About This Project

Dr. Bonnie Bassler at Princeton University explains how quorum sensing works, far better than I ever could. Click Here!

Ask the Scientists

What is the context of this research?

The main research goal is to structurally identify the compounds that are secreted by Chlamydomonas reinhardtii, a photosynthetic, non-pathogenic, motile green algae, that is known to secrete compounds that mimic and interfere with bacterial quorum sensing in Pseudomonas aeruginosa. Quorum sensing is best described by Dr. Bonnie Bassler from Princeton University as shown here.

What is the significance of this project?

P. aeruginosa (the cause many illnesses as shown here),causes deadly lung infections in immunocompromised individuals, mainly the elderly. Mortality rates as high as 87% are known to exist, even in developed countries, and the quorum sensing pathway helps the bacteria form biofilms, resist antibiotics, and secrete chemicals that are cytotoxic and destroy the body's defenses. Quorum sensing is essentially how bacteria "talk" to one another. This is done be releasing small compounds, known as autoinducers that are fairly species specific. Surrounding bacteria detect these autoinducers, and as a community gene expression is altered. Autoinducers help transcribe genes that are necessary for the formation of biofilms, which help protect the bacteria from antibiotics, and for the production of other products. C. reinhardtii extract has been shown to not only turn on quorum sensing in P. aeruginosa, but it also has the ability to block it. By blocking the quorum sensing pathway in P.aeruginosa, it is thought that communication within the bacterial population would fail, leading to the success of antibiotic therapy. Information obtained by isolating and structurally identifying the compounds that are secreted by C. reinhardtii would aid in the development of products that could be used with antibiotic therapy, if not the compounds themselves.

What are the goals of the project?

Currently I have duplicated results showing that C. reinhardtii does in fact secrete quorum sensing like compounds. Since large amounts of algae need to be grown to isolate a very small amount of extract (20L of algae in liquid culture yields about 2mL of extract), the funds would allow me to purchase products needed for media, glass carboys to grow the algae in, and other items needed for culturing. To obtain the extract, the supernatant of centrifuged cells must be extracted in ethyl acetate and then separated via a separatory funnel. Funds would help pay for any necessary reagents, mainly ethyl acetate and methanol (explained later). TLC plating is used to primitively separate the extract, which is then assayed via GC/MS. Funds would help purchase items needed for TLC plating. Once quorum sensing like compounds have been detected via GC/MS, HPLC will be used to further purify the extract into small fractions. Funds would help pay for HPLC columns and reagents, mainly methanol. Funds will also help pay for any other processes that cannot be carried out at my university and must be contracted out, such as LC/MS and chemical spray-ionization/MS. If successfully funded, funds would be used to buy equipment that would help me increase the amount of algae that can be grown at one time (i.e. orbital shakers, light set-ups, ventilation equipment). Funds would also pay for trips to conferences so that I may present my research.