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1.
J Basic Microbiol ; 59(11): 1112-1124, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31502316

RESUMO

Microcystis aeruginosa blooms are a worldwide serious environmental problem and bloom control with bacteria is promising. In this study, a Bacillus licheniformis strain Sp34 with potent algicidal and inhibitory effects on the microcystins synthesis against fast-growing M. aeruginosa was isolated from Dianchi Lake. Sp34 killed the bloom-causing algal strain M. aeruginosa DCM4 of Dianchi Lake with an initial Chlorophyll-a concentration of 2.0 mg/L at a cell density of no less than 1.35 × 105 CFU/ml. It can also efficiently kill some other harmful algal species, such as M. wesenbergii and Phormidium sp. The algicidal activity of Sp34 relied on the release of algicidal substances, which had good heat (-20°C to 121°C) and acid-base (pH 3-11) resistance. In addition, the high algicidal activity depended on the good growth of algae indicated by the significantly positive correlations between algal growth and algicidal ratio (p < .001). The algicidal effect of Sp34 involved causing oxidative stress, lipid peroxidation, and morphological injury of algal cells, along with DNA damage and dysfunction of DNA-repair function, weakening the photosynthesis system, and inhibiting microcystin synthesis. In general, Sp34 can kill fast-growing M. aeruginosa and inhibit algal microcystin synthesis efficiently, so, it is a promising biocontrol agent to mitigate cyanobacterial blooms.


Assuntos
Bacillus licheniformis/metabolismo , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Microcystis/efeitos dos fármacos , Antibiose , Bacillus licheniformis/classificação , Bacillus licheniformis/genética , Bacillus licheniformis/crescimento & desenvolvimento , Clorofila/análogos & derivados , Clorofila/biossíntese , Clorofila/genética , Eutrofização/efeitos dos fármacos , Lagos/microbiologia , Microcistinas/biossíntese , Microcistinas/genética , Microcystis/genética , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Transcrição Genética/efeitos dos fármacos
2.
Sci Total Environ ; 688: 380-388, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31233918

RESUMO

In freshwater aquaculture ponds, cyanobacterial blooms and microcystins (MCs) pollution have attracted considerable attention due to their toxic effects. To provide an insight into cyanobacterial problems in aquaculture ponds, MCs distribution, bioaccumulation, and Microcystis genotype succession in a fishpond were investigated from May 2017 to November 2017. The distribution of MCs in filtered water, seston, and sediment varied considerably among months. MCs concentrations in filtered water, seston, and sediment ranged from 1.16 to 3.66 µg/L, 0.64 to 13.98 µg/g DW, and 1.34 to 5.90 µg/g DW, respectively. In addition, chemical oxygen demand was positively correlated with sestonic MCs concentrations. MCs concentrations accumulated in different tissues of market-size fish were in the order of liver > kidney > intestine > muscle. MCs content in muscle was 4.3 times higher than the WHO recommended tolerable daily intake level. Twenty-four ITS genotypes of Microcystis were identified from a total of 653 sequences. During the survey period, considerable genotype variation and rapid genotype succession were observed and dominant genotype was absent. A redundancy analysis revealed that Microcystis genotypes could significantly influence the variations in the proportions of the potentially toxic Microcystis, which could in turn influence the MCs concentrations in seston.


Assuntos
Aquicultura , Monitoramento Ambiental , Microcistinas/análise , Microcystis/genética , Animais , Peixes , Microcystis/crescimento & desenvolvimento
3.
J Microbiol ; 57(6): 450-460, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31012060

RESUMO

Next-generation DNA sequencing technology was applied to generate molecular data from semiarid reservoirs during well-defined seasons. Target sequences of 16S-23S rRNA ITS and cpcBA-IGS were used to reveal the taxonomic groups of cyanobacteria present in the samples, and genes coding for cyanotoxins such as microcystins (mcyE), saxitoxins (sxtA), and cylindrospermopsins (cyrJ) were investigated. The presence of saxitoxins in the environmental samples was evaluated using ELISA kit. Taxonomic analyses of high-throughput DNA sequencing data showed the dominance of the genus Microcystis in Mundaú reservoir. Furthermore, it was the most abundant genus in the dry season in Ingazeira reservoir. In the rainy season, 16S-23S rRNA ITS analysis revealed that Cylindrospermopsis raciborskii comprised 46.8% of the cyanobacterial community in Ingazeira reservoir, while the cpcBAIGS region revealed that C. raciborskii (31.8%) was the most abundant taxon followed by Sphaerospermopsis aphanizomenoides (17.3%) and Planktothrix zahidii (16.6%). Despite the presence of other potential toxin-producing genera, the detected sxtA gene belonged to C. raciborskii, while the mcyE gene belonged to Microcystis in both reservoirs. The detected mcyE gene had good correlation with MC content, while the amplification of the sxtA gene was related to the presence of STX. The cyrJ gene was not detected in these samples. Using DNA analyses, our results showed that the cyanobacterial composition of Mundaú reservoir was similar in successive dry seasons, and it varied between seasons in Ingazeira reservoir. In addition, our data suggest that some biases of analysis influenced the cyanobacterial communities seen in the NGS output of Ingazeira reservoir.


