Protein and the Planet

Being a biochemist, who is also concerned with sustainability, I was interested to look into where biotechnology and specifically recombinant proteins are being applied as solutions to help combat the impact we humans have had (and are still having) on the environment. It seemed especially topical at the moment given the recent COP26 meeting in Glasgow, UK.

As a global community, with sole responsibility for the custody of our planet, we are facing growing, unbelievably interlinked and therefore complex challenges to maintain our home. Rockström et al  [1] presented these issues as nine planetary boundaries, three of which, they argue we have already exceeded (Fig 1).

Figure 1: The inner green shading represents the proposed safe operating space for nine planetary systems. The red wedges represent an estimate of the current position for each variable. The boundaries in three systems (rate of biodiversity loss, climate change and human interference with the nitrogen cycle), have already been exceeded. Taken from [1].

Our response to these challenges needs to be global, creative and collaborative. Technology will of course be part of the solution, but we should not and cannot afford to rely completely on that. Tony Jupiter in his excellent book “What has nature ever done for us?” [2] presents many examples of how, if we change the way we think about and interact with nature, both we and the environment will be better off and often the proposed solutions do not involve significant sacrifices to our lifestyles in the long term. (Mind you, I didn’t know how much I needed to worry about soil until I had read his book).

The focus of this article is to present selected examples that illustrate where recombinant proteins and biotechnology are being used as part of the response to protect our planet. A small snapshot, if you will, to see how the biotech sector measures up against that old adage, “if you are not part of the solution then you are part of the problem”.

Enzymes for laundry

Probably one of the best examples is the use of enzymes in laundry, where their inclusion to replace traditional surfactants has led to a reduction in the temperature (therefore electricity), the amount of water required per wash and the level of chemicals released to the environment. The global impact of this is difficult to calculate, but there is no doubt that it is massive. As an indication, Novozyme estimate that in Latin America 110,000 tonnes CO_2eq (CO₂ equivalent of all combined greenhouse gases) and 65 billion m³ water could be saved per annum if households switched to using biological detergents [3]. Unilever recently announced a partnership with Arzeda [4], with the aim of improving the efficiency of enzymes for their cleaning and laundry products, thereby hoping to reduce the carbon footprint of our laundry even further.

Food: Protein

There is a growing body of evidence and opinion in the scientific community that the current levels of meat and dairy consumption are linked to an increase in obesity and that the production of protein for food has a huge adverse impact on biodiversity, soil quality and climate change [5]. This presents obvious opportunities for change, but if we do nothing the situation will only get worse with increasing global population and affluence. In their landmark paper, Poore and Nemecek [6] calculate that our food supply chain accounts for 26% of anthropogenic CO_2eq emissions. Within those numbers, they show that, with respect to the way we produce food protein, animal protein and beef in particular have the biggest carbon footprint (Figure 2). Since their paper, there has been an increase in the level of discussion surrounding what we eat and the idea that one of the best and simplest ways we can reduce our individual carbon footprint is to eat less meat.

Figure 2: Estimated greenhouse gas (kg CO2eq) per 100g protein production. Taken from [7].

Now there are certainly no barriers to going more or totally vegetarian and biotechnology has certainly played its part in the options that are increasingly available to us. For example, the fermentation and production of mycoproteins such as Quorn [8] and Enough [9]. However, there is one recent example that I find particularly intriguing. To make their products more appealing to non-vegetarians, Impossible foods [10] produce the haem-containing, soy bean leghaemoglobin protein recombinantly in yeast.

Figure 3: 3D structure of soy bean leghaemoglobin (PDB:1FSL)

This is purely to mimic the haem-containing proteins found in meat, to make their burgers, sausages etc look and taste more “meat like”. To me, with the vegetarian options that are already available, there is no particular reason to go to all this effort, it is only a trick that aims to change peoples’ habits. But if it encourages more people to eat less meat, then I am all for it. Certainly, the claims made by Impossible Foods are worthy of attention. “Impossible Burgers made with leghaemoglobin generate 87% less greenhouse gases, require 95% less land and use 75% less water to produce than burgers from cows, it would be grossly irresponsible to the planet and its people not to pursue this path” [11].

Plastics

By virtue of one of plastics most useful properties, its durability, plastic pollution is an increasingly serious problem. The global accumulated plastic waste in the environment is predicted to reach 12,000 million tons by the year of 2050 [12]; perhaps no better exemplified than by the largest of the five ocean garbage patches, the “Great Pacific Garbage patch” which is estimated to contain more than 80,000 tonnes of waste plastic [13]. There is nothing inherently wrong with our use of plastic, but that is only if we can truly recycle it all and none is left as waste in the environment, which clearly, we are drastically failing to do.

One option is to develop biodegradable materials to replace our use of plastics. Some recombinant proteins with good thermal and mechanical properties are proving to be good candidates for this. For example, Spiber Inc. have engineered “Brewed Protein 1” which is based on spider silk and this is showing great promise as a plastic replacement [14].

