Bleaching of coral reefs in tropical/subtropical has long been a global issue leading to the devastation of the marine environment and marine ecosystems. We have found that the survival of corals is strongly associate with viable zooxanthellae living symbiotically within the coral polyps. Healthy coral symbiosis is based on mutualistic relationships among coral, Zooxanthellae, and other symbiont bacteria with nutritional exchange and metabolic interaction to an equilibrium state. When the environmental stress by global climate change appears, this equilibrium will be broken and coral symbiosis is disassociated.
The problem we want to solve:
Bearing in mind that bleached coral reefs need rescue, we seek to find possible solutions with the nutrients or metabolites critical for the health of coral symbiosis. It is our goal to reinstall nutritional equilibrium and metabolic balance for the coral micro-ecosystem under global climate change with a multidisciplinary nutritional enhancement strategy. For this purpose, we prepared ourselves by holding seminars, distributing online surveys, consulting with professionals, writing pop-science articles, analyzing big data, and interacting with different stakeholders. As a result, we realized that the key for the prevention of coral bleaching is not to remain the sea environment unchanged which is impossible, it is, therefore, more feasible to enhance the coral reefs to resist environmental stress. We are excited about the phenomenon told by the staff of the coral institute when we visited them that some coral polyps would escape being bleached, unlike their neighbors. These escaped corals were more energetic and rich of nutrition. We were very surprised and decided to focus our study on the effects of essential nutrients on the robustness of coral symbiosis in the deteriorative marine environment. This way of thinking has led us to design our subsequent experiments.
The solution we proposed:
Through a series of exploration and experiments, we have seen the importance of some nutrients, such as N, P and vitamin B12 (VB12) on the maintenance of healthy coral reefs. In particular, VB12 was found to be a most critical nutrient for the growth of healthy symbiont zooxanthellae. We thus directed our experimental efforts on the improvement of micro ecosystem for the coral symbiosis by supply of sufficient VB12. Production of vitamin B12 in the coral micro-ecoenvironment was made a "smart" probiotic bacterium, Pseudomonas denitrificans. which was modified in a synthetic biology way to enhance its VB12 productivity.
A wonderful idea for the future:
We have achieved a promising result in the lab with the aid of coral-on-a-chip made by microfluidic device which indicate the success of our nutritional enhancement strategy at a single coral polyp level. Here synthetic biology of Pseudomonas denitrificans enabled production of VB12 to sustain a strong growth of Zooxanthellae with elevated temperature, it would in turn support corals to avoid bleaching.
We are optimistic about its real applications in the vast marine environment. In order to move forward along this direction, we have set up a long-term collaboration with Sanya Institute of Coral Ecology on the tropical island, Hainan in China who are working at sea to protect coral reefs. There is a huge number of works to be done to improve our current research and eventually scale it up to the actual marine applications. We are determined to work hard to pursue our dream. Our ultimate goal for this iGEM project is to integrate molecular biology, marine biology, and synthetic biology to save the most beautiful coral reefs, and the tropical marine environment/ecosystem they have created so that our blue planet is sustainable. We imagine that in the future we can produce a large quantity of marine probiotic bacteria for coral nutrition. It can be spread into the marine regions where coral reefs grow, then coral bleaching will vanish, just like the Greek goddess CHLORIS uses her sticker to sprinkle the magic, where she has touched, the spring would come back...
1.Jennifer L. Matthews, Jean-Baptiste Raina, Tim Kahlke, Justin R. Seymour Madeleine J. H. van Oppen, and David J. Suggett; Symbiodiniaceae-bacteria interactions: rethinking metabolite exchange in reef-building corals as multi- partner metabolic networks