1
|
Mohamed ZA, Elnour RO, Alamri S, Hashem M. Biodegradation of the cyanobacterial toxin anatoxin-a by a Bacillus subtilis strain isolated from a eutrophic lake in Saudi Arabia. Arch Microbiol 2024; 206:348. [PMID: 38990418 DOI: 10.1007/s00203-024-04074-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2024] [Revised: 06/22/2024] [Accepted: 06/24/2024] [Indexed: 07/12/2024]
Abstract
Anatoxin-a (ATX-a) is a neurotoxin produced by some species of cyanobacteria. Due to its water solubility and stability in natural water, it could pose health risks to human, animals, and plants. Conventional water treatment techniques are not only insufficient for the removal of ATX-a, but they also result in cell lysis and toxin release. The elimination of this toxin through biodegradation may be a promising strategy. This study examines for the first time the biodegradation of ATX-a to a non-toxic metabolite (Epoxy-ATX-a) by a strain of Bacillus that has a history of dealing with toxic cyanobacteria in a eutrophic lake. The Bacillus strain AMRI-03 thrived without lag phase in a lake water containing ATX-a. The strain displayed fast degradation of ATX-a, depending on initial toxin concentration. At the highest initial concentrations (50 & 100 µg L- 1), total ATX-a degradation took place in 4 days, but it took 6 & 7 days at lower concentrations (20, 10, and 1 µg L- 1, respectively). The ATX-a biodegradation rate was also influenced by the initial toxin concentration, reaching its maximum value (12.5 µg L- 1 day- 1) at the highest initial toxin concentrations (50 & 100 µg L- 1). Temperature and pH also had an impact on the rate of ATX-a biodegradation, with the highest rates occurring at 25 and 30 ºC and pH 7 and 8. This nontoxic bacterial strain could be immobilized within a biofilm on sand filters and/or sludge for the degradation and removal of ATX-a and other cyanotoxins during water treatment processes, following the establishment of mesocosm experiments to assess the potential effects of this bacterium on water quality.
Collapse
Affiliation(s)
- Zakaria A Mohamed
- Department of Botany and Microbiology, Faculty of Science, Sohag University, Sohag, 82524, Egypt.
| | - Rehab O Elnour
- Biology Department, Faculty of Sciences and Arts, King Khalid University, Dahran Al-Janoub, Abha, Saudi Arabia
| | - Saad Alamri
- Department of Biology, College of Science, King Khalid University, Abha, 61413, Saudi Arabia
| | - Mohamed Hashem
- Botany and Microbiology Department, Faculty of Science, Assiut University, Assiut, 71516, Egypt
| |
Collapse
|
2
|
Haida M, El Khalloufi F, Mugani R, Essadki Y, Campos A, Vasconcelos V, Oudra B. Microcystin Contamination in Irrigation Water and Health Risk. Toxins (Basel) 2024; 16:196. [PMID: 38668621 PMCID: PMC11054416 DOI: 10.3390/toxins16040196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 04/29/2024] Open
Abstract
Microcystins (MCs), natural hepatotoxic compounds produced by cyanobacteria, pose significant risks to water quality, ecosystem stability, and the well-being of animals, plants, and humans when present in elevated concentrations. The escalating contamination of irrigation water with MCs presents a growing threat to terrestrial plants. The customary practice of irrigating crops from local water sources, including lakes and ponds hosting cyanobacterial blooms, serves as a primary conduit for transferring these toxins. Due to their high chemical stability and low molecular weight, MCs have the potential to accumulate in various parts of plants, thereby increasing health hazards for consumers of agricultural products, which serve as the foundation of the Earth's food chain. MCs can bioaccumulate, migrate, potentially biodegrade, and pose health hazards to humans within terrestrial food systems. This study highlights that MCs from irrigation water reservoirs can bioaccumulate and come into contact with plants, transferring into the food chain. Additionally, it investigates the natural mechanisms that organisms employ for conjugation and the microbial processes involved in MC degradation. To gain a comprehensive understanding of the role of MCs in the terrestrial food chain and to elucidate the specific health risks associated with consuming crops irrigated with water contaminated with these toxins, further research is necessary.
Collapse
Affiliation(s)
- Mohammed Haida
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco; (M.H.); (R.M.); (Y.E.); (B.O.)
| | - Fatima El Khalloufi
- Natural Resources Engineering and Environmental Impacts Team, Multidisciplinary Research and Innovation Laboratory, Polydisciplinary Faculty of Khouribga, Sultan Moulay Slimane University of Beni Mellal, B.P, 45, Khouribga 25000, Morocco;
| | - Richard Mugani
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco; (M.H.); (R.M.); (Y.E.); (B.O.)
| | - Yasser Essadki
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco; (M.H.); (R.M.); (Y.E.); (B.O.)
| | - Alexandre Campos
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208 Porto, Portugal;
| | - Vitor Vasconcelos
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208 Porto, Portugal;
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Brahim Oudra
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco; (M.H.); (R.M.); (Y.E.); (B.O.)
