title: Selenite reduction by the obligate aerobic bacterium Comamonas testosteroni S44 isolated from a metal-contaminated soil.
abstract: BACKGROUND
  Selenium (Se) is an essential trace element in most organisms but has to be carefully handled since there is a thin line between beneficial and toxic concentrations. Many bacteria have the ability to reduce selenite (Se(IV)) and (or) selenate (Se(VI)) to red elemental selenium that is less toxic.
  
  
  RESULTS
  A strictly aerobic bacterium, Comamonas testosteroni S44, previously isolated from metal(loid)-contaminated soil in southern China, reduced Se(IV) to red selenium nanoparticles (SeNPs) with sizes ranging from 100 to 200 nm. Both energy dispersive X-ray Spectroscopy (EDX or EDS) and EDS Elemental Mapping showed no element Se and SeNPs were produced inside cells whereas Se(IV) was reduced to red-colored selenium in the cytoplasmic fraction in presence of NADPH. Tungstate inhibited Se(VI) but not Se(IV) reduction, indicating the Se(IV)-reducing determinant does not contain molybdenum as co-factor. Strain S44 was resistant to multiple heavy and transition metal(loid)s such as Se(IV), As(III), Cu(II), and Cd(II) with minimal inhibitory concentrations (MIC) of 100 mM, 20 mM, 4 mM, and 0.5 mM, respectively. Disruption of iscR encoding a transcriptional regulator negatively impacted cellular growth and subsequent resistance to multiple heavy metal(loid)s.
  
  
  CONCLUSIONS
  C. testosteroni S44 could be very useful for bioremediation in heavy metal(loid) polluted soils due to the ability to both reduce toxic Se(VI) and Se(IV) to non-toxic Se (0) under aerobic conditions and to tolerate multiple heavy and transition metals. IscR appears to be an activator to regulate genes involved in resistance to heavy or transition metal(loid)s but not for genes responsible for Se(IV) reduction.
authors.forename: Shixue
authors.initials: S
authors.lastname: Zheng
authors.forename: Jing
authors.initials: J
authors.lastname: Su
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.forename: Rong
authors.initials: R
authors.lastname: Yao
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.forename: Yujia
authors.initials: Y
authors.lastname: Deng
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China. gejiao@mail.hzau.edu.cn.
authors.forename: Gejiao
authors.initials: G
authors.lastname: Wang
authors.forename: Christopher
authors.initials: C
authors.lastname: Rensing
mesh_terms: D000332:Aerobiosis; D002681:China; D020604:Comamonas testosteroni / Q000302:isolation & purification* / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D019216:Metals, Heavy / Q000633:toxicity; D008826:Microbial Sensitivity Tests; D009249:NADP / Q000378:metabolism; D053758:Nanoparticles / Q000378:metabolism; D010084:Oxidation-Reduction; D020887:Selenious Acid / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission; D028561:Transition Elements / Q000633:toxicity
chemical_list: D019216:Metals, Heavy; D012989:Soil Pollutants; D028561:Transition Elements; D009249:NADP; D020887:Selenious Acid
references.citation: FEBS J. 2011 Aug;278(15):2689-701
references.pmid: 21624051
references.citation: J Bacteriol. 2011 May;193(9):2141-8
references.pmid: 21357486
references.citation: Biometals. 1999 Jun;12(2):141-9
references.pmid: 10406083
references.citation: Annu Rev Microbiol. 2006;60:107-30
references.pmid: 16704340
references.citation: DNA Seq. 2000;10(6):365-77
references.pmid: 10826693
