Biotechnological production of mannitol by Lactobacillus reuteri CRL1101 during different growth stages.

ORTIZ ME, RAYA R, MOZZI F.

Egmond aan Zee, Holanda

Simposio; 10th Symposium on Lactic Acid Bacteria. Celebrating 30 years of Lab research; 2011

Federation of European Microbiological Societies and the Nethertlands Society for Microbiology

Mannitol, a polyol produced by bacteria, yeasts, fungi, and plants, is largely used as natural sweetener in the food industry. Moreover, it has been claimed to display several health-promoting (low-caloric, low-glycemic and anticariogenic) effects. In recent years, the biotechnological production of mannitol by lactic acid bacteria (LAB) has been investigated as an alternative to the chemical industrial production. Certain heterofermentative LAB are efficient mannitol producers in the presence of fructose when it is used as an alternative electron acceptor. To evaluate the effect of the growth phase on mannitol production by Lactobacillus reuteri CRL 1101, fructose pulses (5 %, w/v) were added to different growth phase cultures (lag: 1 h, log: 6 h and stationary: 10 h). Fermentation were carried out in MRS medium supplemented with glucose, glucose:fructose or sucrose (2, 0.1:2 and 2 % w/v, respectively) during 72 h. The highest mannitol production (221 mmol l-1) was obtained when fructose was added at the lag or log phase to cultures previously grown on glucose. The addition of fructose enabled to maintain the cell viability constant throughout the fermentation. When L. reuteri CRL 1101 was grown on sucrose, an enhancement on mannitol production was observed when the fructose pulse was added at the lag or log phase; however, the amount of mannitol formed did not reach that from glucose cultures. Besides mannitol, the strain produced lactic and acetic acids. The strain could use simultaneously glucose or sucrose as energy source and fructose as alternative electron acceptor. To enhance mannitol production by L. reuteri CRL 1101 fructose should be available at either the lag or log growth phase of cultures grown in glucose or sucrose as energy source.