| |
Collapse
|
3
|
Alhaithloul HAS, Mohamed ZA, Saber AA, Alsudays IM, Abdein MA, Alqahtani MM, AbuSetta NG, Elkelish A, Pérez LM, Albalwe FM, Bakr AA. Performance evaluation of Moringa oleifera seeds aqueous extract for removing Microcystis aeruginosa and microcystins from municipal treated-water. Front Bioeng Biotechnol 2024; 11:1329431. [PMID: 38362588 PMCID: PMC10868579 DOI: 10.3389/fbioe.2023.1329431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Accepted: 12/29/2023] [Indexed: 02/17/2024] Open
Abstract
Introduction: Toxic microcystins (MCs) produced by cyanoprokaryotes -particularly by the cosmopolitan cyanobacterium Microcystis aeruginosa- pose adverse effects on aquatic organisms and their ecosystem and may also cause serious impacts on human health. These harmful monocyclic heptapeptides are the most prevalent cyanotoxins reported in freshwaters and must be eliminated for avoiding MCs release in receiving water bodies. Hence, this work aimed to test the efficacy of Moringa oleifera seeds water-based extract (MO) as a natural coagulant for removing cyanobacteria (especially M. aeruginosa), microalgae, and its associated MCs from pre-treated municipal wastewaters. Methodology: Four different MO coagulant doses (25, 50, 75 and 100 mg L-1) were investigated for cyanobacteria and microalgae removal by conventional coagulation assays and morphology-based taxonomy studies. Additionally, water turbidity and chlorophyll a (Chl a) content were also determined. Further, the presence and concentration of MCs soluble in water, remaining in the particulate fraction, and flocculated within the residual sludge were assessed using high-performance liquid chromatography coupled with diode array detection (HPLC-DAD). Results: The treatment with MO at 100 mg L-1 substantially reduced the number of cyanobacterial and microalgal species in the treated samples (average removal rate of 93.8% and 86.9%, respectively). These results agreed with a ∼44% concomitant reduction in Chl a and ∼97% reduction in water turbidity (a surrogate marker for suspended solids content). Notably, MCs concentrations in the treated water were significantly lowered to 0.6 ± 0.1 µg L-1 after addition of 100 mg L-1 MO. This value is below the WHO recommended limits for MCs presence in drinking water (<1.0 µg L-1). Discussion: The present study provides promising insights into the applicability of MO as a cost-effective, reliable, and sustainable natural coagulant, particularly for using in developing countries, to eliminate harmful cyanobacteria and cyanotoxins in municipal water treatment facilities.
Collapse
Affiliation(s)
| | - Zakaria A. Mohamed
- Microbiology and Botany Department, Faculty of Science, Sohag University, Sohag, Egypt
| | - Abdullah A. Saber
- Botany Department, Faculty of Science, Ain Shams University, Cairo, Egypt
| | | | - Mohamed A. Abdein
- Seeds Development Department, El-Nada Misr Scientific Research and Development Projects, Mansoura, Egypt
| | - Mesfer M. Alqahtani
- Department of Biological Sciences, Faculty of Science and Humanities, Shaqra University, Shaqraa, Saudi Arabia
| | - Noha G. AbuSetta
- Microbiology and Botany Department, Faculty of Science, South Valley University, Qena, Egypt
| | - Amr Elkelish
- Department of Biology, College of Science, Imam Muhammad bin Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
- Department of Botany and Microbiology, Faculty of Science, Suez Canal University, Ismailia, Egypt
| | - Leonardo Martín Pérez
- Facultad de Química e Ingeniería del Rosario, Pontificia Universidad Católica Argentina (UCA), Rosario, Argentina
- Laboratory of Environmental and Sanitary Microbiology (MSMLab-UPC), Universitat Politècnica de Catalunya-BarcelonaTech, Terrassa, Spain
| | | | - Asmaa A. Bakr
- Microbiology and Botany Department, Faculty of Science, Sohag University, Sohag, Egypt
| |
Collapse
|
4
|
Falfushynska H, Kasianchuk N, Siemens E, Henao E, Rzymski P. A Review of Common Cyanotoxins and Their Effects on Fish. TOXICS 2023; 11:toxics11020118. [PMID: 36850993 PMCID: PMC9961407 DOI: 10.3390/toxics11020118] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/23/2023] [Accepted: 01/23/2023] [Indexed: 05/31/2023]
Abstract
Global warming and human-induced eutrophication drive the occurrence of various cyanotoxins in aquatic environments. These metabolites reveal diversified mechanisms of action, encompassing cyto-, neuro-, hepato-, nephro-, and neurotoxicity, and pose a threat to aquatic biota and human health. In the present paper, we review data on the occurrence of the most studied cyanotoxins, microcystins, nodularins, cylindrospermopsin, anatoxins, and saxitoxins, in the aquatic environment, as well as their potential bioaccumulation and toxicity in fish. Microcystins are the most studied among all known cyanotoxins, although other toxic cyanobacterial metabolites are also commonly identified in aquatic environments and can reveal high toxicity in fish. Except for primary toxicity signs, cyanotoxins adversely affect the antioxidant system and anti-/pro-oxidant balance. Cyanotoxins also negatively impact the mitochondrial and endoplasmic reticulum by increasing intracellular reactive oxygen species. Furthermore, fish exposed to microcystins and cylindrospermopsin exhibit various immunomodulatory, inflammatory, and endocrine responses. Even though cyanotoxins exert a complex pressure on fish, numerous aspects are yet to be the subject of in-depth investigation. Metabolites other than microcystins should be studied more thoroughly to understand the long-term effects in fish and provide a robust background for monitoring and management actions.
