry weight. The glycosidic-substitution analysis revealed a highly branched complex chemical structure with a large number of sugar residues. The cyanoflan high molecular mass fractions (above 1 MDa) and entangled structure is consistent with its high apparent viscosity in aqueous solutions and high emulsifying activity. It showed to be a typical non-Newtonian fluid with pseudoplastic behavior. Altogether, these results confirm that cyanoflan is a versatile carbohydrate polymer that can be used in different biotechnological applications, such as emulsifying/thickening agent in food or cosmetic industries.

2.
Int J Biol Macromol ; 136: 1219-1227, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31233798

RESUMO

Cyanobacterial extracellular carbohydrate polymers are particularly attractive for biotechnological applications. Previously, we determined the monosaccharidic composition of the polymer of a Synechocystis ΔsigF overproducing mutant. Here, we further characterized this polymer, demonstrated that it is possible to recover it in high yields, and successfully use it for biomedical research. This amorphous polymer is formed by a mesh of fibrils/lamellar structures with high porosity, is constituted by high molecular mass fractions, is highly sulfated and displays low viscosity, even in highly concentrated aqueous solutions. FTIR analysis confirmed the presence of several functional groups. We demonstrated that the ΔsigF polymer has strong biological activity, decreasing the viability of melanoma, thyroid and ovary carcinoma cells by inducing high levels of apoptosis, through p53 and caspase-3 activation. Therefore, the ΔsigF Synechocystis mutant is a promising platform for the sustainable production of biological active carbohydrate polymer(s) with the desired characteristics for biomedical applications.


Assuntos
Proteínas de Bactérias/genética , Carboidratos/química , Carboidratos/farmacologia , Espaço Extracelular/metabolismo , Mutação , Fator sigma/genética , Synechocystis/citologia , Synechocystis/genética , Antineoplásicos/química , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Biopolímeros/química , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Humanos , Peso Molecular , Reologia
3.
Environ Microbiol ; 21(3): 1140-1150, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30761715

RESUMO

Toxic Microcystis spp. blooms constitute a serious threat to water quality worldwide. Aeromonas veronii was isolated from Microcystis sp. colonies collected in Lake Kinneret. Spent Aeromonas media inhibits the growth of Microcystis aeruginosa MGK isolated from Lake Kinneret. The inhibition was much stronger when Aeromonas growth medium contained spent media from MGK suggesting that Aeromonas recognized its presence and produced secondary metabolites that inhibit Microcystis growth. Fractionations of the crude extract and analyses of the active fractions identified several secondary metabolites including lumichrome in Aeromonas media. Application of lumichrome at concentrations as low as 4 nM severely inhibited Microcystis growth. Inactivation of aviH in the lumichrome biosynthetic pathway altered the lumichrome level in Aeromonas and the extent of MGK growth inhibition. Conversely, the initial lag in Aeromonas growth was significantly longer when provided with Microcystis spent media but Aeromonas was able to resume normal growth. The longer was pre-exposure to Microcystis spent media the shorter was the lag phase in Aeromonas growth indicating the presence of, and acclimation to, secondary MGK metabolite(s) the nature of which was not revealed. Our study may help to control toxic Microcystis blooms taking advantage of chemical languages used in the interspecies communication.