Assuntos
Biodiversidade , Cianobactérias/classificação , Cianobactérias/isolamento & purificação , Água Potável/microbiologia , Análise de Sequência de DNA/métodos , Microbiologia da Água , Abastecimento de Água , Toxinas Bacterianas/análise , Toxinas Bacterianas/genética , Toxinas Bacterianas/isolamento & purificação , Brasil , Cianobactérias/genética , DNA Bacteriano/análise , Monitoramento Ambiental/métodos , Genes Bacterianos/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Metagenômica/métodos , Microcystis/genética , RNA Ribossômico 16S/genética , RNA Ribossômico 23S/genética , Saxitoxina/genética , Estações do Ano , Uracila/análogos & derivados
4.
Ecotoxicol Environ Saf ; 177: 18-24, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30954008

RESUMO

Flavonoids are natural polyphenolic compounds from plants. As a new biotechnological algaecide, the molecular mechanism of plant flavonoids on the inhibition of Microcystis aeruginosa is still unknown. Therefore, in this study, we analyzed the variation of expressions of photosynthesis-related genes, microcystin synthesis-related genes and the genes involved in N and P acquisition in M. aeruginosa under the flavonoids stress. The results showed that the expression of psbD1, psaB and rbcL related to photosynthesis were influenced by three flavonoids but with different changing tendencies. The transcription of mcyA, mcyD and mcyH related to microcystin synthesis were decreased after 5-d of exposure, which could block microcystin synthesis. Meanwhile, flavonoids treatments resulted in the inhibition of N and P acquisition related genes transcription to affect the absorption of N and P in algal cells, and further influenced the physiological metabolic process of M. aeruginosa.


Assuntos
Flavonoides/farmacologia , Microcistinas/metabolismo , Microcystis/efeitos dos fármacos , Feromônios/farmacologia , Fotossíntese , Metabolismo Secundário , Flavonoides/metabolismo , Variação Genética , Microcistinas/genética , Microcystis/genética , Microcystis/metabolismo , Nutrientes , Feromônios/metabolismo
5.
Sci Total Environ ; 660: 501-511, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30640117

RESUMO

The composition of microbial communities can vary at the microspatial scale between free-living (FL) and particle-attached (PA) niches. However, it remains unclear how FL and PA bacterial communities respond to cyanobacterial blooms across water depths. Here, we examined the community dynamics of the FL (0.2-3 µm) and PA (>3 µm) bacterioplankton based on 16S rRNA gene high-throughput sequencing in a subtropical stratified reservoir under Microcystis aeruginosa bloom and non-bloom conditions. Both FL and PA bacterioplankton communities showed different responses in alpha- and beta-diversities to the bloom, suggesting the idea that the responses of bacterial community could depend on lifestyle. Specifically, abundant PA subcommunities showed a greater variation between bloom and non-bloom groups than abundant FL ones. In contrast, rare FL subcommunities exhibited a stronger response to water depth than rare PA ones. Furthermore, the rare taxa exhibited a preference for PA status, shaped and stimulated by the M. aeruginosa bloom. Our analyses also showed that PA bacterial communities were generally more diverse and appeared to be more responsive to routinely measured environmental variables than FL bacteria. Microcystis blooms had a facilitative influence on specific bacteria by mediating the transitions from free-living to particle-attached lifestyles. Altogether, these findings highlight the importance of bacterial lifestyle and abundance in understanding the dynamics of microbial community in cyanobacterial bloom aquatic ecosystem.


