Study On Production Of Mannitol By Leuconostoc Using Brown Sugar And Sugar Cane Juice As Raw Material

Mannitol is a kind of sugar alcohol with six carbon atoms existing in nature widely, which is mainly used in food, medicine and chemical industries. Compared with catalytic hydrogenation method, microbial transformation for production of mannitol has obvious advantages, such as mild reaction conditions, without sorbitol, and so on. Leuconostoc strain is a kind of heteromorphosis lactic acid bacteria of Gram-positive, which is generally regarded as safe organisisms by the U.S. FDA. Leuconostoc mesenteroides can produce several functional carbohydrates, such as mannitol, and so on.Effects of fermentation period, brown sugar, inoculation amount, initial pH, yeast extract, K2HPO4, MgSO4·7H2O, ammonium citrate, sodium acetate on production of mannitol by L. mesenteroides CGMCC 1.10327 using brown sugar as carbon source were respectively investigated. The results showed that when concentration of brown sugar in the medium was 90 g/L and fermentation period was 20 h, mannitol had the highest yield of 33.0 g/L. It was conductive to production of mannitol when inoculation amount was 1 % and initial pH of medium was 6.0. Amount of yeast extract added to medium was optimized and the best concentration was 2 g/L. Amount of K2HPO4, MgSO4·7H2O, ammonium citrate, sodium acetate were optimized and the best concentration were 2 g/L, 2 g/L, 5 g/L, 2 g/L. Medium supplemented with amino acids helped to raise production of mannitol. It was conductive to production of mannitol when medium was respectively supplemented with 0.01 g/L alanine, 0.005 g/L glycine and 0.015 g/L valine. Orthogonal test design of three factors and three levels was conducted, when valine, alanine, glycine were chosen as experimental factors. The best combination were 0.015 g/L valine, 0.01 g/L alanine, 0.005 g/L glycine and production of mannitol was 37.8 g/L.Effects of fermentation time, temperature, initial pH, yeast extract, brown sugar, glycine, ammonium citrate, ammonium chloride, ammonium nitrate on production of mannitol by L. mesenteroides CGMCC 1.10327 using sugar cane juice as medium were respectively investigated. The results showed that when sugar cane juice was used as medium and fermentation period was 24 h, mannitol had the highest yield of 29.7 g/L. It was conductive to production of mannitol when temperature was 30 °C and initial pH was 6.8. When medium was supplemented with 0.2 g/L yeast extract, prodution of mannitol was 30.5 g/L. When medium was supplemented with 2.50 g/L brown sugar, production of mannitol was 34.0 g/L. Amount of glycine, ammonium citrate, ammonium chloride, ammonium nitrate were optimized and the best concentration were 0.01 g/L, 1.5 g/L, 2.50 g/L, 0.75 g/L. Orthogonal test design of three factors and three levels was conducted and brown sugar, glycine and ammonium nitrate were chosen as experimental factors. The best combination was 2.50 g/L brown sugar, 0.01 g/L glycine and 0.75 g/L ammonium nitrate and production of mannitol was 34.2 g/L.In this paper, production of mannitol by L. mesenteroides using brown sugar and sugar cane juice is studied for the purpose of lowering fermentation medium and compostion of medium is optimized. It provides a low-cost method for industrial production by microbial transformation.