scholarly journals Cyanobacterial Toxin Degrading Bacteria: Who Are They?

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Konstantinos Ar. Kormas ◽  
Despoina S. Lymperopoulou
Keyword(s):  
Meta Analysis ◽  
Toxin Production ◽  
Cyanobacterial Blooms ◽  
Ecological Knowledge ◽  
Cyanobacterial Toxin ◽  
Molecular Approaches ◽  
Degrading Bacteria ◽  
Ecological Problems ◽  
Ecosystem Level ◽  
Toxin Degradation

Cyanobacteria are ubiquitous in nature and are both beneficial and detrimental to humans. Benefits include being food supplements and producing bioactive compounds, like antimicrobial and anticancer substances, while their detrimental effects are evident by toxin production, causing major ecological problems at the ecosystem level. To date, there are several ways to degrade or transform these toxins by chemical methods, while the biodegradation of these compounds is understudied. In this paper, we present a meta-analysis of the currently available 16S rRNA andmlrA(microcystinase) genes diversity of isolates known to degrade cyanobacterial toxins. The available data revealed that these bacteria belong primarily to the Proteobacteria, with several strains from the sphingomonads, and one from each of theMethylobacillusandPaucibactergenera. Other strains belonged to the generaArthrobacter, Bacillus, andLactobacillus. By combining the ecological knowledge on the distribution, abundance, and ecophysiology of the bacteria that cooccur with toxic cyanobacterial blooms and newly developed molecular approaches, it is possible not only to discover more strains with cyanobacterial toxin degradation abilities, but also to reveal the genes associated with the degradation of these toxins.

scholarly journals Microbial diversity and toxin risk in tropical freshwater reservoirs of Cape Verde

2018 ◽  
Author(s):  
Ana P. Semedo-Aguiar ◽  
José B. Pereira-Leal ◽  
Ricardo B. Leite
Keyword(s):  
Microbial Diversity ◽  
Global Climate ◽  
Amplicon Sequencing ◽  
Toxin Production ◽  
Cape Verde ◽  
Cyanobacterial Blooms ◽  
Rrna Gene ◽  
Water Reservoirs ◽  
Cyanobacterial Toxin ◽  
Close Relationship

AbstractThe Cape Verde islands are part of the African Sahelian arid belt that possesses an irregular rainy season between August and October. This erratic rain pattern has prompted the need for water reservoirs, now critical for the country’s sustainability. Worldwide, freshwater cyanobacterial blooms are increasing in frequency due to global climate change and eutrophication of water bodies, particularly in reservoirs. To date there have been no risk assessments of cyanobacterial toxin production in these man-made structures. We evaluated this potential risk using 16S rRNA gene amplicon sequencing and full metagenome sequencing in freshwater reservoirs of Cape Verde.Our analysis revealed the presence of several potentially toxic cyanobacterial genera in all sampled reservoirs (Poilão, Saquinho and Faveta). In Faveta Microcystis sp., a genus well known for toxin production and bloom-formation, dominated our samples, while a green algae of the genus Cryptomonas and Gammaproteobacteria dominated Saquinho and Poilão.Taking advantage of the dominance of Microcystis in the Faveta reservoir, we were able to reconstruct and assemble its genome, extracted from a metagenome of bulk DNA from Faveta water. We named it Microcystis cf. aeruginosa CV01, for which a phylogenetic analysis revealed to have a close relationship with other genomes from those taxa, as well as other continental African strains, suggesting geographical coherency. In addition, it revealed several clusters of known toxin-producing genes. This assessment of Cape Verdean freshwater microbial diversity and potential for toxin production reinforces the need to better understand the microbial ecology as a whole of water reservoirs on the rise.

scholarly journals Effects of Malachite Green on the Microbiomes of Milkfish Culture Ponds

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 411
Author(s):  
Chu-Wen Yang ◽  
Yi-Tang Chang ◽  
Chi-Yen Hsieh ◽  
Bea-Ven Chang
Keyword(s):  
Infectious Diseases ◽  
Microbial Communities ◽  
Malachite Green ◽  
Fish Farming ◽  
Cyanobacterial Blooms ◽  
Anoxygenic Phototrophic Bacteria ◽  
Fish Mortality ◽  
Veterinary Drug ◽  
Degrading Bacteria ◽  
Microbial Infections