4.
Microbiologyopen ; 8(6): e00753, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30675753

RESUMO

Many cyanobacteria produce extracellular polymeric substances (EPS) mainly composed of heteropolysaccharides with unique characteristics that make them suitable for biotechnological applications. However, manipulation/optimization of EPS biosynthesis/characteristics is hindered by a poor understanding of the production pathways and the differences between bacterial species. In this work, genes putatively related to different pathways of cyanobacterial EPS polymerization, assembly, and export were targeted for deletion or truncation in the unicellular Synechocystis sp. PCC 6803. No evident phenotypic changes were observed for some mutants in genes occurring in multiple copies in Synechocystis genome, namely ∆wzy (∆sll0737), ∆wzx (∆sll5049), ∆kpsM (∆slr2107), and ∆kpsM∆wzy (∆slr2107∆sll0737), strongly suggesting functional redundancy. In contrast, Δwzc (Δsll0923) and Δwzb (Δslr0328) influenced both the amount and composition of the EPS, establishing that Wzc participates in the production of capsular (CPS) and released (RPS) polysaccharides, and Wzb affects RPS production. The structure of Wzb was solved (2.28 Å), revealing structural differences relative to other phosphatases involved in EPS production and suggesting a different substrate recognition mechanism. In addition, Wzc showed the ATPase and autokinase activities typical of bacterial tyrosine kinases. Most importantly, Wzb was able to dephosphorylate Wzc in vitro, suggesting that tyrosine phosphorylation/dephosphorylation plays a role in cyanobacterial EPS production.

5.
Microb Ecol ; 78(2): 482-493, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30535915

RESUMO

Inoculation of soils with cyanobacteria is proposed as a sustainable biotechnological technique for restoration of degraded areas in drylands due to the important role that cyanobacteria and their exopolysaccharides (EPS) play in the environment. So far, few studies have analyzed the macromolecular and chemical characteristics of the polysaccharidic matrix in induced cyanobacterial biocrusts and the scarce existing studies have mainly focused on sandy soil textures. However, the characteristics of the cyanobacterial polysaccharidic matrix may greatly depend on soil type. The objective of this study was to examine the macromolecular distribution and monosaccharidic composition of the polysaccharidic matrix induced by inoculation of two cyanobacterial species common in arid environments, Phormidium ambiguum (non N-fixing) and Scytonema javanicum (N-fixing) in different soil types. S. javanicum promoted a higher release in the soil of the more soluble and less condensed EPS fraction (i.e., the loosely bound EPS fraction, LB-EPS), while P. ambiguum showed a higher release of the less soluble and more condensed EPS fraction (i.e., the tightly bound EPS fraction, TB-EPS). LB-EPSs were mainly composed of low MW molecules (< 50 kDa), while TB-EPSs were mainly composed of high MW molecules (1100-2000 kDa). The two EPS fractions showed a complex monosaccharidic composition (from 11 to 12 different types of monosaccharides), with glucose as the most abundant monosaccharide, in particular in the poorer soils characterized by lower organic C contents. In more C-rich soils, high abundances of galactose, mannose, and xylose were also found. Low abundance of uronic acids and hydrophobic monosaccharides, such as fucose and rhamnose, was found in the EPS extracted from the inoculated soils. Our results point to the influence of soil type on the macromolecular distribution and monosaccharide composition of the polysaccharidic matrix in induced biocrusts, which is likely to affect biocrust development and their role in soil structure and nutrient cycling in restored dryland soils.


Assuntos
Cianobactérias/metabolismo , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/metabolismo , Microbiologia do Solo , Solo/química , Cianobactérias/classificação , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Clima Desértico
6.
Environ Microbiol ; 21(1): 343-359, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30394639

RESUMO

Cyanobacterial alternative sigma factors are crucial players in environmental adaptation processes, which may involve bacterial responses related to maintenance of cell envelope and control of secretion pathways. Here, we show that the Group 3 alternative sigma factor F (SigF) plays a pleiotropic role in Synechocystis sp. PCC 6803 physiology, with a major impact on growth and secretion mechanisms, such as the production of extracellular polysaccharides, vesiculation and protein secretion. Although ΔsigF growth was significantly impaired, the production of released polysaccharides (RPS) increased threefold to fourfold compared with the wild-type. ΔsigF exhibits also impairment in formation of outer-membrane vesicles (OMVs) and pili, as well as several other cell envelope alterations. Similarly, the exoproteome composition of ΔsigF differs from the wild-type both in amount and type of proteins identified. Quantitative proteomics (iTRAQ) and an in silico analysis of SigF binding motifs revealed possible targets/pathways under SigF control. Besides changes in protein levels involved in secretion mechanisms, our results indicated that photosynthesis, central carbon metabolism and protein folding/degradation mechanisms are altered in ΔsigF. Overall, this work provided new evidences about the role of SigF on Synechocystis physiology and associates this regulatory element with classical and non-classical secretion pathways.