Assuntos
Eutrofização , Lagos/microbiologia , Microbiota/fisiologia , Microcystis/fisiologia , China , Sequenciamento de Nucleotídeos em Larga Escala , Microbiota/genética , Microcystis/genética , Dinâmica Populacional , RNA Bacteriano/análise , RNA Ribossômico 16S/análise
6.
J Environ Sci (China) ; 76: 359-367, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30528027

RESUMO

Microcystis panniformis is a bloom forming species with flat panniform-like colonies. This species was recently found in Lake Taihu, China. To specifically characterize M. panniformis based on isolated strains, morphological examination on colonial transition and genetic examination are needed. Three M. panniformis strains isolated from a water bloom sample in Lake Taihu were characterized by molecular analysis and toxin quantification. Phylogenetic analysis based on both 16S rRNA gene and internal transcribed spacer (ITS) between 16S and 23S rRNA genes were performed and compared to facilitate easy identification of the species. Relatively high similarities (98%-99%) were shown in 16S rDNA sequences between the strains of M. panniformis and those of other Microcystis species, whereas the similarities for ITS sequences were 88%-95%. In the phylogenetic tree based on the 16S rDNA sequences, the M. panniformis and M. aeruginosa strains were intermixed together with no clear division, whereas all of the M. panniformis strains were clustered together in a single clade based on the ITS sequences based phylogenyetic tree. The mcyE gene was detected in all three strains, and microcystin was determined by high-performance liquid chromatography. The molecular detection and toxin production of M. panniformis strains are of great significance for the environmental risk assessment of Microcystis blooms.


Assuntos
Monitoramento Ambiental , Lagos/microbiologia , Microcistinas/análise , Microcistinas/biossíntese , Microcystis/metabolismo , Toxinas Biológicas/análise , Toxinas Biológicas/biossíntese , China , Microcystis/genética , Filogenia , RNA Ribossômico 16S/genética , RNA Ribossômico 23S/genética
7.
Sci Total Environ ; 654: 129-134, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30439689

RESUMO

Sertraline hydrochloride (Ser-HCl), a widely used antidepressant, becomes an aquatic contaminant via metabolic excretion and improper disposal; however, it is unknown how Ser-HCl affects aquatic microbial communities. The present study investigated the effects of Ser on the structures of aquatic microbial communities via high-throughput sequencing analyses. Ser-HCl treatment inhibited the growth of two model algae (the green alga, Chlorella vulgaris, and the cyanobacterium, Microcystis aeruginosa) and decreased the chlorophyll a (Chl-a) concentration in the microcosm to reduce the photosynthetic efficiency. High-throughput sequencing analyses showed that exposure to Ser-HCl disturbed the balance of cyanobacteria species by stimulating the growth of specific cyanobacteria. Among eukaryotes, the richness as well as the diversity indices were significantly enhanced after 5 days of Ser-HCl treatment but sharply decreased with exposure time. Nucleariida occupied an absolute majority (97.83%) within the eukaryotes, implicating that Ser-HCl disturbed the ecological equilibrium in microcosms. Ser-HCl will continue to be an environmental contaminant due to its wide usage and production. Our current study clarified the potential ecological risk of Ser-HCl to aquatic microorganisms. These findings suggest that more attention should be given to the negative effects of these bioactive pollutants on aquatic environments.


Assuntos
Antidepressivos/toxicidade , Chlorella vulgaris/efeitos dos fármacos , Microbiota/efeitos dos fármacos , Microcystis/efeitos dos fármacos , Sertralina/toxicidade , Poluentes Químicos da Água/toxicidade , Chlorella vulgaris/genética , Chlorella vulgaris/metabolismo , Clorofila/metabolismo , Ecotoxicologia , Sequenciamento de Nucleotídeos em Larga Escala , Microbiota/genética , Microbiota/fisiologia , Microcystis/genética , Microcystis/metabolismo , Fotossíntese/efeitos dos fármacos , RNA Ribossômico 16S/genética
8.
ACS Chem Biol ; 14(1): 67-75, 2019 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-30556994

RESUMO

The cyanobacterial genus Microcystis is known to produce an elaborate array of structurally unique and biologically active natural products, including hazardous cyanotoxins. Cytotoxic aeruginoguanidines represent a yet unexplored family of peptides featuring a trisubstituted benzene unit and farnesylated arginine derivatives. In this study, we aimed at assigning these compounds to a biosynthetic gene cluster by utilizing biosynthetic attributes deduced from public genomes of Microcystis and the sporadic distribution of the metabolite in axenic strains of the Pasteur Culture Collection of Cyanobacteria. By integrating genome mining with untargeted metabolomics using liquid chromatography with mass spectrometry, we linked aeruginoguanidine (AGD) to a nonribosomal peptide synthetase gene cluster and coassigned a significantly smaller product to this pathway, microguanidine (MGD), previously only reported from two Microcystis blooms. Further, a new intermediate class of compounds named microguanidine amides was uncovered, thereby further enlarging this compound family. The comparison of structurally divergent AGDs and MGDs reveals an outstanding versatility of this biosynthetic pathway and provides insights into the assembly of the two compound subfamilies. Strikingly, aeruginoguanidines and microguanidines were found to be as widespread as the hepatotoxic microcystins, but the occurrence of both toxin families appeared to be mutually exclusive.


