Background: The development of bio-based production leads to an increasing demand for rapid engineering of multiple complex phenotypes into a single production host. The approach of genome shuffling is providing a powerful platform for improving multiple complex phenotypes in ill-characterized hosts.

Objectives: The main objectives of this study were to improve acid tolerance and lactic acid production from Lactobacillus rhamnosus through genome shuffling.

Methods: In the present study, the genome shuffling was used to improve the acid tolerance of while simultaneously enhancing lactic acid production. A total of 10 yoghurt samples were randomly collected in sterilized glass bottles from farmers directly and were processed immediately for isolation of the lactic acid bacteria. The isolated 5 strains of Lactobacillus rhamnosus treated for adaptation of Low pH. Adapted wild-type strain in pH 4.0 medium was then used as the parental, or starter, for genome shuffling. All the isolated Lactobacillus rhamnosus strains were mutagenized using nitrosoguanidine (NTG) while genome shuffling was carried out using standard method. From the results, it was observed that, the mutants showed a small increase, from 6.1 to 11.2 g/l, in production of l-lactic acid in comparison with the Wild type strain.

Conclusions: In conclusion, genome shuffling successfully improved the tolerance of L. rhamnosus towards acid. The research here demonstrated that genome shuffling could greatly accelerate the improvement of important phenotypes of microorganisms by developing their ability to circumvent the extreme process condition.