Article Abstract:
Site-directed mutagenesis was used to investigate the cloning, sequencing and overexpression in Escherichia coli cells of the low-specificity L-threonine aldolase (L-TA) gene from the Pseudomonas strain NCIMB 10558, purification and characterization of the recombinant enzyme and the identification of the active-site lysine residue of the enzyme. The amino acid sequence displayed less than 20% identity with those of low-specificity L-TA from Saccharomyces cerevisiae, L-allo-threonine aldolase from Aeromonas jandaei and other hypothetical proteins from other microorganisms.
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Article Abstract:
A delta 5-desaturase-defective mutant, termed Mut44, of the fungus Mortierella alpina 1S-4 was found to exhibit high mycelial dihomo-gamma-linolenic acid (DHGA) activity. The mutant grew in a simple medium with significant DHGA productivity. Various factors affecting the DHGA production were the glucose and yeast extract concentrations and growth temperature. There were no problems, however, with the inhibitors present in oils. Most of the DHGA was present in the triglyceride fraction among lipid classes.
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Article Abstract:
A novel Mortierella alpina mutant (M209-7) derived from the delta12 desaturase-defective Mut48 strain produced greater amounts of 5,811-eicosatrienoic acid (mead acid) compared to its parent strain. The M209-7 strain was similar to Mut48 in morphology, glucose consumption, total fatty acid composition and growth. Furthermore, optimization of cultivation temperature and glucose feeding enhanced the synthesis of mead acid by the mutant Mortierella alpina M209-7 strain.
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