Mannitol 2-dehydrogenase activity at different growth phases in Lactobacillus reuteri CRL 1101

ORTIZ, M.E.; BLECKWEDEL J.; RAYA R.R.; MOZZI F.

Mendoza

Congreso; XLVIII Reunión Científica Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2012

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Mannitol is a sugar alcohol used in food, chemical, and pharmaceutical industries. Microbial mannitol production is being investigated as an alternative approach to the current industrial chemical production. Lactic acid bacteria, particularly Lactobacillus, are efficient mannitol producers in presence of fructose through mannitol 2-dehydrogenase (MDH) enzyme activity. In this work, the highest MDH activity (3.94 U/mg protein) was observed in Lactobacillus reuteri CRL1101 log phase cells (8 h) grown under agitated conditions in MRS broth (glucose 2%, w/v) supplemented in lag phase with fructose (5%, w/v). Although in these conditions, mannitol production (16.4 g/l) was higher than those in static culture (10.4 g/l), the highest mannitol production (40.3 g/l) was obtained in the static culture after 72 h. The CRL1101 mdh gene (99% identity with mdh of L. reuteri ATCC 53608 and L. reuteri; GenBank: AAS55855.1 and ABF06654.1, respectively) and a putative transcriptional regulator gene that might be related to its regulation were amplified by using specific primers designed from Lreu_1860 and Lreu_1859 of ATCC53608 strain. The structural genes and potential promoter and terminator sequences have been identified. Although L. reuteri CRL1101 are recalcitrant to electroporation, the potential isolation of mdh mutants, using pJP042 and p29cat232Small plasmids, is currently being evaluated.