Assuntos
Eutrofização , Guanidinas/metabolismo , Microcystis/genética , Vias Biossintéticas
9.
J Toxicol Environ Health A ; 81(21): 1142-1149, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30430926

RESUMO

Global proliferation of cyanobacterial blooms associated with climate change and eutrophication constitutes a serious environmental threat. In Hunan Province a freshwater pond located in Changsha City was found to contain high concentrations of cyanobacteria, however, the characteristics of these cyanobacteria at present are not known. This study thus aimed to isolate, identify the most common bloom-forming cyanobacteria in this region and determine the toxigenic characteristics of the predominant cyanobacteria. The cyanobacteria were isolated by serial dilution and identified using polymerase chain reaction (PCR). The cyanotoxins generated by the cyanobacterium were detected using high-performance liquid chromatography with an ultra-high resolution LTQ Orbitrap Velos Pro ETD mass spectrometry equipped with electrospray ionization interface (HPLC-ESI-MS). One  species of cyanobacterium was isolated and identified as Microcystis sp. YFM1 according to the sequence of the 16S ribosome deoxyribonucleic acid (16S rDNA). It was found that this cyanobacterium contained microcystin synthetase B gene (mcyB) and produced three types of cyanotoxins including microcystin-LR, RR and YR. Our findings indicate that the Microcystis sp. YFM1 isolated from the freshwater pond in Hunan Province exhibits unique characteristics distinguishable from other known cyanobacteria.


Assuntos
Eutrofização , Microcystis/isolamento & purificação , Tanques/microbiologia , China , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas , Microcistinas/análise , Microcystis/classificação , Microcystis/genética , Filogenia , RNA Bacteriano/análise , RNA Ribossômico 16S/análise
10.
Ecotoxicol Environ Saf ; 166: 192-199, 2018 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-30269014

RESUMO

Harmful cyanobacterial blooms are a growing threat to freshwater ecosystems worldwide due to the production of microcystin (MC), which can have detrimental effects on water quality and human health. The relations between MC-producing Microcystis, MC production, and environmental variables especially nutrient conditions in eutrophic lakes, Lake Taihu and Lake Yanghe, were investigated during the bloom season of 2015. Results showed that toxigenic cells contributed to 8.94-75.68% and 7.87-58.69% of the total Microcystis in Lake Taihu and Lake Yanghe, respectively. The dynamics of toxigenic cells and MC production were positively associated with NH3-N concentration in Lake Taihu, while positively associated with the concentrations of TP, TDP and PO4-P in Lake Yanghe, indicating that the dominant nutrient factor affecting the toxic blooms was nitrogen in Lake Taihu, whereas it was phosphorus in Lake Yanghe. The significant relationship between TLR eq (total MC after transformation of MC-RR and MC-YR into MC-LR) and Chlorophyll-a (Chl-a) concentration implied that Chl-a could be an alternative measure to predict MC risk in the two lakes, and the safe threshold value of Chl-a was proposed as 25.38 and 31.06 µg/L in Lake Taihu and Lake Yanghe, respectively.


Assuntos
Lagos/microbiologia , Microcistinas/análise , Microcystis/genética , China , Clorofila/análogos & derivados , Clorofila/análise , Genótipo , Lagos/química , Nitrogênio/análise , Nutrientes , Fósforo/análise
11.
FEMS Microbiol Ecol ; 94(12)2018 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-30289447

RESUMO

Cyanobacterial blooms are characterized by intense growth of one or few species that will dominate the phytoplankton community for periods of few months to an entire year or more. However, even during persistent blooms, important seasonal changes among dominant species can be observed. Pampulha reservoir is a tropical eutrophic reservoir presenting permanent blooms. To identify the main species in this environment, a closer analysis performed by microscopy and 16S-rRNA DGGE revealed Cylindrospermopsis raciborskii as highly dominant throughout the year. The second most abundant group comprised species belonging to the Microcystis genus. They followed a well-defined seasonal pattern described by interesting species-specific ecological trends. During thermal stratification in the rainy/warmer season, C. raciborskii dominated in the water column, while Microcystis spp. were abundant at the end of the dry season, a period characterized by higher total phosphorus concentrations. Phylogenetic analyses confirmed the two dominant taxa and their seasonal trends. The results showed that cyanobacteria major controlling factors were strongly species dependent, shifting from physical/climate related (stratification) to more chemical driven (nutrients/eutrophication). Identifying these drivers is therefore essential for the understanding of the bloom dynamics and the real risks associated with each species, and to eventually adopt the most appropriate and effective management strategies.


