Bacterial Protein for Food and Feed Generated Via Renewable Energy

Global Food Security 22 (2019) 25–32 Contents lists available at ScienceDirect Global Food Security journal homepage: www.elsevier.com/locate/gfs Bacterial protein for food and feed generated via renewable energy and T direct air capture of CO2: Can it reduce land and water use? ∗ Jani Sillmana, , Lauri Nygrena, Helena Kahiluotoa, Vesa Ruuskanena, Anu Tamminenb, Cyril Bajamundib, Marja Nappab, Mikko Wuokkob, Tuomo Lindha, Pasi Vainikkac, Juha-Pekka Pitkänenc, Jero Aholaa a LUT School of Energy Systems, Lappeenranta University of Technology, 53850, Lappeenranta, Finland b VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT, Finland c Solar Foods Ltd, 00320, Helsinki, Finland ARTICLE INFO ABSTRACT Keywords: The global food demand is projected to significantly increase. To maintain global food security in the future, Carbon dioxide protein production needs to become more efficient regarding the use of limited land and water resources. Direct air capture Protein-rich biomass can be produced via direct air capture of CO2 with the help of H2-oxidizing bacteria and Hydrogen-oxidizing bacteria renewable electricity in a closed, climate-independent system. This quantitative literature review conservatively Microbial protein (MP) estimated the direct land and water use of bacterial protein production relying on secondary data for the Microbial biomass components of the technology and for the reference protein sources. A several times higher potential protein Bio-electrochemical system Land use yield per land area can be achieved by this technology with approximately one-tenth of the water use compared Carbon capture and utilization to that required for soybean production. Environmental sustainability 1. Introduction Rosegrant et al., 2009). Consequently, there is a need for novel ap- proaches to realise environmentally sustainable, climate-resilient pro- The growing human population and the projected decline of agri- tein production that is less dependent on land and water and has the cultural yields due to climate change challenge global food security ability to adapt to climate change (FAO, 2017; Campbell et al., 2016). (Godfray et al., 2010; Porter et al., 2014). To provide the increasing Proteins are one of the main components in food, and their avail- population with a sufficient amount of protein, approximately 110% ability, quality and environmental impacts are good indicators by more crop protein will have to be produced in 2050 than in 2005, ac- which to measure food security (Coles et al., 2016). The lack of access cording to the estimate of Tilman et al. (2011).), while the availability to high-quality protein due to unequal distribution in the world causes of additional arable land and water for agricultural use is limited (FAO, malnutrition, especially in developing countries. For example, millions 2017). Currently, agriculture (excluding fibre, rubber and tobacco) of children subsist on poor sources of essential amino acids (Semba, accounts for 43% of the World’s ice-free and desert-free land area 2016). In the future, the access to high-quality protein will become even (Poore and Nemecek, 2018) and 70% of freshwater use (AQUASTAT, more challenging due to the increase in protein demand along with 2016). There are also competing claims for land and freshwater use population growth and increase in wealth under climate change. To from urbanization, the forest industry, biofuel production and carbon produce high-quality proteins to maintain food security with minimal stock conservation (e.g., Gibbs et al., 2007) via forests. In addition, environmental impact, microbial proteins (MPs), especially bacteria- agriculture, forestry and other land uses cause approximately one based MPs, are seen as promising alternatives compared to traditional quarter of anthropogenic greenhouse gas emissions and most nutrient animal- and plant-based proteins (Litchfield, 1989; Matassa et al., emissions (FAO, 2017; Smith et al., 2014). The production of animal 2016). For example, in animal feed, MPs from gram-negative soil bac- proteins accounts for the major part of the use of these resources, even terium Curpiavidus necator have been found to be comparable with though their share of the global protein consumption is approximately those from basic protein sources, such as soymeal and fishmeal, and one third only (Campbell et al., 2017; Rojas-Downing et al., 2017; include all essential amino acids required for growth (Volova and ∗ Corresponding author. E-mail address: jani.sillman@lut.fi (J. Sillman). https://doi.org/10.1016/j.gfs.2019.09.007 Received 6 February 2019; Received in revised form 21 September 2019; Accepted 24 September 2019 2211-9124/ © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/). J. Sillman, et al. Global Food Security 22 (2019) 25–32 Barashkov, 2010; Schøyen, 2007). direct air capture (DAC), bioreactors with an in situ water electrolyser There are several beneficial characteristics that bacterial proteins and separation of the bacterial biomass from the cultivation medium. have over other protein