Collapse
Affiliation(s)
- Halina Falfushynska
- Department of Marine Biology, Institute for Biological Sciences, University of Rostock, 18059 Rostock, Germany
- Faculty of Electrical, Mechanical and Industrial Engineering, Anhalt University for Applied Sciences, 06366 Köthen, Germany
| | - Nadiia Kasianchuk
- Faculty of Biology, Adam Mickiewicz University, 61712 Poznan, Poland
| | - Eduard Siemens
- Faculty of Electrical, Mechanical and Industrial Engineering, Anhalt University for Applied Sciences, 06366 Köthen, Germany
| | - Eliana Henao
- Research Group Integrated Management of Ecosystems and Biodiversity XIUÂ, School of Biological Sciences, Universidad Pedagógica y Tecnológica de Colombia, Tunja 150003, Colombia
| | - Piotr Rzymski
- Department of Environmental Medicine, Poznan University of Medical Sciences, 61701 Poznan, Poland
- Integrated Science Association (ISA), Universal Scientific Education and Research Network (USERN), 61701 Poznań, Poland
| |
Collapse
|
5
|
Christensen VG, Olds HT, Norland J, Khan E. Phytoplankton community interactions and cyanotoxin mixtures in three recurring surface blooms within one lake. JOURNAL OF HAZARDOUS MATERIALS 2022; 427:128142. [PMID: 35042050 DOI: 10.1016/j.jhazmat.2021.128142] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
Cyanobacteria can produce numerous secondary metabolites (cyanotoxins) with various toxicities, yet data on cyanotoxins in many lakes are limited. Moreover, little research is available on complex relations among cyanobacteria that produce toxins. Therefore, we studied cyanobacteria and 19 cyanotoxins at three sites with recurring blooms in Kabetogama Lake (USA). Seven of 19 toxins were detected in various combinations. Anabaenopeptin A and B were detected in every sample. Microcystin-YR was detected more frequently than microcystin-LR, unlike other lakes in the region. Microcystin-YR concentrations, however, generally were low; two samples exceeded drinking water guidelines and no samples exceeded recreational guidelines. Anabaenopeptins correlated with six cyanobacterial taxa, most of which lack available literature on peptide production. The potential toxin producing cyanobacteria, Microcystis, was significantly correlated to microcystin-YR. Pseudanabaena sp. and Synechococcus sp. had strong negative correlations with several toxins that may indicate competition or stress between organisms. Non-metric multidimensional scaling identified three cyanobacterial pairs that may reflect symbiotic or antagonistic relations. This study highlights interactions among cyanobacteria and multiple cyanotoxins and the methods used may be useful for uncovering additional patterns in cyanobacteria communities in other systems, leading to further understanding of how those interactions lead to toxin production.
Collapse
Affiliation(s)
- Victoria G Christensen
- US Geological Survey, Upper Midwest Water Science Center, 2280 Woodale Dr., Mounds View , MN, USA; North Dakota State University, Environmental and Conservation Sciences Program, 1300 Albrecht Blvd., Fargo, ND 58102, USA
| | - Hayley T Olds
- US Geological Survey, Upper Midwest Water Science Center, 2280 Woodale Dr., Mounds View , MN, USA
| | - Jack Norland
- North Dakota State University, Environmental and Conservation Sciences Program, 1300 Albrecht Blvd., Fargo, ND 58102, USA
| | - Eakalak Khan
- University of Nevada, Las Vegas, Civil and Environmental Engineering Department, 4505 S. Maryland Pkwy, Las Vegas, NV 89154, USA
| |
Collapse
|
6
|
Cyanotoxins uptake and accumulation in crops: Phytotoxicity and implications on human health. Toxicon 2022; 211:21-35. [DOI: 10.1016/j.toxicon.2022.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/03/2022] [Accepted: 03/07/2022] [Indexed: 12/16/2022]
|
7
|
Porzani SJ, Lima ST, Metcalf JS, Nowruzi B. In Vivo and In Vitro Toxicity Testing of Cyanobacterial Toxins: A Mini-Review. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2021; 258:109-150. [PMID: 34622370 DOI: 10.1007/398_2021_74] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Harmful cyanobacterial blooms are increasing and becoming a worldwide concern as many bloom-forming cyanobacterial species can produce toxic metabolites named cyanotoxins. These include microcystins, saxitoxins, anatoxins, nodularins, and cylindrospermopsins, which can adversely affect humans, animals, and the environment. Different methods to assess these classes of compounds in vitro and in vivo include biological, biochemical, molecular, and physicochemical techniques. Furthermore, toxic effects not attributable to known cyanotoxins can be observed when assessing bloom material. In order to determine exposures to cyanotoxins and to monitor compliance with drinking and bathing water guidelines, it is necessary to have reliable and effective methods for the analysis of these compounds. Many relatively simple low-cost methods can be employed to rapidly evaluate the potential hazard. The main objective of this mini-review is to describe the assessment of toxic cyanobacterial samples using in vitro and in vivo bioassays. Newly emerging cyanotoxins, the toxicity of analogs, or the interaction of cyanobacteria and cyanotoxins with other toxicants, among others, still requires bioassay assessment. This review focuses on some biological and biochemical assays (MTT assay, Immunohistochemistry, Micronucleus Assay, Artemia salina assay, Daphnia magna test, Radionuclide recovery, Neutral red cytotoxicity and Comet assay, Enzyme-Linked Immunosorbent Assay (ELISA), Annexin V-FITC assay and Protein Phosphatase Inhibition Assay (PPIA)) for the detection and measurement of cyanotoxins including microcystins, cylindrospermopsins, anatoxin-a, saxitoxins, and nodularins. Although most bioassay analyses often confirm the presence of cyanotoxins at low concentrations, such bioassays can be used to determine whether some strains or blooms of cyanobacteria may produce other, as yet unknown toxic metabolites. This review also aims to identify research needs and data gaps concerning the toxicity assessment of cyanobacteria.
