What is Schizochytrium sp.? A Sustainable Omega-3 Source

Schizochytrium sp. is a single-celled marine microorganism with scientific and commercial interest. It belongs to a group of organisms called thraustochytrids, found in coastal marine habitats and associated with decaying mangrove leaves. These organisms are not plants but are classified as heterokonts, functioning as decomposers in their environment.

First described in the 1960s, this microalga was noted for its ability to accumulate large amounts of lipids (oils) within its cell. This characteristic is central to its importance in biotechnology. Schizochytrium sp. has become a focus for research and industrial development due to its capacity to produce high concentrations of valuable nutrients.

The Role of Schizochytrium in Omega-3 Production

The primary reason for the focus on Schizochytrium sp. is its ability to produce omega-3 fatty acids, particularly docosahexaenoic acid (DHA). The oil produced by this microalga consists of 35-50% DHA, making it one of the most concentrated natural sources. This production occurs through a polyketide synthase (PKS) pathway, a metabolic route efficient at creating long-chain fatty acids like DHA.

DHA is a structural component of cell membranes, with its highest concentrations found in the brain and retina. Its presence is linked to brain development, cognitive function, and maintaining normal vision. While the human body can convert other omega-3s into DHA, the process is limited, making direct dietary intake an effective way to ensure adequate levels.

In addition to its high DHA content, Schizochytrium sp. also produces smaller quantities of another omega-3, eicosapentaenoic acid (EPA), though it is predominantly recognized as a DHA producer. Research has explored methods to increase the EPA yield, aiming to create a product that provides both fatty acids. The fatty acids within the algal oil are in the triglyceride form, a bioavailable structure for the body.

Commercial Cultivation and Production

Large-scale production of Schizochytrium sp. occurs in controlled industrial facilities, not the ocean. The process uses fermentation, similar to how yeast is used in baking or brewing. The microalgae are grown in large, sealed, stainless-steel containers called bioreactors. This contained system ensures cultivation is axenic, meaning only the desired strain is present without contamination.

Inside the bioreactors, the microalgae are provided with a nutrient-rich medium. This includes a simple carbon source, often glucose from corn or sugarcane, which the algae consume for energy and growth. They are also supplied with nitrogen, salts, and vitamins to support multiplication and oil production.

Since Schizochytrium sp. is heterotrophic, it does not require light, allowing for high cell densities in the fermentation tanks. This controlled process allows producers to manage parameters like temperature, pH, and oxygen levels to maximize growth and oil synthesis. The entire cycle is relatively short, and the algal biomass can contain more than 50% lipids by dry weight. The oil is then extracted from the harvested cells and refined into a pure final product.

Applications in Human and Animal Nutrition

The oil from Schizochytrium sp. is a widespread ingredient in human and animal nutrition due to its high DHA concentration. In human nutrition, a prominent use is in infant formula. DHA is added to formulas to support the brain and visual development of infants who are not breastfed.

For adults, the algal oil serves as a source of omega-3s for vegetarians, vegans, and others who do not consume fish. It is found in softgel supplements as a plant-based alternative to fish oil capsules. The oil is also used to fortify foods and beverages like plant-based milks, yogurts, and juices to increase their nutritional value.

In animal nutrition, Schizochytrium sp. is a feed additive, particularly in aquaculture. When added to the feed of farmed fish, like salmon or sea bream, it enriches their flesh with DHA. This not only improves the health of the fish but also increases the omega-3 content for consumers. Its use extends to livestock and pets, leading to products like omega-3 enriched eggs from hens fed a diet containing the microalgae.

A Sustainable Alternative to Traditional Omega-3 Sources

Schizochytrium sp. offers environmental advantages over traditional fish oil. Commercial fishing for omega-3s targets small, oil-rich forage fish like anchovies and sardines, which are a foundational part of marine ecosystems. Cultivating microalgae on land reduces fishing pressure on these wild populations and avoids the ecological disruption of industrial fishing, such as bycatch.

Purity is another benefit of algal oil. Because Schizochytrium sp. is grown in a controlled environment, its oil is free from the ocean-borne contaminants that can accumulate in wild fish. These pollutants, including heavy metals like mercury and persistent organic pollutants like PCBs and dioxins, bioaccumulate up the food chain. Algal oil production bypasses this process, resulting in a cleaner product.

Schizochytrium sp. provides a direct source of DHA. Fish do not produce DHA themselves; they obtain it by consuming smaller organisms that have fed on microalgae. By cultivating the microalgae directly, it is possible to go straight to the original source.