7.
Microbiol Res ; 197: 49-55, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28219525

RESUMO

The ability of Rhodopseudomonas palustris cells to rapidly acclimate to high light irradiance is an essential issue when cells are grown under sunlight. The aim of this study was to investigate the photo-acclimation process in Rhodopseudomonas palustris 42OL under different culturing conditions: (i) anaerobic (AnG), (ii) aerobic (AG), and (iii) under H2-producing (HP) conditions both at low (LL) and high light (HL) irradiances. The results obtained clearly showed that the photosynthetic unit was significantly affected by the light irradiance at which Rp. palustris 42OL was grown. The synthesis of carotenoids was affected by both illumination and culturing conditions. At LL, lycopene was the main carotenoid synthetized under all conditions tested, while at HL under HP conditions, it resulted the predominant carotenoid. Oppositely, under AnG and AG at HL, rhodovibrin was the major carotenoid detected. The increase in light intensity produced a deeper variation in light-harvesting complexes (LHC) ratio. These findings are important for understanding the ecological distribution of PNSB in natural environments, mostly characterized by high light intensities, and for its growth outdoors.


Assuntos
Aclimatação/fisiologia , Rodopseudomonas/fisiologia , Rodopseudomonas/efeitos da radiação , Aclimatação/efeitos da radiação , Biomassa , Carotenoides/biossíntese , Hidrogênio/metabolismo , Luz , Licopeno , Fotobiologia/métodos , Fótons , Rodopseudomonas/metabolismo , Luz Solar
8.
Bioresour Technol ; 216: 941-7, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27341463

RESUMO

The present study was aimed at assessing the biotransformation of dark fermented agroindustrial residues and energy crops for the production of hydrogen and poly-ß-hydroxybutyrate (PHB), in lab-scale photofermentation. The investigation on novel substrates for photofermentation is needed in order to enlarge the range of sustainable feedstocks. Dark fermentation effluents of ensiled maize, ensiled giant reed, ensiled olive pomace, and wheat bran were inoculated with Rhodopseudomonas palustris CGA676, a mutant strain suitable for hydrogen production in ammonium-rich media. The highest hydrogen producing performances were observed in wheat bran and maize effluents (648.6 and 320.3mLL(-1), respectively), both characterized by high initial volatile fatty acids (VFAs) concentrations. Giant reed and olive pomace effluents led to poor hydrogen production due to low initial VFAs concentrations, as the original substrates are rich in fiber. The highest PHB content was accumulated in olive pomace effluent (11.53%TS), ascribable to magnesium deficiency.


Assuntos
Biotecnologia/métodos , Produtos Agrícolas/metabolismo , Hidrogênio/metabolismo , Hidroxibutiratos/metabolismo , Poliésteres/metabolismo , Rodopseudomonas/metabolismo , Biomassa , Produtos Agrícolas/química , Fibras na Dieta/metabolismo , Ácidos Graxos Voláteis/metabolismo , Fermentação , Magnésio/metabolismo , Propionatos/metabolismo , Resíduos , Zea mays/metabolismo
9.
Appl Microbiol Biotechnol ; 100(17): 7765-75, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27188779

