KEY RESOURCES TABLE.

REAGENT or RESOURCE	SOURCE	IDENTIFIER
Bacterial and virus strains
Limosilactobacillus reuteri PTA-6475	ATCC	Strain MM4-1A
Chemicals, peptides, and recombinant proteins
De Man, Rogosa, and Sharpe (MRS) Media	MilliporeSigma	Cat# MHA00MRS2
De Man, Rogosa, and Sharpe (MRS) Agar	MilliporeSigma	Cat# 110660
5% H2, 5% CO2, 90% N2 anaerobic gas mixture	Linde Gas & Equipment, Praxair Distribution	Cat# BI NICDHYC1-K
Critical commercial assays
MagAttract PowerSoil DNA Kit	Qiagen	Cat #27100-4-EP
Deposited data
16S ribosomal RNA (rRNA) gene amplicon sequencing data	NCBI SRA	BioProject PRJNA878523
Original unprocessed data	This paper; Mendeley	https://doi.org/10.17632/z6wz8kpk3n.1
Galaxy Computation Tool	Huttenhower Lab	http://huttenhower.sph.harvard.edu/galaxy
Agile Toolkit for Incisive Microbial Analyses (ATIMA2) Platform	Petrosino Lab	https://atima.research.bcm.edu
Experimental models: Organisms/strains
C57Bl/6N	Taconic Biosciences	Cat# B6-M; Cat# B6-F
Germ-free mice (C57Bl/6N background)	UTMB Germ Free Mouse Facility	N/A
Software and algorithms
ANY-maze Video Tracking Software	Stoelting	https://www.stoeltingco.com/anymaze/video-tracking/software.html
Prism 9.0	Graphpad	https://www.graphpad.com/scientific-software/prism
Adobe Illustrator CS6	Adobe	https://www.adobe.com
Miseq Software	Illumina	https://support.illumina.com/sequencing/sequencing_software/miseq_reporter/downloads.html
R	The R Foundation	https://www.r-project.org/about.html
R Studio	R Studio	https://rstudio.com/
Other
Ugo Basile Sociability Cage, Mouse, w/Gray Enclosures	Stoelting	Cat# 60450
Small Mouse ‘Stranger’ Enclosures (wire cages), set/2, Gray	Stoelting	Cat# 60451
Open Field, 40cm, Gray	Stoelting	Cat# 60101
Reciprocal Social Interaction Box, Clear Acrylic	The Container Store	Cat# 10071077
Regular diet chow	Lab Diets	Cat# 5001
High-fat diet chow	Research Diets	Cat# D12492
Bed-O’cobs 1/8 mouse home cage bedding	The Andersons Plant Nutrient	Cat# 8B