Assuntos
Cylindrospermopsis/classificação , Cylindrospermopsis/crescimento & desenvolvimento , Eutrofização/fisiologia , Microcystis/classificação , Microcystis/crescimento & desenvolvimento , Cylindrospermopsis/genética , Microcystis/genética , Fósforo/análise , Filogenia , Fitoplâncton/classificação , RNA Ribossômico 16S/genética , Estações do Ano
12.
Harmful Algae ; 78: 47-55, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30196924

RESUMO

Harmful cyanobacteria producing toxic microcystins are a major concern in water quality management. In recent years, hydrogen peroxide (H2O2) has been successfully applied to suppress cyanobacterial blooms in lakes. Physiological studies, however, indicate that microcystin protects cyanobacteria against oxidative stress, suggesting that H2O2 addition might provide a selective advantage for microcystin-producing (toxic) strains. This study compares the response of a toxic Microcystis strain, its non-toxic mutant, and a naturally non-toxic Microcystis strain to H2O2 addition representative of lake treatments. All three strains initially ceased growth upon H2O2 addition. Contrary to expectation, the non-toxic strain and non-toxic mutant rapidly degraded the added H2O2 and subsequently recovered, whereas the toxic strain did not degrade H2O2 and did not recover. Experimental catalase addition enabled recovery of the toxic strain, demonstrating that rapid H2O2 degradation is indeed essential for cyanobacterial survival. Interestingly, prior to H2O2 addition, gene expression of a thioredoxin and peroxiredoxin was much lower in the toxic strain than in its non-toxic mutant. Thioredoxin and peroxiredoxin are both involved in H2O2 degradation, and microcystin may potentially suppress their activity. These results show that microcystin-producing strains are less prepared for high levels of oxidative stress, and are therefore hit harder by H2O2 addition than non-toxic strains.


Assuntos
Peróxido de Hidrogênio/metabolismo , Microcistinas/metabolismo , Microcystis/metabolismo , Estresse Oxidativo , Fotossíntese , Transcriptoma , Toxinas Bacterianas/metabolismo , Genes Bacterianos , Proliferação Nociva de Algas/fisiologia , Microcystis/genética , Mutação
13.
PLoS One ; 13(9): e0203953, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30248115

RESUMO

Blooms of Microcystis and other harmful cyanobacteria can degrade water quality by producing cyanotoxins or other toxic compounds. The goals of this study were (1) to facilitate understanding of community structure for various aquatic microorganisms in brackish water and freshwater regions with emphasis on cyanobacteria, and (2) to test a hypothesis that Microcystis genotypes that tolerate higher salinity were blooming in brackish water environments during the severe drought, 2014. Shotgun metagenomic analysis revealed that cyanobacteria dominated the brackish water region while bacteria dominated the freshwater region. A group of cyanobacteria (e.g., Aphanizomenon, Microcystis, Planktothrix, Pseudanabaena), bacteria (e.g., Bacillus, Porphyrobacter), and diatoms (Phaeodactylum and Thalassiosira) were abundant in the brackish water region. In contrast, Hassallia (cyanobacteria) and green algae (Nannochloropsis, Chlamydomonas, and Volvox) were abundant in the landward freshwater region. Station variation was also apparent. One landward sampling station located downstream of an urbanized area differed substantially from the other stations in terms of both water chemistry and community structure, with a higher percentage of arthropods, green algae, and eukaryotes. Screening of the Microcystis internal transcribed spacer region revealed six representative genotypes, and two of which were successfully quantified using qPCR (Genotypes I and VI). Both genotypes occurred predominantly in the freshwater region, so the data from this study did not support the hypothesis that salinity tolerant Microcystis genotypes bloomed in the brackish water region in 2014.


Assuntos
Cianobactérias/genética , Cianobactérias/isolamento & purificação , Microbiologia da Água , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Biodiversidade , Clorófitas/classificação , Clorófitas/genética , Cianobactérias/classificação , DNA Bacteriano/genética , Diatomáceas/classificação , Diatomáceas/genética , Diatomáceas/isolamento & purificação , Estuários , Água Doce/microbiologia , Genótipo , Proliferação Nociva de Algas , Metagenômica , Microcystis/genética , Microcystis/isolamento & purificação , Filogenia , Reação em Cadeia da Polimerase , Águas Salinas , Salinidade , São Francisco , Análise Espaço-Temporal
14.
Antonie Van Leeuwenhoek ; 111(12): 2425-2440, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30069722

