Synthetic Mutualism and the Intervention Dilemma

Abstract

Ecosystems are complex networks of interacting individuals co-evolving with their environment. As such, changes to an interaction can influence the whole ecosystem. However, to predict the outcome of these changes, considerable understanding of processes driving the system is required. Synthetic biology provides powerful tools to aid this understanding, but these developments also allow us to change specific interactions. Of particular interest is the ecological importance of mutualism, a subset of cooperative interactions. Mutualism occurs when individuals of different species provide a reciprocal fitness benefit. We review available experimental techniques of synthetic biology focused on engineered synthetic mutualistic systems. Components of these systems have defined interactions that can be altered to model naturally occurring relationships. Integrations between experimental systems and theoretical models, each informing the use or development of the other, allow predictions to be made about the nature of complex relationships. The predictions range from stability of microbial communities in extreme environments to the collapse of ecosystems due to dangerous levels of human intervention. With such caveats, we evaluate the promise of synthetic biology from the perspective of ethics and laws regarding biological alterations, whether on Earth or beyond. Just because we are able to change something, should we?

Synthetic Symbiosis under Environmental Disturbances

“…Since mutualisms bind organisms together to enhance their survival, they come at the cost of binding the fates of all involved species together (45). Changing the environment inadvertently or purposefully via anthropogenic activity and climate change can be costly not just to one set of species but to the ecosystem at large (20). Beyond conservation biology, mutualistic interactions also lie at the heart of translational biology, affecting applied human health and biotechnology (46).…”

“…Complex population dynamics in response to temporal, spatial, and environmental factors can be dissected by fine-tuning and manipulating these synthetic systems (18,19). Numerous synthetic systems developed are especially mutualistic in their interaction pattern (20). We use Saccharomyces cerevisiae synthetic mutualistic systems that rely on cross-feeding of metabolites between two strains (15) as a simple model to reflect the mathematical theory developed in the following sections.…”

Uneven declines between corals and cryptobenthic fish symbionts from multiple disturbances

“…Whether organisms persist in the short-term during extreme consecutive disturbances will determine their recovery potential and those of associated organisms (6)(7)(8). We need to understand whether ecological relationships are resilient to consecutive disturbances in order to better align future strategies for ecosystem conservation (6,9).…”

“…One such ecological relationship that may prove fragile from consecutive disturbances is mutualism, which occurs in many taxa (6,9). Mutual symbioses are observed in all environments and even promote life in otherwise inhospitable areas (9).…”

“…One such ecological relationship that may prove fragile from consecutive disturbances is mutualism, which occurs in many taxa (6,9). Mutual symbioses are observed in all environments and even promote life in otherwise inhospitable areas (9). A small shift in environmental conditions may change the nature of such relationships, like mutualism becoming parasitism, or relationships ceasing if one symbiont becomes locally threatened (6).…”