Another option is to try and degrade the waste plastic back to useful organic molecules as part of a biorefinery recycling concept [15] [16][17]. However, most plastics are difficult to break down. For example, Polyethyleneterephthalate (PET), the most common polyester plastic, is very difficult to depolymerise due to restricted access to ester bonds. Recently, research teams have looked to microbes that produce certain hydrolases, esterases, lipases and cutinases as a means to break down plastics [18], [19]. Developing from this approach, recombinant PET hydrolase and mono(2-hydroxyethyl) terephthalate MHETase have been produced and purified to use as tools to biologically degrade PET [20], [21].

Biofuels

Recombinant proteins may also come to play a role in how we wean ourselves away from the use of fossil fuels to power our vehicles. Electric, battery powered motors are all well and good for our cars, but we many need other options for the larger vehicles that require more power, such as lorries, ships and planes. Bioethanol fits the bill, but the majority of this fuel is produced by sugar fermentation using sugar cane, molasses and corn as feedstock. These of course are food crops and have high value as such. It would be better and more sustainable if other sources could be used. Cellulose is the most abundant organic molecule on the planet, but again is very resilient to depolymerisation. To address this, teams are looking to engineer cellulases and lignocellulases to provide a way to release the sugars for subsequent bioethanol and/or biobutanol production [22] [23] [24]. These cellulases are a mixture of different cellulolytic enzymes (endoglucanases, exoglucanases, and b-glucosidases among others) that act synergistically on cellulose.

On another route (cheesy pun intended), hydrogen is being considered as a fuel to power vehicles and as a means to provide heating to buildings – the so called “hydrogen economy”. Currently the vast majority of hydrogen is produced using fossil fuels with processes such as natural gas reforming (or steam methane reforming) [25], [26] which are high CO_2eq producing processes and are, as such, unsustainable. I was fortunate to work for a start-up company, BioH2, where we had cloned the [NiFe] hydrogenase from the cyanobacterium Synechocystis sp. PCC6803 into E.coli. Our aim was to be able to use industrial waste sugar streams to feed fermentations of the engineered E.coli to produce hydrogen [27]. Several other teams are pursuing similar approaches, reviewed in Maeda et al [28]. The Zhang lab has taken this idea one step further and are attempting to construct a synthetic metabolic pathway with purified recombinant proteins for the complete conversion of glucan and water to hydrogen and carbon dioxide [29], [30]. These ideas are still a way off being viable as a means to produce hydrogen, but are certainly worth pursuing, again as part of a biorefinery concept.

Final comments

My hope for this article is that the examples presented shine a small light on how biotechnology is very much going to be part of our ongoing efforts to care for our planet. There are of course many, many other examples that I haven’t discussed, such as producing synthetic rhino horn to swamp the market and reduce poaching (biodiversity) [31], engineered proteins used for green chemistry (e.g [32] [33] [34] ), biosensors to monitor pollution [35] and perhaps my favourite, Unilever’s idea to use ice structuring proteins (ISP) widely found in nature in, for example,  fish enabling them to survive in freezing arctic waters.  Unilever uses ISP to make their ice cream with less sugar and fat (healthier) and also to keep it smooth and reduce the temperature (energy) required during shipping [36].

Please note "All products containing ISP will include ISP in the ingredient list and information will be made available via customer carelines and websites." [36]

References

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[2]         T. Juniper, What has nature ever done for us? How money really does grow on trees. Profile Books, 2013.

[3]         Novozyme, ‘Enabling greener detergents with enzymes – better for cleaning , planet and business’, 2020.

[4]         Arzeda, ‘Biology meets cloud computing and AI: Unilever partners with Arzeda to harness the power of computer designed enzymes’. https://www.arzeda.com/news/arzeda-unilever.

[5]         H. Aiking, ‘Future protein supply’, Trends Food Sci. Technol., vol. 22, no. 2–3, pp. 112–120, Mar. 2011, doi: 10.1016/j.tifs.2010.04.005.

[6]         J. Poore and T. Nemecek, ‘Reducing food’s environmental impacts through producers and consumers’, Science (80-. )., vol. 360, no. 6392, pp. 987–992, Jun. 2018, doi: 10.1126/science.aaq0216.

[7]         The Guardian, ‘Avoiding meat and dairy is “single biggest way” to reduce your impact on Earth’. https://www.theguardian.com/environment/2018/may/31/avoiding-meat-and-dairy-is-single-biggest-way-to-reduce-your-impact-on-earth.

[8]         Quorn Foods, ‘Quorn’. .

[9]         3FBIO, ‘Enough Food’. .

[10]       Impossible Foods, ‘Impossible Foods’. .

[11]       M. Eisen, ‘HOW GMOS CAN SAVE CIVILIZATION (AND PROBABLY ALREADY HAVE)’. https://impossiblefoods.com/blog/how-gmos-can-save-civilization-and-probably-already-have.