Intensive fish farming through aquaculture is vulnerable to infectious diseases that can increase fish mortality and damage the productivity of aquaculture farms. To prevent infectious diseases, malachite green (MG) has been applied as a veterinary drug for various microbial infections in aquaculture settings worldwide. However, little is known regarding the consequences of MG and MG-degrading bacteria (MGDB) on microbial communities in milkfish culture ponds (MCPs). In this study, small MCPs were used as a model system to determine the effects of MG on the microbial communities in MCPs. The addition of MG led to cyanobacterial blooms in the small MCP. The addition of MGDB could not completely reverse the effects of MG on microbial communities. Cyanobacterial blooms were not prevented. Microbial communities analyzed by next generation sequencing revealed that cyanobacterial blooms may be due to increase of nitrogen cycle (including nitrogen fixation, nitrate reduction and anammox) associated microbial communities, which raised the levels of ammonium in the water of the small MCP. The communities of anoxygenic phototrophic bacteria (beneficial for aquaculture and aquatic ecosystems) decreased after the addition of MG. The results of this investigation provide valuable insights into the effects of MG in aquaculture and the difficulties of bioremediation for aquatic environments polluted by MG.

Dynamics of the prokaryotic and eukaryotic microbial community during a cyanobacterial bloom

2021 ◽  
Author(s):  
Yilin Qian ◽  
Kunihiro Okano ◽  
Miwa Kodato ◽  
Michiko Arai ◽  
Takeru Yanagiya ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Negative Correlation ◽  
Aquatic Environment ◽  
Cyanobacterial Bloom ◽  
Cyanobacterial Blooms ◽  
Gene Copy ◽  
Degrading Bacteria ◽  
Freshwater Bodies ◽  
Predator Community

Abstract Toxic cyanobacterial blooms frequently develop in eutrophic freshwater bodies worldwide. Microcystis species produce microcystins (MCs) as a cyanotoxin. Certain bacteria that harbor the mlr gene cluster, especially mlrA, are capable of degrading MCs. However, MCs-degrading bacteria may possess or lack mlr genes (mlr+ and mlr− genotypes, respectively). In this study we investigated the genotype that predominantly contributes to biodegradation and cyanobacterial predator community structure with change in total MCs concentration in an aquatic environment. The two genotypes co-existed but mlr+ predominated, as indicated by the negative correlation between mlrA gene copy abundance and total MCs concentration. At the highest MCs concentrations, predation pressure by Phyllopoda, Copepoda, and Monogononta (rotifers) was reduced; thus, MCs may be toxic to cyanobacterial predators. The results suggest cooperation between MCs-degrading bacteria and predators may reduce Microcystis abundance and MCs concentration.

scholarly journals Harmful phytoplankton blooms and fish mortality in a eutrophicated reservoir of northeast Brazil

2008 ◽  
Vol 51 (4) ◽  
pp. 633-641 ◽  
Author(s):  
Naithirithi Tiruvenkatachary Chellappa ◽  
Sarah Laxhmi Chellappa ◽  
Sathyabama Chellappa
Keyword(s):  
Cyanobacterial Bloom ◽  
Hplc Method ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Fish Mortality ◽  
Cylindrospermopsis Raciborskii ◽  
Northeast Brazil ◽  
Cyanobacterial Toxin ◽  
Bloom Formation ◽  
Harmful Effects

The aim of this work was to study the eutrophication in the tropical freshwater ecosystems and the consequent cyanobacterial bloom formation and economical damage to fisheries and harmful effects to public health. Mass fish mortality due to toxin producing cyanobacterial blooms was registered during December 2003 in Marechal Dutra Reservoir, Acari/RN, Northeast Brazil. Phytoplankton and fish samplings were carried out on alternate days during the episode of fish mortality and monthly during January to June 2004. The cyanobacterial toxin was identified and quantified from the seston samples and liver of the dead fishes using the standard HPLC method. The results indicated that the toxic blooms of Cylindrospermopsis raciborskii and Microcystis aeruginosa were persistent for two weeks and represented 90% of the phytoplankton species assemblages. The lethally affected fishes were Oreochromis niloticus, Plagioscion squamosissimus, Cichla monoculus, Prochilodus brevis, Hoplias malabaricus and Leporinus friderici. The microcystin levels varied from 0.07 to 8.73µg L-1 the seston samples and from 0.01 to 2.59µg g-1in the liver samples of the fishes during the bloom period.

