Industrial Biotechnology Shaping Corn Biorefineries of the Future

Bio-based markets, enabled by synthetic biology and increased emphasis on sustainability, are growing in the United States and around the world. Over the last five years, an exponential increase in investments in synthetic biology has been observed. Large amounts of renewable carbon in the form of fermentable sugars will be required to enable the production of next-generation biopolymer, biochemical, biofuel, and food products. In North America, sugars from corn (maize) will be the most abundant carbon source available to drive the industrial biotechnology engine. The demand for renewable carbon will improve stability in agricultural economies and support regional agricultural job creation. Traditional corn processing facilities are responding to this need by retrofitting their processing facilities to produce low-cost sugars or redirecting sugars from shrinking high-fructose corn syrup and dextrose markets to high-growth industrial biotechnology markets. However, there are still challenges that must be overcome to convert this opportunity into commercial reality. To succeed, new product and process development initiatives must meet economic, regulatory, quality, and other requirements within budget and time constraints. Translational research facilities that are specifically intended to accelerate commercialization and reduce the risk of utilizing new technologies will play a crucial role in realizing the opportunities offered by industrial biotechnology. Growth in Industrial Biotechnology Industrial biotechnology is growing at a fast pace in the United States and around the world, shaping the biorefineries of the future and the development of biomaterials, renewable chemicals, bio-based ingredients, foods, and agricultural products. Recent estimates by the Biotechnology Innovation Organization put the global economic value of industrial biotechnology at US$355 billion (2). There are many reasons for this tremendous growth in industrial biotechnology (13). For example, • Sustainability has become a megatrend in consumer products • Advancements in synthetic biology and metabolic engineering • Availability of abundant, low-cost carbon required for fermentation • Bridging of the gap between innovations and commercialization for biorefineries Sustainability as a Megatrend Industrial biotechnology is enabling a circular economy with increased use of renewables, production of new materials that reduce waste and have superior functionality, products with better life cycles and improved compostability, and use of materials that have better reuse and upcycling applications at end-of-life (15). Major consumer goods companies are using higher amounts of biopolymers and highlighting the sustainability of their products to market them. Consumers also are demanding greener products, which is creating a market demand for bioproducts. nova-Institute’s new market and trend report estimates that the total production volume of bio-based polymers was 8.0 million tonnes in 2018 and is expected to reach 9.6 million tonnes by 2023 (5). As population growth outpaces food supplies (especially meat products), sustainability in food production systems is becoming increasingly important. Recent trends in plant-based products (e.g., meatless burgers, chicken, eggs, shrimp) are becoming more popular and experiencing explosive growth in the United States. In addition to the United States, meatless markets also are expected to grow in Europe and Asia. With worldwide consumption of meat increasing, by 2050 sustainable meat production in certain parts of the world will become challenging. In 2017, China, in an effort to reduce Chinese meat consumption by 50%, announced a multimillion dollar deal to import lab-grown meat from companies in Israel (4). Water, fossil energy, labor, land, and feed use, as well as emissions and nitrogen run-off, associated with producing plant-based meat products are an order of magnitude lower compared with animal meat products (11). Advances in Synthetic Biology and Metabolic Engineering Advances in synthetic biology and metabolic engineering have reduced the cost of developing new bioproducts with complex and novel biosynthetic pathways. The ability to express novel enzymes and construct novel pathways has made it possible to produce a wide variety of bioproducts that previously were not possible or were very expensive to produce. There have been several key developments over the past 10 years. However, the key game changer has been the developments in synthetic biology that have resulted from CRISPER-Cas9 technology. So, what is CRISPER-Cas9 technology? “CRISPR” is an abbreviation for “clusters of regularly interspaced short palindromic repeats” (6,10). To simplify the discussion, CRISPRCas9 is a genome-editing tool. The genomes of various organisms encode series of messages and instructions within their DNA sequences. Genome editing involves changing those sequences