Team:HK SSC/Description

Microcystis aeruginosa is one of the highly deleterious freshwater cyanobacteria; it is well-known for causing harmful algae blooms in rivers and lakes. These algae blooms produce a large number of microcystins and neurotoxins, which potentially leads to death of fish and human as well as contamination of fresh water. However, M. aeruginosa also poses ecological value in oxygen synthesis and absorption in heavy metal.

We can see how these cyanobacteria have such a significant impact on the aquatic system which could subject to adverse impacts on the aquatic ecosystem as a whole. Take Lake Taihu as an example; the algae blooms are a serious threat to drinking water supplies and agriculture supplies. Chinese ecologists and marine biologists describe the lake as the smell of decaying fish. In the United States, such harmful cyanobacterial algae blooms have inflicted around 2 billion USD a year in losses as the water is unfit for drinking, recreation and agriculture.

Through investigation on the cause of algae blooms, we found out that farmland and factories are usually built next to rivers and lakes, as water is vital for both agriculture and industrial uses. Since chemical fertilizers and sewage all contain nitrates and phosphates, this catalyzes the reproduction of cyanobacteria such as Microcystis Aeruginosa. However, we realized that limiting the use of fertilizers and the amount of sewage released from factories are impractical because this would affect the efficiency of production.

Therefore, instead of limiting the use of such fertilizers, our project not only aims to mutate M. aeruginosa through modifying its toxin-producing gene but also aims to characterize the cyanobacteria’s ability to absorb heavy metal. Dcas9 is transformed into and co-expressed in the toxin-producing gene in Microcystis aeruginosa. As dcas9 serves the purpose to block transcription, the transcription of the toxin-producing gene cannot be carried out. Hence the toxin-producing ability of M. aeruginosa is eliminated.

Bibliography:

https://e360.yale.edu/features/on_lake_taihu_china_moves_to_battle_massive_algae_blooms

https://link.springer.com/article/10.1007/s11783-008-0062-4

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3229228/

https://www.ncbi.nlm.nih.gov/pubmed/15533019

https://www.ncbi.nlm.nih.gov/pubmed/28862419

Forastier, Marina Elizabet, et al. “Occurrence and Toxicity of Microcystis Aeruginosa (Cyanobacteria) in the Paraná River, Downstream of the Yacyretá Dam (Argentina).” Revista De Biologia Tropical, U.S. National Library of Medicine, Mar. 2016, www.ncbi.nlm.nih.gov/pubmed/28862419. Accessed 21 May 2019.