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(A.K.A. "blue-green algae")

By Valerie Anne Edwards, President Alken-Murray Corporation

Updated: December 6, 2006

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Photosynthetic Cyanobacteria have chlorophyll a and carotenoids in addition to some unusual accessory pigments named phycobilins. The blue pigment, phycocyanin and the red one, phycoerythrin, absorb wavelengths of light for photosynthesis that are missed by chlorophyll and the carotenoids. In biochemical detail, Cyanobacteria are especially similar to the chloroplasts of red algae (Rhodophyta). Cyanobacteria prefer a neutral to alkaline pH (6.5 to 9) and will not grow in an acidic environment. Relative to other oxygenic phototrophs, Cyanobacteria often grow under fairly extreme environmental conditions such as high temperature and salinity, and will even form 3 inch thick mats below an ice layer in the arctic. Cyanobacteria also appear to prefer waters that have higher levels of phosphorus than ammonia, since they can "fix atmospheric nitrogen" into water-soluble ammonia-nitrogen, whenever nitrogen becomes limited in the environment. The other major class of pigments present in Cyanobacteria are the carotenoids. These are hydrocarbon-like pigments, similar in structure to vitamin A and found in all photosynthetic organisms. The colors of the sheaths in different species, include light gold, yellow, brown, red, green, blue, violet, and blue-black, impart color to individual cells and colonies as well as to "blooms" of Cyanobacteria in aquatic environments.

As true Bacteria, Cyanobacteria contain peptidoglycan or murein in their cell walls. Most Cyanobacteria have a Gram-negative type cell wall that consists of a deeply pigmented outer membrane component, which is a mucilaginous sheath, even though they show a distant phylogenetic relationship with Gram-positive bacteria. Some of the filamentous Cyanobacteria are motile by means gliding or rotating around a longitudinal axis. Short segments (hormogonia) may break off from a Cyanobacterial colony and glide away from their parent colony at rates as rapid as 10 micrometers per second. The mechanism for this movement is unexplained but may be connected to the extrusion of slime (mucilage) through small pores in their cell wall, together with contractile waves in one of the surface layers of the wall. x Cyanobacteria form filaments and may grow in large masses or "tufts" one meter or more in length. Some strains are unicellular, a few form branched filaments, and a few form irregular plates or irregular colonies. Cyanobacterial cells usually divide by binary fission, and the resulting progeny cells may separate to form new colonies. In addition, filaments may break into fragments, called hormogonia, which separate and develop into new colonies. Some species of Cyanobacteria form resistant spores, called akinetes, enlarged cells around which thickened outer walls develop. Akinetes are resistant to heat, freezing and drought (desiccation) and thus allow the Cyanobacteria to survive unfavorable environmental conditions. They are functionally analogous to bacterial endospores, but they bear little resemblance and lack the extraordinary resistance properties of endospores.

Although many species of Cyanobacteria cause very few harmful effects on plants or animals, if they bloom in large numbers and then die and decay in aquaculture ponds, lakes, reservoirs, rivers, etc., they increase the BOD (biological oxygen demand), which robs fish and other aquatic residents of their required dissolved oxygen Related dino-flagellates have drawn a lot of public interest since scientists discovered that runoff from CAFO's into rivers in the state of Maryland, USA, caused these dinoflagellates to deliver the potent neurotoxin, Saxitoxin to shell-fish found in these rivers. Death by paralytic shellfish poisoning awaited animals and humans consuming these poisoned bivalves. Anabaena flos-aquae,[1] Aphanizomenon flos-aquae and Anabaena circinalis are species of the Nostocales Order of the Cyanobacteria phyllum, reported to be responsible for producing the highly potent neurotoxins, Saxitoxin, Microcystin LR, Nodularin L , Anatoxin-a and Aplysiatoxin,[2], which are contained within the cell until they are lysed, ingested by animals, or the cells simply become old and leaky. Cell lysis usually occurs when the water is treated with a chemical, biocide such as copper sulfate. A Brazilian paper cites production of additional toxins by Microcystis, Planktothrix, Lyngbya and Cylindrospermopsis raciborskii [3]. Other reports have suggested that ALL species of Cyanobacteria produce "cyanotoxins" and "cyanide" when killed rapidly. Geosim, a cause of off-flavors in fish, is similarly released by Cyanobacteria, when cells are stressed by fish/animal ingestion or by application of a biocide to the pond, lake, reservoir or river where they reside

Alken-Murray is only aware of one Saxitoxin 96-well ELISA kit , manufactured by Abraxis, LLC, with a range in water of 0.02 – 0.4 ppb (ng/mL)., which can be purchased from Environmental Assurance Monitoring LLC. EAM also offers kits to detect mycrocystins, nodularins, yessotoxin, cylindrospermopsin and domoic acid. This link is also available from our supplier links page.

