Microbial Toxins BIOC 422 Algai Toxins Dr Ayat

Microbial Toxins (BIOC 422) Algai Toxins Dr. Ayat B. Al-Ghafari Associate Professor of Biomedical Sciences e. mail: abalghafari@kau. edu. sa

What is Algae? • Algae refers to a large and diverse group of aquatic organisms that contain chlorophyll and carry out oxygenic photosynthesis. • Most algae contain chlorophyll and are thus green in colour. However, a few kinds of common algae are not green but appear brown or red…. . WHY? >> Because in addition to chlorophyll, other pigments (such a carotenoids) are present which mask the green color.

What is Algae? • They are plant-like organisms that come in a variety of shapes and sizes – ranging from microscopic to large seaweed that may be over 100 feet long. • They are found all over the planet, and can live in sea water, fresh water, and brackish water (a combination of fresh and sea water). • Algae are vitally important building blocks of the food chain and ecosystem.

When Algae Becomes Toxic? (HABs) • Phytoplankton blooms, micro-algal blooms, toxic algae, red tides, or harmful algae, are all terms for naturally occurring phenomena. • About 300 hundred species of micro algae are reported at times to form mass occurrence, so called algal blooms. • Nearly one fourth of these (300) species are know to produce toxins. The scientific community refers to these events with a generic term, ‘Harmful Algal Bloom’ (HAB). (Not all algal blooms are harmful! some can actually be beneficial. Phytoplankton are found at the base of the marine food chain therefore all other life in the ocean relies on phytoplankton).

When Algae Becomes Toxic? (HABs) q. What are Harmful Algal Bloom’ (HAB)? üharmful algal blooms (HABs): occurs when colonies of algae and cyanobacteria that live in the sea and freshwater—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds.

When Algae Becomes Toxic? (HABs) q. Why are HABs harmful? üProliferations of microalgae in marine or salty waters can cause massive fish kills, contaminate seafood with toxins, and alter ecosystems in ways that humans perceive as harmful. üHarmful effects of HABs include: A broad classification of HABs distinguishes two groups of organisms: 1. The toxin producers: producing toxins that are harmful to people and animals which can contaminate seafood or kill fish, 2. The high-biomass producers: can cause hypoxia (an absence of oxygen) in the water when they decompose, and these lower oxygen levels may kill other plants and animals in the water. >> Some HABs have characteristics of both.

http: //oceanservice. noaa. gov/facts/habharm. html

What causes harmful algal blooms? Harmful algal blooms need: • Temperature: >>The growth is sustained during the warmer months of the year. Water temperatures above 25°C are optimal for the growth of blue-green algae. >>Higher water temperatures in tropical regions may cause blue–green algal blooms to persist throughout the year. • Sunlight: Algal blooms absorb sunlight, making water even warmer and promoting more blooms. • Slow-moving water: algal bloom flourish in calm water • Nutrients (nitrogen and phosphorus): >>Nutrient pollution from human activities makes the problem worse, leading to more severe blooms that occur more often. >>runoff and soil erosion from fertilized agricultural areas and lawns, erosion from river banks, river beds, land clearing (deforestation), and sewage waste are the major sources of phosphorus and nitrogen entering water ways.

Harmful Algal Bloom (HAB)-Associated Illness q Exposures to the HABs’ toxins can occur when people or animals have direct contact with contaminated water by: • Swimming • Breathing in aerosols (tiny airborne droplets or mist that contain toxins) from recreational activities or wind-blown sea spray • Swallowing toxins by drinking contaminated water or eating contaminated fish or shellfish

Harmful Algal Bloom (HAB)-Associated Illness q Human and animal illnesses and symptoms can vary depending on: • how they were exposed, • how long they were exposed • and the particular HAB toxin involved.

Harmful Algal Bloom (HAB)-Associated Illness I. Freshwater Environments: • a harmful algal bloom (HAB) in freshwater is most commonly caused by a type of photosynthetic bacteria (bacteria that use sunlight to create food) called cyanobacteria. “Because they are photosynthetic and aquatic, cyanobacteria are often called "blue-green algae". This name is convenient for talking about organisms in the water that make their own food, but does not reflect any relationship between the cyanobacteria and other organisms called algae. Cyanobacteria are relatives of the bacteria, not eukaryotes, and it is only the chloroplast in eukaryotic algae to which the cyanobacteria are related”. • Some species of cyanobacteria produce toxins called cyanotoxins. • Depending on the specific chemical structure: cyanotoxins can be neurotoxins , hepatotoxins, dermatoxins, or other toxins that affect the stomach or intestines.

"blue-green algae"

Harmful Algal Bloom (HAB)-Associated Illness I. Freshwater Environments: A. Skin contact and inhalation: People or animals exposed to cyanotoxins through direct skin contact or inhalation may experience the following symptoms : • • • Skin irritation Eye irritation Nose irritation Throat irritation Respiratory illness B. Ingestion: People who ingest cyanotoxins may experience the following symptoms : • • Abdominal pain Headache Neurological symptoms Vomiting Diarrhea Liver damage Kidney damage

Harmful Algal Bloom (HAB)-Associated Illness II. Marine Environments: • Marine or saltwater harmful algal bloom (HAB) toxins can cause a variety of illnesses in humans and animals. • Two major groups of marine phytoplankton (the microscopic marine plants) produce HAB toxins: “diatoms” and “dinoflagellates” • Some common marine HAB toxins include brevetoxins, ciguatoxins, domoic acid, okadic acid, and dinophysistoxins • Exposure to marine HAB toxins can occur through: ü direct contact by swimming, ü breathing in aerosolized toxins (toxins in water turned into tiny airborne droplets or mist), ü or eating toxin-contaminated shellfish or finfish.

Harmful Algal Bloom (HAB)-Associated Illness II. Marine Environments: q Dinoflagellates (Marine HABs ) appear red in color are commonly referred to as red tides>>> can produce toxins called brevetoxins. Exposure to brevetoxins in humans can cause various symptoms, including the following : • Respiratory irritation (coughing, sneezing) • Shortness of breath • Throat irritation • Eye irritation • Skin irritation

Harmful Algal Bloom (HAB)-Associated Illness II. Marine Environments: q Ingestion: Eating Contaminated Seafood and Marine Toxin Poisoning • Marine HAB toxins can build up in seafood when fish or shellfish eat toxin-producing algae. • Humans and animals that eat these contaminated fish or shellfish can become poisoned from HAB toxins, making them sick. • Symptoms of HAB toxin poisoning can vary depending on the type of HAB toxin. >> Five human food poisoning are presently recognized to be caused by consumption of contaminated seafood: 1. amnesic shellfish poisoning - ASP 2. ciguatera fish poisoning - CFP 3. diarrhetic shellfish poisoning - DSP 4. neurotoxic shellfish poisoning - NSP 5. paralytic shellfish poisoning - PSP