Whole genome shuffling

Two major advances describe the construction of mutants with an apparently significantly higher probability of improved phenotype. The method involves whole-genome shuffling - with protoplast fusion - of a small number of parental strains... 

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. 

Acid-tolerant lactic acid bacteria would solve this latter problem and have indeed been obtained from screening [44] and via whole genome shuffling [45]. Alternatively, a lactate dehydrogenase gene could be inserted in a yeast, such as S. cerevisiae. These grow well at low pH and efficiently channel carbon into the glycolysis pathway under anaerobic conditions [46, 47]. Such constructs were indeed found to produce up to 55 g L-1 of lactic acid at pH 3.6 [46]. 

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