Classical mutagenesis

However, one should keep in mind that by classical mutagenesis of seeds, poppy plants were obtained which produced 3% thebaine instead of morphine and codeine, providing a simple supply of thebaine [115]. 

Production strains, established through classical mutagenesis and screening to produce metabolites at a commercial level, were often started from strains known to overproduce at least some amount of the desired product. These strains had already overcome some of the natural regulation to keep from overproducing metabolites. However, this often led to strains that could overproduce more than one endproduct. To maximize production of the... 

Excluding classical mutagenesis and selection on solid media, there are several reports on evolutionary engineering of simple cellular subsystems with an applied background. For example, experiments were performed with an E. coli strain that produced an aromatic compound and carried a deletion of the phosphotransferase system (PTS) for glucose uptake. Spontaneous glucose revertants were selected that apparently utilized a non-PTS system for glucose uptake... 

The best pyridoxine production process reported so far is based on the a-proteobacterium S. meliloti IF014782, a natural pyridoxine overproducer. A derivative of IF014782 obtained by classical mutagenesis and overexpressing PdxJ and Epd provided 1.3 gl pyridoxine [348], which is still too low to beat the chemical processes. 

In a follow-up study, we used a similar classical mutagenesis approach to isolate cerulenin-resistant mutants from the Maurivin PDM strain that produce significantly lower amounts of acetic acid during fermentation (Cordente, Cordero-Bueso, Pretorius, Curtin, 2013). Acetic acid, a by-product formed during yeast alcoholic fermentation,... 

In addition to optimizing fermentation parameters, fungal strain improvement and selection, either by classical mutagenesis or more sophisticated targeted molecular genetic approaches, are important research avenues to increase productivity and yield of industrial fermentations (Ruijter et al, 2002). 

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