scholarly journals Advancing Knowledge on Cyanobacterial Blooms in Freshwaters

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2583
Author(s):  
Elisabeth Vardaka ◽  
Konstantinos Ar. Kormas
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Mathematical Modelling ◽  
Ecological Status ◽  
Toxin Production ◽  
Cyanobacterial Blooms ◽  
Special Issue ◽  
Research Papers ◽  
Cyanobacterial Species ◽  
Water Quality Deterioration

Cyanobacterial blooms have become a frequent phenomenon in freshwaters worldwide; they are a widely known indicator of eutrophication and water quality deterioration. Information and knowledge contributing towards the evaluation of the ecological status of freshwaters, particularly since many are used for recreation, drinking water, and aquaculture, is valuable. This Special Issue, entitled “Advancing Knowledge on Cyanobacterial Blooms in Freshwaters”, includes 11 research papers that will focus on the use of complementary approaches, from the most recently developed molecular-based methods to more classical approaches and experimental and mathematical modelling regarding the factors (abiotic and/or biotic) that control the diversity of not only the key bloom-forming cyanobacterial species, but also their interactions with other biota, either in freshwater systems or their adjacent habitats, and their role in preventing and/or promoting cyanobacterial growth and toxin production.

Development of polymerase chain reaction and fluorescent in situ hybridisation techniques for the detection of a bacterial strain that degrades the cyanobacterial toxin microcystin LR

2005 ◽  
Vol 56 (8) ◽  
pp. 1127 ◽  
Author(s):  
D. G. Bourne ◽  
R. L. Blakeley ◽  
P. Riddles ◽  
G. J. Jones
Keyword(s):  
Polymerase Chain Reaction ◽  
Environmental Samples ◽  
In Situ Hybridisation ◽  
Cyanobacterial Blooms ◽  
Chain Reaction ◽  
Fluorescent In Situ Hybridisation ◽  
Cyanobacterial Toxin ◽  
Specific Amplification ◽  
Polymerase Chain

Polymerase chain reaction (PCR) and fluorescent in situ hybridisation (FISH) techniques were developed for the detection of a Sphingomonas bacterium (strain MJ-PV), previously demonstrated to degrade the cyanobacterial toxin microcystin LR. A PCR amplification protocol using the primer set Sph-f1008/Sph-r1243 demonstrated specific amplification of the target 16S ribosomal DNA (rDNA) of strain MJ-PV. A 16S ribosomal RNA (rRNA) targeted probe, Sph-r1264, labelled with a rhodamine fluorescent dye was successfully used in whole-cell FISH for the detection of MJ-PV in seeded controls. DNA primers and a PCR protocol were developed for the specific amplification of a gene, mlrA, which codes for the enzyme MlrA, responsible for hydrolysis of the cyanobacterial toxin microcystin LR. A survey using 16S rDNA and mlrA primers on extracted DNA from environmental samples of a lake that suffers regular toxic cyanobacterial blooms demonstrated no amplified products indicative of the presence of MJ-PV or mlrA. Although not detecting the MJ-PV strain in the tested environmental samples, these developed methods are useful to study the distribution of strain MJ-PV demonstrated to degrade mycrocystin LR in seeded bioremediation trails, as well as the distribution and the regulation of mlrA shown to be involved in mycrocystin LR degradation.

