Three "E"s of Bioethics analysis: Environment, Efficiency, Economic

1. Environment impact

(1) Drawbacks of traditional Nitrogen fertilizer

Nitrogen fertilizer is the chief culprit of eutrophication, which will cause algal bloom, loss of oxygen, loss of biodiversity. (Lassaletta et al, 2010 & Mian et al, 2009)

Some of the unabsorbed chemical nitrogen fertilizer runs off because of rainfall and irrigation in the form of compound, but most of them runs off in the form of soluble salt, such as NH₄⁺,NO₃^— or volatilizes in the air and drops back to land with rainfall . (Bouwman et al, 2001 & Pan, 2009) In China, less than half of the fertilizer N applied was taken up by crops Zhang et al (2008) and Ti et al (2011) reported that Chemical fertilizer accounts for 56.3% of N input and in oil rape (such as soybean , including peanut) field, but 4.35 % leaches, 3.19% Runs off and 5.5% volatilizes.

All of these ways will disturb the hydrosphere and cause underground water pollution and surface water eutrophication. (Huang et al, 2009)

In China, stream total N concentration has been increasing since 1980s. (Yang et al, 1999). According to Xu’s (2014) research on total nitrogen concentrations in surface water of typical Agro- and forest-ecosystem in China between 2004 and 2009, the median total N concentrations of still surface water were significantly higher in the agro-(1.5mg•L^-1) and oasis agro-ecosystem (1.8mg•L^-1) than in the forest ecosystems (1.0mg•L^-1). This was also the case for flowing surface water, with total N concentrations of 2.4 mg•L^-1,1.8 mg•L^-1 and 0.5mg•L^-1 for the agro-, oasis agro- and forest-ecosystem respectively and unpolluted water must with N lower than 1.0mg•L^-1.

Nitrogen pollution has become a wide problem in China. If the usage of Nitrogen fertilizer is not reduced, other solutions will never solve it fundamentally. More and more algae bloom will appear again and again.

Fig.1 Nitrogen concentration in different types of soil in China. Human agriculture has caused great increase of Nitrogen.

Fig. 2 Places surveyed byYang (2014) This picture shows the places (icons) that Yang et al surveyed between 2004 to 2009.

References

Bouwman, A., Boumans, L. & Batjes, N. (2002) Estimation of global NH3 volatilization loss from synthetic fertilizers and animal manure applied to arable lands and grasslands. Global Biogeochemical Cycles, 16: 801-814.

Huang, D. F. , Wang, G. , Li, W. H. (2009) Present status, mechanisms，and control techniques of nitrogen and phosphorus non-point source pollution from vegetable fields．Chinese Journal of Applied Ecology, 20 ( 4) : 991-1001.

Huang, D. F. , Wang, G. , Li, W. H. (2009) Effects of different fertilization modes on vegetable growth, fertilizer nitrogen utilization and nitrogen loss from vegetable field. Chinese Journal of Applied Ecology, 20(3): 631-638.

Lassaletta, L., Garcia, H., Gimeno, B.S. & Rovira, J.V. (2009) Agriculture-induced increase in nitrate concentrations in stream waters of a large Mediterranean catchment over 25 years (1981–2005). Science of the Total Environment, 407(23): 6034–6043.

Mian, I.A., Begum, S.M., Ridealg, M., McClean, C.J. & Cresser, M.S. (2010) Spatial and temporal trends in nitrate concentration in the river Derwent, North Yorkshire and its need for NVZ status. Science of the Total Environment, 408(4):702–712.

Ti, C.P., Xia, Y.Q., Pan, J.J., Gu,G.M., & Yan, X.Y. (2011) Nutrient Cycling in Agroecosystems, 91(1):55-66.

Xu, Z., Zhang, X., Xie, J., Yuan, G., Tang, X., et al. (2014) Total nitrogen concentrations in surface water of typical agro- and forest-ecosystem in China, 2004-2009. PLoS ONE, 9(3):1-7.

