Production and Release of Selenomethionine and Related Organic Selenium Species by Microorganisms in Natural and Industrial Waters

Abstract

Laboratory algal cultures exposed to selenate were shown to produce and release selenomethionine, selenomethionine oxide, and several other organic selenium metabolites. Released discrete organic selenium species accounted for 1.6-13.1% of the selenium remaining in the media after culture death, with 1.3-6.1% of the added selenate recovered as organic metabolites. Analysis of water from an industrially impacted river collected immediately after the death of massive annual algal blooms showed that no selenomethionine or selenomethionine oxide was present. However, other discrete organic selenium species, including a cyclic oxidation product of selenomethionine, were observed, indicating the previous presence of selenomethionine. Industrial biological treatment systems designed for remediation of selenium-contaminated waters were shown to increase both the concentration of organic selenium species in the effluent, relative to influent water, and the fraction of organic selenium to up to 8.7% of the total selenium in the effluent, from less than 1.1% in the influent. Production and emission of selenomethionine, selenomethionine oxide, and other discrete organic selenium species were observed. These findings are discussed in the context of potentially increased selenium bioavailability caused by microbial activity in aquatic environments and biological treatment systems, despite overall reductions in total selenium concentration.

A rapid and sensitive IC-ICP-MS method for determining selenium speciation in natural waters

“…Inorganic Se species (Se IV and Se VI ) maintained excellent peak shape and resolution at low concentrations when a standard solution containing inorganic Se species (200 ng L -1 ) was injected into the IC-ICP-MS ( Figure 1A). Similar to the behavior of arsenite (As III ) in a method using a HNO 3 mobile phase and AS7 column for arsenic speciation, 22 quantities in biologically productive waters, 26,27 two selenoamino acids (SeMet and MeSeCys)…”

Advancement in Non-Biological Selenium Removal Treatment Systems – Results of Continuous Pilot Scale Operations

“…This means that water containing even trace levels of organoselenium is much more likely to cause chronic toxicity and environmental impacts in the receiving environment than water containing more elevated levels of inorganic selenium. As organoselenium is generated by bacterial action, biological water treatment systems may in some cases increase the rate of selenium bioaccumulation in the receiving environment despite the fact that they remove the majority of the total selenium from the feed water (LeBlanc & Wallschläger, 2016, Sandy, 2016.…”

Adsorption by Granular Activated Carbon and Nano Zerovalent Iron from Wastewater: A Study on Removal of Selenomethionine and Selenocysteine

“…It exists in the form of SeMet and SeCys in the effluent of industrial wastewaters [5], emanating from mostly mining, oil and gas refineries and coal-fired power plants. SeMet and SeCys are known to have higher bioavailability than inorganic selenium species as it is readily absorbed [3,5]. As a result, the ecotoxicological effect of organic Se (SeMet and SeCys) in aqueous environments is increased.…”

“…The process relies on the use of microbial mediation for selenium species removal [25][26][27][28]. However, the presence of SeMet has been reported in the effluents of an industrial biological treatment system [5]. It stands to reason that biological treatment techniques are among the primary sources of organic Se pollution in wastewaters.…”

“…It stands to reason that biological treatment techniques are among the primary sources of organic Se pollution in wastewaters. The transformation of inorganic selenium species to the organic form is mainly due to the microbial activities [5,29]. As a result, the existence of organic Se (SeMet and SeCys) in wastewaters remains an environmental contaminant of concern and the remediation techniques have rarely been researched.…”