Aphanizomenon flos-aquae

Aphanizomenon flos-aquae
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Cyanobacteria
Class: Cyanophyceae
Order: Nostocales
Family: Aphanizomenonaceae
Genus: Aphanizomenon
Species:
A. flos-aquae
Binomial name
Aphanizomenon flos-aquae
(Linnaeus) Ralfs ex Bornet & Flahault, 1888

Aphanizomenon flos-aquae is a diverse group of cyanobacteria with both toxic and non-toxic[1][2] strains found in brackish and freshwater environments globally, including the Baltic Sea and the Great Lakes. Recent genome sequencing efforts have identified 18 distinct varieties[3] of Aphanizomenon flos-aquae, revealing its genetic complexity.

Cyanobacteria were the first organisms to achieve photosynthesis.[4] Chlorophyll and phycocyanine—two pigments contained in cyanobacteria—allow the vegetative cells to absorb light and transform it into nutrients.[4]

The genus Aphanizomenon is defined as a cluster of eight morphospecies, including Aphanizomenon flos-aquae. [5]

Morphology

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Heterocysts on Aphanizomenon flos-aquae
Heterocysts on Aphanizomenon flos-aquae

One of the main morphological characteristics of the genus Aphanizomenon is the tendency to form fascicles of trichomes containing mainly vegetative cells. [6][5]

The individual vegetative cells that form Aphanizomenon flos-aquae are cylindrical and elongated. Each cell is composed of hyaline.[5]

Aphanizomenon flos-aquae forms typically bent trichomes that are grouped into fascicles up to 2 centimeters long.[6] These trichomes can also be found as single free-floating units. [5]Within these fascicles, heterocysts often appear at various intervals on the trichomes.[7]

When attached to a trichome, heterocysts import carbohydrates which may act as a reducing agent and an energy source for nitrogen fixation.[8] It has been shown that heterocysts contain a nitrogenase complex which allows them to take part in nitrogen fixation. Other requirements for nitrogen fixation include ATP, low potential electrons, and an anaerobic environment. [8]

Life cycle

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The life cycle of Aphanizomenon flos-aquae depends on various environmental conditions such as water temperature, dissolved oxygen content, and pH.

During the winter, Aphanizomenon flos-aquae persists as akinetes deep in the layers of sediment.[7] These dormant cyanobacterial cells will last all season until the water temperature rises again in the spring. During the springtime, the akinetes go through a recruitment phase as they germinate and disperse into the water column.[7] Different species of phytoplankton can provide interspecific competition for Aphanizomenon flos-aquae if they are outnumbered. Due to higher temperatures, and higher pH levels in the summer, Aphanizomenon flos-aquae begin to flourish and eventually form dense mats known as ‘blooms’ in late summer.[7] The blooms dissipate in autumn as the water temperature and pH drop again and the conditions are more favorable to akinete development.[7]

Ecology

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Aphanizomenon flos-aquae bloom on the Upper Klamath Lake, Oregon

Aphanizomenon flos-aquae can form dense surface aggregations in freshwater (known as "cyanobacterial blooms").[9] These blooms occur in areas of high nutrient loading, historical or current.

During bloom formation, Aphanizomenon flos-aquae photosynthetically produces biomass. These accumulated mats of biomass can grow due to the concentration of nutrients available in eutrophic ecosystems accompanied by high reproductive rates and water temperatures.[10]

At high concentrations, these blooms can be ecologically harmful to the aquatic species that cohabitate with the cyanobacteria. In addition to their odiferous presence, cyanobacterial blooms have been associated with lowered dissolved oxygen content, increased turbidity, and the accelerated release of nutrients from sediments.[10]

Toxicity

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Toxic Algal Bloom in an inlet of Blue Mesa Reservoir in Western Colorado

Aphanizomenon flos-aquae has both toxic and nontoxic forms.[11] Most sources worldwide are toxic containing both hepatic and neuroendotoxins.[12]

Most cyanobacteria (including Aphanizomenon) produce BMAA, a neurotoxin amino acid implicated in ALS/Parkinsonism.[13][14][15]

The toxicity of A. flos-aquae has been reported in Canada,[16] Germany,[17][18] and China.[19]

Some Aphanizomenon flos-aquae varieties are known to produce endotoxins, the toxic chemicals released when cells die. Once released (lysed), and ingested, these toxins can damage liver and nerve tissues in mammals. In areas where water quality is not closely monitored, the World Health Organization has assessed toxic algae as a health risk, citing the production of anatoxin-a, saxitoxins, and cylindrospermopsin.[20] Dogs have been reported to have become ill or have fatal reactions after swimming in rivers and lakes containing toxic A. flos-aquae.

The FDA recognizes certain varieties of AFA blue-green algae as safe for consumption,[21] stating in 2024 that "Properly harvested BGA is safe to eat and is used in some dietary supplements and food products."