Collapse
Affiliation(s)
- Samaneh J Porzani
- Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Stella T Lima
- Center for Nuclear Energy in Agriculture, University of Sao Paulo, Piracicaba, Brazil
| | | | - Bahareh Nowruzi
- Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran.
| |
Collapse
|
8
|
Romanis CS, Pearson LA, Neilan BA. Cyanobacterial blooms in wastewater treatment facilities: Significance and emerging monitoring strategies. J Microbiol Methods 2020; 180:106123. [PMID: 33316292 DOI: 10.1016/j.mimet.2020.106123] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 12/06/2020] [Accepted: 12/08/2020] [Indexed: 12/30/2022]
Abstract
Municipal wastewater treatment facilities (WWTFs) are prone to the proliferation of cyanobacterial species which thrive in stable, nutrient-rich environments. Dense cyanobacterial blooms frequently disrupt treatment processes and the supply of recycled water due to their production of extracellular polymeric substances, which hinder microfiltration, and toxins, which pose a health risk to end-users. A variety of methods are employed by water utilities for the identification and monitoring of cyanobacteria and their toxins in WWTFs, including microscopy, flow cytometry, ELISA, chemoanalytical methods, and more recently, molecular methods. Here we review the literature on the occurrence and significance of cyanobacterial blooms in WWTFs and discuss the pros and cons of the various strategies for monitoring these potentially hazardous events. Particular focus is directed towards next-generation metagenomic sequencing technologies for the development of site-specific cyanobacterial bloom management strategies. Long-term multi-omic observations will enable the identification of indicator species and the development of site-specific bloom dynamics models for the mitigation and management of cyanobacterial blooms in WWTFs. While emerging metagenomic tools could potentially provide deep insight into the diversity and flux of problematic cyanobacterial species in these systems, they should be considered a complement to, rather than a replacement of, quantitative chemoanalytical approaches.
Collapse
Affiliation(s)
- Caitlin S Romanis
- School of Environmental and Life Sciences, University of Newcastle, Newcastle 2308, Australia
| | - Leanne A Pearson
- School of Environmental and Life Sciences, University of Newcastle, Newcastle 2308, Australia
| | - Brett A Neilan
- School of Environmental and Life Sciences, University of Newcastle, Newcastle 2308, Australia.
| |
Collapse
|
9
|
Kumar P, Rautela A, Kesari V, Szlag D, Westrick J, Kumar S. Recent developments in the methods of quantitative analysis of microcystins. J Biochem Mol Toxicol 2020; 34:e22582. [PMID: 32662914 DOI: 10.1002/jbt.22582] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 05/21/2020] [Accepted: 06/30/2020] [Indexed: 12/15/2022]
Abstract
Cyanotoxins are produced by the toxic cyanobacterial species present in algal blooms formed in water bodies due to nutrient over-enrichment by human influences and natural environmental conditions. Extensive studies are available on the most widely encountered cyanotoxins, microcystins (MCs) in fresh and brackish water bodies. MC contaminated water poses severe risks to human health, environmental sustainability, and aquatic life. Therefore, commonly occurring MCs should be monitored. Occasionally, detection and quantification of these toxins are difficult due to the unavailability of pure standards. Enzymatic, immunological assays, and analytical techniques like protein phosphatase inhibition assay, enzyme-linked immunosorbent assay, high-performance liquid chromatography, liquid chromatography-mass spectrometry, and biosensors are used for their detection and quantification. There is no single method for the detection of all the different types of MCs; therefore, various techniques are often combined to yield reliable results. Biosensor development offered a problem-solving approach in the detection of MCs due to their high accuracy, sensitivity, rapid response, and portability. In this review, an endeavor has been made to uncover emerging techniques used for the detection and quantification of the MCs.
Collapse
Affiliation(s)
- Piyush Kumar
- School of Biochemical Engineering, Indian Institute of Technology (Banaras Hindu University) Varanasi, Varanasi, Uttar Pradesh, India
| | - Akhil Rautela
- School of Biochemical Engineering, Indian Institute of Technology (Banaras Hindu University) Varanasi, Varanasi, Uttar Pradesh, India
| | - Vigya Kesari
- Department of Botany, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - David Szlag
- Department of Chemistry, Lumigen Instrument Center, Wayne State University, Detroit, Michigan
| | - Judy Westrick
- Department of Chemistry, Lumigen Instrument Center, Wayne State University, Detroit, Michigan
| | - Sanjay Kumar
- School of Biochemical Engineering, Indian Institute of Technology (Banaras Hindu University) Varanasi, Varanasi, Uttar Pradesh, India
| |
Collapse
|
10
|
Mohamed Z, Ahmed Z, Bakr A, Hashem M, Alamri S. Detection of free and bound microcystins in tilapia fish from Egyptian fishpond farms and its related public health risk assessment. J Verbrauch Lebensm 2019. [DOI: 10.1007/s00003-019-01254-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
11
|
Jaša L, Sadílek J, Kohoutek J, Straková L, Maršálek B, Babica P. Application of passive sampling for sensitive time-integrative monitoring of cyanobacterial toxins microcystins in drinking water treatment plants. WATER RESEARCH 2019; 153:108-120. [PMID: 30703675 DOI: 10.1016/j.watres.2018.12.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 12/18/2018] [Accepted: 12/22/2018] [Indexed: 06/09/2023]
Abstract
Calibrated adsorption-based passive samplers were used for time-integrative monitoring of microcystins (MCs) in three full-scale drinking water treatment plants (DWTPs) in the Czech Republic during two vegetation seasons (Jun-Nov), in parallel with traditional discrete sampling. MCs were detected in epilimnetic water samples at concentrations up to 14 μg/L, but their levels in raw water in DWTPs were below 1 μg/L WHO guideline value for drinking water. Conventional treatment technologies (coagulation/filtration) eliminated cyanobacteria and intracellular toxins but had a limited removal efficiency for extracellular toxins. MCs were regularly detected in final treated water, especially in DWTPs equipped only with the conventional treatment, but their concentrations were below the quantitation limit of discrete sampling (<25 ng/L). Passive samplers in combination with LC-MS/MS analysis provided excellent sensitivity allowing to detect time-weighted average (TWA) concentrations of MCs as low as 20-200 pg/L after 14-d deployment. Median MC TWA concentrations in the treated water from the individual DWTPs were 1-12 ng/L, and most likely did not present significant health risks. Passive samplers well reflected spatiotemporal variations of MCs, actual concentrations of extracellular toxins, MC removal efficiency in DWTPs, and toxin concentrations in the treated water. Passive sampling can be effectively used for assessment and management of MC health risks during DWTP operation.
