Team:Newcastle/Description
IGEM 2018
Description
Context
Problems With Fertiliser
Description
The Problem
The United Nations estimates global population has increased by 1 billion over 12 years and will near 9.8 billion by 2050 [4]. This increase means that demand has also grown at an unparalleled rate. However, a more pressing issues is that of food security. Food security is defined as one’s ability to have adequate access to sufficient food. Said food must be safe and nutritious as for an individual to maintain a healthy and active lifestyle.
To match demand, the agricultural sector utilises synthetic fertilisers to improve crop growth. Nitrogen, phosphate and potassium (NPK) based fertilisers are used as they provide crops with essential macronutrients required for growth. NPK consumption is predicted to increase to 201.7 million tonnes by the end of 2020 [5].
Synthetic NPK fertilisers significant increases and yield of popular crops such as maize and soybean (3) but they also play a large role in in climate change. Nitrogenous fertilisers are produced by the Haber-Bosch process. This process is highly energy intensive, requiring 600kg of natural gas to produce 1000kg of ammonium, producing 670 million tonnes of CO2 per annum [6].
Repeatedly, studies show fertiliser application has a negative long-term impact on soil health. Synthetic fertilisers cause soil pH to decrease which degrades soil crumbs. This results in compact soil with reduced water drainage and air circulation; both of which have negative impacts on plant-root health [7].
This is not the only local impact of synthetic fertilisers. Accumulation of plant nutrients in bodies of water, resulting from surface run-off, leads to eutrophication. Eutrophication, from Greek meaning ‘well-nourished’, impacts water quality and allows algal blooming [8]. Algal blooming can impact biodiversity through toxin production and promotion of a hypoxic environment[9]
Eutrophication may have a larger humanitarian impact in the future. Eutrophication causes an increase in grey water percentage; the polluted water associated with industry. If grey water is not processed, then clean drinking water availability is reduced. This will likely impact rural areas of less economically developed countries where money and infrastructure is not readily available to cover water processing costs.
Residents are forced to either drink unsafe water or travel further to access water that is safer, however, these oases may become even rarer as water sources become exhausted or contaminated. This issue becomes more concerning when considering that 48% of the total population of Africa relies upon agriculture [10], a continent that experienced a 10.6% increase in total fertiliser demand between 2012 and 2018 [11].
These issues are expected to become more widespread in the future, with the aforementioned population increase and current demands for agriculture produce putting more pressure on farmers to maintain, if not increase, usage of synthetic fertilisers. As such, to overcome risks moving into the future, research into more sustainable nitrogen fertilisers and their substitutes should be pursued.
Description
Solution
An effective solution would overcome both the energy expenditure and pollution associated with inorganic fertilisers but without losing properties such as broad and simple usage. Therefore our solution aims to create a single-application, broad host range sustainable alternative in the form of an engineered root endophyte that acts as a microbial adapter. This endophyte is Pseudomonas sp..
A Gram-negative bacterium with a diverse metabolism, Pseudomonas sp. has been highlighted as a diverse plant growth promoting bacterium [12] capable of colonising a broad range of plant roots [13].
Pseudomonas sp. is known as a natural plant growth promoter for numerous reasons;
- It produces a siderophore that liberates iron [14], consequentially liberating phosphorus too.[15]
- It has anti-fungal properties (protecting from pathogens).[16]
- It is nematophagous and produces nematode/protozoa repellents, protecting from parasites. [17]
- Produces anti-insectal toxins, protecting from pests. [18]
- Induces systemic resistance and tolerance.[19]
With all these features, Pseudomonas sp. is already an ideal organism for improving crop yields, but the Newcastle iGEM project takes this a step further.
By engineering Pseudomonas sp. to express novel genes the team aims to manipulate the soil microbial community via chemical attraction/repulsion to achieve desired processes. In our case this is a nutrient sustaining soil but there are no limits! From soil remediation to pest control, this project aims to create a chassis out of Pseudomonas sp. so future scientists can manipulate the soil community in any way they like.
Our prototype focuses on sustaining the amount of Nitrogen present in soils without adding fertiliser or causing run-off. To combat this, we have introduced flavonoid biosynthesis genes to Pseudomonas sp. that attract free-living/non-nodulating nitrogen fixing bacteria to improve the nitrogen content of the soil [20].
This method means that one application is all that is needed to improve the nutrient availability for a plants life-time. This combined with the other protective roles of Pseudomonas sp. acts to improve crop yields without genetically modifying plants and without Nitrogen/Phosphorus fertilisers. Even if we only reduce fertiliser use by a tiny amount, globally this would make a huge difference in terms of energy usage and pollution.
GROWING IN URBAN SPACES
Advantages of Contained Agriculture
The effects of climate change are becoming more noticeable as time progresses; we are losing staggering amounts of valuable farmland due to mass flooding, freak weather events, soil erosion, infectious diseases and deforestation. Over the next 50 years, farming is going to become even more marginalised [21].
One way of protecting our crops and the land we use for agriculture is by growing within controlled, contained environments. Growing indoors is already a well-established practice; greenhouses are widely used and guarantee a safer, and more predictable method of growing all year round. There are many benefits of applying the contained, controlled environments found in greenhouses into urban spaces, these include:
- Providing cities with fresh produce all year round.
