Core Species Derived from Multispecies Interactions Facilitate the Immobilization of Cadmium

Abstract

Microbial consortia have opened new avenues for heavy-metal remediation. However, the limited understanding of the overall effect of interspecific interactions on remediation efficacy hinders its application. Here, the effects of multispecies growth and biofilm formation on Cd immobilization were explored from direct and multiple interactions through random combinations of two or three rhizosphere bacteria. In monocultures, Cd stress resulted in an average decrease in planktonic biomass of 26%, but through cooperation, the decrease was attenuated in dual (21%) and triple cultures (13%), possibly involving an increase in surface polysaccharides. More than 65% of the co-cultures exhibited induction of biofilm formation under Cd stress, which further enhanced the role of biofilms in Cd immobilization. Notably, excellent biofilm-forming ability or extensive social induction makes Pseudomonas putida and Brevundimonas diminuta stand out in multispecies biofilm formation and Cd immobilization. These two core species significantly increase the colonization of soil microorganisms on rice roots compared to the control, resulting in a 40% decrease in Cd uptake by rice. Our study enhances the understanding of bacterial interactions under Cd stress and provides a novel strategy for adjusting beneficial soil consortia for heavymetal remediation.

Effect of Seed Priming with Cations on Cadmium Accumulation in Wheat Seedings under Cadmium-Contaminated Weakly Alkaline Soil

“…Previous work reported that by utilizing essential nutrients, like Zn and Mn, the buildup of Cd in plants can be reduced because of the competition between Cd and these nutrients for the same membrane transporters. − Moreover, seed priming can induce stress and immune responses by increasing the production of signal- and defense-related metabolites and genes, resulting in a prompt and robust defense mechanism against potential stresses . Meanwhile, seed priming can lead to a restructuring of transcription and plant metabolism, which could modify the release of metabolites into the rhizosphere, ultimately indirectly influencing the rhizomicrobiome. , It is widely known that the rhizomicrobiome is closely related to the bioavailability and migration of Cd . It can be speculated that priming wheat seeds could potentially affect the absorption of Cd through the regulation of Cd transporters, changes in transcription and plant metabolism, and the recruitment of beneficial microbiota …”