Collapse
Affiliation(s)
- Libor Jaša
- Department of Experimental Phycology and Ecotoxicology, Institute of Botany of the CAS, Lidická 25/27, 602 00, Brno, Czech Republic; RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00, Brno, Czech Republic
| | - Jan Sadílek
- Department of Experimental Phycology and Ecotoxicology, Institute of Botany of the CAS, Lidická 25/27, 602 00, Brno, Czech Republic; RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00, Brno, Czech Republic
| | - Jiří Kohoutek
- RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00, Brno, Czech Republic
| | - Lucie Straková
- Department of Experimental Phycology and Ecotoxicology, Institute of Botany of the CAS, Lidická 25/27, 602 00, Brno, Czech Republic
| | - Blahoslav Maršálek
- Department of Experimental Phycology and Ecotoxicology, Institute of Botany of the CAS, Lidická 25/27, 602 00, Brno, Czech Republic; RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00, Brno, Czech Republic
| | - Pavel Babica
- Department of Experimental Phycology and Ecotoxicology, Institute of Botany of the CAS, Lidická 25/27, 602 00, Brno, Czech Republic; RECETOX, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00, Brno, Czech Republic.
| |
Collapse
|
12
|
Christophoridis C, Zervou SK, Manolidi K, Katsiapi M, Moustaka-Gouni M, Kaloudis T, Triantis TM, Hiskia A. Occurrence and diversity of cyanotoxins in Greek lakes. Sci Rep 2018; 8:17877. [PMID: 30552354 PMCID: PMC6294760 DOI: 10.1038/s41598-018-35428-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 10/30/2018] [Indexed: 02/07/2023] Open
Abstract
Toxic cyanobacteria occur in Greek surface water bodies. However, studies on the occurrence of cyanotoxins (CTs) are often limited to mainly microcystins (MCs), with use of screening methods, such as ELISA, that are not conclusive of the chemical structure of the CT variants and can be subject to false positive results. A multi-lake survey in Greece (14 lakes) was conducted in water and biomass, targeted to a wide range of multi-class CTs including MCs, nodularin-R (NOD), cylindrospermopsin (CYN), anatoxin-a (ANA-a) and saxitoxins (STXs), using multi-class/variant LC-MS/MS analytical workflows, achieving sensitive detection, definitive identification and accurate quantitation. A wide variety of CTs (CYN, ANA-a, STX, neoSTX, dmMC-RR, MC-RR, MC-YR, MC-HtyR, dm3MC-LR, MC-LR, MC-HilR, MC-WR, MC-LA, MC-LY, MC-LW and MC-LF), were detected, with MCs being the most commonly occurring. In biomass, MC-RR was the most abundant toxin, reaching 754 ng mg−1 dw, followed by MC-LR (458 ng mg−1 dw). CYN and ANA-a were detected for the first time in the biomass of Greek lakes at low concentrations and STXs in lakes Trichonis, Vistonis and Petron. The abundance and diversity of CTs were also evaluated in relation to recreational health risks, in a case study with a proven history of MCs (Lake Kastoria).
Collapse
Affiliation(s)
- Christophoros Christophoridis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", Patr. Grigoriou E' & Neapoleos 27, 15341, Athens, Greece
| | - Sevasti-Kiriaki Zervou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", Patr. Grigoriou E' & Neapoleos 27, 15341, Athens, Greece
| | - Korina Manolidi
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", Patr. Grigoriou E' & Neapoleos 27, 15341, Athens, Greece
| | - Matina Katsiapi
- School of Biology, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
| | - Maria Moustaka-Gouni
- School of Biology, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
| | - Triantafyllos Kaloudis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", Patr. Grigoriou E' & Neapoleos 27, 15341, Athens, Greece.,Water Quality Control Department, Athens Water Supply and Sewerage Company - EYDAP SA, Athens, Greece
| | - Theodoros M Triantis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", Patr. Grigoriou E' & Neapoleos 27, 15341, Athens, Greece
| | - Anastasia Hiskia
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", Patr. Grigoriou E' & Neapoleos 27, 15341, Athens, Greece.