Microcystin toxin has been found in all 16 samples of A. flos-aquae products sold as food supplements in Germany and Switzerland, originating from Lake Klamath: 10 of 16 samples exceeded the safety value of 1 μg microcystin per gram.[22] University professor Daniel Dietrich warned parents not to let children consume A. flos-aquae products, since children are even more vulnerable to toxic effects, due to lower body weight, and the continuous intake might lead to accumulation of toxins. Dietrich also warned against quackery schemes selling these cyanobacteria as medicine against illnesses such as attention deficit hyperactivity disorder, causing people to omit their regular drugs.

Medical research

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The Klamath people have been ingesting A. flos-aquae for centuries. [23] These bacteria contain significant amounts of various phenethylamines. This class of chemicals is often considered as general purpose neuromodulators, making them potentially effective at combating depression and anxiety. [24]

Klamin is an extract of A. flos-aquae that concentrates the various phenylethylamine derivatives which can act as MAO-B inhibitors.[24] This emerging nutritional supplement has been proven to aid neurodegenerative diseases. [25]

Additionally, a Canadian study studying the effect of A. flos-aquae on the immune and endocrine systems, as well as on general blood physiology, found that consuming A. flos-aquae had a profound effect on natural killer cells (NKCs).[26] A. flos-aquae triggers the movement of 40% of the circulating NKCs from the blood to tissues.[27] Once in the tissues, the NKCs main function is immune surveillance to eliminate cancerous or other infected cells.[27]

As a food supplement

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Main article: Aphanizomenon flos-aquae (dietary supplement)

Some compressed tablets of powdered A. flos-aquae cyanobacteria (named as "blue-green algae") have been sold as food supplements, notably those filtered from Upper Klamath Lake in Oregon.[28]

