Bacillus subtilis Colonization of Arabidopsis thaliana Roots Induces Multiple Biosynthetic Clusters for Antibiotic Production

Abstract

Beneficial and probiotic bacteria play an important role in conferring immunity of their hosts to a wide range of bacterial, viral, and fungal diseases. Bacillus subtilis is a Gram-positive bacterium that protects the plant from various pathogens due to its capacity to produce an extensive repertoire of antibiotics. At the same time, the plant microbiome is a highly competitive niche, with multiple microbial species competing for space and resources, a competition that can be determined by the antagonistic potential of each microbiome member. Therefore, regulating antibiotic production in the rhizosphere is of great importance for the elimination of pathogens and establishing beneficial host-associated communities. In this work, we used B. subtilis as a model to investigate the role of plant colonization in antibiotic production. Flow cytometry and imaging flow cytometry (IFC) analysis supported the notion that Arabidopsis thaliana specifically induced the transcription of the biosynthetic clusters for the non-ribosomal peptides surfactin, bacilysin, plipastatin, and the polyketide bacillaene. IFC was more robust in quantifying the inducing effects of A. thaliana, considering the overall heterogeneity of the population. Our results highlight IFC as a useful tool to study the effect of association with a plant host on bacterial gene expression. Furthermore, the common regulation of multiple biosynthetic clusters for antibiotic production by the plant can be translated to improve the performance and competitiveness of beneficial members of the plant microbiome.

Arabidopsis thaliana induces multigenerational stress tolerance against biotic and abiotic stressors and memorization of host colonization in Bacillus subtilis

“…S11). These results are consistent with our previous findings that A. thaliana and Eruca sativa induce pks expression 41,42 .…”

“…3F). Notably, our previous results using flow cytometry confirm the induction of the biosynthetic clusters for the antibiotics surfactin and bacillaene by the root, as well as the repression of lactate dehydrogenase 28 .…”

“…Measurements were performed every 30 min at 30°C for 30 h, using a microplate reader (Infinite M Plex; Tecan, Austria, or Synergy 2; BioTek, Winooski, VT, USA). Luciferase activity was normalized to avoid artifacts related to differential cell numbers as RLU/OD 42…”

“…Luciferase activity was normalized to avoid artifacts related to differential cell numbers as RLU/OD 42…”

Context-dependent differences in the functional responses of Lactobacillaceae strains to fermentable sugars

“…Interestingly, alterations in cell clumping did not perfectly correlate with the response to acid stress as judged by cell growth as LGG had pronounceable growth upon utilization of glucose, while L. paracasei failed to increase it carrying capacity with glucose. To further assess whether alterations in cell properties account for the differential colony morphology, we used imaging flow cytometry ( Narayana et al, 2020 ; Maan et al, 2021 ). While imaging flow cytometry was sporadically used to monitor aggregation ( Konieczny et al, 2021 ), it was never applied to probiotic bacteria.…”