Yang, A.L. & Zhu, Y.M. (1999) Study on nonpoint source pollution in surface water environment. Advance of Environmental Sciences, 7(5):60–67.

Zhang, F. S., Wang, Y.Q., Zhang, W.F., Cui, Z.L., Ma, W.Q., et al. (2008) Nutrient use efficiencies of major cereal crops in China and measures for improvement. Acta Pedologica Sinica, 45(5): 915–924.

(2) Drawbacks of Traditional Molybdenum fertilizer

In order to decrease nitrogen fertilizer’s usage, molybdenum fertilizer is commonly applied in cereal plants fields, because molybdenum is a microelement that in both important for azotobacter and cereal plants and the mechanism is discussed in the introduction part.

The Application of molybdenum is usually in two ways. The first way is seed dressing and the second is plant spraying. Liu (1987) did research in Xinxiang about the application of molybdenum fertilizer ((NH₄)₂MoO₄).

• Method 1: no application of (NH₄)₂MoO₄.
• Method 2: put the peanut seeds in 0.1% (NH₄)₂MoO₄ solution for 12 hours before planting
• Method 3: dip the peanut seeds in 0.5% (NH₄)₂MoO₄ solution for a short time
• Method 4: spray 0.1% (NH₄)₂MoO₄ on plants when they flowers
• Method 5: method 2 and method 4
• Method 6: method 3 and method 4

The application of molybdenum fertilizer and productin increase researcher in Xinxiang(Liu, 1987)

It is easy to find that method 5 can obtain the highest yield. The phenomenon reveals that Mo is of great importance during both germination and growing period, but too much Mo will not increase the production, even reduce it.

For the maximum production, proper amount of Mo is essential. Traditional way is hard to control molybdenum concentration near peanut roots, because there are many factors effecting the concentration of molybdenum fertilizer around peanut roots, such as rainfall, the condition of peanut roots.

Traditional way may also waste molybdenum, because molybdenum near roots is easily absorbed by roots or transported into nitrogen-fixing bacteria. However, further molybdenum will not initiatively get close to roots. Although there is no exact experimental figure about that, our model may reveal the low efficiency of it.

Traditional way may even cause heavy mental pollution.

The national upper-level threshold standard of Mo is 0.005mg/L in water and 2.0 mg/kg in soil. (Zhang, 2012) The usual molybdenum spraying process is as follows according to Gao & Dong (1998). During the seeding stage and early blossom stage, 30~35 kg 0.3% (NH₄)₂MoO₄ per mu (666.67 square meters) will be spray to the leaves for 2~3 times. During flowering stage, 50~70 kg 0.3% (NH₄)₂MoO₄ per mu (666.67 square meters) will be sprayed to the leaves for 2~3 times. If it rains or winds heavily in the future 24 hours, the same process should be done again. Only in spraying process, even if not affected by rainfall, every square meter may receive 710mg Mo. If it rains, the amount may receive 1000mg. If the dressing process is also calculated, the amount of Molybdenum may still be more and fertilizing year by year will finally pollute water and soil.

References

Gao, Z. Q. & Dong., J. F. (1998) Molybdenum application and effects on peanuts [花生钼肥施用效果与技术]. Henan Science and Technology, 3:13.

Liu, Y., Wang, G. D. & Ma, L. X. (1987) The effects of molybdenum fertilizer on peanuts [花生施用钼肥增产效果的研究河南农业科学]. Journal of Henan, 4: 14.

Zhao, Y. X. (2012) The Backeground values of heavy metal in the environmental an food chain in western Henan province. Henan University of Science and Technology, master thesis.