Environmental factors associated with a toxic bloom of Microcystis aeruginosa

2000 ◽  
Vol 57 (1) ◽  
pp. 231-240 ◽  
Author(s):  
Jean M Jacoby ◽  
Diane C Collier ◽  
Eugene B Welch ◽  
F Joan Hardy ◽  
Michele Crayton
Keyword(s):  
Environmental Factors ◽  
Microcystis Aeruginosa ◽  
Toxin Production ◽  
Water Transparency ◽  
Cyanobacterial Blooms ◽  
Zooplankton Abundance ◽  
Factors Associated ◽  
Water Column Stability ◽  
Microcystin Concentration ◽  
Toxic Bloom

Environmental factors associated with the occurrence of toxic cyanobacterial blooms and toxin production were investigated during the summers of 1994 and 1995 in Steilacoom Lake, Washington. A pronounced and prolonged toxic bloom of Microcystis aeruginosa occurred during summer 1994 but not during 1995. Lake characteristics that were associated with the toxic bloom in 1994 were higher total phosphorus, decreased water transparency, high water column stability, high surface water temperature and pH, and decreased lake flushing. Decreased water transparency during 1994 may have been due to significantly lower zooplankton abundance. We hypothesize that this decreased transparency was caused by increased planktivory by higher numbers of coho salmon (Oncorhynchus kisutch) fingerlings during 1994 and (or) inhibition of zooplankton grazing by Microcystis. The success of Microcystis over other cyanobacteria was associated with low nitrogen to phosphorus ratios and low nitrate-nitrogen with sufficient ammonium-nitrogen concentrations. Toxin production (i.e., micrograms of microcystin per gram of plankton biomass) was not constant over the duration of detectable toxicity; hence, no relationship was found between Microcystis abundance and microcystin concentration. However, microcystin concentration was positively correlated with increasing soluble reactive phosphorus concentrations between 1 and 10 µg·L-1, indicating that toxin production may have been limited by phosphorus.

scholarly journals A global meta-analysis of ITS rDNA sequences from material belonging to the genus Ganoderma (Basidiomycota, Polyporales) including new data from selected taxa

MycoKeys ◽  
2020 ◽  
Vol 75 ◽  
pp. 71-143
Author(s):  
Vassiliki Fryssouli ◽  
Georgios Zervakis ◽  
Elias Polemis ◽  
Milton A. Typas
Keyword(s):  
Meta Analysis ◽  
White Rot Fungi ◽  
Global Scale ◽  
Its Rdna ◽  
White Rot ◽  
Phylogenetic Structure ◽  
Molecular Approaches ◽  
Rdna Sequences ◽  
The Status ◽  
Cluster A

Ganoderma P. Karst. is a cosmopolitan genus of white-rot fungi which comprises species with highly-prized pharmaceutical properties, valuable biotechnological applications and of significant phytopathological interest. However, the status of the taxonomy within the genus is still highly controversial and ambiguous despite the progress made through molecular approaches. A metadata analysis of 3908 nuclear ribosomal internal transcribed spacer (ITS) rDNA sequences obtained from GenBank/ENA/DDBJ and UNITE was performed by targeting sequences annotated as Ganoderma, but also sequences from environmental samples and from material examined for the first time. Ganoderma taxa segregated into five main lineages (Clades A to E). Clade A corresponds to the core of laccate species and includes G. shanxiense and three major well-supported clusters: Cluster A.1 (‘G. lucidum sensu lato’) consists of taxa from Eurasia and North America, Cluster A.2 of material with worldwide occurrence including G. resinaceum and Cluster A.3 is composed of species originating from all continents except Europe and comprises G. lingzhi. Clade B includes G. applanatum and allied species with a Holarctic distribution. Clade C comprises taxa from Asia and Africa only. Clade D consists of laccate taxa with tropical/subtropical occurrence, while clade E harbours the highest number of non-laccate species with a cosmopolitan distribution. The 92 Ganoderma-associated names, initially used for sequences labelling, correspond to at least 80 taxa. Amongst them, 21 constitute putatively new phylospecies after our application of criteria relevant to the robustness/support of the terminal clades, intra- and interspecific genetic divergence and available biogeographic data. Moreover, several other groups or individual sequences seem to represent distinct taxonomic entities and merit further investigation. A particularly large number of the public sequences was revealed to be insufficiently and/or incorrectly identified, for example, 87% and 78% of entries labelled as G. australe and G. lucidum, respectively. In general, ITS demonstrated high efficacy in resolving relationships amongst most of the Ganoderma taxa; however, it was not equally useful at elucidating species barriers across the entire genus and such cases are outlined. Furthermore, we draw conclusions on biogeography by evaluating species occurrence on a global scale in conjunction with phylogenetic structure/patterns. The sequence variability assessed in ITS spacers could be further exploited for diagnostic purposes.

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