sources. Bacteria-based MPs have high protein Separating CO2 from ambient air to produce MP by binding CO2 to the contents ranging from 50% to 83% of the dry biomass, and the bacteria biomass without increasing atmospheric CO2 makes the application have high growth rates relative to other protein sources (Anupama and less-dependent on location compared solutions with point sources of Ravindra, 2000; Jørgensen, 2011; Litchfield, 1989; Matassa et al., 2016; CO2 (e.g., Matassa et al., 2015; Pikaar et al., 2018; Yu, 2014). The Srividya et al., 2014; Upadhaya et al., 2016.). The bacterial conversion greatest potential of the approach is to decouple protein production efficiency from substrates to protein-rich biomass is high compared to from the use of agricultural land and minimal water use, in comparison that of other MP sources, such as yeasts and fungi, and to that of tra- with traditional protein sources, whereas the climate impact crucially ditional protein sources. MP production is usually based on inexpensive depends on the used energy source. Here we have assumed a renewable carbon substrates, including waste, which are available in large quan- energy source, which increases the land use, and thus provide a con- tities (Matassa et al., 2015, 2016; Upadhaya et al., 2016; Øverland, servative estimate of the potential to reduce land and water use. 2012; Steinkraus, 1986). In addition, the production process for MPs The aim of this study is to quantify the potential reduction in land can be designed as a closed system highly independent of seasonal and water use from bacterial MP production via the use of direct air changes, making efficient nutrient use without runoff to the sur- capture of CO2, a water electrolyser and renewables in comparison with rounding environment possible, and the system does not require her- soybean production and other MPs available on markets having studied bicides or pesticides (Israelidis, 1987; Pikaar et al., 2017). MP pro- requirement of land and water. Soybeans are a widely used plant-based duction applications can have higher solar-to-biomass efficiencies than protein source with a high protein content and high yields, making those of crops, but efficiencies among different applications vary soybean protein a well-suited plant-based protein for comparison (Day, greatly. Regarding the biomass of crops that can be harvested annually, 2013; Mekonnen and Hoekstra, 2012; FAOSTAT, 2018). The land and the yearly average solar-to-biomass efficiency does not typically exceed freshwater use were assessed based on the energy and raw material 1%. During the growing season, the energy use efficiency may reach requirements of the system components reported in the literature. 3.5% for C3 plants, such as most staple cereals and vegetables, and 4.3% for C4 plants, such as maize (corn), sorghum and sugarcane, and even the theoretical efficiency is limited to 6% (Blankenship et al., 2. Materials and methods 2011; Zhu et al., 2008). Using the cyanobacterium Arthrospira plan- tensis, an efficiency of 2% has been reached (Tredici and Zittelli, 1998), 2.1. System boundary and methods while significantly higher solar-to-biomass efficiencies of up to 10% have been achieved using H2-oxidizing bacteria (Liu et al., 2016). The studied system consists of the determined energy and material The possibility of producing MP using H2-oxidizing bacteria has consumption of the components of technologies of MP production. The long been known (Schlegel, 1965). H2-oxidizing bacteria are able to performance data from the best electricity-to-biomass efficiency of a utilize H2 as an energy source, with the help of CO2 and O2, for mi- lab-scale bioreactor found in literature was used for energy consump- crobial growth (Yu, 2014). H2 and O2 can be produced by electrolysing tion calculations. For other processes, the electricity consumptions of water inside a bioreactor (Schlegel, 1965), and CO2 can be separated commercially available products and estimates from literature were from the atmospheric air by adsorbents (Leung et al., 2014). Although used. The energy requirements for producing nutrients for microbial CO2 separation and water electrolysis are energy-intensive processes, growth were neglected. The theoretical energy and material require- there exists a growing interest in opportunities for MP production, ments of the application were determined by calculating the stoichio- because renewable energy sources can be used. (e.g., Matassa et al., metry of the substance requirements for biomass growth and by com- 2016; Liu et al., 2016). bining experimental data from system components found in the The growing capacity of wind and solar power increases utility literature. The production process was assumed to be a closed system. fluctuation, leading to occasional oversupplying of power. In particular, Thermal energy was assumed to be taken from waste heat sources. The the availability of solar energy is increasing due to the rapid decline in technologies selected consisted of direct electrolysis in the bioreactor, its production costs.

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