scholarly journals Identification of Detoxification Esterase StrH Initiating Strobilurin Fungicides Degradation in Hyphomicrobium sp. DY-1

2021 ◽  
Author(s):  
Wankui Jiang ◽  
Qinqin Gao ◽  
Lu Zhang ◽  
Yali Liu ◽  
Mingliang Zhang ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Catalytic Efficiency ◽  
Aquatic Organisms ◽  
Degradation Process ◽  
Maximum Activity ◽  
Cyanobacterial Blooms ◽  
Strobilurin Fungicides ◽  
Novel Esterase ◽  
Esterase Gene ◽  
Harmful Cyanobacterial Blooms

Strobilurin fungicides are widely used in agricultural production due to their broad-spectrum and fungal mitochondrial inhibitory activities. However, their massive application has detained the growth of eukaryotic algae and increased the collateral damage in freshwater systems, notably the harmful cyanobacterial blooms (HCBs). In this study, a strobilurin fungicide-degrading strain Hyphomicrobium sp. DY-1 was isolated and characterized successfully. Moreover, a novel esterase gene strH responsible for the de-esterification of strobilurin fungicides was cloned, and the enzymatic properties of StrH were studied. For trifloxystrobin, StrH displayed the maximum activity at 50°C and pH 7.0. The catalytic efficiency (kcat/Km) of StrH for different strobilurin fungicides were 196.32±2.30 μM−1·s−1 (trifloxystrobin), 4.64±0.05 μM−1·s−1 (picoxystrobin), 2.94±0.02 μM−1·s−1 (pyraclostrobin), and (2.41±0.19)×10−2 μM−1·s−1 (azoxystrobin). StrH catalyzed the de-esterification of a variety of strobilurin fungicides generating the corresponding parent acid to achieve the detoxification of strobilurin fungicides and relieve strobilurin fungicides growth inhibition on Chlorella. This research will provide insight into the microbial remediation of strobilurin fungicides-contaminated environments. IMPORTANCE Strobilurin fungicides have been widely acknowledged as an essential group of pesticides worldwide. So far, their residues and toxic effects on aquatic organisms have been reported in different parts of the world. Microbial degradation could eliminate xenobiotics from the environment. Therefore, the degradation of strobilurin fungicides by microorganisms has also been reported. However, little is known about the involvement of enzyme or gene in strobilurin fungicides degradation. In this study, a novel esterase gene strH responsible for the detoxification of strobilurin fungicides was cloned in the newly isolated strain Hyphomicrobium sp. DY-1. This degradation process detoxifies the strobilurin fungicides and relieves their growth inhibition on Chlorella.

scholarly journals A Brief Review of the Structure, Cytotoxicity, Synthesis, and Biodegradation of Microcystins

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2147
Author(s):  
Anjali Krishnan ◽  
Xiaozhen Mou
Keyword(s):  
Health Hazard ◽  
Aquatic Organisms ◽  
Water Soluble ◽  
Cyanobacterial Blooms ◽  
Aquatic Environments ◽  
Natural Environments ◽  
Exposure Pathway ◽  
Environmental Transformation ◽  
Cyclic Heptapeptide ◽  
Harmful Cyanobacterial Blooms

Harmful cyanobacterial blooms pose an environmental health hazard due to the release of water-soluble cyanotoxins. One of the most prevalent cyanotoxins in nature is microcystins (MCs), a class of cyclic heptapeptide hepatotoxins, and they are produced by several common cyanobacteria in aquatic environments. Once released from cyanobacterial cells, MCs are subjected to physical chemical and biological transformations in natural environments. MCs can also be taken up and accumulated in aquatic organisms and their grazers/predators and induce toxic effects in several organisms, including humans. This brief review aimed to summarize our current understanding on the chemical structure, exposure pathway, cytotoxicity, biosynthesis, and environmental transformation of microcystins.

scholarly journals Inhibition of Extracellular Enzymes Exposed to Cyanopeptides

2020 ◽  
Vol 74 (3) ◽  
pp. 122-128
Author(s):  
Christine M. Egli ◽  
Regiane S. Natumi ◽  
Martin R. Jones ◽  
Elisabeth M.-L. Janssen
Keyword(s):  
Extracellular Enzymes ◽  
Heterotrophic Bacteria ◽  
Hydrolytic Enzymes ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Biologically Relevant ◽  
Metabolic Functions ◽  
Harmful Cyanobacterial Blooms ◽  
Quality Assessments