RESUMO

The Carpathian Basin is a lowland plain located mainly in Hungary. Due to the nature of the bedrock, alluvial deposits, and a bowl shape, many lakes and ponds of the area are characterized by high alkalinity. In this study, we characterized temporal changes in eukaryal and bacterial community dynamics with high throughput sequencing and relate the changes to environmental conditions in Lake Velence located in Fejér county, Hungary. The sampled Lake Velence microbial populations (algal and bacterial) were analyzed to identify potential correlations with other community members and environmental parameters at six timepoints over 6 weeks in the Spring of 2012. Correlations between community members suggest a positive relationship between certain algal and bacterial populations (e.g. Chlamydomondaceae with Actinobacteria and Acidobacteria), while other correlations allude to changes in these relationships over time. During the study, high nitrogen availability may have favored non-nitrogen fixing cyanobacteria, such as the toxin-producing Microcystis aeruginosa, and the eutrophic effect may have been exacerbated by high phosphorus availability as well as the high calcium and magnesium content of the Carpathian Basin bedrock, potentially fostering exopolymer production and cell aggregation. Cyanobacterial bloom formation could have a negative environmental impact on other community members and potentially affect overall water quality as well as recreational activities. To our knowledge, this is the first prediction for relationships between photoautotrophic eukaryotes and bacteria from an alkaline, Hungarian lake.


Assuntos
Cianobactérias/genética , Eutrofização , Lagos/microbiologia , Consórcios Microbianos/genética , Feófitas/genética , Filogenia , Acidobacteria/classificação , Acidobacteria/genética , Acidobacteria/isolamento & purificação , Acidobacteria/metabolismo , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Actinobacteria/metabolismo , Álcalis/química , Cálcio/química , Cálcio/metabolismo , Clorofíceas/classificação , Clorofíceas/genética , Clorofíceas/metabolismo , Cianobactérias/classificação , Cianobactérias/isolamento & purificação , Cianobactérias/metabolismo , DNA de Algas/genética , DNA Bacteriano/genética , Hungria , Concentração de Íons de Hidrogênio , Magnésio/química , Magnésio/metabolismo , Microcystis/classificação , Microcystis/genética , Microcystis/isolamento & purificação , Microcystis/metabolismo , Nitrogênio/química , Nitrogênio/metabolismo , Feófitas/classificação , Feófitas/isolamento & purificação , Feófitas/metabolismo , Fósforo/química , Fósforo/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Microbiologia da Água
15.
Toxins (Basel) ; 10(7)2018 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-30041444

RESUMO

Microcystis aeruginosa is the most common species responsible for toxic cyanobacterial blooms and is considered a significant contributor to the production of cyanotoxins, particularly the potent liver toxins called microcystins. Numerous studies investigating Microcystis spp. blooms have revealed their deleterious effects in freshwater environments. However, the available knowledge regarding the global phosphoproteomics of M. aeruginosa and their regulatory roles in toxin generation is limited. In this study, we conducted comparative phosphoproteomic profiling of non-toxic and toxin-producing strains of M. aeruginosa. We identified 59 phosphorylation sites in 37 proteins in a non-toxic strain and 26 phosphorylation sites in 18 proteins in a toxin-producing strain. The analysis of protein phosphorylation abundances and functions in redox homeostasis, energy metabolism, light absorption and photosynthesis showed marked differences between the non-toxic and toxin-producing strains of M. aeruginosa, indicating that these processes are strongly related to toxin generation. Moreover, the protein-protein interaction results indicated that BJ0JVG8 can directly interact with the PemK-like toxin protein B0JQN8. Thus, the phosphorylation of B0JQN8 appears to be associated with the regulatory roles of toxins in physiological activity.


Assuntos
Proteínas de Bactérias/metabolismo , Toxinas Bacterianas/metabolismo , Microcystis/metabolismo , Proteínas de Bactérias/genética , Toxinas Bacterianas/genética , Microcystis/genética , Fosforilação , Proteômica
16.
Harmful Algae ; 77: 1-10, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30005796

RESUMO

Mycosporine-like amino acids (MAAs) are UV-absorbing metabolites found in cyanobacteria. While their protective role from UV in Microcystis has been studied in a laboratory setting, a full understanding of the ecology of MAA-producing versus non-MAA-producing Microcystis in natural environments is lacking. This study presents a new tool for quantifying MAA-producing Microcystis and applies it to obtain insight into the dynamics of MAA-producing and non-MAA-producing Microcystis in Lake Erie. This study first developed a sensitive, specific TaqMan real-time PCR assay that targets MAA synthetase gene C (mysC) of Microcystis (quantitative range: 1.7 × 101 to 1.7 × 107 copies/assay). Using this assay, Microcystis was quantified with a MAA-producing genotype (mysC+) in water samples (n = 96) collected during March-November 2013 from 21 Lake Erie sites (undetectable - 8.4 × 106 copies/ml). The mysC+ genotype comprised 0.3-37.8% of the Microcystis population in Lake Erie during the study period. The proportion of the mysC+ genotype during high solar UV irradiation periods (mean = 18.8%) was significantly higher than that during lower UV periods (mean = 9.7%). Among the MAAs, shinorine (major) and porphyra (minor) were detected with HPLC-PDA-MS/MS from the Microcystis isolates and water samples. However, no significant difference in the MAA concentrations existed between higher and lower solar UV periods when the MAA concentrations were normalized with Microcystis mysC abundance. Collectively, this study's findings suggest that the MAA-producing Microcystis are present in Lake Erie, and they may be ecologically advantageous under high UV conditions, but not to the point that they exclusively predominate over the non-MAA-producers.


