Mannitol bacteria

Fom- title compounds, 5-deoxy KDG Me estw, 5-epi KDG Me ester, 4-0-Me KDG Me ester and 4-deoxy KDG Me ester were prepared either from D-glucono-l,5-lactone or from 1,2 5,6 di-O-isopropylidene-D-mannitol. Biological tests perfcHined rat these molecules have shown that the compounds modified on the C-5 position (5-deoxy KDG Me ester and 5-epi KDG Me ester) are gratuitous inducers of the e>q>ression of pectinase genes in the phytopathogenic bacteria Erwinia Chrysanthemi when the C-4 modified molecules (4-0-Me KDG Me ester and 4-deoxy KDG Me ester) are not inducers. 

Osmotic laxative effects are also produced by the polyhydric alcohols, mannitol and sorbitol, which unlike glucose cannot be transported through the intestinal mucosa, as well as by the non-hydrolyzable disaccharide, lactubse. Fermentation of lactulose by colon bacteria results in acidification of bowel contents and microfloral damage. Lactulose is used in hepatic failure in order to prevent bacterial production of ammonia and its subsequent absorption (absorbable NH3 nonabsorbable NH4+), so as to forestall hepatic coma. 

More than seventy years ago the impressive discovery was made that bioreduction of mannitol, glycerol and starch yields butanol. Fermentations in which butyric acid, butanol and acetone are formed from carbohydrates by different bacilli (butyl bacteria) belong in this group. The term butyl bacteria as a generic name for microbes producing the genetically related substances of the four-carbon series was proposed in 1921" and has been applied since then. The approximate course of these reactions is shown by the following formulations which, however, do not explain the mechanism ... 

Saline laxatives like MgS04, Mg(OH)2, Mg2 Citrate and Na+ Phosphates act via their osmotic pressure to retain water in the colon. Other osmotic laxatives are carbohydrates such as lactulose, glycerin, sorbitol, and mannitol. They are not absorbed and are resistant to digestion in the small intestine. Most agents are orally administered. It should be noted however that glycerin, sodium phosphates and sorbitol are formulated for rectal use. From lactulose lactic and acetic acids are formed by intestinal bacteria and apart from its osmotic effects it thus acidifies the content of the colon. The reduction of the pH stimulates motility and secretion. 

Active compounds were retested in medium containing glycerol as a carbon source. Glycerol does not require PFK for introduction into bacterial energy metabolism pathways. Compounds that were as toxic to the recombinant bacteria in the presence of glycerol as they were in mannitol could not be acting via inhibition of PFK. Conversely, compounds that are significantly more toxic in... 

Production of Mannitol by Lactic Acid Bacteria A Review... 

Mannitol production by homofermentative lactic acid bacteria 392... 

Mannitol production by heterofermrentative lactic acid bacteria 393... 

PRODUCTION OF MANNITOL BY LACTIC ACID BACTERIA A REVIEW... 

Some microorganisms can specifically produce mannitol from glucose or fructose without making a sorbitol byproduct (Smiley et al., 1967 Song et al., 2002 Wisselink et al, 2002 Saha, 2003). Mannitol, at 180g/L, can be easily recovered from the fermentation broth by cooling crystallization. Thus, research efforts have been directed toward production of mannitol by fermentation and enzymatic means (Vandamme and Soetaert, 1995). In this paper, the authors review the production of mannitol by lactic acid bacteria. 

MANNITOL PRODUCTION BY HOMOFERMENTATIVE LACTIC ACID BACTERIA... 

MANNITOL PRODUCTION BY HETEROFERMENTATIVE LACTIC ACID BACTERIA 393... 

Several heterofermentative LAB belonging to the genera Lactobacillus, Leu-conostoc, and Oenococcus can produce mannitol from fructose effectively (Saha, 2003). In addition to mannitol, these bacteria may produce lactic acid, acetic acid, carbon dioxide, and ethanol. The process is based on the ability of the LAB to use fructose as an electron acceptor and reduce it to mannitol with the participation of the enzyme mannitol 2-dehydrogenase (EC 1.1.1.38). 

Several heterofermentative LAB produce mannitol in large amounts, using fructose as an electron acceptor. Mannitol produced by heterofermentative bacteria is derived from the hexose phosphate pathway (Soetaert et al., 1999 Wisselink et al., 2002). The process makes use of the capability of the bacterium to utilize fructose as an alternative electron acceptor, thereby reducing it to mannitol with the enzyme mannitol dehydrogenase. In this process, the reducing equivalents are generated by conversion of one-third fructose to lactic acid and acetic acid. The enzyme reaction proceeds according to (theoretical) Equation 21.1 ... 

Chalfan, Y., Levy, R., and Mateles, R. 1.1975. Detection of mannitol formation by bacteria. Appl. Microbiol., 30, 476. 

Racine, E, and Saha, B. C. 2006. Fed-batch and continuous production of mannitol by a heterofermentative lactic acid bacteria. In McKeon, M., and Barton, F. II (Eds.), Proc. United States—Japan Cooperative Program in Natural Resources Food and Agriculture Panel Meeting, Sonoma, CA (pp. BT13-BT17). 

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