Extremely alkaline (pH > 12) ground water hosts diverse microbial community

George S. Roadcap, Robert A. Sanford, Qusheng Jin, José R. Pardinas, Craig M. Bethke

Research output: Contribution to journalArticlepeer-review


Chemically unusual ground water can provide an environment for novel communities of bacteria to develop. Here, we describe a diverse microbial community that inhabits extremely alkaline (pH > 12) ground water from the Lake Calumet area of Chicago, Illinois, where historic dumping of steel slag has filled in a wetland. Using microbial 16S ribosomal ribonucleic acid gene sequencing and microcosm experiments, we confirmed the presence and growth of a variety of alkaliphilic β-Proteobacteria, Bacillus, and Clostridium species at pH up to 13.2. Many of the bacterial sequences most closely matched those of other alkaliphiles found in more moderately alkaline water around the world. Oxidation of dihydrogen produced by reaction of water with steel slag is likely a primary energy source to the community. The widespread occurrence of iron-oxidizing bacteria suggests that reduced iron serves as an additional energy source. These results extend upward the known range of pH tolerance for a microbial community by as much as 2 pH units. The community may provide a source of novel microbes and enzymes that can be exploited under alkaline conditions.

Original languageEnglish (US)
Pages (from-to)511-517
Number of pages7
JournalGround Water
Issue number4
StatePublished - Jul 2006

ASJC Scopus subject areas

  • Water Science and Technology
  • Computers in Earth Sciences


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