| |
Collapse
|
13
|
Dziga D, Maksylewicz A, Maroszek M, Budzyńska A, Napiorkowska-Krzebietke A, Toporowska M, Grabowska M, Kozak A, Rosińska J, Meriluoto J. The biodegradation of microcystins in temperate freshwater bodies with previous cyanobacterial history. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 145:420-430. [PMID: 28772230 DOI: 10.1016/j.ecoenv.2017.07.046] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/17/2017] [Accepted: 07/18/2017] [Indexed: 06/07/2023]
Abstract
Cyanobacterial blooms and cyanotoxins occur in freshwater lakes and reservoirs all over the world. Bacterial degradation of microcystins (MC), hepatotoxins produced by several cyanobacterial species, has also been broadly documented. However, information regarding MC biodegradation in European water bodies is very limited. In this paper, the occurrence and identification of MC biodegradation products was documented for 21 European lakes and reservoirs, many of which have well-documented cyanobacterial bloom histories. Varying cyanobacterial abundance and taxonomical composition were documented and MC producers were found in all the analysed samples. Planktothrix agardhii was the most common cyanobacterial species and it formed mass occurrences in four lakes. MC biodegradation was observed in 86% of the samples (18 out of 21), and four products of dmMC-LR decomposition were detected by HPLC and LC-MS methods. The two main products were cyclic dmMC-LR with modifications in the Arg-Asp-Leu region; additionally one product was recognized as the tetrapeptide Adda-Glu-Mdha-Ala. The composition of the detected products suggested a new biochemical pathway of MC degradation. The results confirmed the hypothesis that microcystin biodegradation is a common phenomenon in central European waters and that it may occur by a mechanism which is different from the one previously reported. Such a finding implies the necessity to develop a more accurate methodology for screening bacteria with MC biodegradation ability. Furthermore, it warrants new basic and applied studies on the characterization and utilization of new MC-degrading strains and biodegradation pathways.
Collapse
Affiliation(s)
- Dariusz Dziga
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30387 Krakow, Poland.
| | - Anna Maksylewicz
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30387 Krakow, Poland
| | - Magdalena Maroszek
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30387 Krakow, Poland
| | - Agnieszka Budzyńska
- Department of Water Protection, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61614 Poznań, Poland
| | | | - Magdalena Toporowska
- Department of Hydrobiology, University of Life Sciences in Lublin, Dobrzańskiego 37, 20262 Lublin, Poland
| | - Magdalena Grabowska
- Department of Hydrobiology, University of Białystok, Ciołkowskiego 1J, 15245 Białystok, Poland
| | - Anna Kozak
- Department of Water Protection, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61614 Poznań, Poland
| | - Joanna Rosińska
- Department of Water Protection, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61614 Poznań, Poland
| | - Jussi Meriluoto
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Tykistökatu 6A, 20520 Turku, Finland
| |
Collapse
|
14
|
A qPCR-Based Tool to Diagnose the Presence of Harmful Cyanobacteria and Cyanotoxins in Drinking Water Sources. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:ijerph14050547. [PMID: 28531121 PMCID: PMC5451997 DOI: 10.3390/ijerph14050547] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/14/2017] [Accepted: 05/17/2017] [Indexed: 11/30/2022]
Abstract
Harmful cyanobacteria have been an important concern for drinking water quality for quite some time, as they may produce cyanotoxins and odorants. Microcystis and Cylindrospermopsis are two common harmful cyanobacterial genera detected in freshwater lakes and reservoirs, with microcystins (MCs) and cylindrospermopsin (CYN) as their important metabolites, respectively. In this study, two sets of duplex qPCR systems were developed, one for quantifying potentially-toxigenic Microcystis and Microcystis, and the other one for cylindrospermopsin-producing cyanobacteria and Cylindrospermopsis. The duplex qPCR systems were developed and validated in the laboratory by using 338 samples collected from 29 reservoirs in Taiwan and her offshore islands. Results show that cell numbers of Microcystis and Cylindorspermopsis enumerated with microscopy, and MCs and CYN concentrations measured with the enzyme-linked immuno-sorbent assay method, correlated well with their corresponding gene copies determined with the qPCR systems (range of coefficients of determination R2 = 0.392−0.740). The developed qPCR approach may serve as a useful tool for the water industry to diagnose the presence of harmful cyanobacteria and the potential presence of cyanotoxins in source waters.
Collapse
|
15
|
McGregor GB, Sendall BC. Iningainema pulvinus gen nov., sp nov. (Cyanobacteria, Scytonemataceae) a new nodularin producer from Edgbaston Reserve, north-eastern Australia. HARMFUL ALGAE 2017; 62:10-19. [PMID: 28118884 DOI: 10.1016/j.hal.2016.11.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 11/26/2016] [Accepted: 11/30/2016] [Indexed: 05/12/2023]
Abstract
A new nodularin producing benthic cyanobacterium Iningainema pulvinus gen nov., sp nov. was isolated from a freshwater ambient spring wetland in tropical, north-eastern Australia and characterised using combined morphological and phylogenetic attributes. It formed conspicuous irregularly spherical to discoid, blue-green to olive-green cyanobacterial colonies across the substratum of shallow pools. Morphologically Iningainema is most similar to Scytonematopsis Kiseleva and Scytonema Agardh ex Bornet & Flahault. All three genera have isopolar filaments enveloped by a firm, often layered and coloured sheath; false branching is typically geminate, less commonly singly. Phylogenetic analyses using partial 16S rRNA sequences of three clones of Iningainema pulvinus strain ES0614 showed that it formed a well-supported monophyletic clade. All three clones were 99.7-99.9% similar, however they shared less than 93.9% nucleotide similarity with other cyanobacterial sequences including putatively related taxa within the Scytonemataceae. Amplification of a fragment of the ndaF gene involved in nodularin biosynthesis from Iningainema pulvinus confirmed that it has this genetic determinant. Consistent with these results, analysis of two extracts from strain ES0614 by HPLC-MS/MS confirmed the presence of nodularin at concentrations of 796 and 1096μgg-1 dry weight. This is the third genus of cyanobacteria shown to produce the cyanotoxin nodularin and the first report of nodularin synthesis from the cyanobacterial family Scytonemataceae. These new findings may have implications for the aquatic biota at Edgbaston Reserve, a spring complex which has been identified as a priority conservation area in the central Australian arid and semiarid zones, based on patterns of endemicity.
