Métabolisme sucre-citrate chez Leuconostoc mesenteroides

Abstract

Sugar citrate cometabolism in Leuconostoc mesenteroides. Bacteria from the genus Leuconostoc play roles in the dairy industry. The most important functions of this bacteria are their ability to produce CO2 and flavour compounds through lactose heterofermentation and citrate utilization. Although the biotechnological role of the citrate metabolism is very important and widely appreciated, little is known about the genetic properties of Leuconostoc spp. In our laboratory, we cloned the genes responsible for citrate metabolism (clyR mae citCDEFGOP cluster), for D-lactate dehydrogenase (ldhD) and for phosphotransacetylase (pta). In addition we have planned to construct new vectors and we have tried to improve a method to introduce recombinant DNA molecules into Leuconostoc as well. Characterization of the plasmid involved in this study is still in progress. The nucleotide sequence analysis of p22R revealed the presence of C5 cytosine methylase gene typical of type II restriction/modification system. The low transformation efficiency of some strains of Leuconostoc may be due to the presence of that plasmid. The construction of the defective strain for restriction activity could be very useful to genetic manipulations of Leuconostoc in the future.