Living together: Microbial communities are more than the sum of their parts

Newswise — Microbial communities serve as crucial biotechnology suppliers, supporting processes like biofuel production, food innovation, and enhanced crop growth. The success of engineered communities hinges on predicting the compatibility and cooperation of microorganisms. A widely accepted rule suggests that if two microbes can coexist, they should also thrive in larger microbial communities. However, recent research published in Science challenges this notion, revealing that the rule doesn't always hold true.

Similar to plants and animals, microorganisms form intricate ecological communities comprising multiple species that coexist harmoniously. These communities are widespread across the globe and play a pivotal role in biotechnology advancements. They are intentionally designed for various applications, such as biofuel production, biorefineries, novel food creation, and agricultural enhancement. Consequently, an important objective in biotechnology is to master the art of engineering these microbial communities to optimize the benefits they offer.

However, a significant challenge lies in the fact that not all microorganisms can coexist within these communities. Even when a microbial community is thoughtfully designed and exhibits high potential, it's likely that certain members will eventually face extinction. As a result, scientists are now exploring approaches to predict whether different species can indeed coexist in harmony.

One of the intriguing puzzles scientists are trying to unravel is the incredible diversity observed in bacterial communities. How can such a multitude of species manage to coexist within the same community? Djordje Bajić, an Assistant Professor in Industrial Microbiology at Delft University of Technology, sums up this endeavor by expressing their efforts to comprehend this astonishing diversity and its implications for bacterial communities.

A simple rule

A collaborative research effort involving the University of Pennsylvania, Centro Nacional de Biotecnología of the Spanish National Research Council, Delft University of Technology, and Yale University aimed to understand how bacterial coexistence functions within complex communities. The study, led by Chang et al., focused on examining a widely discussed hypothesis stating that for multiple species (let's call them A, B, and C) to coexist as a community, each pair of species must also coexist independently. For instance, A must coexist with B, B with C, and C with A. This hypothesis gained traction due to its simplicity and potential to predict coexistence in intricate microbial communities.

To put the hypothesis to the test, the researchers dismantled twelve different microbial communities comprising three to ten coexisting species. They then observed and assessed the coexistence of all possible pairs of microorganisms. Surprisingly, contrary to the hypothesis, most of the pairs failed to coexist independently. In essence, the study's findings indicated that the simple predictive rule for coexistence may not hold true in all cases, implying that the dynamics of coexistence within these communities are more complex and nuanced than previously thought. In such scenarios, the whole community appears to be more than just the sum of its individual parts.

New predictive tools

Chang's research paper underscores the challenging task of predicting which microbes can coexist, highlighting the pressing need for developing new predictive tools. While this might be perceived as discouraging news, it actually represents a significant advancement by establishing that within microbial communities, the whole exhibits far more complexity than the mere sum of its individual parts. This insight will be instrumental in constructing innovative models that can ultimately facilitate the engineering of microbial communities.

Djordje Bajić, Assistant Professor in Industrial Microbiology, emphasizes the pursuit of understanding the remarkable diversity observed in bacterial communities. The question of how such a multitude of species manage to coexist within the same community remains a compelling mystery. Unraveling the mechanisms of bacterial coexistence holds paramount importance as microbial communities inhabit nearly every surface on our planet. Bajić explains that these communities play crucial roles in global element cycling and profoundly influence the health of our own gut microbiome.

The study's impact extends beyond scientific curiosity, with potential implications in numerous practical applications. It will serve as a foundation for developing models and technologies aimed at designing microbiomes and guiding existing ones toward desired states. Such applications span various fields, including healthcare, wastewater treatment, and the production of sustainable biopesticides and biofertilizers based on microbes. In essence, this research will significantly contribute to our understanding of microbial communities and their role in shaping the broader microbiome landscape.

The party of the bacteria

Imagine you're attending a lively party, and you naturally get along well with many guests, but there are also a few individuals you don't particularly like. Conventionally, it's believed that to have a good time at the party, you must enjoy the company of every single person there. However, this study challenges that notion. Just like at the party, in microbial communities, the traditional idea was that every species must coexist harmoniously for the community to thrive. But, as we now know, that's not always the case.

At the party, you can choose to interact mainly with the people you like, ignoring those you don't feel a connection with. Alternatively, you might engage in conversations with those less preferred individuals if others you enjoy are also part of the discussion. The key is that the collective dynamics and interactions with different groups of people shape your overall experience. Similarly, in microbial communities, the coexistence of species isn't solely determined by individual interactions but is influenced by the complex network of relationships and interdependencies among the microorganisms.

In essence, this study reminds us that the success of a party or a microbial community doesn't hinge on everyone getting along perfectly. Rather, it's the interactions, connections, and interplay between different groups that contribute to the overall harmony and positive outcomes. So, just like at a party, a thriving microbial community can be a dynamic and diverse environment where the whole is more than the sum of its parts.