references.citation: Proc Natl Acad Sci U S A. 2011 Aug 16;108(33):13480-5
references.pmid: 21808043
references.citation: Microbiol Mol Biol Rev. 2008 Mar;72(1):110-25, table of contents
references.pmid: 18322036
references.citation: Appl Environ Microbiol. 2003 Dec;69(12):7063-72
references.pmid: 14660350
references.citation: Biochem J. 2007 Nov 15;408(1):19-28
references.pmid: 17688424
references.citation: Biochemistry. 2012 Jun 5;51(22):4453-62
references.pmid: 22583201
references.citation: Environ Microbiol. 2005 Feb;7(2):153-64
references.pmid: 15658983
references.citation: Arch Microbiol. 2002 Sep;178(3):193-201
references.pmid: 12189420
references.citation: Science. 1981 Feb 6;211(4482):600-1
references.pmid: 6779378
references.citation: PLoS One. 2014 Jan 22;9(1):e86763
references.pmid: 24466226
references.citation: Br J Nutr. 2001 May;85(5):517-47
references.pmid: 11348568
references.citation: Appl Environ Microbiol. 2004 Jan;70(1):52-60
references.pmid: 14711625
references.citation: Curr Microbiol. 2006 Apr;52(4):305-9
references.pmid: 16550462
references.citation: J Biol Chem. 2004 Dec 3;279(49):50662-9
references.pmid: 15371444
references.citation: Environ Sci Technol. 2012 Jan 17;46(2):571-9
references.pmid: 22129299
references.citation: Proc Natl Acad Sci U S A. 2001 Dec 18;98(26):14895-900
references.pmid: 11742080
references.citation: Anal Biochem. 1976 May 7;72:248-54
references.pmid: 942051
references.citation: Curr Microbiol. 2007 Oct;55(4):344-9
references.pmid: 17882505
references.citation: Biometals. 1998 Sep;11(3):223-7
references.pmid: 9850565
references.citation: Nat Struct Mol Biol. 2013 Jun;20(6):740-7
references.pmid: 23644595
references.citation: Microb Cell Fact. 2010 Jul 05;9:52
references.pmid: 20602763
references.citation: Environ Int. 2005 Feb;31(2):233-41
references.pmid: 15661289
references.citation: Microbiology (Reading). 2006 Mar;152(Pt 3):731-743
references.pmid: 16514153
references.citation: Curr Microbiol. 2014 Mar;68(3):311-6
references.pmid: 24474405
references.citation: Appl Environ Microbiol. 1996 Apr;62(4):1214-9
references.pmid: 8919782
references.citation: Appl Environ Microbiol. 2007 Nov;73(21):6854-63
references.pmid: 17827320
references.citation: Curr Microbiol. 2009 May;58(5):493-8
references.pmid: 19189180
references.citation: Mol Microbiol. 2006 Jul;61(1):206-18
references.pmid: 16824106
references.citation: Appl Environ Microbiol. 1999 Nov;65(11):4734-40
references.pmid: 10543779
references.citation: Lancet. 2000 Jul 15;356(9225):233-41
references.pmid: 10963212
references.citation: Mol Microbiol. 2013 Feb;87(3):478-92
references.pmid: 23075318
references.citation: Nanotechnology. 2011 May 13;22(19):195605
references.pmid: 21430311
references.citation: Appl Environ Microbiol. 2007 Jun;73(11):3519-27
references.pmid: 17435005
references.citation: Curr Microbiol. 2014 Jul;69(1):69-74
references.pmid: 24604150
references.citation: J Proteome Res. 2010 Dec 3;9(12):6135-47
references.pmid: 20932056
references.citation: Mol Microbiol. 2006 May;60(4):1058-75
references.pmid: 16677314
references.citation: Appl Environ Microbiol. 2007 Mar;73(6):1914-20
references.pmid: 17261520
references.citation: J Mol Biol. 1990 Oct 5;215(3):403-10
references.pmid: 2231712
references.citation: Appl Environ Microbiol. 2006 Aug;72(8):5173-80
references.pmid: 16885262
references.citation: Res Microbiol. 2011 Sep;162(7):671-9
references.pmid: 21704702
references.citation: Microb Cell Fact. 2012 Jul 09;11:64
references.pmid: 22607265