See also

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References

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  1. ^ Park, Hae-Kyung; Kwon, Mi-Ae; Lee, Hae-Jin; Oh, Jonghee; Lee, Su-Heon; Kim, In-Soo (August 2018). "Molecular Verification of Bloom-forming Aphanizomenon flos-aquae and Their Secondary Metabolites in the Nakdong River". International Journal of Environmental Research and Public Health. 15 (8): 1739. doi:10.3390/ijerph15081739. ISSN 1660-4601. PMC 6121560. PMID 30104548.
  2. ^ Aparicio Medrano, E.; Uittenbogaard, R. E.; van de Wiel, B. J. H.; Dionisio Pires, L. M.; Clercx, H. J. H. (1 December 2016). "An alternative explanation for cyanobacterial scum formation and persistence by oxygenic photosynthesis". Harmful Algae. 60: 27–35. Bibcode:2016HAlga..60...27A. doi:10.1016/j.hal.2016.10.002. ISSN 1568-9883. PMID 28073560.
  3. ^ "Genome". NCBI. Retrieved 13 October 2024.
  4. ^ a b "Aphanizomenon Flos-Aquae Klamath Valley Botanicals". Klamath Valley Botanicals Blue green Algae. Retrieved 5 December 2023.
  5. ^ a b c d Cires, Samuel; Ballot, Andreas (April 2016). "A review of the phylogeny, ecology and toxin production of bloom-forming Aphanizomenon spp. and related species within the Nostocales (cyanobacteria)". Harmful Algae. 54: 21–43. Bibcode:2016HAlga..54...21C. doi:10.1016/j.hal.2015.09.007. PMID 28073477.
  6. ^ a b Komárek, Jiří; Komárková, Jaroslava (1 January 2006). "Diversity of Aphanizomenon-like cyanobacteria". Fottea. 6 (1): 1–32.
  7. ^ a b c d e Yamamoto, Yoshimasa; Nakahara, Hiroyuki (2009). "Life Cycle of Cyanobacterium Aphanizomenon flos-aquae" (PDF). Taiwania. 54 (2): 113–117.
  8. ^ a b Böhme, Herbert (1 September 1998). "Regulation of nitrogen fixation in heterocyst-forming cyanobacteria". Trends in Plant Science. 3 (9): 346–351. Bibcode:1998TPS.....3..346B. doi:10.1016/S1360-1385(98)01290-4. ISSN 1360-1385.
  9. ^ "Cyanobacteria/Cyanotoxins". US EPA. 2 January 2014. Archived from the original on 17 October 2015. Retrieved 23 October 2015.
  10. ^ a b Paerl, Hans; Fulton, Rolland; Moisander, Pia; Dyble, Julianne (2001). "Harmful Freshwater Algal Blooms, With an Emphasis on Cyanobacteria". The Scientific World Journal. 1: 76–113. doi:10.1100/tsw.2001.16. PMC 6083932. PMID 12805693.
  11. ^ Carmichael, Wayne W. (January 1994). "The Toxins of Cyanobacteria". Scientific American. 270 (1): 78–86. Bibcode:1994SciAm.270a..78C. doi:10.1038/scientificamerican0194-78. ISSN 0036-8733. PMID 8284661.
  12. ^ Karina Preußela, Fastnera Jutta; Federal Environmental Agency, FG II 3.3, Corrensplatz 1, 14195 Berlin, Germany; Department of Limnology of Stratified Lakes, Institute of Freshwater Ecology and Inland Fisheries, Alte Fischerhütte 2, 16775 Stechlin, Germany; 15 October 2005[verification needed]
  13. ^ Cox, PA; Sacks, OW (2002). "Cycad neurotoxins, consumption of flying foxes, and ALS-PDC disease in Guam". Neurology. 58 (6): 956–9. doi:10.1212/wnl.58.6.956. PMID 11914415. S2CID 12044484.
  14. ^ Holtcamp W (2012). "The Emerging Science of BMAA: Do Cyanobacteria Contribute to Neurodegenerative Disease?". Environmental Health Perspectives. 120 (3): 110–16. doi:10.1289/ehp.120-a110. PMC 3295368. PMID 22382274.
  15. ^ Jonasson S, Eriksson J, Berntzon L, Spácil Z, Ilag LL, Ronnevi LO, Rasmussen U, Bergman B (2010). "Transfer of a cyanobacterial neurotoxin within a temperate aquatic ecosystem suggests pathways for human exposure". Proceedings of the National Academy of Sciences. 107 (20): 9252–7. Bibcode:2010PNAS..107.9252J. doi:10.1073/pnas.0914417107. PMC 2889067. PMID 20439734.
  16. ^ Saker ML, Jungblut AD, Neilan BA, Rawn DF, Vasconcelos VM (October 2005). "Detection of microcystin synthetase genes in health food supplements containing the freshwater cyanobacterium Aphanizomenon flos-aquae" (PDF). Toxicon. 46 (5): 555–62. Bibcode:2005Txcn...46..555S. doi:10.1016/j.toxicon.2005.06.021. PMID 16098554.
  17. ^ Preussel K, Stüken A, Wiedner C, Chorus I, Fastner J (February 2006). "First report on cylindrospermopsin producing Aphanizomenon flos-aquae (Cyanobacteria) isolated from two German lakes". Toxicon. 47 (2): 156–62. Bibcode:2006Txcn...47..156P. doi:10.1016/j.toxicon.2005.10.013. PMID 16356522.
  18. ^ Toxin content and cytotoxicity of algal dietary supplements Archived 19 December 2013 at the Wayback Machine, by Dr. Alexandra H. Heussner
  19. ^ Chen Y, Liu J, Yang W (May 2003). "Effect of Aphanizomenon flos-aquae toxins on some blood physiological parameters in mice". Wei Sheng Yan Jiu [Journal of Hygiene Research] (in Chinese). 32 (3): 195–7. PMID 12914277.
  20. ^ World Health Organization (2006). Guidelines for drinking-water quality. First addendum to third edition. Volume 1. Recommendations. Geneva: World Health Organization. ISBN 978-92-4-154674-4. Archived from the original on 1 April 2017.
  21. ^ Program, Human Foods (26 September 2024). "Natural Toxins in Food". FDA. Retrieved 13 October 2024.
  22. ^ "AFA-Algen – Giftcocktail oder Gesundheitsbrunnen?" [AFA algae - toxic cocktail fountain or health?] (Translated from German). Universität Konstanz. Archived from the original on 9 February 2012. Retrieved 18 May 2012.
  23. ^ "Aphanizomenon Flos-Aquae - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 5 December 2023.
  24. ^ a b Nuzzo, D.; Presti, G.; Picone, P.; Galizzi, G.; Gulotta, E.; Giuliano, S.; Mannino, C.; Gambino, V.; Scoglio, S.; Di Carlo, M. (17 September 2018). "Effects of the Aphanizomenon flos-aquae Extract (Klamin®) on a Neurodegeneration Cellular Model". Oxidative Medicine and Cellular Longevity. 2018: e9089016. doi:10.1155/2018/9089016. ISSN 1942-0900. PMC 6166380. PMID 30310529.
  25. ^ Sedriep, S; Xia, X (22 March 2011). "Beneficial Nutraceutical Modulation of Cerebral Erythropoietin Expression and Oxidative Stress: An Experimental Study". Journal of Biological Regulators & Homeostatic Agents. 25 (2): 187–194. PMID 21880207.
  26. ^ Effects of the Blue Green Algae Aphanizomenon flos-aquae on Human Natural Killer Cells. – Chapter 3.1 of the IBC Library Series, Volume 1911, Phytoceuticals: Examining the health benefit and pharmaceutical properties of natural antioxidants and phytochemicals
  27. ^ a b "AFA Blue-Green Algae". Markito Fitness & Nutrition. Retrieved 5 December 2023.
  28. ^ Spolaore P, Joannis-Cassan C, Duran E, Isambert A (February 2006). "Commercial applications of microalgae". Journal of Bioscience and Bioengineering. 101 (2): 87–96. doi:10.1263/jbb.101.87. PMID 16569602. S2CID 16896655.
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