Construction and analysis of a high-CO2-requiring mutant of the cyanobacterium Anabaena sp. strain PCC7120

W. Tianfu, S. Lirong, L. Yongding

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A mutant of Anabaena sp. strain PCC7120 requiring high CO2 was generated using Tn5 mutagenesis. This is the first data for a filamentous cyanobacterium. The mutant was capable of growing at 5% CO2, but incapable of growing at air levels of CO2. Southern hybridization analysis indicated that the Anabaena genome was inserted by the transposon at one site. The apparent photosynthetic affinity of the mutant to external dissolved inorganic carbon (DIC) was about 300 times lower that of the wild type (WT), and the medium alkalization rate as well as the carboxysomal carbonic anhydrase activity of the mutant was also lower than those of the WT. When the mutant was transferred from the culture medium bubbled with 5% CO2 to higher DIC (8.4% CO2) or 1% CO2, it showed similar responses to the WT. However, aberrant carboxysomes were found in the mutant cells through ultrastructural analysis, indicating it was most probably the wrong organization of the carboxysomes that eventually led to the inefficient operation of carboxysomal carbonic anhydrase and the subsequent defectiveness of the mutant in utilizing DIC.

Original languageEnglish (US)
Pages (from-to)1077-1083
Number of pages7
JournalAustralian Journal of Plant Physiology
Issue number11
StatePublished - 2000


  • Anabaena sp. strain PCC7120
  • Apparent photosynthetic affinity
  • CCM mutant
  • Carbonic anhydrase activity
  • Carboxysomes
  • Medium alkalization rate
  • Transposon

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)


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