Cyanobacteria

Cyanobacteria are common in both fresh and salt waters and on soil.  Many of us recognize their old name blue-green algae and may be short filaments and single or clumps of cells.  They play an import role in producing oxygen in nature.  Populations  are usually held in check by low nutrients or moisture.  Changes in environment have stimulated the cyanobacteria growth with high phosphorus levels to form large colonies called mats when on soil or blooms in water.  These large colonies are a source of Cyanotoxins that impact humans and animals and the focus of this site.   

Cyanotoxins

While Cyanobacteria produce cyanotoxins with their cell wall the toxin is not released into the water or soil until the cell dies and degrades.  The cyanobacteria is capable of producing over 84 toxins but we are going to focus on a non-canonical amino acid called BMAA (β-N-methylamino-l-alanine).  All cyanobacteria have the pathway to produce BMAA toxin and the majority (95%) produce it at detectable levels.  

Exposure to blue-green algae — or cyanobacteria — can kill pets in as little as 15–20 minutes. Animals can be exposed to blue-green algae and its toxins by simply contacting any affected water body, including ponds, lakes, streams, rivers, or even residential decorative ponds and neglected swimming pools.  “Just grabbing a ball or a stick from the water or even licking algae off their fur can be fatal,” said Dr. Chelsea Sykes, a diagnostic toxicologist at Washington State University’s Washington Animal Disease Diagnostic Laboratory.

Supportive evidence it is a real problem

BMAA has been associated with slow-developing neurodegenerative diseases like ALS (amyotrophic lateral sclerosis) and PDC (Parkinson dementia complex).  The number, concentration, frequency of exposure and family history appears to be critical.   

1. Cyanobacteria and BMAA exposure from desert dust: A possible link to sporadic ALS among Gulf War veterans

Summary: The deserts of Qatar have widespread cyanobacterial crusts and mats (56% of microhabitats). These cyanobacterial crusts help bind desert sands and only active growing during brief spring rains. Disturbed of the dry crusts by United States Military vehicular traffic or other military activities produces significant dust.  BMAA and other cyanotoxins were detected in the dried crusts and could be inhaled.  The authors suggest that inhalation of BMAA, DAB, and other aerosolized cyanotoxins may constitute a significant risk factor for the development of ALS and other neurodegenerative diseases.

2. A cluster of amyotrophic lateral sclerosis in New Hampshire: A possible role for toxic cyanobacteria blooms

Summary: Lake Mascoma near Enfield, NH with a history of Cyanobacteria blooms has nine ALS patient living in the area.  The incidence of sporadic ALS is 10 to 25 times the expected incidence of 2/100,000/year for the region. The authors suggest that the high incidence of ALS in this potential cluster could be directly related to chronic exposure to cyanobacterial neurotoxins such as BMAA. They claim routes of toxin exposure may include inhalation of aerosolized toxins, consuming fish, or ingestion of lake water. 

3. Co-occurrence of the Cyanotoxins BMAA, DABA and Anatoxin-a in Nebraska Reservoirs, Fish, and Aquatic Plants

Summary: BMAA were detected in 31 fish tissue samples collected between 2009 and 2010.  Detectable levels of BMAA was found in bottom feeding fish or the fish that depend on aquatic plants and algae as their main food source, such as catfish, drum, and carp.   BMAA levels in carp were 1.39 to 2.57 µg/g, bass were 0.364 to 0.416 µg/g, crappie were 0.6 to 0.62 µg/g, walleye were 0.6 to 0.67 µg/g and bluegill were 0.056 µg/g.  

4. Assessing Cyanobacterial Harmful Algal Blooms as Risk Factors for Amyotrophic Lateral Sclerosis

Summary: Seasonal cyanobacterial blooms often reoccur in the same waters and recent studies show a link between these blooms and elevated risks of amyotrophic lateral sclerosis (ALS).  Authors used satellite remote sensing to assess cyanobacterial levels in lakes greater than 8 ha (n-4117) of northern New England to assess relationships with ALS cases. Data showed a cyanobacteria exposure of 100 ug/L or 100 ppb increased the risk of ALS by 46%.  The research is the first regionally comprehensive map of PC for thousands of lakes and integrated robust spatial uncertainty.  The outcomes support the hypothesis that cyanotoxins increase the risk of ALS, which helps our understanding of the etiology of ALS.

I feel there is enough evidence that BMAA should be avoided.  Not because of a direct link to ALS (amyotrophic lateral sclerosis) and PDC (Parkinson dementia complex) but rather the terminal nature of the disease.  

Special Thank You

I owe my passion for studying algae to Dr. Barbara Hayhome of the University of Nebraska at Omaha.  Her passion for these small plants rubbed off.  She was an amazing teacher and mentor.  

Barbara Hayhome (1942-1995) joined the University of Nebraska at Omaha in 1978 as a Professor of Biology, ascending to chair of that department in 1984. She specialized in genetics and phycology.  In 1989, she was appointed Assistant Vice Chancellor of Academic Affairs for UNO. She also served as Associate Dean for Graduate Studies. She passed away in 1995, from cancer.