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

• Published in: World journal of microbiology & biotechnology Vol. 11; no. 6; pp. 665 - 668
• Main Authors: RAO, N. S, SHAKILA, T. M, BAGCHI, S. N
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.11.1995
• Subjects: Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Fundamental and applied biological sciences. Psychology; Mission oriented research; Physiology and metabolism; Assimilation; Single cell protein; Biosynthesis; Phormidium uncinatum; Resistance; Enzymatic activity; Membrane transport; Aminoacid; Analog; Cyanobacteria; Production; Microorganism culture; Bacteria; Mutation; Biological accumulation; Application
• ISSN: 0959-3993; 1573-0972
• DOI: 10.1007/BF00361013

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.