Meet the tiny ocean fungus that kills toxic algae

Algae, image by Tim Sandle
 

Scientists have discovered a newly identified marine fungus that can infect and kill toxic algae responsible for harmful blooms. The microscopic parasite, named Algophthora mediterranea, attacks algae such as Ostreopsis cf. ovata, which produces toxins that can irritate the lungs, skin, and eyes of people exposed during coastal blooms. Remarkably, the fungus can infect several different algae species and even survive on pollen, suggesting it is far more adaptable than most known marine parasites.

Researchers at Yokohama National University in Japan have identified a previously unknown species of marine fungus capable of killing harmful algae that form toxic blooms.

The organism, named Algophthora mediterranea, is a microscopic chytrid fungus that can infect a wide variety of hosts. Chytrids are a diverse group of aquatic fungi, and the discovery suggests they may influence marine ecosystems more strongly than scientists once believed.

The researchers found that this fungus acts as a lethal parasite in Ostreopsis cf. ovata, a species of algae responsible for toxic blooms that can negatively affect human health. The study describing the discovery was published in Mycologia.

Toxic Algae and Their Health Risks

Harmful algal blooms have become an increasing concern in oceans, rivers, and lakes around the world. These outbreaks occur when algae grow rapidly and excessively, often triggered by high nutrient levels and warmer water temperatures. Such blooms can degrade water quality, disrupt ecosystems, and release toxins that threaten both wildlife and people.

Large blooms of Ostreopsis cf. ovata have been reported more frequently in the Mediterranean over recent decades. This alga produces a toxin called ovatoxin (OVTX), which can cause symptoms in humans including runny nose, coughing, shortness of breath, conjunctivitis, itching, and dermatitis.

A Newly Identified Algae Killing Fungus

Algophthora mediterranea was first detected in Spanish seawater in 2021 by scientists from the Institut de Ciències del Mar (ICM) in Spain, led by Dr. E. Garcés and Dr. A. Reñé. The species was later formally described by Professor Maiko Kagami and PhD student Núria Pou-Solà at Yokohama National University.

Genetic analysis confirmed that the organism represents not only a newly identified species but also an entirely new genus. The researchers named the genus Algophthora by combining the word 'alga' with the Greek word 'phthora', meaning 'destruction'.

Scientists observed that the fungus parasitizes cells of O. cf. ovata and can kill them within a few days. Additional experiments showed that it can also infect several other algae species and can even feed on pollen grains.

Studying the Parasite in Detail

To better understand the organism, the researchers isolated the fungus and recorded time-lapse images every ten minutes over a four-day period. They also examined samples using scanning electron microscopy (SEM), a technique in which a focused beam of electrons scans the surface of a specimen to create highly detailed images. The fungus was also analyzed through DNA sampling.

Reference:

Núria Pou-Solà, Kensuke Seto, Alan Denis Fernández-Valero, Jordina Gordi, Esther Garcés, Albert Reñé, Maiko Kagami. Algophthora mediterranea , gen. et sp. nov.: Novel dinoflagellate- and diatom-infecting generalist marine chytrid from the Mediterranean Sea. Mycologia, 2025; 118 (1): 10 DOI: 10.1080/00275514.2025.2577604 

 

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)

Algae and biofuels

Algae and anchor

The complete genetic makeup of a species of ecologically important algae, which may aid in biofuel production, has been sequenced by scientists. This is only the second time that researchers have sequenced the genome of one of these ecologically important algae, known as haptophytes.

University of Washington scientists have sequenced the complete genetic makeup of one of these algae. The haptophytestudied is Chrysochromulina tobin. The organism thrives in oceans across the globe. The researchers spent years on a series of experiments to sequence all of Chrysochromulina's genes and understand how this creature turns different genes on and off throughout the day. In the process, they discovered that Chrysochromulina would make an ideal subject for investigating how algae make fat, a process important for nutrition, ecology and biofuel production.

For further details see:

Blake T. Hovde, Chloe R. Deodato, Heather M. Hunsperger, Scott A. Ryken, Will Yost, Ramesh K. Jha, Johnathan Patterson, Raymond J. Monnat, Steven B. Barlow, Shawn R. Starkenburg, Rose Ann Cattolico.Genome Sequence and Transcriptome Analyses of Chrysochromulina tobin: Metabolic Tools for Enhanced Algal Fitness in the Prominent Order Prymnesiales (Haptophyceae).PLOS Genetics, 2015; 11 (9): e1005469 DOI:10.1371/journal.pgen.1005469



 Posted by Dr. Tim Sandle

Bladderwrack and bacterial resistance

The bladderwrack Fucus vesiculosus is a species of brown algae, found along the North Atlantic coasts. The algae has an interesting defence mechanism against bacterial infections.

Bacteria generally play a crucial role in the life of seaweeds. Also the bladderwrack lives in symbiosis with many types of bacteria that feed it with certain growth factors and nutrients. On the other hand, some other bacterial species can harm the seaweed. To deter them, Fucus produces different chemical compounds.

In terms of climate change, under changed light or temperature conditions the production of single defensive compounds decreased in comparison to unchanged conditions.

For further details, refer to:

Mahasweta Saha, Martin Rempt, Stephanie B. Stratil, Martin Wahl, Georg Pohnert, Florian Weinberger. Defence Chemistry Modulation by Light and Temperature Shifts and the Resulting Effects on Associated Epibacteria of Fucus vesiculosus. PLoS ONE, 2014; 9 (10): e105333 DOI: 10.1371/journal.pone.0105333

Posted by Tim Sandle

Photosynthetically productive light distributed to symbiotic microalgae

Iridescent cells in the mantle tissue of giant clams spread light of a wavelength that drives photosynthesis to microalgae that provide nutrition for the animals, the University of Pennsylvania’s Alison Sweeney and colleagues reported in Journal of the Royal Society Interface.

In their paper, the researchers likened the symbiotic system to an electric transformer, “which changes energy flux per area in a system while conserving total energy.” Given this parallel, the authors proposed that the clam system might inspire the development of more efficient and resilient photovoltaic materials.

These so-called iridocytes not only distribute photosynthetically productive light to the algae, they also reflect nonproductive light, the researchers showed. “At incident light levels found on shallow coral reefs, this arrangement may allow algae within the clam system to both efficiently use all incident solar energy and avoid the photodamage and efficiency losses,” the researchers wrote in their paper.

Source: The Scientist