A new system of classification for the phyllum Cyanophyte has been proposed by by Komárek and Anagnostidis , as found on the internet by Alken-Murray President, Valerie Anne Edwards at

  • Order Chroococcales is assigned to ALL unicellular Cyanophytes. Seven (7) clearly distinguished families comprise this order.
  • Order Oscillatoriales is characterised by simple filaments without branching or false branching and without heterocytes
  • Order Nostocales is characterised by filamentous species sometimes with false branching, but always with heterocytes
  • Order Stigonematales is characterised by filamentous species with true branching

Many of the species of Cyanobacteria known for releasing harmful toxins into aquatic environments belong to the order Nostocales, especially Anabaena flos-aquae, Anabaena circinalis, Anabaenopsis, Nostocaida limicola, Aphanizomenon flos-aguae, and Cylindrospermopsis, while other trouble-makers, including Planktothrix and Lyngbya belong to the Order Oscillatoria. Additional filamentous species cause serious interferences for municipal and industrial wastewater treatment plants by producing a biosurfactant that enables them to spread in an ultra-thin layer atop a bulking mass of foam that interferes with process control.

Cyanobacteria rarely develops into a dominant nuisance in seriously polluted or eutrophic ponds, lakes, lagoons, rivers, canals or streams because macro-algae and aquatic plants, including water lilies, ferns, cat tails, duck weed, etc. grow rapidly, taking up significant physical volume as they ingest BOTH dissolved and suspended pollution from the water column, as they dig their roots into the rich organic sludge found at the bottom of polluted, eutrophic water bodies. Once the water column of a lake, pond, reservoir or river has been bioremediated by application of the correct Alken Clear-Flo 1000 series products (usually a combination of Alken Clear-Flo 1006 and Alken Clear-Flo 1100-50x,) and the organic sludge layer has also been digested by application of Alken Clear-Flo 1005, the environment will no longer attract overgrowth of algae and plants that would otherwise inhibit invasion by Cyanobacteria. Thus, the cleaner and more pristine a water body becomes, the more susceptible to Cyanobacteria invasion it becomes. Wastewater treatment system managers have learned that allowing their system to develop a low F/M (food to biomass) ratio will favor development of filamentous Cyanobacteria, especially when nitrogen is a growth-limiting nutrient in the particular system. When these conditions combine, Cyanobacteria will produce a sugary biosurfactant (Nocardia amarae is known to produce the biosurfactant "Trehalose") that allows them to spread out into an ultra-thin layer, floating on the surface above a cushion of brown, sticky foam. Presenting a higher ratio of surface area to volume allows Cyanobacteria a selective advantage for securing nutrients in nutrient limited environments. Utilizing their ability to "fix atmospheric dinitrogen" into "water-soluble ammonia-nitrogen" along with their limited ability to utilize sunlight to help them "fix carbon dioxide" into "water-soluble organic carbon compounds" changes the rate-limiting nutrient, which they MUST obtain from the water column, into water-soluble phosphate (also labeled ortho-phosphate). Cyanobacteria LACK acid tolerance, thriving in a neutral to alkaline pH range(6.5 to 9). If fish and other desired species in a water-body covered in Cyanobacteria can tolerate pH changes, it is possible to adjust the environment so that it is less appealing to overgrowth of Cyanobacteria. Follow directions below:

  1. Titrate, in the laboratory,the amount of hydrochloric (Muriatic) acid necessary to reduce pH to the range of 5.5 to 6.0 for a few days.
  2. Titrate, in the laboratory, the amount of natural "dolomitic limestone" (calcium and magnesium carbonate) necessary to convert all soluble phosphate into small bound rocks of calcium and magnesium phosphate, removing this important food source from the resident Cyanobacteria
  3. Adjust the actual dosage of dolomitic limestone to the aquatic body so that final pH is NOT allowed to increase above 6.5, while a majority of soluble phosphate has been removed from the water column.
  4. If mechanical aeration is available, increase blower speeds, so that dissolved oxygen levels remain above 5 mg/L (ppm) during the entire treatment. Maintaining high levels of DO will inhibit bacteria from solubilizing bound phosphate and polyphosphate polymers. Alken-Murray uses three strains known to solubilize phosphate under anaerobic conditions. Alken Clear-Flo 1000 used to be the primary Bacillus treatment ordered by aquaculture hatcheries, for its ability to increase growth of desired micro-algae. Extensive laboratory tests finally revealed that Bacillus subtilis (strain 003) and Bacillus thuringiensis (strain 679), in Alken Clear-Flo 1000, were responsible for solubilizing bound phosphates into the water column, within 12 hours. Although we still use that BT strain in a variety of other formulas, we offset its phosphate-solubilizing activity by including one of our vegetative, gram-negative PAB (Polyphosphate Accumulating Bacteria) to help offset their activity.

