Micrograph of algae

Micrograph of algae.
Credit: Masaki Ihara Ph.D., Interdisciplinary Cluster for Cutting Edge Research Institute for Biomedical Sciences, Shinshu University

Algae have struggled for years to be competitive with petroleum-derived chemical production. Algae are more favorable to petroleum from an environmental standpoint but the production cost of culturing, collecting, extracting and refining adds up to make the process too expensive for practical use. There is a need to improve production efficiency to reduce the cost of algae-derived products in order for them to be a viable alternative to petroleum-derived products.

Recently a research team led by Alice Uchida and Masaki Ihara, of Shinshu University, succeeded in developing a method of cultivating microalgae by solving issues related to cultivation; collection/recovery of compounds and extraction/purification of products.

At the beginning of the study the researchers struggled to find a type of algae that could withstand mechanical shearing; they were not sure such an algae existed. However, after an extensive search, they were able to find Tolypothrix filamentous cyanobacteria and were able to cultivate them continuously for two years with little cell damage despite mechanical shearing of the compounds bound to the cell surface.

Collected algal bodies.
Credit: Masaki Ihara Ph.D., Interdisciplinary Cluster for Cutting Edge Research Institute for Biomedical Sciences, Shinshu University

They grew the algae in non-sterile agricultural water and performed 87-day milking cycles which yielded 90 to 140 mg/L of extracellular carbohydrates every three weeks. There was no need for a solvent for extraction or purification, dramatically simplifying and decreasing the cost of processing.

It is necessary to keep the algal cells alive during extraction. By preserving the algae, there is no need to cultivate and multiply the algae. Secondly, the algae they chose naturally gather together for ease of collection. Thirdly, the compounds desired for harvest (polysaccharides [carbohydrates] and phycobiliproteins) are released outside of the algae and bound to the cell surface. Phycobiliproteins are currently in demand for food additives and cosmetic applications.

This non-destructive continuous milking system is a practical and effective method of algae-derived chemical production. The Ihara lab hopes to enable petroleum-based products to be replaced by algae-derived products that inflict less strain on the environment. In order to do so, algae production needs to happen on a much, much larger scale.

The search continues for tough algae that can survive in a variety of environments, and the study researchers hope to be able to collaborate with researchers from a variety of fields, including fermentation engineering, chemical engineering, polymer chemistry – specifically algal biomass conversion technology – and environmental and forest conservation studies, in order to study the effects of large-scale algae culture on the environment.

—Courtesy Shinshu University

Read more: Alice Uchida et al, Production of extracellular polysaccharides and phycobiliproteins from Tolypothrix sp. PCC7601 using mechanical milking systems, Algal Research (2020).  DOI: 10.1016/j.algal.2020.101929