RESUMO

Bioremediation of heavy metals using microorganisms can be advantageous compared to conventional physicochemical methods due to the use of renewable resources and efficiencies of removal particularly cations at low concentrations. In this context, cyanobacteria/cyanobacterial extracellular polymeric substances (EPS) emerge as a valid alternative due to the anionic nature and particular composition of these polymers. In this work, various culture fractions of the unicellular cyanobacterium Cyanothece sp. CCY 0110 were employed in bioremoval assays using three of the most common heavy metal pollutants in water bodies-copper, cadmium, and lead-separately or in combined systems. Our study showed that the released polysaccharides (RPS) were the most efficient fraction, removing the metal(s) by biosorption. Therefore, this polymer was subsequently used to evaluate the interactions between the metals/RPS binding sites using SEM-EDX, ICP-OES, and FTIR. Acid and basic pretreatments applied to the polymer further improve the process efficiency, and the exposure to an alkaline solution seems to alter the RPS conformation. The differences observed in the specific metal bioremoval seem to be mainly due to the RPS organic functional groups available, mainly carboxyl and hydroxyl, than to an ion exchange mechanism. Considering that Cyanothece is a highly efficient RPS-producer and that RPS can be easily separated from the culture, immobilized or confined, this polymer can be advantageous for the establishment/improvement of heavy metal removal systems.


Assuntos
Biodegradação Ambiental , Cádmio/metabolismo , Cobre/metabolismo , Cyanothece/metabolismo , Chumbo/metabolismo , Metais Pesados/metabolismo , Polissacarídeos Bacterianos/metabolismo , Sítios de Ligação , Poluentes Químicos da Água/metabolismo
10.
Bioresour Technol ; 211: 509-18, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27038259

RESUMO

Aim of this study was to evaluate the suitability of ensiled giant reed, ensiled maize, ensiled olive pomace, wheat bran for combined systems (CS: dark fermentation+anaerobic digestion (AD)) producing hydrogen-rich biogas (biohythane), tested in batch under basic operational conditions (mesophilic temperatures, no pH control). Substrates were also analyzed under a single stage AD batch test, in order to investigate the effects of DF on estimated energy recovery (ER) in combined systems. In CS, maize and wheat bran exhibited the highest hydrogen potential (13.8 and 18.9NLkgVS(-1)) and wheat bran the highest methane potential (243.5NLkgVS(-1)). In one-stage AD, giant reed, maize and wheat bran showed the highest methane production (239.5, 267.3 and 260.0NLkgVS(-1)). Butyrate/acetate ratio properly described the dark fermentation, correlating with hydrogen production (r=0.92). Wheat bran proved to be a promising residue for CS in terms of hydrogen/methane potential and ER.


Assuntos
Biocombustíveis , Conservação de Recursos Energéticos/métodos , Produtos Agrícolas/química , Hidrogênio/metabolismo , Metano/biossíntese , Anaerobiose , Biomassa , Reatores Biológicos , Fibras na Dieta/metabolismo , Digestão , Fermentação , Hidrogênio/análise , Hidrogênio/química , Metano/análise , Metano/química , Olea/metabolismo , Poaceae/metabolismo , Zea mays/química , Zea mays/metabolismo
11.
Stand Genomic Sci ; 11: 24, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26966509

RESUMO

Rhodopseudomonas palustris strain 42OL was isolated in 1973 from a sugar refinery waste treatment pond. The strain has been prevalently used for hydrogen production processes using a wide variety of waste-derived substrates, and cultured both indoors and outdoors, either freely suspended or immobilized. R. palustris 42OL was suitable for many other applications and capable of growing in very different culturing conditions, revealing a wide metabolic versatility. The analysis of the genome sequence allowed to identify the metabolic pathways for hydrogen and poly-ß-hydroxy-butyrate production, and confirmed the ability of using a wide range of organic acids as substrates.

12.
Res Microbiol ; 167(5): 350-6, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26916624

RESUMO

The ability of coping with the damaging effects of high light intensity represents an essential issue when purple non-sulfur bacteria (PNSB) are grown under direct sunlight for photobiological hydrogen production. This study was aimed at investigating whether H2 photo-evolution could represent, for Rhodopseudomonas palustris 42OL, a safety valve to dissipate an excess of reducing power generated under high light intensities. The physiological status of this strain was assessed under anaerobic (AnG) and aerobic (AG) growing conditions and under H2-producing (HP) conditions at low and high light intensities. The results obtained clearly showed that Fv/Fm ratio was significantly affected by the light intensity under which R. palustris 42OL cells were grown, under either AnG or AG conditions, while, under HP, it constantly remained at its highest value. The increase in light intensity significantly increased the H2 production rate, which showed a positive correlation with the maximum electron transfer rate (rETRmax). These findings are important for optimization of hydrogen production by PNSB under solar light.


