Lessons of Algae
Algae is one of the most prolific types of organisms on earth. They range in size from microscopic single celled organisms to giant kelp, which can span hundreds of feet in length. Algae grow in fresh and saltwater environments. They can live their life as free-floating plankton, or form colonies that may snag or attach to solid surfaces. Algae are unique creatures in that they generate energy via photosynthesis, the process of using the sun’s energy and basic elemental compounds to form its structure and generate the energy required for growth and reproduction. Algae can reproduce sexually and asexually. Micro-algae have incredibly short lifecycles, with lifespans of just days or less, and some species able to reproduce every few hours.
(A) Scenedesmus sp.(B) Chlorella sp.(C) Tetraedron caudatum (D) Scenedesmus dimorphus (E) Scenedesmus dimorphus (F) Graesiella emersonii. In V. T. Duong, F. Ahmed, S. R. Thomas-Hall, S. Quigley, E. Nowak, & P. M. Schenk (2015). High protein- and high lipid-producing microalgae from northern Australia as potential feedstock for animal feed and biodiesel. Frontiers in Bioengineering and Biotechnology, 3, 53
Because algae perform photosynthesis like plants and trees, ecologist classify them as primary producers. Primary producers are consumed by many other creatures including bacteria and fungi that breakdown dead material, returning the nutrients to a form for new algae and other primary producers to grow. In aquatic ecosystems there are many organisms that eat algae. Some of the primary consumers, creatures that only eat primary producers such as algae, include small crustaceans, bivalves, and small fish.
Following the trophic pyramid, secondary consumers eat the primary consumers. In aquatic ecosystems common secondary consumers are larger crustaceans, adult form of aquatic insects, and medium to large fish. Tertiary consumers would be the apex predator fish species, and in natural ecosystems might also include aquatic mammals and birds. At the top of the Trophic pyramid are humans, who maintain a great deal of influence over ecosystems by our control of water, partitioning of space, and various forms of pollution.
A model of the Tropic Pyramid demonstrating the diminishing relative energy transfer representing energy lost during consumption as well as the nutrient cycle between primary producers, all consumers, and microbial recyclers.
I first became interested in algae when learning about its potential application in creating biofuel. Some species of algae are extremely dense in lipids and fatty acids. These lipids and oils help give algae their nutritional qualities and capable of being refined into a range of fuels including methane gas, ethanol, biodiesel, and even jet fuel. Wanting to better understand the process of culturing algae I ordered some starter cultures and attempted to grow it out in some disposable water bottles that were on hand. While it was a fun experiment, many aspects of algae’s nutrition and lifecycle remained a mystery to me. The cultures did alright for a few weeks being fed diluted plant nutrients and using reverse osmosis water.
When growing algae, the mixture of water and diluted nutrients and minerals is referred to as the culture media. When growing microalgae, the most common algae culture media is F/2, a half strength of Guillard and Ryther’s 1962 “f Medium”. F/2 is prepared at half strength to reduce stress in most algae cultures. While F/2 is suitable for a wide range of marine and freshwater algae, there are some types of algae that require additional nutrients. Diatoms are a major group of microalgae that in addition to the minerals in F/2, require silica for their cell walls. When culturing diatoms silica must be added to the growing medium to ensure a healthy culture.
Raphidocelis Subcapitata cultures after preparation and inoculation of glass vessels and culture media. These light green fluids will develop into thick green cultures in around 7 days.
Sterilization is extremely important when working with algae cultures. The culture media not only provides ideal growing conditions for algae, but also fungi, bacteria, and other organisms that might be undesirable. When culturing algae for human consumption it is essential to ensure that the growing vessel and culture media have been thoroughly decontaminated. For culture media this might include using heat and steam to sterilize the culture media, and physical components that are heat tolerant such as glass culture vessels. Sub-micron filters might also be used for filtering potential bacteria and fungi contamination from heat sensitive liquid media. Hydrogen peroxide can be used as a disinfectant and could be ideal to cultures that may be sensitive to residues of other cleansers as hydrogen peroxide will breakdown into harmless compounds. When growing algae for live feed purposes, we have found using reverse osmosis water for the preparation of the culture media, and disinfection of growing vessels with dish soap to be sufficient in preventing contamination that would cause a culture crash.
2 main concerns when selecting a growing vessel are light penetration and how easy the material is to clean. While I have successfully used common plastic containers to culture algae, it has also seemed like they are more susceptible to crashing and harder to clean. When culturing algae on a small scale, glass containers are the ideal culture vessel. Glass containers allow for the lightest penetration, are chemical resistant and non-porous, preventing accumulation of biofilms making them easier to clean and sterilize. While they are fragile, glass vessels are more durable and have greater longevity than plastic vessels, and when they do break glass is the more sustainable option as it can more efficiently be recycled. Widespread use of glass vessels across all industries can help reduce microplastic pollution and protect earth’s aquatic habitats where they are accumulating.
Healthy Raphidocelis Subcapitata at the University of Nebraska Lincoln Aquatic Biodiversity and Conservation Laboratory May 2021.
While there might be cultural stigmas against algae and the green huge it gives earths waters, algae are an essential component to earth’s food web and sustaining life both in and out of water. While there are over 50,000 species of algae that have been documented on earth, only a tiny fraction of them have been thoroughly studied by modern science and are reproduced for laboratory or industrial use. Nearly anywhere there is water there is algae. Go out to your nearest lake or pond and you likely could gather a sample containing specimens yet to be thoroughly investigated. From sustainably producing food for both animal and human consumption to creating biofuels that can power jets, and even exploring possibilities yet to be discovered, there lies a tremendous opportunity in society’s growing and continuous understanding of algae.