De-regulated assimilation and over-production of amino acids in analogue-resistant mutants of a cyanobacterium, Phormidium uncinatum

N. S. Rao, T. M. Shakila, S. N. Bagchi

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Mutant strains of Phormidium uncinatum resistant to fluoro-phenylalanine, aztryptophan, fluorotyrosine and azaleucine accumulated a wide range of amino acids, notably glutamic acid, lysine, tyrosine and phenylalanine, and exhibited de-regulated valine and phenylalanine transport. While acetohydroxy acid synthase in azaleucine-resistant mutants lost valine- and leucine-sensitivity, 3-deoxy-Dxxx-arabinoheplulosonate-7-phosphate (DAHP) synthase and prephenate dehydratase in aromatic analogue-resistant strains became phenylalanine-insensitive and shikimate and prephenate dehydrogenases were activated by tyrosine. In addition, activities of nitrate-assimilating enzymes were higher in the mutants, which also exhibited increased nitrogen, protein and phycocyanin contents. The proteins in the mutants were better digested upon enzymatic-treatments and feeding trials than those of the wild type, indicating that they are usable as single-cell protein.

Original languageEnglish (US)
Pages (from-to)665-668
Number of pages4
JournalWorld Journal of Microbiology & Biotechnology
Volume11
Issue number6
DOIs
StatePublished - Nov 1 1995

Keywords

  • Amino-acid assimilation
  • Phormidium uncinatum
  • amino-acid over-production
  • cyanobacteria
  • enzyme de-regulation
  • microbial cell protein

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