Environment-mediated interactions cause an externalized and collective memory in microbes

Microbes typically live in complex communities, interacting with numerous other microbial species. These interactions determine who can persist in a community and how the overall community forms and functions. Microbes often exert interactions by chemically changing the environment, like taking up nutrients or producing toxins. These environmental changes can persist over time. We demonstrate here that such lasting environmental changes can induce a “memory effect,” where current growth conditions influence interaction outcomes in the future. This memory is only stored in the environment and not inside bacterial cells. Only the collective effort of many bacteria can build up this memory, making it an emergent property of bacterial populations. This externalized and collective memory can also impact the assembly of more complex communities and lead to different final compositions depending on the system's past. Overall, we show that to understand interaction outcomes fully, we not only h..., , # Environment-mediated interactions cause an externalized and collective memory in microbes

Dataset DOI: [10.5061/dryad.ksn02v7hp](10.5061/dryad.ksn02v7hp)

## Description of the data and file structure

-> CFU/mL data with 1/2x or 1/100x along with species corresponds to mildly-diluted co-culture or Highly-diluted co-culture, respectively.

-> The term Ca 35 corresponds to *Corynebacterium ammoniagenes* grown in preferred conditions, i.e., at 35degreesCelsiusus and oxic conditions, while Lp 18 refers to Lactobacillus plantarum grown in unpreferred conditions, i.e, at 18 degrees Celsius and oxic conditions.

-> In the community's composition data, species codes correspond to the following species:

1\. 4: *Bacillus toyonensis (Bt)*

2\. 6: *Bacillus flexus(Bf)*

3\. 27: *Rouxiella badensis (Rb)*

4\. 66: *Pseudomonas veronii (Pv)*

5\. 79: *Pseudomonas protegens (Pp)*

6\. 81: *Sphingobacterium multivorum (Sm)*

7\. 107: *Rhodococcus qingshengii (Rq)*

8\. Myb27: *Arthrobacter nitrogua...,