Effect of vanadium toxicity at its different oxidation states on selected bacterial and protozoan isolates in wastewater systems

Abstract

This study assesses and compares vanadium toxicity in its different oxidation states towards bacterial isolates (Pseudomonas putida and Bacillus licheniformis) and protozoan isolates (Peranema sp. and Trachelophyllum sp.). The isolates were exposed to various concentrations of V in mixed liquors and their tolerance to V was assessed at 30 degrees C at a pH of 4. The results revealed that the increase in V oxidation state increased its toxicity to bacterial isolates, whereas its toxicity decreased for protozoan isolates. Among the bacterial isolates, P putida was found to be more tolerant to V3+(24h-median lethal concentration (LC50): 390mg/l), V4+(24h-LC50: 230-250mg/l) and V5+(24h-LC50: 180-200mg/l), whereas for the protozoan isolates, Peranema sp. appeared to be more tolerant to V3+(24 h-LC50: 110-120 mg/l), V4+(24 h-LC50: 160-170 mg/l) and V5+(24 h-LC50: 160-200 mg/l). A comparison of both groups of organisms revealed Trachelophyllum sp. as the most sensitive organism to V at its various oxidation states. The visual and spectrophotometric methods used to assess V reduction revealed that P. putida was the only isolate able to reduce V5+, V4+ and V3+ to V2+ in mixed liquor media. Vanadium (+2) in concentrations of approximately 46.46 mg/l, 29.57 m mg/l and 38.01 mg/l found in the media was treated with V3+, V4+ and V5+, respectively, and inoculated with P. putida. This study revealed that the ability of V reduction, adopted with P putida, can be an effective strategy to remove V from polluted environments. This study also showed that the toxicity of V, in terms of its oxidation states, differs from one species to another and in kingdoms.

Acute toxicity of potentially toxic elements on ciliated protozoa from Lake Maracaibo (Venezuela)

“…The LC 50 values observed for the ciliated protozoa of Lake Maracaibo, in general, are relatively high and comparable to those of other water bodies (Maurya & Pandey, 2020;Kamika & Momba, 2014;Madoni & Romeo, 2006;Madoni et al, 1996). Madoni & Romeo (2006) reported toxic effects of 0.30, 0.89, 0.59 and 0.07 mgCd(II).L -1 , and of 110, 108, 0.1 and 0.1 mgCr(VI).L -1 for the ciliated protozoa Dexiotricha granulosa, Colpidium colpoda, Euplotes aediculatus and Halteria grandinella, respectively, showing great differences in tolerance, as observed in other species of ciliates.…”

“…Some examples of the acute toxicity of pentavalent vanadium on aquatic organisms are: Pseudomonas putida (bacteria) 180-200 mg.L -1 , Trachelophyllum sp. (protozoa) of 120-130 mg.L -1 (Kamika & Momba, 2014), D. magna (microcrustacean) of 1.2 mg.L -1 (Okamoto et al, 2015) and Salmo gairdneri (fish) of 2.0-13.2 mg.L -1 (Stendahl & Sprague, 1982). In the case of Lake Maracaibo, an ecotoxicity of V(V) for P. solida of 401.96 mg.L -1 has been documented; this bivalve has been proposed as a bioindicator for PTE in this ecosystem, due to its ability to incorporate, tolerate and bioaccumulate elements in higher concentrations and proportional to exposure levels (Rojas, 2012).…”

Challenges and Opportunities toward Real Application of VO2-Based Smart Glazing

“…Studies have revealed that the possible toxic effects of V are related to its oxidation state, since this metal element can exhibit several oxidation states (À1 to +5). 102 Two of these oxidation states (V 4+ and V 5+ ) are considered to be predominant in the environment, and inhalation and ingestion are the main routes of absorption. From the perspective of practical application as smart coatings, as a type of common product within easy physical contact, the toxicity of materials needs to be of paramount concern in any investigation.…”

The potential of Pseudomonas for bioremediation of oxyanions

“…Vanadium oxyanions. Multiples studies have reported the reduction of V(V), V(IV) and V(III) to V(II) by multiple Pseudomonas (Lyalkova and Yurkova, 1991;Kamika and Momba, 2014) although the mechanisms by which these bioreactions occur have not been elucidated. Despite this, members of the Pseudomonas genus have shown great potential for effectively removing vanadate from polluted environments.…”