scholarly journals Cerebro: Static Subsuming Mutant Selection

2022 ◽  
pp. 1-1
Author(s):  
Aayush Garg ◽  
Milos Ojdanic ◽  
Renzo Degiovanni ◽  
Thierry Titcheu Chekam ◽  
Mike Papadakis ◽  
...  
Keyword(s):  
Mutant Selection

scholarly journals Allelic Exchange and Mutant Selection Demonstrate that Common Clinical embCAB Gene Mutations Only Modestly Increase Resistance to Ethambutol in Mycobacterium tuberculosis

2009 ◽  
Vol 54 (1) ◽  
pp. 103-108 ◽  
Author(s):  
Hassan Safi ◽  
Robert D. Fleischmann ◽  
Scott N. Peterson ◽  
Marcus B. Jones ◽  
Behnam Jarrahi ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
In Vitro Selection ◽  
Gene Mutations ◽  
Wild Type ◽  
Mutant Selection ◽  
Preferential Growth ◽  
Allelic Exchange ◽  
High Level ◽  
Isogenic Mutants

ABSTRACT Mutations within codon 306 of the Mycobacterium tuberculosis embB gene modestly increase ethambutol (EMB) MICs. To identify other causes of EMB resistance and to identify causes of high-level resistance, we generated EMB-resistant M. tuberculosis isolates in vitro and performed allelic exchange studies of embB codon 406 (embB406) and embB497 mutations. In vitro selection produced mutations already identified clinically in embB306, embB397, embB497, embB1024, and embC13, which result in EMB MICs of 8 or 14 μg/ml, 5 μg/ml, 12 μg/ml, 3 μg/ml, and 4 μg/ml, respectively, and mutations at embB320, embB324, and embB445, which have not been identified in clinical M. tuberculosis isolates and which result in EMB MICs of 8 μg/ml, 8 μg/ml, and 2 to 8 μg/ml, respectively. To definitively identify the effect of the common clinical embB497 and embB406 mutations on EMB susceptibility, we created a series of isogenic mutants, exchanging the wild-type embB497 CAG codon in EMB-susceptible M. tuberculosis strain 210 for the embB497 CGG codon and the wild-type embB406 GGC codon for either the embB406 GCC, embB406 TGC, embB406 TCC, or embB406 GAC codon. These new mutants showed 6-fold and 3- to 3.5-fold increases in the EMB MICs, respectively. In contrast to the embB306 mutants, the isogenic embB497 and embB406 mutants did not have preferential growth in the presence of isoniazid or rifampin (rifampicin) at their MICs. These results demonstrate that individual embCAB mutations confer low to moderate increases in EMB MICs. Discrepancies between the EMB MICs of laboratory mutants and clinical M. tuberculosis strains with identical mutations suggest that clinical EMB resistance is multigenic and that high-level EMB resistance requires mutations in currently unknown loci.

scholarly journals Enhanced production of Clavulanic acid by improving glycerol utilization using reporter-guided mutagenesis of an industrial Streptomyces clavuligerus strain

2021 ◽  
Author(s):  
Chang-Hun Shin ◽  
Hang Soo Cho ◽  
Hyung-Jin Won ◽  
Ho Jeong Kwon ◽  
Chan-Wha Kim ◽  
...  
Keyword(s):  
Clavulanic Acid ◽  
Wild Type Strain ◽  
Random Mutagenesis ◽  
Streptomyces Clavuligerus ◽  
Wild Type ◽  
Mutant Selection ◽  
Enhanced Production ◽  
Industrial Strains ◽  
Glycerol Utilization

Abstract Clavulanic acid (CA) produced by Streptomyces clavuligerus is a clinically important β-lactamase inhibitor. It is known that glycerol utilization can significantly improve cell growth and CA production of S. clavuligerus. We found that the industrial CA-producing S. clavuligerus strain OR generated by random mutagenesis consumes less glycerol than the wild-type strain; we then developed a mutant strain in which the glycerol utilization operon is overexpressed, as compared to the parent OR strain, through iterative random mutagenesis and reporter-guided selection. The CA production of the resulting S. clavuligerus ORUN strain was increased by approximately 31.3 per cent (5.21 ± 0.26 g/L) in a flask culture and 17.4 per cent (6.11 ± 0.36 g/L) in a fermenter culture, as compared to that of the starting OR strain. These results confirmed the important role of glycerol utilization in CA production and demonstrated that reporter-guided mutant selection is an efficient method for further improvement of randomly mutagenized industrial strains.

scholarly journals Improving yield and quality of recombinant proteins in Escherichia coli by stress minimisation and mutant selection

2009 ◽  
Vol 25 ◽  
pp. S244
Author(s):  
Y. Sevastsyanovich ◽  
S. Alfasi ◽  
L. Griffiths ◽  
T. Overton ◽  
J. Cole
Keyword(s):  
Escherichia Coli ◽  
Recombinant Proteins ◽  
Mutant Selection ◽  
Yield And Quality
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