and, thereby, changing the messages. This can be done by inserting a cut or break in the DNA and “tricking” the natural DNA repair mechanisms of a cell into introducing desired changes. CRISPR-Cas9 provides a means to do this. The power of this editing tool when coupled with management of big data allows us to predict the changes in chemicals, proteins, or materials produced by an organism. CRISPR-Cas9 has allowed industrial biotechnology companies to accelerate the development of specialized fermentation organisms from years and millions of dollars in investments using traditional mutation development, to months and tens of thousands of dollars in investments using targeted genome editing. This is a defining moment in the transformation of agricultural feedstocks that are serving a growing industry and an indicator of what might be in store for the new world of biorefineries. Many experts in the industrial microbiology field view synthetic biology and its products as an accelerated growth and expansion of biotechnology progress, similar to the progression experienced since the inception of the information technology (IT) field and its expansion according to Moore’s law. (Moore’s law is the observation made by Intel cofounder Gordon Moore that the number of transistors on a chip doubles every year, while the costs are halved. Moore’s law predicts that this trend will continue into the foreseeable future). Investments made in synthetic biology over the past five years, which approach nearly US$8 billion, serve as an early indicator of the product pipelines that are being developed and clearly shape the opportunities for existing ethanol facilities where fermentable sugars can be diverted to new product fermentations. The most recent data on synthetic biology funding, as presented by SynBioBeta (16), is shown in Figure 1. The rapid pace of further investments is continuing in 2019. All of this indicates there are significant opportunities for expansion of biorefineries throughout the U.S. agricultural economy and, more widely, internationally as agriculture feedstocks are more fully developed to produce fermentable sugars. Within the innovation window, synthetic biology must be considered a disruptive technology related to the launch of commercial products, and we must keep in mind what this means for the products and industry. Bio-based products will change the original trajectory of traditional production, redirecting production to fermentation-based processes (Fig. 2). Bio-based chemicals and materials can exploit opportunities in the US$450 billion specialty markets (Fig. 3). These markets are quite diverse, with significant segmentation, which greatly reduces market risks. Above and beyond these specialty markets, synthetic biology is targeting the following markets as well: animal health, aquaculture, biomass to sugars, nanocarbon and cellulose, biofibers, food ingredients, lubricants, nutraceuticals, microbiome, biostimulants, enzymes, biopesticides, food proteins, and biofertilizers. Availability of Abundant, Low-Cost Carbon Required for Fermentation Based on the continuing investments in synthetic biology and industrial biotechnology, we can confidently predict that there will be significant growth in industrial fermentation over the next decade as products move from lab, to pilot, to demonstration, and, finally, to commercial production. According to a report from the National Academy of Sciences, fermentation and catalytic conversion technologies are going to be a major unit operation that will drive the bioeconomy in the United States and around the world (12). However, to meet the demands of this growing biochemical industry, abundant renewable carbon sources (sugars) are needed at a price point that enables bioproducts to be produced economically. Renewable feedstock, such as cellulosic biomass, is currently being developed for sugar production. Despite intense research and development activities, the production process for extracting sugars from cellulosic biomass remains challenging compared with corn (maize) and other sugar crops due to the recalcitrant structure of cellulosic biomass. Currently, there are only four places around the world where abundant, cost-effective sources of Fig. 1. Funding for synthetic biology companies (2009–2018) (16). Fig. 2. Projected revenue trajectory of bio-based products over time. carbon are available: Brazil (cane); Europe (beets and wheat); Southeast Asia (cassava and cane); and the United States (corn) (7). Corn production is expected to expand in the United States, and by 2030, production yields are expected to be 200–300 bu of corn/acre (8), with more corn available for industrial processing. Major industrial processing of corn is performed by the wetmilling and dry-grind industries. The corn wet-milling industry traditionally has produced corn sugars (i.e., dextrins, glucose, and high-fructose corn syrup) for food and beverage applications, in addition to coproducts for human and animal food p