Global Analysis of Mannitol 2-Dehydrogenase in Lactobacillus reuteri CRL 1101 during Mannitol Production through Enzymatic, Genetic and Proteomic Approaches

ORTIZ ME; BLECKWEDEL J; FADDA S; PICARIELLO G; HEBERT EM; RAYA RR; MOZZI, F.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2017 vol. 12

1932-6203

Several plants, fungi, algae, and certain bacteria produce mannitol, a polyol derived fromfructose. Mannitol has multiple industrial applications in the food, pharmaceutical, and medicalindustries, being mainly used as a non-metabolizable sweetener in foods. Many heterofermentativelactic acid bacteria synthesize mannitol when an alternative electron acceptorsuch as fructose is present in the medium. In previous work, we reported the ability of Lactobacillusreuteri CRL 1101 to efficiently produce mannitol from sugarcane molasses as carbonsource at constant pH of 5.0; the activity of the enzyme mannitol 2-dehydrogenase(MDH) responsible for the fructose conversion into mannitol being highest during the log cellgrowth phase. Here, a detailed assessment of the MDH activity and relative expression ofthe mdh gene during the growth of L. reuteri CRL 1101 in the presence of fructose is presented.It was observed that MDH was markedly induced by the presence of fructose. Adirect correlation between the maximum MDH enzyme activity and a high level of mdh transcriptexpression during the log-phase of cells grown in a fructose-containing chemicallydefined medium was detected. Furthermore, two proteomic approaches (2DE and shotgunproteomics) applied in this study confirmed the inducible expression of MDH in L. reuteri. Aglobal study of the effect of fructose on activity, mdh gene, and protein expressions of MDHin L. reuteri is thus for the first time presented. This work represents a deep insight into thepolyol formation by a Lactobacillus strain with biotechnological potential in the nutraceuticsand pharmaceutical areas.