Screening techniques, mutants

Montenecourt and Eveleigh (37), using a special agar screening technique, have also isolated a cellulase enhanced mutant (NG-14). They suggest, however, that the cellobiohydrolase and the endoglucanase biosynthesis are regulated by different controls. They base this assumption on data for the relative ratios of cellulases obtained from this mutant needed to hydrolyze different substrates. 

Illustrative Mutants of T. reesei Isolated Utilizing These Selective Screening Techniques... 

Utilizing these screening techniques roughly 800,000 colonies have been screened and approximately 100 mutants have been isolated. Complete characterization of these mutants is a slow and tedious process. 

A recently introduced technique that also targets the phenotype is whole genome shuffling. This latter approach involves the amplification of the genetic diversity within a population through genetic recombination [19, 20]. Next, similar to the traditional procedure, the newly created library is screened for mutants with the desired properties. Its main advantage is that improvement is much faster than is possible with classical mutation and selection as described above. 

The development of an agar plate screening technique has allowed the isolation of a range of mutants of Trichoderma reesei capable of biosynthesizing cellulase under conditions of high catabolite repression. Commercial aspects of the production and isolation of hyper-cellulase-producing mutants of T. reesei were discussed. 

The development of an agar plate screening technique has allowed the isolation of a range of mutants of Trichoderma reesei capable of biosynthesizing... 

The first report of a specific screening technique designed to search for p-lactam antibiotic-producing cultures was described by Kitano et al. (1975). A mutant of Pseudomonas aeruginosa highly and specifically sensitive to p-lactam antibiotics was isolated. A similar mutant strain of Escherichia coli highly sensitive to p-lactam antibiotics was used in the detection of nocardicins (Aoki et al., 1976). 

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