Mercury tolerance of thermophilic Bacillus sp and Ureibacillus sp

Kerry Glendinning, Lynne Macaskie, Nigel Brown

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Although resistance of microorganisms to Hg(II) salts has been widely investigated and resistant strains have been reported from many eubacterial genera, there are few reports of mercuric ion resistance in extremophilic microorganisms. Moderately thermophilic mercury resistant bacteria were selected by growth at 62 degrees C on Luria agar containing HgCl2. Sequence analysis of 16S rRNA genes of two isolates showed the closest matches to be with Bacillus pallidus and Ureibacillus thermosphaericus. Minimum inhibitory concentration (MIC) values for HgCl2 were 80 mu g/ml and 30 mu g/ml for these isolates, respectively, compared to 10 mu g/ml for B. pallidus H12 DSM3670, a mercury-sensitive control. The best-characterised mercury-resistant Bacillus strain, B. cereus RC607, had an MIC of 60 mu g/ml. The new isolates had negligible mercuric reductase activity but removed Hg from the medium by the formation of a black precipitate, identified as HgS by X-ray powder diffraction analysis. No volatile H2S was detected in the headspace of cultures in the absence or presence of Hg2+, and it is suggested that a new mechanism of Hg tolerance, based on the production of non-volatile thiol species, may have potential for decontamination of solutions containing Hg2+ without production of toxic volatile H2S.
Original languageEnglish
Pages (from-to)1657-1662
Number of pages6
JournalBiotechnology Letters
Volume27
Issue number21
DOIs
Publication statusPublished - 1 Nov 2005

Keywords

  • Ureibacillus sp.
  • thermophilic bacilli
  • Bacillus sp.
  • mercury resistance

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