A completely new type of microalgae was discovered in the water from the home aquarium. Analyzing DNA samples taken from the algae, scientists from Tokyo University Medakamo discovered a hakoo whose DNA sequence did not match any on record.
This new species is the smallest freshwater green alga known, with unique properties that allow it to be stably cultivated at high densities, meaning it could be effectively used to produce useful products for food and industry.
If you’ve collected seaweed on the beach, waded through leaves in a creek, or cleaned a dirty green aquarium, then you’ll know what algae is. These diverse aquatic organisms thrive on water, light and nutrients and come in all shapes, colors and sizes. Microalgae are an ultra-small type of algae that are invisible to the human eye, but are a vital part of the Earth’s ecosystem and form the basis of all aquatic food chains. They have attracted particular attention from researchers and businesses for their ability to capture carbon dioxide, their use as biofuel, as an alternative source of protein, and more. There are tens of thousands of species of microalgae that continue to thrive in unexpected places.
“We were very surprised to discover a new species of microalgae just in an ordinary home aquarium,” said Professor Sachihiro Matsunaga of the Graduate School of Frontier Sciences. “The algae were taken from the water and grown one by one. The algae’s DNA was fluorescently stained and observed microscopically to find the one with the least amount of DNA per cell. We then sequenced the DNA of this algae and compared it to the DNA of other algae. The results did not match the DNA of any previously reported algae, indicating that it is a new species, and we named it Medakamo hakoo (M. hakoo).
Microalgae consist of a relatively small number of genes, and this uncomplicated form makes them useful for researchers trying to figure out what role different genes play and how they might be used. Of the tens of thousands of known microalgae, many remain uncharacterized. Thanks to this latest study, we now know that not only is it a new species, but it also has the smallest known genome of any freshwater algae, as well as other useful properties.
“M. hakoo contains only one mitochondrion (for energy production) and one chloroplast (which contains chlorophyll and makes food through photosynthesis), whereas normal plant cells contain multiple mitochondria and chloroplasts. This suggests that it is a green alga with an extremely simple cellular structure,” Matsunaga explained. “From our research, we also speculated that it has an unprecedented DNA structure and a novel gene regulatory system. Its cell cycle is also strongly synchronized with the day-night cycle, which is crucial for efficient and stable bioproduction. Due to these natural properties and extremely small size, M. hakoo can be efficiently cultured at high cell density, enabling the mass production of substances such as highly functional foods, cosmetics and biofuels at low cost.”
The researchers plan to continue exploring the potential applications of M. hakoo, both in the laboratory and in the wider world. “Aquatic green algae are the original organisms of today’s land plants. With this research, we can better understand the minimum number of genes needed for an organism to develop and thrive in different environments, which we will continue to study,” Matsunaga said. “In the future, I would like to find ways to collaborate and create useful substances from the mass cultivation of M. hakoo.”
Written by: Vaishali Verma