[12]       R. Geyer, J. R. Jambeck, and K. L. Law, ‘Production, use, and fate of all plastics ever made’, Sci. Adv., vol. 3, no. 7, Jul. 2017, doi: 10.1126/sciadv.1700782.

[13]       The Ocean Clean Up, ‘The Great Pacific Garbage Patch’. https://theoceancleanup.com/great-pacific-garbage-patch/.

[14]       Y. Tachibana et al., ‘Environmental biodegradability of recombinant structural protein’, Sci. Rep., vol. 11, no. 1, p. 242, Dec. 2021, doi: 10.1038/s41598-020-80114-6.

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[19]       J. Kaushal, M. Khatri, and S. K. Arya, ‘Recent insight into enzymatic degradation of plastics prevalent in the environment: A mini - review’, Clean. Eng. Technol., vol. 2, p. 100083, Jun. 2021, doi: 10.1016/j.clet.2021.100083.

[20]       R. Z. Janatunaim and A. Fibriani, ‘Construction and Cloning of Plastic-degrading Recombinant Enzymes (MHETase)’, Recent Pat. Biotechnol., vol. 14, no. 3, pp. 229–234, Sep. 2020, doi: 10.2174/1872208314666200311104541.

[21]       B. C. Knott et al., ‘Characterization and engineering of a two-enzyme system for plastics depolymerization’, Proc. Natl. Acad. Sci., vol. 117, no. 41, pp. 25476–25485, Oct. 2020, doi: 10.1073/pnas.2006753117.

[22]       F. Contreras et al., ‘Engineering Robust Cellulases for Tailored Lignocellulosic Degradation Cocktails’, Int. J. Mol. Sci., vol. 21, no. 5, p. 1589, Feb. 2020, doi: 10.3390/ijms21051589.

[23]       A. Kuila and V. Sharma, Genetic and Metabolic Engineering for Improved Biofuel Production from Lignocellulosic Biomass. Elsevier, 2020.

[24]       F. C. Barbosa, M. A. Silvello, and R. Goldbeck, ‘Cellulase and oxidative enzymes: new approaches, challenges and perspectives on cellulose degradation for bioethanol production’, Biotechnol. Lett., vol. 42, no. 6, pp. 875–884, Jun. 2020, doi: 10.1007/s10529-020-02875-4.

[25]       Planete Energie, ‘Hydrogen Production’. https://www.planete-energies.com/en/medias/close/hydrogen-production.

[26]       US Energy Information Administration, ‘Hydrogen Explained - hydrogen production’. https://www.eia.gov/energyexplained/hydrogen/production-of-hydrogen.php.

[27]       M. A. Wells et al., ‘Engineering a non-native hydrogen production pathway into Escherichia coli via a cyanobacterial [NiFe] hydrogenase’, Metab. Eng., vol. 13, no. 4, 2011, doi: 10.1016/j.ymben.2011.01.004.

[28]       T. Maeda, V. Sanchez-Torres, and T. K. Wood, ‘Hydrogen production by recombinant Escherichia coli strains’, Microb. Biotechnol., vol. 5, no. 2, pp. 214–225, Mar. 2012, doi: 10.1111/j.1751-7915.2011.00282.x.

[29]       Y.-H. P. Zhang, ‘A sweet out-of-the-box solution to the hydrogen economy: is the sugar-powered car science fiction?’, Energy Environ. Sci., vol. 2, no. 3, p. 272, 2009, doi: 10.1039/b818694d.

[30]       J. A. Rollin et al., ‘High-yield hydrogen production from biomass by in vitro metabolic engineering: Mixed sugars coutilization and kinetic modeling’, Proc. Natl. Acad. Sci., vol. 112, no. 16, pp. 4964–4969, Apr. 2015, doi: 10.1073/pnas.1417719112.

[31]       G. A. Bonaci and M. Markus, ‘Synthetic rhinoceros horn analogues’, 2015.

[32]       R. A. Sheldon, ‘Engineering a more sustainable world through catalysis and green chemistry’, J. R. Soc. Interface, vol. 13, no. 116, p. 20160087, Mar. 2016, doi: 10.1098/rsif.2016.0087.

[33]       A. Kate, L. K. Sahu, J. Pandey, M. Mishra, and P. K. Sharma, ‘Green catalysis for chemical transformation: The need for the sustainable development’, Curr. Res. Green Sustain. Chem., vol. 5, p. 100248, 2022, doi: 10.1016/j.crgsc.2021.100248.

[34]       N. Turner, ‘Turner Lab’. https://www.turner-biocatalysis.com/.

[35]       M. Campàs, B. Prieto-Simón, and J.-L. Marty, ‘A review of the use of genetically engineered enzymes in electrochemical biosensors’, Semin. Cell Dev. Biol., vol. 20, no. 1, pp. 3–9, Feb. 2009, doi: 10.1016/j.semcdb.2009.01.009.

[36]       Unilever, ‘Cool ice cream innovations’. https://www.unileverusa.com/brands/innovation/cool-ice-cream-innovations/.