Collapse
Affiliation(s)
- Glenn B McGregor
- Queensland Department of Science, Information Technology and Innovation, GPO Box 5078 Brisbane 4001, Australia.
| | - Barbara C Sendall
- Queensland Department of Health, Forensic and Scientific Services, 39 Kessels Road, Coopers Plains, Qld 4108, Australia
| |
Collapse
|
16
|
Buratti FM, Manganelli M, Vichi S, Stefanelli M, Scardala S, Testai E, Funari E. Cyanotoxins: producing organisms, occurrence, toxicity, mechanism of action and human health toxicological risk evaluation. Arch Toxicol 2017; 91:1049-1130. [DOI: 10.1007/s00204-016-1913-6] [Citation(s) in RCA: 258] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 12/13/2016] [Indexed: 12/11/2022]
|
17
|
Salmaso N, Cerasino L, Boscaini A, Capelli C. PlankticTychonema(Cyanobacteria) in the large lakes south of the Alps: phylogenetic assessment and toxigenic potential. FEMS Microbiol Ecol 2016; 92:fiw155. [DOI: 10.1093/femsec/fiw155] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/08/2016] [Indexed: 12/24/2022] Open
|
18
|
Mohamed ZA, Deyab MA, Abou-Dobara MI, El-Sayed AK, El-Raghi WM. Occurrence of cyanobacteria and microcystin toxins in raw and treated waters of the Nile River, Egypt: implication for water treatment and human health. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:11716-11727. [PMID: 25854210 DOI: 10.1007/s11356-015-4420-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 03/20/2015] [Indexed: 06/04/2023]
Abstract
Monitoring of cyanobacteria and their associated toxins has intensified in raw water sources of drinking water treatment plants (WTPs) in most countries of the world. However, it is not explored yet for Egyptian WTPs. Therefore, this study was undertaken to investigate the occurrence of cyanobacteria and their microcystin (MC) toxins in the Nile River source water of Damietta WTP during warm months (April-September 2013) and to evaluate the removal efficiency of both cyanobacterial cells and MCs by conventional methods used in this plant as a representative of Egyptian drinking WTPs. The results showed that the source water at the intake of Damietta WTP contained dense cyanobacterial population (1.1-6.6 × 107 cells L(-1)) dominated by Microcystis aeruginosa. This bloom was found to produce MC-RR and MC-LR. Both cyanobacterial cell density and intracellular MCs in the intake source water increased with the increase in temperature and nutrients during the study period, with maximum values obtained in August. During treatment processes, cyanobacterial cells were incompletely removed by coagulation/flocculation/sedimentation (C/F/S; 91-96.8%) or sand filtration (93.3-98.9%). Coagulation/flocculation induced the release of MCs into the ambient water, and the toxins were not completely removed or degraded during further treatment stages (filtration and chlorination). MCs in outflow tank water were detected in high concentrations (1.1-3.6 μg L - 1), exceeding WHO provisional guideline value of 1 μg L - 1 for MC-LR in drinking water. Based on this study, regular monitoring of cyanobacteria and their cyanotoxins in the intake source water and at different stages at all WTPs is necessary to provide safe drinking water to consumers or to prevent exposure of consumers to hazardous cyanobacterial metabolites.
Collapse
Affiliation(s)
- Zakaria A Mohamed
- Botany Department, Faculty of Science, Sohag University, Sohag, 82524, Egypt,
| | | | | | | | | |
Collapse
|
19
|
Mohamed ZA, Hashem M, Alamri SA. Growth inhibition of the cyanobacterium Microcystis aeruginosa and degradation of its microcystin toxins by the fungus Trichoderma citrinoviride. Toxicon 2014; 86:51-8. [DOI: 10.1016/j.toxicon.2014.05.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 03/06/2014] [Accepted: 05/07/2014] [Indexed: 11/26/2022]
|
20
|
Mohamed ZA, Al-Shehri AM. Grazing on Microcystis aeruginosa and degradation of microcystins by the heterotrophic flagellate Diphylleia rotans. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2013; 96:48-52. [PMID: 23856124 DOI: 10.1016/j.ecoenv.2013.06.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/13/2013] [Accepted: 06/15/2013] [Indexed: 06/02/2023]
Abstract
Cyanobacterial toxins can cause damage in aquatic ecosystems worldwide, as well as the poisoning of livestock, plants and humans when ingested in large amounts. Although many studies investigated grazing of harmful cyanobacteria by metazoan plankton, grazing of cyanobacteria by hetertophic flagellates is largely unexplored. This laboratory study investigated grazing of toxic Microcystis aeruginosa by the heterotrophic flagellate Diphylleia rotans isolated from a Saudi hypertrophic lake. D. rotans was able to feed on M. aeruginosa with estimated ingestion (10.2 to 16.5 prey flagellate (-1)d(-1)) and specific growth rates (0.71 to 0.99d(-1)) differed with the increase in the initial density of the flagellate. Grazing increased microcystin production within Microcystis cells during first two days of incubation, and afterwards induced the release of these toxins into the medium. The concentrations of releasing microcystin were strongly reduced in grazing-treated cultures compared to controls, indicating the degradation of microcystins by D. rotans growing under axenic conditions. Taken these results, D. rotans can play an important role in the reduction of Microcystis biomass and microcystin toxins, and thus could be used as a safe bioagent for the biocontrol of harmful algal blooms in aquatic environments.
