Bioaccumulation of Vanadium by Vanadium-Resistant Bacteria Isolated from the Intestine of Ascidia sydneiensis samea

Abstract

Isolation of naturally occurring bacterial strains from metal-rich environments has gained popularity due to the growing need for bioremediation technologies. In this study, we found that the vanadium concentration in the intestine of the vanadium-rich ascidian Ascidia sydneiensis samea could reach 0.67 mM, and thus, we isolated vanadium-resistant bacteria from the intestinal contents and determined the ability of each bacterial strain to accumulate vanadium and other heavy metals. Nine strains of vanadium-resistant bacteria were successfully isolated, of which two strains, V-RA-4 and S-RA-6, accumulated vanadium at a higher rate than did the other strains. The maximum vanadium absorption by these bacteria was achieved at pH 3, and intracellular accumulation was the predominant mechanism. Each strain strongly accumulated copper and cobalt ions, but accumulation of nickel and molybdate ions was relatively low. These bacterial strains can be applied to protocols for bioremediation of vanadium and heavy metal toxicity.

Symbiotic Associations in Ascidians: Relevance for Functional Innovation and Bioactive Potential

“…In the intestine, the abundant genera ( Treponema and Borrelia ) likely attach to its surface or live within intestinal cells as symbionts, aiding in the accumulation of vanadium from the intestinal lumen. Treponema and Borrelia genera were also abundant in the intestinal content, which reinforces their involvement in vanadium accumulation [ 148 , 149 ]. Vibrio and Shewanella are suggested to increase the concentration of vanadium in the intestinal lumen facilitating vanadium sequestration [ 149 ].…”

“…Treponema and Borrelia genera were also abundant in the intestinal content, which reinforces their involvement in vanadium accumulation [ 148 , 149 ]. Vibrio and Shewanella are suggested to increase the concentration of vanadium in the intestinal lumen facilitating vanadium sequestration [ 149 ]. Another suggested strategy that can aid ascidians colonization is the regulation of their bacterial community for nutritional gains through phagocytosis [ 53 , 84 , 128 ].…”

“…High levels of vanadium are accumulated in blood cells of ascidians belonging to Phlebobranchia order; this metal is absorbed from seawater in a +5 state, then the reduction to a +4 state occurs in ascidians tissues and it is accumulated in a +3 state in vanadocytes (specialized blood cells) [ 148 ]. This sequestration capacity has been associated to ascidians bacterial symbionts as Pseudomonas , Ralstonia and Shewanella [ 148 , 149 ].…”

Response to vanadate exposure in Ochrobactrum tritici strains

“…Vanadium resistant microorganisms have been isolated from environmental contaminated sites such as phytoremediation plants (up to 30 mM Na 3 VO 4 ), V mining-impacted soils [17] and the intestine of the vanadium-rich ascidian Ascidia sydneiensis samea (10 mM Na 3 VO 4 ) [18][19][20]. However, the molecular mechanisms underlying vanadium resistance in microorganisms are still poorly understood.…”

Extreme Environments and High-Level Bacterial Tellurite Resistance

“…This is mainly due to the fact that the latter metals have long been known as essential for life through their involvement in many cellular activities [6][7][8]. Bacterial interactions with tellurite have received attention [9][10][11][12], but much is still unknown about high-level resistance. In recent years, there has been more focus in this area due to increased environmental contamination from industrial activities [13,14].…”