GABA accumulation in response to different nitrogenous compounds in unicellular cyanobacterium Synechocystis sp. PCC 6803

Curr Microbiol. 2015 Jan;70(1):96-102. doi: 10.1007/s00284-014-0687-4. Epub 2014 Sep 12.


GABA accumulation and glutamate decarboxylase (GAD) activity, the principal enzyme involved in GABA formation, was investigated in cyanobacterium Synechocystis sp. PCC 6803 wild-type (WT) and gad knockout mutant strains grown in medium containing different nitrogenous compounds. Nitrate was the best nitrogen source for GAD activity and GABA accumulation followed by nitrite, ammonium, and urea. An increase in the accumulation of GABA was observed in WT and mutant cells grown for 24 h in medium supplemented with 0.5 mM putrescine or spermidine with a parallel increase in GAD activity. The mutant could not accumulate GABA at all the conditions tested except when supplemented with putrescine or spermidine, where high GABA levels were observed in both WT and mutant strains. Glutamate supplementation up to 10 mM for 24 h resulted in a significant increase in both GAD activity and GABA content. Overall results suggested that optimization of nitrogen source and nitrogenous compounds supplementation was effective for the enhancement of GABA accumulation in Synechocystis.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Gene Expression Regulation, Bacterial
  • Glutamate Decarboxylase / genetics
  • Glutamate Decarboxylase / metabolism
  • Nitrogen / metabolism
  • Nitrogen Compounds / metabolism*
  • Putrescine / metabolism
  • Spermidine / metabolism
  • Synechocystis / enzymology
  • Synechocystis / genetics
  • Synechocystis / metabolism*
  • gamma-Aminobutyric Acid / biosynthesis*


  • Bacterial Proteins
  • Nitrogen Compounds
  • gamma-Aminobutyric Acid
  • Glutamate Decarboxylase
  • Nitrogen
  • Spermidine
  • Putrescine