Impact of Different Microbial Biostimulants and Salt Stress on the Endophytome of the Edible Part of Lettuce and Tomato Plants

TL;DR

This study shows that using microbial biostimulants and salt stress can change the microbes in edible plants, potentially improving gut health when consumed.

Contribution

The study reveals how agricultural practices affect the edible plant microbiome and its potential impact on human gut health.

Findings

Microbial biostimulants and salt stress significantly reshape the endophytic microbiome in lettuce and tomato.

Treatments increased the abundance of plant-beneficial bacteria like Pantoea and Stenotrophomonas.

Salt stress boosted microbial diversity and favored phyla linked to a healthy human gut microbiome.

Abstract

The human gut microbiota plays a critical role in health throughout life. While fruits and vegetables are well-known sources of nutrients and prebiotics, recent studies suggest they may also contribute viable microorganisms to the gut microbiome, particularly when consumed raw. However, the impact of agricultural practices—such as the use of microbial biostimulants or exposure to salt stress—on the composition of the edible plant microbiome remains poorly understood. In this study, we performed a comprehensive metataxonomic analysis of the endophytic microbiome in the edible tissues (leaves or fruits) of lettuce (Lactuca sativa) and tomato (Solanum lycopersicum), cultivated under standard conditions with or without microbial biostimulants and salt stress. Our results show that microbial biostimulants—Priestia megaterium (PGPB) and Rhizophagus irregularis (AMF)—as well as moderate salt stress, significantly reshape the composition and diversity of endophytes in both crops. Notably, the PGPB and NaCl treatments enhanced the abundance of bacterial genera such as Pantoea, Stenotrophomonas, and Massilia, which are associated with plant health and may have probiotic potential. Salt stress also increased alpha-diversity indices and favored the presence of Firmicutes and Bacteroidota, phyla commonly linked to a healthy human gut microbiome. Agronomic inputs used in organic and conventional farming, such as microbial biostimulants or controlled salt exposure, may represent novel strategies to enhance the microbial quality of fresh produce and promote gut microbial diversity through diet.

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