Assuntos
Hidrogênio/metabolismo , Luz , Rodopseudomonas/metabolismo , Rodopseudomonas/efeitos da radiação , Aerobiose , Anaerobiose , Transporte de Elétrons , Fosfatidiletanolaminas , Rodopseudomonas/crescimento & desenvolvimento
13.
Appl Microbiol Biotechnol ; 100(6): 2917-26, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26762392

RESUMO

Hydrogen represents a possible alternative energy carrier to face the growing request for energy and the shortage of fossil fuels. Photofermentation for the production of H2 constitutes a promising way for integrating the production of energy with waste treatments. Many wastes are characterized by high salinity, and polluted seawater can as well be considered as a substrate. Moreover, the application of seawater for bacterial culturing is considered cost-effective. The aims of this study were to assess the capability of the metabolically versatile freshwater Rhodopseudomonas palustris 42OL of producing hydrogen on salt-containing substrates and to investigate its salt stress response strategy, never described before. R. palustris 42OL was able to produce hydrogen in media containing up to 3 % added salt concentration and to grow in media containing up to 4.5 % salinity without the addition of exogenous osmoprotectants. While the hydrogen production performances in absence of sea salts were higher than in their presence, there was no significant difference in performances between 1 and 2 % of added sea salts. Nitrogenase expression levels indicated that the enzyme was not directly inhibited during salt stress, but a regulation of its expression may have occurred in response to salt concentration increase. During cell growth and hydrogen production in the presence of salts, trehalose was accumulated as a compatible solute; it protected the enzymatic functionality against salt stress, thus allowing hydrogen production. The possibility of producing hydrogen on salt-containing substrates widens the range of wastes that can be efficiently used in production processes.


Assuntos
Hidrogênio/metabolismo , Pressão Osmótica , Rodopseudomonas/efeitos dos fármacos , Rodopseudomonas/metabolismo , Sais/metabolismo , Meios de Cultura/química , Água Doce/microbiologia , Nitrogenase/análise , Rodopseudomonas/química , Rodopseudomonas/crescimento & desenvolvimento , Salinidade , Trealose/análise
14.
Data Brief ; 4: 152-8, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26217780

RESUMO

The proteomes of the highly efficient extracellular polymeric substances (EPS)-producer cyanobacterium Cyanothece sp. CCY 0110, grown in medium supplemented with an essential metal (Cu(2+)) or a non-essential metal (Cd(2+)),were compared using iTRAQ technology. The data were obtained within a larger study that evaluated the overall effects of different heavy metals on growth/survival, EPS production and ultrastructure of this cyanobacterium [1]. To allow a broader understanding of the strategies triggered to coupe with toxic effects of the metals, Cyanothece's proteomes were evaluated after chronic and acute exposure to Cu(2+) and Cd(2+) in two independent 8-plex iTRAQ studies. For the chronic exposure 0.1 mg/l of Cu(2+) or 5 mg/l of Cd(2+) were used for 10 and 20 days, while in the acute experiments the cells were exposed to 10× these concentrations for 24 h. 202 and 268 proteins were identified and quantified for studies 1 (Cu(2+)) and 2 (Cd(2+)), respectively. The majority of the proteins with significant fold changes were associated with photosynthesis, CO2 fixation and carbohydrate metabolism, translation, and nitrogen and amino acid metabolism.

15.
Life (Basel) ; 5(2): 1218-38, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25837843

RESUMO

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.