- Reducing the Carbon footprint of crop production due to reduced food millage.
- No agricultural run-off.
- Limited need for pesticides and herbicides.
- Safer crops as there is less risk of contamination.
- Reduced spoilage because of shorter transportation times and reduced handling.
- Less agricultural pollution.
With developing technologies in the field of sustainable energy, it could one day be possible to engineer contained growth systems that are self-sustaining in regards to its energy usage. By carefully controlling the parameters within these environments, we are able to emulate perfect surroundings that allow the crops to grow to their full potential, maximising yield.
Our project plans to use genetically modified bacteria, which means we will be working with GMO’s, but what are GMO’s? - “Genetically modified organisms (GMOs) can be defined as organisms (i.e. plants, animals or microorganisms) in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating and/or natural recombination.”[22]
Integrations of GMO’s into the natural environment pose many concerns to both science and ecological communities. Introducing gm crops into the wild holds the potential to introduce engineered genes into foreign species. The effects of GMO release are widely unidentified, this is the main area of concern as there so many unknowns.
The use of GM bacteria means that we have to take precautions when integrating it into the real world. We have identified the ways to ensure systems are enclosed and risk of GM run-off is minimised on our Safety Page.
Description
REFERENCES
1. Jousset, A., et al. (2009). "Predators promote defence of rhizosphere bacterial populations by selective feeding on non-toxic cheaters." The Isme Journal 3: 666
2. Jousset, A., et al. (2009). "Predators promote defence of rhizosphere bacterial populations by selective feeding on non-toxic cheaters." The Isme Journal 3: 666
3. Vanitha SC & Umesha S (2011) Pseudomonas fluorescens mediated systemic resistance in tomato is driven through an elevated synthesis of defense enzymes. Biologia Plantarum 55(2):317-322.
4. United Nations, Department of Economic and Social Affairs, Population Division (2017) World Population Prospects: The 2017 Revision, Key Findings and Advance Tables. https://population.un.org/wpp/Publications/Files/WPP2017_KeyFindings.pdf
5. Food and Agriculture Organization of the United Nations (2015) World Fertilizer Trends and Outlook to 2018. http://www.fao.org/3/a-i4324e.pdf
6. Usman MN, MG; Musa, I (2015) Effect of Three Levels of NPK Fertilizer on Growth Parameters and Yield of Maize-Soybean Intercrop. International Journal of Scientific and Research Publications 5(9).
7. Pfromm PH (2017) Towards sustainable agriculture: Fossil-free ammonia. Journal of Renewable and Sustainable Energy 9(3):034702.
8. Bitew YA, M (2017) Impact of Crop Production Inputs on Soil Health: A Review. Asian Journal of Plant Sciences 16(3):109-131.
9. Yang X-e, Wu X, Hao H-l, & He Z-l (2008) Mechanisms and assessment of water eutrophication. Journal of Zhejiang University. Science. B 9(3):197-209.
10. Carmichael WW (2001) Health Effects of Toxin-Producing Cyanobacteria: “The CyanoHABs”. Human and Ecological Risk Assessment: An International Journal 7(5):1393-1407.
11. New Partnership for Africa's Development (2013) Agriculture in Africa - Transformation and Outlook. http://www.un.org/en/africa/osaa/pdf/pubs/2013africanagricultures.pdf
12. Food and Agriculture Organization of the United Nations (2017) World Fertilizer Trends and Outlook to 2020. http://www.fao.org/3/a-i6895e.pdf
13. Bergey, D. H., et al. (1984). Bergey's manual of systematic bacteriology. Baltimore, MD, Williams & Wilkins.
14. Gómez-Lama Cabanás C, Schilirò E, Valverde-Corredor A, & Mercado-Blanco J (2014) The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots. Frontiers in Microbiology 5:427.
15. Gross, H. and J. Loper (2009). Genomics of secondary metabolite production by Pseudomonas spp.
16. Sharma SB, Sayyed RZ, Trivedi MH, & Gobi TA (2013) Phosphate solubilizing microbes: sustainable approach for managing phosphorus deficiency in agricultural soils. SpringerPlus 2:587.
17. Ruffner, B., et al. (2013). "Oral insecticidal activity of plant-associated pseudomonads." Environmental Microbiology 15(3): 751-763.
18. Jousset, A., et al. (2009). "Predators promote defence of rhizosphere bacterial populations by selective feeding on non-toxic cheaters." The Isme Journal 3: 666
19. Vanitha SC & Umesha S (2011) Pseudomonas fluorescens mediated systemic resistance in tomato is driven through an elevated synthesis of defense enzymes. Biologia Plantarum 55(2):317-322.
20. Maheshwari DK (2012) Bacteria in Agrobiology: Plant Probiotics (Springer Berlin Heidelberg).
21. Despommier D (2011) The vertical farm: Controlled environment agriculture carried out in tall buildings would create greater food safety and security for large urban populations. J fur Verbraucherschutz und Leb 6(2):233–236.
22.World Health Organization. (2018). Q&A: genetically modified food. [online] Available at: http://www.who.int/foodsafety/areas_work/food-technology/faq-genetically-modified-food/en/ [Accessed 13 Sep. 2018].