Harmful cyanobacterial blooms in freshwater ecosystems produce bioactive secondary metabolites including cyanopeptides that pose ecological and human health risks. Only adverse effects of one class of cyanopeptides, microcystins, have been studied extensively and have consequently been included in water quality assessments. Inhibition is a commonly observed effect for enzymes exposed to cyanopeptides and has mostly been investigated for human biologically relevant model enzymes. Here, we investigated the inhibition of ubiquitous aquatic enzymes by cyanobacterial metabolites. Hydrolytic enzymes are utilized in the metabolism of aquatic organisms and extracellularly by heterotrophic bacteria to obtain assimilable substrates. The ubiquitous occurrence of hydrolytic enzymes leads to the co-occurrence with cyanopeptides especially during cyanobacterial blooms. Bacterial leucine aminopeptidase and alkaline phosphatase were exposed to cyanopeptide extracts of different cyanobacterial strains ( Microcystis aeruginosa wild type and microcystin-free mutant, Planktothrix rubescens) and purified cyanopeptides. We observed inhibition of aminopeptidase and phosphatase upon exposure, especially to the apolar fractions of the cyanobacterial extracts. Exposure to the dominant cyanopeptides in these extracts confirmed that purified microcystins, aerucyclamide A and cyanopeptolin A inhibit the aminopeptidase in the low mg L–1 range while the phosphatase was less affected. Inhibition of aquatic enzymes can reduce the turnover of nutrients and carbon substrates and may also impair metabolic functions of grazing organisms.

Research on Allelochemicals with Material Properties Exuded by Submerged Freshwater Macrophyte Elodea nuttallii

2014 ◽  
Vol 1023 ◽  
pp. 71-74 ◽  
Author(s):  
Yun Ni Gao ◽  
Li Ping Zhang ◽  
Bi Yun Liu ◽  
Yong Yuan Zhang ◽  
Zhen Bin Wu
Keyword(s):  
Phenolic Acids ◽  
High Growth ◽  
Aquatic Organisms ◽  
High Growth Rate ◽  
Cyanobacterial Blooms ◽  
Elodea Nuttallii ◽  
Inhibitory Effects ◽  
Methanol Fraction ◽  
Culture Density ◽  
Harmful Cyanobacterial Blooms

Elodea nuttallii is well-known for its successful invasion to Europe and Asia. In addition to its high growth rate and nutrient storage capacity, chemical defense was recently found to play an important role in excluding other aquatic organisms. To reveal the chemical nature of its allelopathic effects on cyanobacterial development, extraction of plant exudates with different solvents and eluted procedures followed by 72h bioassays with Microcystis aeruginosa was conducted. The results showed that the fraction eluted with methanol exhibited the strongest inhibitory effects, which indicated that the anti-cyanobacterial active allelochemicals released by E.nuttallii was hydrophilic. Then ten phenolic acids were identified in the purified methanol fraction of Elodea exudates by GC-MS analysis. Quantification of the four phenolic acids therein showed the release contents were lower than 10μg/L when E.nuttallii was cultivated at 10g FW/L, which increased with the increasing culture density. When the culture density was 100g FW/L, the detected contents of vanillic acid, protocatechuic acid, ferulic acid and caffeic acid in E.nuttallii culture water were 23.41μg/L, 17.56 μg/L, 12.31 μg/L and 18.93μg/L, respectively. These results were helpful to understand the allelopathy mechanisms of E.nuttallii in aquatic ecosystems and useful in control of harmful cyanobacterial blooms.

scholarly journals Phytoremediation of CYN, MC-LR and ANTX-a from Water by the Submerged Macrophyte Lemna trisulca

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 699
Author(s):  
Małgorzata Kucała ◽  
Michał Saładyga ◽  
Ariel Kaminski
Keyword(s):  
Electrical Conductivity ◽  
Chlorophyll A ◽  
Growth And Development ◽  
Cyanobacterial Blooms ◽  
Biotechnological Potential ◽  
Intracellular Pool ◽  
Ph Values ◽  
Bg11 Medium ◽  
Total Pool ◽  
Harmful Cyanobacterial Blooms

Cyanotoxins are harmful to aquatic and water-related organisms. In this study, Lemna trisulca was tested as a phytoremediation agent for three common cyanotoxins produced by bloom-forming cyanobacteria. Cocultivation of L. trisulca with Dolichospermum flos-aquae in BG11 medium caused a release of the intracellular pool of anatoxin-a into the medium and the adsorption of 92% of the toxin by the plant—after 14 days, the total amount of toxin decreased 3.17 times. Cocultivation with Raphidopsis raciborskii caused a 2.77-time reduction in the concentration of cylindrospermopsin (CYN) in comparison to the control (62% of the total pool of CYN was associated with the plant). The greatest toxin limitation was noted for cocultivation with Microcystis aeruginosa. After two weeks, the microcystin-LR (MC-LR) concentration decreased more than 310 times. The macrophyte also influenced the growth and development of cyanobacteria cells. Overall, 14 days of cocultivation reduced the biomass of D. flos-aquae, M. aeruginosa, and R. raciborskii by 8, 12, and 3 times, and chlorophyll a concentration in comparison to the control decreased by 17.5, 4.3, and 32.6 times, respectively. Additionally, the macrophyte stabilized the electrical conductivity (EC) and pH values of the water and affected the even uptake of cations and anions from the medium. The obtained results indicate the biotechnological potential of L. trisulca for limiting the development of harmful cyanobacterial blooms and their toxicity.

scholarly journals Resilience of Microbial Communities after Hydrogen Peroxide Treatment of a Eutrophic Lake to Suppress Harmful Cyanobacterial Blooms