16.
J Proteomics ; 120: 75-94, 2015 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-25779463

RESUMO

UNLABELLED: The effects of several heavy metals on the growth/survival, EPS production, ultrastructure and protein profiles of the highly efficient extracellular polymeric substances (EPS)-producer cyanobacterium Cyanothece sp. CCY 0110 were evaluated. Our results clearly show that each heavy metal affects the cells in a particular manner, triggering distinctive responses. Concerning chronic exposure, cells were more affected by Cu(2+) followed by Pb(2+), Cd(2+), and Li(+). The presence of metal leads to remarkable ultrastructural changes, mainly at the thylakoid level. The comparison of the proteomes (iTRAQ) allowed to follow the stress responses and to distinguish specific effects related to the time of exposure and/or the concentration of an essential (Cu(2+)) and a non-essential (Cd(2+)) metal. The majority of the proteins identified and with fold changes were associated with photosynthesis, CO2 fixation and carbohydrate metabolism, translation, and nitrogen and amino acid metabolism. Moreover, our results indicate that during chronic exposure to sub-lethal concentrations of Cu(2+), the cells tune down their metabolic rate to invest energy in the activation of detoxification mechanisms, which eventually result in a remarkable recovery. In contrast, the toxic effects of Cd(2+) are cumulative. Unexpectedly, the amount of released polysaccharides (RPS) was not enhanced by the presence of heavy metals. BIOLOGICAL SIGNIFICANCE: This work shows the holistic effects of different heavy metals on the cells of the highly efficient EPS-producer the cyanobacterium Cyanothece sp. CCY 0110. The growth/survival, EPS production, ultrastructure, protein profiles and stress response were evaluated. The knowledge generated by this study will contribute to the implementation of heavy-metal removal systems based on cyanobacteria EPS or their isolated polymers.


Assuntos
Proteínas de Bactérias/metabolismo , Cyanothece/fisiologia , Cyanothece/ultraestrutura , Metais Pesados/farmacologia , Proteoma/metabolismo , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/fisiologia , Cyanothece/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/fisiologia
17.
N Biotechnol ; 32(1): 109-20, 2015 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-24355428

RESUMO

The growing concern for the increase of the global warming effects due to anthropogenic activities raises the challenge of finding novel technological approaches to stabilize CO2 emissions in the atmosphere and counteract impinging interconnected issues such as desertification and loss of biodiversity. Biological-CO2 mitigation, triggered through biological fixation, is considered a promising and eco-sustainable method, mostly owing to its downstream benefits that can be exploited. Microorganisms such as cyanobacteria, green algae and some autotrophic bacteria could potentially fix CO2 more efficiently than higher plants, due to their faster growth. Some examples of the potential of biological-CO2 mitigation are reported and discussed in this paper. In arid and semiarid environments, soil carbon sequestration (CO2 fixation) by cyanobacteria and biological soil crusts is considered an eco-friendly and natural process to increase soil C content and a viable pathway to soil restoration after one disturbance event. Another way for biological-CO2 mitigation intensively studied in the last few years is related to the possibility to perform carbon dioxide sequestration using microalgae, obtaining at the same time bioproducts of industrial interest. Another possibility under study is the exploitation of specific chemotrophic bacteria, such as Ralstonia eutropha (or picketii) and related organisms, for CO2 fixation coupled with the production chemicals such as polyhydroxyalkanoates (PHAs). In spite of the potential of these processes, multiple factors still have to be optimized for maximum rate of CO2 fixation by these microorganisms. The optimization of culture conditions, including the optimal concentration of CO2 in the provided gas, the use of metabolic engineering and of dual purpose systems for the treatment of wastewater and production of biofuels and high value products within a biorefinery concept, the design of photobioreactors in the case of phototrophs are some of the issues that, among others, have to be addressed and tested for cost-effective CO2 sequestration.


