# Resource diversity and supply drive colonization resistance

## TL;DR

This study explores how resource diversity and supply affect the ability of microbial communities to resist invasion by pathogens.

## Contribution

The paper introduces a computational model to show how environmental resources shape colonization resistance in microbial communities.

## Key findings

- Colonization resistance is negatively correlated with resource supply and diversity, except under limited resource supply.
- Cross-feeding weakens colonization resistance by increasing resource diversity, but this effect disappears with limited resources.
- The richness-resistance relationship is non-monotonic and influenced by environmental characteristics.

## Abstract

The human microbiota plays a key role in resisting the colonization of pathogenic microbes, a process known as colonization resistance. However, there is a need to better understand the mechanisms by which colonization of invaders is blocked. Environmental resource supply and resource diversity are essential factors in forming these communities but testing how the environment affects resistance in natural communities is challenging. Here we use a consumer-resource model and computational invasion simulations to investigate how environmental resource diversity and supply affect the richness-resistance relationship, overall colonization resistance, and cross-feeding dynamics. We find a non-monotonic trend between species richness and resistance, shaped by environmental characteristics. Our results show that colonization resistance is negatively correlated with both resource supply and resource diversity except when resource supply is limited. Lastly, we observe that cross-feeding weakens colonization resistance by increasing the diversity of available resources, but this trend disappears with limited resource supply. This work provides insights about colonization resistance in microbial communities of consumers, resources, and resource conversion and exchange.

Resident microbial communities, such as those inhabiting different parts of our body, can resist colonization by other microbes, a property called colonization resistance. Colonization resistance is important for protecting us from pathogens, bringing up the need to better understand the mechanisms that affect it. Here we use a consumer-resource model to investigate how resources supplied in the environment can influence invasion outcomes including colonization resistance. We implement a computational invasion assay and simulate many instances of resident communities encountering invaders to infer how different parameters such as the supply of resources or exchange of metabolites between species affect colonization resistance. We find that colonization resistance is negatively correlated with both resource supply and resource diversity, except when resource supply is limited. We also show that cross-feeding between species weakens colonization resistance by increasing the diversity of available resources, but this trend disappears with limited resource supply. Collectively, our work highlights the impact of resources in shaping colonization resistance, offering useful insights that can guide future efforts to control colonization resistance.