Assuntos
Toxinas Bacterianas/metabolismo , Proliferação Nociva de Algas , Lagos/microbiologia , Microcystis/metabolismo , Reação em Cadeia da Polimerase em Tempo Real/métodos , Toxinas Bacterianas/análise , Microcystis/genética , Microcystis/crescimento & desenvolvimento , Ohio , Análise Espaço-Temporal
17.
Proc Natl Acad Sci U S A ; 115(27): 7141-7146, 2018 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-29915055

RESUMO

Cyanobacteria are important photosynthetic organisms inhabiting a range of dynamic environments. This phylum is distinctive among photosynthetic organisms in containing genes encoding uncharacterized cystathionine ß-synthase (CBS)-chloroplast protein (CP12) fusion proteins. These consist of two domains, each recognized as stand-alone photosynthetic regulators with different functions described in cyanobacteria (CP12) and plants (CP12 and CBSX). Here we show that CBS-CP12 fusion proteins are encoded in distinct gene neighborhoods, several unrelated to photosynthesis. Most frequently, CBS-CP12 genes are in a gene cluster with thioredoxin A (TrxA), which is prevalent in bloom-forming, marine symbiotic, and benthic mat cyanobacteria. Focusing on a CBS-CP12 from Microcystis aeruginosa PCC 7806 encoded in a gene cluster with TrxA, we reveal that the domain fusion led to the formation of a hexameric protein. We show that the CP12 domain is essential for hexamerization and contains an ordered, previously structurally uncharacterized N-terminal region. We provide evidence that CBS-CP12, while combining properties of both regulatory domains, behaves different from CP12 and plant CBSX. It does not form a ternary complex with phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate dehydrogenase. Instead, CBS-CP12 decreases the activity of PRK in an AMP-dependent manner. We propose that the novel domain architecture and oligomeric state of CBS-CP12 expand its regulatory function beyond those of CP12 in cyanobacteria.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Cloroplastos/genética , Cistationina beta-Sintase/genética , Microcystis/genética , Família Multigênica , Proteínas de Bactérias/metabolismo , Proteínas de Cloroplastos/metabolismo , Cistationina beta-Sintase/metabolismo , Microcystis/metabolismo , Domínios Proteicos
18.
Ecotoxicol Environ Saf ; 161: 214-220, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29885617

RESUMO

Cyanobacteria release abundant volatile organic compounds (VOCs), which can poison other algae and cause water odor. To uncover the effects of nitrogen (N) nutrients on the formation of cyanobacteria VOCs, the cell growth, VOC emission and the expression of genes involving in VOC formation in Microcystis aeruginosa were investigated under different N conditions. With the supplement of NaNO3, NaNO2, NH4Cl, urea, Serine (Ser) and Arginine (Arg) as the sole N source, NaNO3, urea and Arg showed the best effects on M. aeruginosa cell growth, and limited N supply inhibited the cell growth. M. aeruginosa released 26, 25, 23, 27, 23 and 25 compounds, respectively, in response to different N forms, including furans, sulfocompounds, terpenoids, benzenes, hydrocarbons, aldehydes, and esters. Low-N especially Non-N condition markedly promoted the VOC emission. Under Non-N condition, four up-regulated genes involving in VOC precursor formation were identified, including the genes of pyruvate kinase, malic enzyme and phosphotransacetylase for terpenoids, the gene of aspartate aminotransferase for benzenes and sulfocompounds. In eutrophic water, cyanobacteria release different VOC blends using various N forms, and the reduction of N amount caused by cyanobacteria massive growth can promote algal VOC emission by up-regulating the gene expression.


