Team:BUCT-China/Description

Description

Description

Engineering 

Microbulbifer hydrolyticus 

for plastic

      degradation and value-added products

Abstract

Plastics are widely used in industry and households because of their low-weight, durability and low-production cost. Nowadays, the consumption of plastics has risen sharply. However, the lack of effective waste plastics management poses a major threat to the environment. For the past few years, new technology about biodegradation of plastics has been a hot spot. Polyethylene (PE) and polystyrene (PS) are the most important mass-produced plastics, which are difficult to be degraded by the microorganism. Recently, we observed a strain Microbulbifer hydrolyticus , which has the ability to degrade PE and PS. In this study, we would try to investigate the mechanism of PE biodegradation, and find the key enzymes. Meanwhile, based on the genome sequencing and synthetic biology, we aim to construct an artificial metabolic pathway, engineering this strain to enhance the ability to plastics biodegrading. Furthermore, the strain could utilize plastics to synthetic value-added products, such as PHA, etc.


Inspiration

Environmental issues cannot be ignored, so many topics on plastic degradation are being studied. In our surroundings, we could see many plastic garbage, and some abandoned plastic garbage seems to have been degraded by nature.In fact a large part of which becomes micro-plastics in ocean and land,then entering the animal’s body through the food chain even our human beings. Because those tiny plastic is really difficult to be collected,so there is currently no good way to deal with these micro-plastic whether using chemical or physical methods,and it has become an urgent part of the problem of plastic pollution. Besides,though many plastics can be degraded and recycled, but it is estimated that roughly 50% plastic will be buried in the land rather deal with them. So it has a large space to improve them in this area. Such as PE can also be degraded into CO2 but its hard to be reused.So recycle is indeed a big problem. Based on the above two issues:collect and recycle, we try to use microbes to find more effective methods. So we are trying to do something on PE in order to contribute a little to our environment, which have profound realistic meaning.


Advantage and disadvantage of plastics

Plastics are widely used in industrial and household applications because of their low weight, durability and low production cost (Andradeeey, 2015). The widespread use of plastics, the lack of waste management and casual social behavior render the production rate is much faster than the degradation rate which poses a major threat to the environment (Leja and Lewandowicz, 2010).

Plastics are hardly to be degraded

Most commonly used plastics are synthetic polymers obtained from petrochemical hydrocarbons and derivatives (Geyer et al., 2017). Polyethylene (PE) and polystyrene (PS) are amongst the most important mass-produced plastics and largely manufactured into short-life products including packaging materials for food and disposable dishware (2018). PE and PS are very stable polymers and notably resistant to biodegradation (Ho et al., 2017).

The recycling of plastic is a bigger problem

Actually almost all the plastic could be degraded by some method but how to recycle and reuse them is a serious problem, it is estimated that roughly 50% plastic will be buried in the land rather deal with them so it has a large space to improve them in this area.

Biodegradation is the future

Shimpi et al. reported the biodegradation of 

modified 

PS 

by 

using 

a pure 

strain of 

Pseudomonas 

aeruginosa 

(Shimpi 

et al., 

2012). 

Motta 

et al. 

used 

the 

Curvularia 

species 

to 

investigate 

the 

degradation 

of 

atactic 

PS. 

These 

results 

suggested 

that 

the 

biodegradation 

of PS 

material 

through 

using 

selected 

microbial 

strains 

might 

become a 

feasible 

solution 

for 

reducing 

the 

huge 

amount 

of 

waste 

and 

disposed 

plastics 

(Motta 

et 

al., 

2009).

What we can do

In our lab we also observed a strain 

Microbulbifer 

hydrolyticus 

is 

able 

to 

degrade 

PE. 

The 

strain 

was 

already 

sequenced. 

Based 

on 

the 

genome 

sequence 

and 

synthetic 

biology, we 

aim 

to 

construct 

artificial 

metabolic 

pathway, 

engineering 

this 

strain 

in 

order 

to 

enhance 

the 

ability 

for 

degrading 

plastics; 

furthermore, 

the 

strain could 

utilize 

plastics 

to 

synthesis 

value-added 

products, 

such 

as 

PHA, 

etc..

References

[1]Andrady, A. L. (2015). Plastic Products: Plastics and Environmental Sustainability.Hoboken, NJ: John Wiley & Sons, 83–119. doi: 10.1002/9781119009405.ch4

[2]Leja, K., and Lewandowicz, G. (2010). Polymer biodegradation and biodegradablepolymers - a review. Pol. J. Environ. Stud. 19, 255–266.

[3]Geyer, R., Jambeck, J. R., and Law, K. L. (2017). Production, use, and fate of allplastics ever made. Sci. Adv. 3:e1700782. doi: 10.1126/sciadv.1700782

[4]Ho, B. T., Roberts, T. K., and Lucas, S. (2017). An overview on biodegradationof polystyrene and modified polystyrene: the microbial approach. Crit. Rev.Biotechnol. 38, 1–13. doi: 10.1080/07388551.2017.1355293

[5]Plastics Europe (2018). Plastics – the Facts 2018. Available at: www.plasticseurope.org retrieved in 2018.

[6]Shimpi, N., Mishra, S., and Kadam, M. (2012). Biodegradation of polystyrene(PS)-poly(lactic acid) (PLA) nanocomposites using Pseudomonas aeruginosa.Macromol. Res. 20, 181–187. doi: 10.1007/s13233-012-0026- 1

[7]Motta, O., Proto, A., De, C. F., De, C. F., Santoro, E., Brunetti, L., et al. (2009).Utilization of chemically oxidized polystyrene as co-substrate by filamentousfungi. Int. J. Hyg. Environ. Health 212, 61–66. doi: 10.1016/j.ijheh.2007.09.014