title: Unusual radioresistance of nitrogen-fixing cultures of Anabaena strains.
abstract: Nitrogen-fixing cultures of two species of the filamentous, heterocystous cyanobacterium Anabaena, namely Anabaena sp. strain L-31 and Anabaena torulosa were found to be highly tolerant to 60Co gamma radiation. No adverse effect on diazotrophic growth and metabolism were observed up to a dose of 5 kGy. At higher doses, radiation tolerance showed a correspondence with the inherent osmotolerance, with Anabaena L-31 being the more radiation tolerant as well as osmotolerant strain. In Anabaena L-31, exposure to 6 kGy of gamma rays resulted in genome disintegration, but did not reduce viability. Irradiation delayed heterocyst differentiation and nitrogen fixation, and marginally affected diazotrophic growth. All the affected parameters recovered after a short lag, without any discernible postirradiation phenotype. The radiation tolerance of these Gram-negative photoautodiazotrophs is comparable with that of the adiazotrophic photoautotrophic cyanobacterium Chroococcidiopsis or adiazotrophic heterotroph Deinococcus radiodurans. This is the first report of extreme radioresistance in nitrogen-fixing Anabaena cultures.
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
authors.forename: Harinder
authors.initials: H
authors.lastname: Singh
authors.forename: Tonina
authors.initials: T
authors.lastname: Fernandes
authors.forename: Shree Kumar
authors.initials: SK
authors.lastname: Apte
mesh_terms: D017033:Anabaena / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D004269:DNA, Bacterial; D005720:Gamma Rays; D009586:Nitrogen Fixation; D011836:Radiation Tolerance
chemical_list: D004269:DNA, Bacterial
references.citation: Nucleic Acids Res. 2003 Jun 15;31(12):2995-3005
references.pmid: 12799425
references.citation: Proc Natl Acad Sci U S A. 1971 Jan;68(1):124-6
references.pmid: 5276282
references.citation: J Bacteriol. 1968 Dec;96(6):2138-43
references.pmid: 5724976
references.citation: Appl Environ Microbiol. 2000 Jun;66(6):2620-6
references.pmid: 10831446
references.citation: Appl Environ Microbiol. 2006 Dec;72(12):7873-8
references.pmid: 17056698
references.citation: Water Res. 2005 Dec;39(20):5017-26
references.pmid: 16289234
references.citation: Appl Environ Microbiol. 1993 Mar;59(3):899-904
references.pmid: 16348897
references.citation: Microbiol Rev. 1994 Dec;58(4):755-805
references.pmid: 7854254
references.citation: Annu Rev Microbiol. 1980;34:497-536
references.pmid: 6108091
references.citation: Appl Environ Microbiol. 2000 Apr;66(4):1489-92
references.pmid: 10742231
references.citation: Microbiology (Reading). 2008 Jan;154(Pt 1):317-325
references.pmid: 18174150
references.citation: J Bacteriol. 1987 Sep;169(9):4128-34
references.pmid: 3305481
references.citation: Appl Environ Microbiol. 1997 May;63(5):1647-56
references.pmid: 16535588
references.citation: Microbiology (Reading). 2000 Nov;146 ( Pt 11):2877-2889
references.pmid: 11065366
references.citation: Nat Biotechnol. 1998 Oct;16(10):929-33
references.pmid: 9788348
references.citation: Annu Rev Microbiol. 1980;34:183-207
references.pmid: 6776883
references.citation: Microbiol Rev. 1992 Jun;56(2):340-73
references.pmid: 1620069
references.citation: Appl Environ Microbiol. 1995 Jan;61(1):234-8
references.pmid: 7534052
references.citation: Appl Environ Microbiol. 1980 May;39(5):1078-80
references.pmid: 16345570
references.citation: Mikrobiologiia. 1973 Mar-Apr;42(2):307-11
references.pmid: 4203668
references.citation: Microbiology (Reading). 1998 Jun;144 ( Pt 6):1557-1563
references.pmid: 9639926
references.citation: J Bacteriol. 1996 Feb;178(3):633-7
references.pmid: 8550493
references.citation: Oecologia. 1984 Jun;62(3):418-423
references.pmid: 28310898
references.citation: Nature. 1970 Oct 10;228(5267):181-3
references.pmid: 4990051
references.citation: Extremophiles. 2005 Jun;9(3):219-27
references.pmid: 15844015
references.citation: Nat Biotechnol. 2000 Jan;18(1):85-90
references.pmid: 10625398
references.citation: Annu Rev Genet. 1996;30:59-78
references.pmid: 8982449
references.citation: Extremophiles. 2009 Jan;13(1):49-57
references.pmid: 18931823
references.citation: Annu Rev Microbiol. 1997;51:203-24
references.pmid: 9343349