Collapse
Affiliation(s)
- Zakaria A Mohamed
- Department of Botany, Faculty of Science, Sohag University, Sohag 82524, Egypt.
| | | |
Collapse
|
21
|
Metcalf JS, Banack SA, Kotut K, Krienitz L, Codd GA. Amino acid neurotoxins in feathers of the Lesser Flamingo, Phoeniconaias minor. CHEMOSPHERE 2013; 90:835-9. [PMID: 23123117 DOI: 10.1016/j.chemosphere.2012.09.094] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 09/13/2012] [Accepted: 09/26/2012] [Indexed: 05/03/2023]
Abstract
The Lesser Flamingo (Phoeniconaias minor) is known to use cyanobacteria (primarily Arthrospira) as a major food source in the East African Rift Valley lakes. Periodically, mass mortalities have occurred, associated with the cyanobacterial toxins (cyanotoxins), microcystins and anatoxin-a. Deposition of these cyanotoxins into P. minor feathers has been shown to occur, consistent with the presence of cyanotoxins in the livers, stomach and faecal contents after dietary intake. As cyanobacteria have been shown to also produce the neurotoxins β-N-methylamino-L-alanine (BMAA) and 2,4-diaminobutyric acid (DAB), stored wing feathers, previously recovered from flamingos which had been exposed to microcystins and anatoxin-a and had subsequently died, were analysed for these neurotoxic amino acids. Trace amounts of BMAA were detected in extracts from Lake Nakuru flamingo feathers, with DAB also present at concentrations between 3.5 and 8.5 μg g(-1) dry weight in feathers from both lakes. Toxin recovery by solid-phase extraction of feather digests was tested with spiked deuterated BMAA and showed good recovery when analysed by LC-MS/MS (80-94%). This is the first report of these neurotoxic amino acids in birds. We discuss the origin and significance of DAB, alongside other cyanotoxins of dietary origin, in the feathers of the Lesser Flamingo.
Collapse
Affiliation(s)
- J S Metcalf
- Institute for Ethnomedicine, Box 3464, Jackson, WY 83001, USA.
| | | | | | | | | |
Collapse
|
22
|
Biodegradation of cylindrospermopsin toxin by microcystin-degrading bacteria isolated from cyanobacterial blooms. Toxicon 2012; 60:1390-5. [PMID: 23085421 DOI: 10.1016/j.toxicon.2012.10.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 09/10/2012] [Accepted: 10/10/2012] [Indexed: 11/21/2022]
Abstract
Cylindrospermopsin (CYN) is highly water soluble and stable cyanotoxin which can persist in water sources and pose health hazards to human, animals and plants. Consequently, there is a need to fully understand the fate of CYN in the aquatic environment, in particular, its biodegradation by endemic organisms. Although there is evidence of CYN degradation by microbial population, bacterial strains responsible for the toxin degradation are not yet identified. This study reports for the first time CYN degradation by Bacillus strain (AMRI-03) isolated from cyanobacterial blooms. In degradation batch experiment, the strain grew well in the presence of CYN without showing any lag period, and this growth increased with the initial CYN concentration. CYN degradation occurred rapidly, and the complete degradation was dependent on the initial CYN concentration. It occurred after 6 days at the highest concentration (300 μg L(-1)) compared to 7 and 8 days at lower concentrations (10 & 100 μg L(-1)). Also, the degradation rate correlated positively with the initial CYN concentration with maximum value (50 μg L(-1) day(-1)) obtained at the highest CYN concentration. Furthermore, the biodegradation rate of CYN by this strain depended remarkably on temperature and pH. The highest biodegradation rates were obtained at 25 and 30 °C, and at pH 7 and pH 8. Taken that such microcystin-degrading strain can also degrade CYN, bacterial strains reported worldwide as microcystin degraders could be tested for their capability of CYN degradation.
Collapse
|
23
|
Alamri SA. Biodegradation of microcystin-RR by Bacillus flexus isolated from a Saudi freshwater lake. Saudi J Biol Sci 2012; 19:435-40. [PMID: 23961204 DOI: 10.1016/j.sjbs.2012.06.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 05/23/2012] [Accepted: 06/02/2012] [Indexed: 11/17/2022] Open
Abstract
A bacterium capable of degrading microcystin-RR (MC-RR) was isolated from a Saudi eutrophic lake which was previously reported to have microcystin-producing cyanobacteria. Based on the analysis of the 16S rRNA gene sequence, the isolated strain SSZ01, most likely belong to the genus Bacillus with a highest sequence similarity (99%) with Bacillus flexus strain EMGA5. It was found that B. flexus strain SSZ01, possesses an mlrA gene encoding the most important enzyme for MC degradation. This strain was capable of degrading MC-RR, at a concentration of 10 mg l(-1), in batch experiments under environmentally relevant conditions. The degradation of MC-RR was completely removed within 4 d. The degradation of MC-RR by this strain occurred in a rich medium nutrient broth (NB), indicating that this could likely occur along with other organic compounds found in the environment. Therefore, the coexistence of such bacteria with MCs in the same environment can contribute to the self-purification of the ecosystem from such potent toxins. This is the first study to report that B. flexus can degrade MCs.
Collapse
Affiliation(s)
- Saad A Alamri
- Department of Biological Science, College of Science, King Khalid University, P.O. Box 10255, Abha 61321, Saudi Arabia
| |
Collapse
|