Commercial development of microalgal biotechnology: from the test tube to the marketplace

Abstract

While humans have taken limited advantage of natural populations of microalgae for centuries (Nostoc in Asia and Spirulina in Africa and North America for sustenance), it is only recently that we have come to realize the potential of microalgal biotechnology. Microalgal biotechnology has the potential to produce a vast array of products including foodstuffs, industrial chemicals, compounds with therapeutic applications and bioremediation solutions from a virtually untapped source. From an industrial (i.e. commercial) perspective, the goal of microalgal biotechnology is to make money by developing marketable products. For such a business to succeed the following steps must be taken: identify a desirable metabolite and a microalga that produces and accumulates the desired metabolite, establish a large-scale production process for the desired metabolite, and market the desired metabolite. So far, the commercial achievements of microalgal biotechnology have been modest. Microalgae that produce dozens of desirable metabolites have been identified. Aided by high throughput screening technology even more leads will become available. However, the successes in large-scale production and product marketing have been few. We will discuss those achievements and difficulties from the industrial point of view by considering examples from industry, specially our own experience at Mera Pharmaceuticals.

Introduction

Microalgae are an extremely heterogeneous group of organisms. To be called a microalga, the organism needs to be small (usually microscopic), unicellular (but can be colonial with little or no cell differentiation), colorful (due to photosynthetic and accessory pigments), occur mostly in water (but not necessarily) and most likely be photoautotrophic (but not necessarily all the time). Phylogenetically, microalgae can be prokaryotic or eukaryotic and, in evolutionary terms, recent or very ancient. This very diversity makes microalgae, as a group, a potentially rich source of a vast array of chemical products with applications in the feed, food, nutritional, cosmetic, pharmaceutical and even fuel industries.

The history of microalgal utilization from natural populations is centuries old (Nostoc in Asia and Spirulina in Africa and Mexico). However, the purposeful cultivation of microalgae is only a few decades old. During the 20th century, researchers and commercial producers developed several cultivation technologies that are in use today to produce microalgal biomass: open ponds [1], enclosed photobioreactors (PBRs) [2] and fermentation reactors [3].

The status of microalgal applications in aquaculture, food, specialty chemicals and environmental applications has been reviewed recently [3], [4], [5], [6]. In this paper we will concentrate on aspects of algal biotechnology that are related to producing high value compounds such as nutraceuticals and pharmaceuticals.

Microalgae are not a well-studied group from a biotechnological point of view. Of the tens of thousands of microalgal species believed to exist, only a few thousand strains are kept in collections around the world, only a few hundred have been investigated for chemical content and only a handful have been cultivated in industrial quantities (tons per year quantities). Because they are largely unexplored, the microalgae represent a rich opportunity for discovery; the expected rate of rediscovery (finding metabolites already described) is expected to be far lower than for other groups of better-studied organisms [7] (Fig. 1).