Ledger, T., Zuniga, A., Kraiser, T., Dasencich, P., Donoso, R., Perez-Pantoja, D., et al. (2012). Aromatic compounds degradation plays a role in colonization of Arabidopsis thaliana and Acacia caven by Cupriavidus pinatubonensis JMP134. Antonie Van Leeuwenhoek, 101(4), 713–723.
Abstract: Plant rhizosphere and internal tissues may constitute a relevant habitat for soil bacteria displaying high catabolic versatility towards xenobiotic aromatic compounds. Root exudates contain various molecules that are structurally related to aromatic xenobiotics and have been shown to stimulate bacterial degradation of aromatic pollutants in the rhizosphere. The ability to degrade specific aromatic components of root exudates could thus provide versatile catabolic bacteria with an advantage for rhizosphere colonization and growth. In this work, Cupriavidus pinatubonensis JMP134, a well-known aromatic compound degrader (including the herbicide 2,4-dichlorophenoxyacetate, 2,4-D), was shown to stably colonize Arabidopsis thaliana and Acacia caven plants both at the rhizoplane and endorhizosphere levels and to use root exudates as a sole carbon and energy source. No deleterious effects were detected on these colonized plants. When a toxic concentration of 2,4-D was applied to colonized A. caven, a marked resistance was induced in the plant, showing that strain JMP134 was both metabolically active and potentially beneficial to its host. The role for the beta-ketoadipate aromatic degradation pathway during plant root colonization by C. pinatubonensis JMP134 was investigated by gene inactivation. A C. pinatubonensis mutant derivative strain displayed a reduced ability to catabolise root exudates isolated from either plant host. In this mutant strain, a lower competence in the rhizosphere of A. caven was also shown, both in gnotobiotic in vitro cultures and in plant/soil microcosms.
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Rodríguez-Valdecantos, G., Torres-Rojas, F., Muñoz-Echeverría, S., Mora-Ruiz, M. D., Rosselló-Móra, R., Cid-Cid, L., et al. (2023). Aromatic compounds depurative and plant growth promotion rhizobacteria abilities of Allenrolfea vaginata (Amaranthaceae) rhizosphere microbial communities from a solar saltern hypersaline soil. Front. Microbiol., 14, 1251602.
Abstract: Introduction: This work investigates whether rhizosphere microorganisms that colonize halophyte plants thriving in saline habitats can tolerate salinity and provide beneficial effects to their hosts, protecting them from environmental stresses, such as aromatic compound (AC) pollution.Methods: To address this question, we conducted a series of experiments. First, we evaluated the effects of phenol, tyrosine, 4-hydroxybenzoic acid, and 2,4-dichlorophenoxyacetic (2,4-D) acids on the soil rhizosphere microbial community associated with the halophyte Allenrolfea vaginata. We then determined the ability of bacterial isolates from these microbial communities to utilize these ACs as carbon sources. Finally, we assessed their ability to promote plant growth under saline conditions.Results: Our study revealed that each AC had a different impact on the structure and alpha and beta diversity of the halophyte bacterial (but not archaeal) communities. Notably, 2,4-D and phenol, to a lesser degree, had the most substantial decreasing effects. The removal of ACs by the rhizosphere community varied from 15% (2,4-D) to 100% (the other three ACs), depending on the concentration. Halomonas isolates were the most abundant and diverse strains capable of degrading the ACs, with strains of Marinobacter, Alkalihalobacillus, Thalassobacillus, Oceanobacillus, and the archaea Haladaptatus also exhibiting catabolic properties. Moreover, our study found that halophile strains Halomonas sp. LV-8T and Marinobacter sp. LV-48T enhanced the growth and protection of Arabidopsis thaliana plants by 30% to 55% under salt-stress conditions.Discussion: These results suggest that moderate halophile microbial communities may protect halophytes from salinity and potential adverse effects of aromatic compounds through depurative processes.
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