Improvement of lysine production by analog-sensitive and auxotroph mutants of the acetylene-utilizing bacterium Gordona bronchialis (Rhodococcus bronchialis).
An acetylene utilizing Gordona (Rhodococcus) bronchialis strain, screened for the production of fine chemicals, was found to be capable of producing small amounts of lysine. Attempts to produce amino-acid analog-resistant and/or sensitive mutants and auxotrophs of this strain with increased lysine production were made following UV-irradiation or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment. The bacterium exhibited surprisingly high resistance levels to the aforementioned mutagens which is attributed to highly effective inborn-repair systems. Natural resistance to high levels of S-(2-aminoethyl)-L-cysteine (AEC) (2%) was observed, in contrast with D, L-aspartic acid hydroxamate (AAH), L-lysine hydroxamate (LHX) and beta-fluoropyruvate (FP). A variety of amino-acid analog-resistant (AAHr, LHXr) or analog-sensitive (FPs) mutants were produced following UV-irradiation or MNNG treatment. Similarly, a large number of auxotrophs (68) of different types were also obtained. From these, one FPs mono-auxotroph and two poly-auxotrophs (with at least one requirement for the aspartic acid family) showed an increased lysine production (approximately 1.8 g/L) comparable (4 g/L) to that found in other bacteria capable of utilizing long-chain hydrocarbons (1).
Kyriacou
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A
Laboratory of General and Agricultural Microbiology, Department of Agricultural Biology and Biotechnology, Athens, Greece.
Balis
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C
Typas
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MA
D000114:Acetylene / Q000378:metabolism*; D001216:Asparagine / Q000031:analogs & derivatives / Q000494:pharmacology; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D008239:Lysine / Q000031:analogs & derivatives / Q000096:biosynthesis* / Q000494:pharmacology; D009154:Mutation; D011773:Pyruvates / Q000494:pharmacology; D012240:Rhodococcus / Q000378:metabolism*
D011773:Pyruvates; C024848:beta-aspartylhydroxamic acid; C039763:lysine hydroxamate; C000204:S-2-aminoethyl cysteine; D001216:Asparagine; D008239:Lysine; D003545:Cysteine; D000114:Acetylene