Assuntos
Bactérias/metabolismo , Ciclo do Carbono , Dióxido de Carbono/metabolismo , Mudança Climática , Conservação dos Recursos Naturais , Solo/química , Microbiologia da Água , Conservação dos Recursos Naturais/economia
18.
FEMS Microbiol Lett ; 359(2): 193-200, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25131902

RESUMO

Rhizobacterial communities associated with Phragmites australis (Cav.) Trin. ex Steud. in a hypersaline pond close to Wuliangsuhai Lake (Inner Mongolia - China) were investigated and compared with the microbial communities in bulk sediments of the same pond. Microbiological analyses have been done by automated ribosomal intergenic spacer analysis (ARISA) and partial 16S rRNA gene 454 pyrosequencing. Although community richness was higher in the rhizosphere samples than in bulk sediments, the salinity seemed to be the major factor shaping the structure of the microbial communities. Halanaerobiales was the most abundant taxon found in all the different samples and Desulfosalsimonas was observed to be present more in the rhizosphere rather than in bulk sediment.


Assuntos
Bactérias/classificação , Bactérias/genética , Consórcios Microbianos , Poaceae/microbiologia , Rizosfera , Salinidade , China , Sedimentos Geológicos/microbiologia , RNA Ribossômico 16S , Microbiologia do Solo
19.
Carbohydr Polym ; 92(2): 1408-15, 2013 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-23399171

RESUMO

Cyanobacterial extracellular polymeric substances (EPS) are heteropolysaccharides that possess characteristics suitable for industrial applications, notably a high number of different monomers, strong anionic nature and high hydrophobicity. However, systematic studies that unveil the conditions influencing EPS synthesis and/or its characteristics are mandatory. In this work, Cyanothece sp. CCY 0110 was used as model organism. Our results revealed that this strain is among the most efficient EPS producers, and that the amount of RPS (released polysaccharides) is mainly related to the number of cells, rather than to the amount produced by each cell. Light was the key parameter, with high light intensity enhancing significantly RPS production (reaching 1.8 g L(-1)), especially in the presence of combined nitrogen. The data showed that RPS are composed by nine different monosaccharides (including two uronic acids), the presence of sulfate groups and peptides, and that the polymer is remarkably thermostable and amorphous in nature.


Assuntos
Cyanothece/citologia , Cyanothece/metabolismo , Espaço Extracelular/metabolismo , Polissacarídeos Bacterianos/biossíntese , Proteínas de Bactérias/metabolismo , Reatores Biológicos , Proliferação de Células , Técnicas de Cultura , Cyanothece/crescimento & desenvolvimento , Indústrias , Polissacarídeos Bacterianos/metabolismo
20.
Microb Ecol ; 65(3): 700-8, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23299348

RESUMO

The supportive and negative evidence for the stress gradient hypothesis (SGH) led to an ongoing debate among ecologists and called for new empirical and theoretical work. In this study, we took various biological soil crust (BSCs) samples along a spatial gradient with four environmental stress levels to examine the fitness of SGH in microbial interactions and evaluate its influence on biodiversity-function relationships in BSCs. A new assessment method of species interactions within hard-cultured invisible soil community was employed, directly based on denaturing gradient gel electrophoresis fingerprint images. The results showed that biotic interactions in soil phototroph community dramatically shifted from facilitation to dominant competition with the improvement of microhabitats. It offered new evidence, which presented a different perspective on the hypothesis that the relative importance of facilitation and competition varies inversely along the gradient of abiotic stress. The path analysis indicated that influence of biotic interactions (r = 0.19, p < 0.05) on ecosystem functions is lower than other community properties (r = 0.62, p < 0.001), including soil moisture, crust coverage, and biodiversity. Furthermore, the correlation between species interactions and community properties was non-significant with low negative influence (r = -0.27, p > 0.05). We demonstrate that the inversion of biotic interaction as a response to the gradient of abiotic stresses existed not only in the visible plant community but also in the soil microbial community.


Assuntos
Bactérias/isolamento & purificação , Fenômenos Fisiológicos Bacterianos , Biodiversidade , Ecossistema , Microbiologia do Solo , Bactérias/classificação , Bactérias/genética , Dados de Sequência Molecular , Filogenia
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