Assuntos
Microcystis/metabolismo , Nitrogênio/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Microcystis/genética , Microcystis/crescimento & desenvolvimento , Nutrientes
19.
PLoS One ; 13(5): e0195205, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29723219

RESUMO

Cyanobacterial blooms are a worldwide environmental problem and frequently occur in eutrophic lakes. Organophosphorus mineralization regulated by microbial alkaline phosphatase provides available nutrients for bloom regeneration. To uncover the dynamics of bacterial alkaline phosphatase activity and microbial backgrounds in relation to organophosphorus mineralization during the decomposition process of cyanobacterial blooms, the response of alkaline phosphatase PhoX-producing bacteria were explored using a 23-day mesocosm experiment with three varying densities of Microcystis biomass from eutrophic Lake Taihu. Our study found large amounts of soluble reactive phosphorus and dissolved organophosphorus were released into the lake water during the decomposition process. Bacterial alkaline phosphatase activity showed the peak values during days 5~7 in groups with different chlorophyll-a densities, and then all decreased dramatically to their initial experimental levels during the last stage of decomposition. Bacterial phoX abundances in the three experimental groups increased significantly along with the decomposition process, positively related to the dissolved organic carbon and organophosphorus released by the Microcystis blooms. The genotypes similar to the phoX genes of Alphaproteobacteria were dominant in all groups, whereas the genotypes most similar to the phoX genes of Betaproteobacteria and Cyanobacteria were also abundant in the low density (~15 µg L-1 chlorophyll-a) group. At the end of the decomposition process, the number of genotypes most similar to the phoX of Betaproteobacteria and Cyanobacteria increased in the medium (~150 µg L-1 chlorophyll-a) and high (~1500 µg L-1 chlorophyll-a) density groups. The released organophosphorus and increased bacterial phoX abundance after decomposition of Microcystis aggregates could potentially provide sufficient nutrients and biological conditions for algal proliferation and are probably related to the regeneration of Microcystis blooms in eutrophic lakes.


Assuntos
Ambiente Controlado , Eutrofização , Genes Bacterianos/genética , Microcystis/genética , Microcystis/metabolismo , Fósforo/metabolismo , Sequência de Bases , Fenômenos Químicos , Variação Genética , Genótipo , Lagos/microbiologia , Minerais/metabolismo , Filogenia
20.
PLoS One ; 13(5): e0196278, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29791446

RESUMO

Lake Okeechobee, FL, USA, has been subjected to intensifying cyanobacterial blooms that can spread to the adjacent St. Lucie River and Estuary via natural and anthropogenically-induced flooding events. In July 2016, a large, toxic cyanobacterial bloom occurred in Lake Okeechobee and throughout the St. Lucie River and Estuary, leading Florida to declare a state of emergency. This study reports on measurements and nutrient amendment experiments performed in this freshwater-estuarine ecosystem (salinity 0-25 PSU) during and after the bloom. In July, all sites along the bloom exhibited dissolved inorganic nitrogen-to-phosphorus ratios < 6, while Microcystis dominated (> 95%) phytoplankton inventories from the lake to the central part of the estuary. Chlorophyll a and microcystin concentrations peaked (100 and 34 µg L-1, respectively) within Lake Okeechobee and decreased eastwards. Metagenomic analyses indicated that genes associated with the production of microcystin (mcyE) and the algal neurotoxin saxitoxin (sxtA) originated from Microcystis and multiple diazotrophic genera, respectively. There were highly significant correlations between levels of total nitrogen, microcystin, and microcystin synthesis gene abundance across all surveyed sites (p < 0.001), suggesting high levels of nitrogen supported the production of microcystin during this event. Consistent with this, experiments performed with low salinity water from the St. Lucie River during the event indicated that algal biomass was nitrogen-limited. In the fall, densities of Microcystis and concentrations of microcystin were significantly lower, green algae co-dominated with cyanobacteria, and multiple algal groups displayed nitrogen-limitation. These results indicate that monitoring and regulatory strategies in Lake Okeechobee and the St. Lucie River and Estuary should consider managing loads of nitrogen to control future algal and microcystin-producing cyanobacterial blooms.


Assuntos
Toxinas Bacterianas/biossíntese , Cianobactérias/patogenicidade , Proliferação Nociva de Algas , Lagos/microbiologia , Rios/microbiologia , Toxinas Bacterianas/genética , Biomassa , Cianobactérias/genética , Cianobactérias/metabolismo , Ecossistema , Emergências , Monitoramento Ambiental/métodos , Estuários , Florida , Genes Bacterianos , Lagos/química , Microcistinas/biossíntese , Microcistinas/genética , Microcystis/genética , Microcystis/metabolismo , Microcystis/patogenicidade , Nitrogênio/análise , Fitoplâncton/genética , Fitoplâncton/metabolismo , Fitoplâncton/patogenicidade , Rios/química , Salinidade , Saxitoxina/biossíntese , Saxitoxina/genética , Microbiologia da Água , Poluentes Químicos da Água/análise
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