Alken-Murray has devised an aquatic treatment product to address the most serious problems caused by overgrowth of filamentous Cyanobacteria, a product offered to our aquatic clientele under the name Alken Clear-Flo 1015, which is headlined by an exceptionally talented bacterial strain, Bacillus megaterium (strain AMC 300), which degrades cyanide, FOG (food Fats, Oils and Greases) ,a favorite diet of Cyanobacteria, and "Trehalose" the primary biosurfactant produced by Nocardia amarae, the best known filamentous troublemaker found in municipal wastewater treatment facilities, notorious for causing disruptive foaming, bulking and violation of NPDES discharge permits. Supporting this special star are six other strains that target "Trehalose" in our general formula, and .three in the "C" version that is contains organisms and chemistry that comply totally with the Canadian DSL. One of the Trehalose-digesting strains of Bacillus also digests both long and short-chain fatty acids, further reducing availability of food that interests filamentous Cyanobacteria.To ensure that ALL surfactants present in an aquatic body will be fully digested, the strains specializing in Trehalose and other natural biosurfactants (including those based on Glucose, Fructose, Glycine, Rhamnose & Ornithine) supported by a pair of Pseudomonas putida (strains 151 & 483) that digest a variety of chemical surfactants, including nonylphenols, linear and branched ethoxylated alcohols and sulfonated surfactants. To deliver better protection of farmed crops from accidental introduction of phenolic sanitizers and related compounds, two strains of Pseudomonas putida (usually strains 369 & 800) were conscripted from our industrial phenol-degrading formula, Alken Clear-Flo 7002 into Alken Clear-Flo 1015,. Strains selected for this product are comfortable functioning within the same temperature and pH range enjoyed by the filamentous species, so that competition could be encouraaged, but we added a soil-isolated Bacillus laevolacticus (strain 494) to digest proteins and amino acids through excursions down to pH 3, along with a Sporosarcina pasteurii (strain 453) , formerly identified as Bacillus pasteurii, to digest FOG up to pH 10. A dosage of 0.56 ppm of Yucca schidigera leaf extract is included in Alken Clear-Flo® 1015 , enhancing bacterial access to the biosurfactant(s), produced by various filamentous species, but Yucca schidigera also inhibits activity of the urease enzyme, commonly produced by fecal bacteria, converting urea into undesirable excesses of ammonia-nitrogen. . Alken Clear-Flo® 1015 should be applied in the specific SAFE dosage prescribed by your Alken-Murray distributor, taking into account the size of your lake/pond and the oxygen level present. Read our tutorial "Control Foaming in Wastewater Caused by Filamentous Bacteria" [5]and then study related microbial treatment, Alken Clear-Flo 7015. When Yucca schidigera concentration is kept at our dosage level, 0.56 ppm, a concentration that is well below the Yucca schidigera toxicity level of 5 ppm, fish are unlikely to suffer suffocation, as they do when surfactants, including Yucca schidigera, Aloe vera and other plant-based surfactants (coconut, soy, corn, etc.)prevent fish gills from trapping oxygen bubbles, causing mechanical suffocation.

Unfortunately, it is unlikely that a small enough dosage of Alken Clear-Flo® 1015 could be calculated for use in an aquarium. Alternative strategies for aquarium owners include a temporary pH adjustment to 6.0 , changing all bulbs, fluorescent fixtures etc. to eliminate the undesirable spectra that encourage Cyanobacteria. The aquarium owner can also use Alken Clear-Flo 1100 or Alken Clear-Flo 1100-50x to eliminate ammonia, one form of nitrogen used by saprophytic bacteria and Cyanobacteria.. Although most species of Cyanobacteria are aerobic, adjusting aeration levels proves more effective in wastewater applications than in lakes and ponds, where fish, crustaceans, protozoa, etc. all require sufficiently high levels of dissolved oxygen for survival to classify any attempt to control species of filamentous Cyanobacteria by controlling the concenration of DO in the water a risky protocol with very little chance for success and a high probability of imperiling the fish and crustaceans.


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