Abstract
Selenite is extremely biotoxic, and as a result of this, exploitation of microorganisms able to reduce selenite to non-toxic elemental selenium (Se0) has attracted great interest. In this study, a bacterial strain exhibiting extreme tolerance to selenite (up to 100 mM) was isolated from the gut of adult Monochamus alternatus and identified as Proteus mirabilis YC801. This strain demonstrated efficient transformation of selenite into red selenium nanoparticles (SeNPs) by reducing nearly 100% of 1.0 and 5.0 mM selenite within 42 and 48 h, respectively. Electron microscopy and energy dispersive X-ray analysis demonstrated that the SeNPs were spherical and primarily localized extracellularly, with an average hydrodynamic diameter of 178.3 ± 11.5 nm. In vitro selenite reduction activity assays and real-time PCR indicated that thioredoxin reductase and similar proteins present in the cytoplasm were likely to be involved in selenite reduction, and that NADPH or NADH served as electron donors. Finally, Fourier-transform infrared spectral analysis confirmed the presence of protein and lipid residues on the surfaces of SeNPs. This is the first report on the capability of P. mirabilis to reduce selenite to SeNPs. P. mirabilis YC801 might provide an eco-friendly approach to bioremediate selenium-contaminated soil/water, as well as a bacterial catalyst for the biogenesis of SeNPs.
Highlights
Selenium (Se) is of considerable environmental importance, as it is an essential micronutrient with a prominent role in the health of various species [1,2]
The red colony color indicates that the strain reduced selenite to elemental red selenium (Se00)
Because a number of bacteria have the ability to mediate reduction of sodium selenite into selenium nanoparticles (SeNPs), we investigated whether P. mirabilis YC801 can reduce selenite to Se0 during formation of SeNPs
Summary
Selenium (Se) is of considerable environmental importance, as it is an essential micronutrient with a prominent role in the health of various species [1,2]. Biological approaches are generally preferred due to additional benefits, such as their eco-friendly characteristics, as well as their abilities to employ self-generating catalysts They can provide a viable and cost-effective approach for bioremediation of excess selenium in contaminated water [14]. Some microorganisms link their selenite reduction capability to the biosynthesis of SeNPs, which can accumulate intracellularly or be deposited extracellularly. Due to their unique physical and chemical properties, SeNPs have some unusual advantages in biosensors, bioremediation, biomedical therapy, and environmental remediation [22,23,24,25,26]. Pa.nmimiraalbgiluistsst[r3a0i]n.sMaorerewovideer,lythdeisPt.rimbiurtaebdiliisnstsroaiilnasnpdowssaetsesrainvatshternanatgueroalf emnevtiarboonlmiceanctt,iavsitwieseltloaws ainrdanhiemavayl gmutesta[l3s0o].rMtooxriecosvuebrs, ttahnecPe.sm, airllaobwiliisnsgtrtahienisr padosaspetsastiaonvatsot draifnfegreeonft menevtiarboonlmiceancttaivl itcieosntdoiwtioanrds h[e3a1v,3y2m], etaanlsdortthouxsic spurbosvtiadnincegs, aallopwoisnsgibtihlietyir aodfapetamtipolnoytoindgiffethreenset emnivcirrooonrmgaennitsaml csonindibtiioonresm[3e1d,3ia2t]i,oanndanthduesnpvriorovnidminegntaapl opsrsoibteilcittiyono.f eTmheprleofyoirneg, tthheesuesme iocrfoPo.rgmainraisbmiliss isntrbaiinorYemC8e0d1iaatisoan baancdteerniavlircohnamsseisnmtalayprportoecvtiidoen.aTnheewre, froarpei,dt,hneouns-ehoafzaPr.dmoiursa,bialnisdsteraasinilyYsCc8a0le1da-supa bbaiocsteyrniathl echtiacsspisatmhwayayprofovridseealenneiwte, rbaipoitdra, nnsofno-rhmazaatirodnouasn, dandSeeNasPisly pscraoldeudc-utiponb.ioIsnyntthhisetisctupdatyh,wwaye fionrveseslteignaitteedbisoetlreannistfeorremdautciotinonanadndSeiNtsPpsopsrsoibdluecmtioonle.cIunlathr ims setcuhdayn,iwsme ,inavsewsteilglaatsedSesNelePnbitieosryednuthcetisoisn, abnydPi.tms piroasbsiliibslestmraoinleYcuCl8a0r1m. echanism, as well as SeNP biosynthesis, by P. mirabilis strain YC801
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