2021 ◽  
Vol 9 (7) ◽  
pp. 1495
Author(s):  
Tim Piel ◽  
Giovanni Sandrini ◽  
Gerard Muyzer ◽  
Corina P. D. Brussaard ◽  
Pieter C. Slot ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Microbial Community ◽  
Microbial Communities ◽  
Microbial Community Composition ◽  
Glycoside Hydrolases ◽  
Microbial Community Analysis ◽  
Cyanobacterial Blooms ◽  
Temporary Increase ◽  
Low Concentrations ◽  
Harmful Cyanobacterial Blooms

Applying low concentrations of hydrogen peroxide (H2O2) to lakes is an emerging method to mitigate harmful cyanobacterial blooms. While cyanobacteria are very sensitive to H2O2, little is known about the impacts of these H2O2 treatments on other members of the microbial community. In this study, we investigated changes in microbial community composition during two lake treatments with low H2O2 concentrations (target: 2.5 mg L−1) and in two series of controlled lake incubations. The results show that the H2O2 treatments effectively suppressed the dominant cyanobacteria Aphanizomenon klebahnii, Dolichospermum sp. and, to a lesser extent, Planktothrix agardhii. Microbial community analysis revealed that several Proteobacteria (e.g., Alteromonadales, Pseudomonadales, Rhodobacterales) profited from the treatments, whereas some bacterial taxa declined (e.g., Verrucomicrobia). In particular, the taxa known to be resistant to oxidative stress (e.g., Rheinheimera) strongly increased in relative abundance during the first 24 h after H2O2 addition, but subsequently declined again. Alpha and beta diversity showed a temporary decline but recovered within a few days, demonstrating resilience of the microbial community. The predicted functionality of the microbial community revealed a temporary increase of anti-ROS defenses and glycoside hydrolases but otherwise remained stable throughout the treatments. We conclude that the use of low concentrations of H2O2 to suppress cyanobacterial blooms provides a short-term pulse disturbance but is not detrimental to lake microbial communities and their ecosystem functioning.

Harmful Cyanobacterial Blooms

2007 ◽  
pp. 207-242 ◽  
Author(s):  
Igor Linkov ◽  
A. Fristachi ◽  
F. K. Satterstrom ◽  
A. Shifrin ◽  
J. Steevens ◽  
...  
Keyword(s):  
Cyanobacterial Blooms ◽  
Harmful Cyanobacterial Blooms

Environmental controls of harmful cyanobacterial blooms in Chinese inland waters

Harmful Algae ◽  
2021 ◽  
Vol 110 ◽  
pp. 102127
Author(s):  
Hai Xu ◽  
Boqiang Qin ◽  
Hans W. Paerl ◽  
Kai Peng ◽  
Qingji Zhang ◽  
...  
Keyword(s):  
Cyanobacterial Blooms ◽  
Inland Waters ◽  
Environmental Controls ◽  
Harmful Cyanobacterial Blooms

scholarly journals Isolation of axenic cyanobacterium and the promoting effect of associated bacterium on axenic cyanobacterium

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Suqin Gao ◽  
Yun Kong ◽  
Jing Yu ◽  
Lihong Miao ◽  
Lipeng Ji ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Specific Interaction ◽  
Cyanobacterial Blooms ◽  
Organic Substrates ◽  
Promoting Effect ◽  
Associated Bacteria ◽  
Purification Technique ◽  
Harmful Cyanobacterial Blooms ◽  
Solid Liquid ◽  
Water Quality Deterioration

Abstract Background Harmful cyanobacterial blooms have attracted wide attention all over the world as they cause water quality deterioration and ecosystem health issues. Microcystis aeruginosa associated with a large number of bacteria is one of the most common and widespread bloom-forming cyanobacteria that secret toxins. These associated bacteria are considered to benefit from organic substrates released by the cyanobacterium. In order to avoid the influence of associated heterotrophic bacteria on the target cyanobacteria for physiological and molecular studies, it is urgent to obtain an axenic M. aeruginosa culture and further investigate the specific interaction between the heterotroph and the cyanobacterium. Results A traditional and reliable method based on solid-liquid alternate cultivation was carried out to purify the xenic cyanobacterium M. aeruginosa FACHB-905. On the basis of 16S rDNA gene sequences, two associated bacteria named strain B905–1 and strain B905–2, were identified as Pannonibacter sp. and Chryseobacterium sp. with a 99 and 97% similarity value, respectively. The axenic M. aeruginosa FACHB-905A (Microcystis 905A) was not able to form colonies on BG11 agar medium without the addition of strain B905–1, while it grew well in BG11 liquid medium. Although the presence of B905–1 was not indispensable for the growth of Microcystis 905A, B905–1 had a positive effect on promoting the growth of Microcystis 905A. Conclusions The associated bacteria were eliminated by solid-liquid alternate cultivation method and the axenic Microcystis 905A was successfully purified. The associated bacterium B905–1 has the potentiality to promote the growth of Microcystis 905A. Moreover, the purification technique for cyanobacteria described in this study is potentially applicable to a wider range of unicellular cyanobacteria.

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