Project description

Abstract / Overview

Microcystis aeruginosa is one of the most common cyanobacteria responsible for harmful algal blooms. This cyanobacterium produces microcystin, a hepatotoxin that damages the liver. However, direct lysis of Microcystis aeruginosa may not best for the environment as it holds ecological values of heavy metal sorption and oxygen synthesis. In this project, we hope to silence the microcystin biosynthesis cluster(mcy) using a catalytically dead Cas9 (dCas9) enzyme lacking endonuclease activity. When the dCas9 enzyme is co-expressed with a guide RNA(sgRNA), the dCas9-sgRNA complex specifically binds to the McyB gene and blocks transcript elongation, leading to the repression of the McyB gene without altering the chromosome of the Microcystis. Here we provide the design of a dCas9-sgRNA expression gene in a shuttle vector that can replicate in both E.coli and cyanobacteria. We will also be conducting downstream analysis to see how our dCas9-sgRNA expression plasmid affects the microcystin-production rate and oxygen synthesis rate of Microcystis.

Project Inspiration

Our project is inspired from various aspects, including school lessons, books, news articles hiking trips, and even previous iGEM teams.

1. School lessons:

   Chemistry: We’ve learnt that certain species of cyanobacteria is capable of nitrogen fixation. We understand the ecological importance of nitrogen fixation. Microcystis aeruginosa can carry out metal sorption. However, they also produce neurotoxins and hepatotoxins, microcystin. These cyclic heptapeptides can cause lethal consequences.

   Chemical structure of Microcystin-LR
   

Biology: We have learnt the cellular structure of cyanobacteria. From teachers and text books, we have had a brief understanding in how photosynthesis is carried out in cyanobacteria. More than half of the world’s oxygen is produced via phytoplankton (including cyanobacteria). On the contrary, we are aware that the bloom of cyanobacteria will blocked sunlight and slow down the photosynthesis rate of other water plants. Certain cyanobacteria (including Microcystis) may even produce toxins that inhibit certain enzymes in animals.

Geography: Through studies in soil and water sources, we learnt how excessive use of fertilizers create eutrophic waters, which gives rise to cyanobacterial blooms. Teachers also taught us how global warming raises the temperature, which favours the rapid growth of cyanobacteria (especially Microcystis Aeruginosa).

1. News Articles

   Cyanobacterial bloom has always been a global concern. Countries from all around the world, especially countries with agricultural industries. New articles from around the world have shown economic losses and environmental damages caused by algal blooms. Severe cases of blue-green algal blooms resulted in the contamination of fresh water sources. Recreational activities in nearby areas have to be banned. Inspired by these articles, we hope to solve the problem of the accumulation of toxic substances produced by harmful algal blooms.

   United Kingdom

   China

   Texas, US

   Laowa, US

   Lake Erie

   Canda

2. Trips

T-PARK

We visited T-PARK, at Tuen Mun Hong Kong, near Deep Bay. This picture is taken facing Shen Zhen. Oyster fisheries are common there. As seen from the photo, certain areas were found to be green. We were unsure whether the green patches are algae or not, and decided to conduct further investigation.

iv: Hiking

Some team members discovered unusual green patches, which were thought to be algae. We were interested in knowing how these organisms impact our daily lives. As we dwell into this topic, we realized that cyanobacteria can bring both benefits and disadvantages to the ecological system. Therefore, we decided to design a project that minimizes the harms that cyanobacteria may bring.