Three "E"s of Bioethics analysis: Environment, Efficiency, Economic

2. Efficiency as a fertilizer

E.Coli cells are about 2.0 μm long and 0.25–1.0 μm in diameter, Escherichia coli and Salmonella typhimurium: Cellular and Molecular Biology with a cell volume of 0.6–0.7 μm₃ The periplasmic space constitutes up to 40% of the total cell volume (Wekipedia, 2014). The normal concentration of binding protein in the periplasmic space is estimated as 35 mg/ml [1]. Nearly 20% binding protein in the periplasmic space is INP protein. Since ModA is linked to INPN, we assume that ModA and INP have similar concentration. The concentration is 4.032 * 10-12 mg/cell.

c(ModA per cell) = V_cell * 40% *C(binding protein in periplasmic space) * 20% = 0.6 μm³ * 40% * 35 mg/ml *20% = 4.032 * 10^-12 mg/cell

The moderate amount of molybdenum per kilogram dry soil is 1.844 mg/kg(Liu, 2005). According to our computer simulation test, about 20% engineering bacteria are supposed to reach the root system successfully according to our Model. We assume that the efficiency of molybdenum fertilizer increases 120% if “Prometheus” is used. Therefore, only 1.537 mg molybdenum is needed per kilogram dry soil.

The bacteria concentration in OD600 =1 bacteria liquid is about 109. Only 381ml bacteria liquid is needed per kilogram dry soil (see formula 2).

Vbacteria liquid = (1.537 mg/kg) / (4.032 * 10^-12 mg/cell) / 10⁹(cell/ml) = 381 ml/kg

References

Liu, P., Wu, J.Z., & Yang, Y. A. (2005). Mo & B supplication and sorption of soybean [钼、硼供给水平对大豆钼、硼吸收与分配的影响]. Journal of Zhejiang University, 31(4):399-407.

Wikipedia. (2014) Retrieved, 2014, October 17th from http://en.wikipedia.org/wiki/Escherichia_coli

Wikipedia. (2014) Retrieved, 2014, October 17th from http://en.wikipedia.org/wiki/Periplasmic_space

Three "E"s of Bioethics analysis: Environment, Efficiency, Economic

3. Economic potential

During the hot summer of July, BNU iGEM team went to Gaomi, Shandong Province. This place is the hometown of Moyan, China’s first Nobel Literature Prize winner. He is famous for whiting the stories in rural China and his hometown is in peanut agriculture zone. We visited the peanut bean field and talked with the local farmers about peanut planting.

On August 1st, 2014, we went to Gaomin and interviewed four farmers and 3 fertilizer & pesticide sellers. According to Miss Deng, when they sow the peanuts seeds, they will use fertilizer and pesticides together. The fertilizer will give peanuts enough nutrition and the pesticides will be kept from rot.

The price of nitrogen fertilizer is about 100 yuan per 100 jin ($32.68 dollars per 100kg). However, potash fertilizer should also be applied. The price of it is 250 yuan per 50 jin ($163.40 per 100kg). For every mu (666.67 square meters), 200 jin (100kg) nitrogen fertilizer, 50 jin (25kg) potash fertilizer and 150 yuan pesticide should be used. When autumn is near, they can harvest peanut kernel 300~400 jin (150~200kg) every mu according to weather condition. The price of peanut kernel is 3.5~4.5 yuan per jin (1.14~1.48 dollar per kilogram). There is agriculture tax in China. After a year work, they will earn 1000 yuan per mu ($245.35 dollars per thousand square meters).

Other farmers represented by Mr Dai and Miss Wang reported that richer families (three or four people in a family) usually have 10 mu (6666 square meters), while some poorer families only have 5 to 6 mu.

Pesticides & fertilizer sellers reported similar questions and one of them told us compound fertilizer would make farming easier. However, they told us that peanut and paddy field usually needed only a litter fertilizer, but the real condition is that if fertilizer is not applied, crop failure is unavoidable.

We think that our E.Coli Prometheus can reduce the usage of nitrogen fertilizer and if designing properly, we can also even bind potassium with it. As we can fertilize directly, potassium will not be wasted, even cause water bloom as normal fertilizers.

The Story of E.coli Prometheus

BNU-China