Lactic acid bacteria carbohydrate metabolism

Kandler, O. (1983). Carbohydrate metabolism in lactic acid bacteria. Anton. Leeuw, 49, 209-224. 

With few exceptions, enzymatic processes in carbohydrates cause degradation. Enzymes are used in the form of pure or semipure preparations or together with their producers, i.e., microorganisms. Currently, semisynthetic enzymes are also in use. Alcoholic fermentation is the most common method of utilization of monosaccharides, sucrose, and some polysaccharides, e.g., starch. Lactic acid fermentation is another important enzymatic process. Lactic acid bacteria metabolize mono- and disaccharides into lactic acid. This acid has a chiral center thus either D(-), L(+), or racemic products can be formed. In the human organism, only the L(+) enantiomer is metabolized, whereas the D(-) enantiomer is concentrated in blood and excreted with urine. Among lactic acid bacteria, only Streptococcus shows specificity in the formation of particular enantiomers, and only the L(+) enantiomer is produced. 

Ganzle, M.G., Vermeulen, N., and Vogel, R.F. 2007. Carbohydrate, peptide and lipid metabolism of lactic acid bacteria in sourdough. Food Microbiology 24 128-138. 

HISTORY. The continuing study of thiamin as a coenzyme in carbohydrate metabolism revealed that this metabolic system required other coenzyme factors in addition to thiamin. In work with lactic acid bacteria, Reed discovered in 1951, that one of these factors is a fat-soluble acid which he named lipoic acid (after the Greek liposior fat). 

Jones RJ, Wescombe PA, Tagg JR (2011) Identifying new protective cultures and culture components for food biopreservation. In Lacroix C (ed) Protective cultures, antimicrobial metabolites and bacteriophages for food and beverage biopreservation. Woodhead, Cambridge, UK, pp 3—26 Kandler O (1983) Carbohydrate metabolism in lactic acid bacteria. Antonie Van Leeuwenhoek 49 209—224... 

The main product of anaerobic degradation of sugars by these organisms is lactic acid. Other products of bacterial carbohydrate metabolism include extracellular dextrans (see p. 40)—insoluble polymers of glucose that help bacteria to protect themselves from their environment. Bacteria and dextrans are components of dental plaque, which forms on inadequately cleaned teeth. When Ca salts and other minerals are deposited in plaque as well, tartar is formed. 

Detection of Malo-Lactic Fermentation. It is imperative that the winemaker, to control malo-lactic fermentation, has a satisfactory method for its detection. Disappearance of malic acid is the indication of the fermentation, but the formation of lactic acid is not sufficient evidence since it might also be formed by yeast and by bacteria from other carbohydrate sources. The rate of conversion of malic acid is expected to reflect bacterial metabolism and growth. In New York State wines, Rice and Mattick (41) showed bacterial growth (as measured by viable count) to be more or less exponential to 106-107 cells/ml, preceding disappearance of malic acid. The rate of loss of malic acid is probably also exponential. Malic acid seems to disappear so slowly that its loss is not detected until a bacterial population of about 106-107 cells/ml is reached then it seems to disappear so rapidly that its complete loss is detected within a few days (41). Rice and Mattick (41) also showed a slight increase in bacterial population for a few days following this. 

Salivary a-amylase is a protein that contributes to the enamel pellicle (Sect. 12.1.3). More importantly, it attaches bacteria, especially streptococci, to teeth surfaces. Thus, following a meal rich in carbohydrates, amylopectin, amylase, and glycogen are digested to maltose at the surface of many oral bacteria. The maltose is taken into the cytosol by a phosphoenolpyruvate transporter homologous to the fructose transporter of S. mutans. Within these bacteria, the maltose is digested to two molecules of glucose 6-phosphate and metabolized to lactic acid. Thus, twice as much acid is produced per mole maltose than per mole sucrose and it contributes to tooth demineralization even if less sucrose is consumed. 

Lactic add is a metabohc product of simple carbohydrates produced by many spedes of bacteria, yeasts, and mycehal fungi mainly through the fermentative metabolic pathway. The stoichiometry for homofermentative production of lactic acid from hexose can be expressed as ... 

Lactic acidosis can occur in patients with SBS and may result in symptoms of ataxia and dehrium. D-Lactic acid is produced by the fermentation of malabsorbed carbohydrates by colonic bacteria, and increased concentrations are associated with small bowel bacterial overgrowth. " The diagnosis of D-lactic acidosis should be considered in patients with a functional colon who have an unexplained metabolic acidosis and an elevated anion gap. ... 

Other approaches to the prevention of traveler s diarrhea are the use of lactobacillus preparations or bismuth subsalicylate. Lactobacilli are bacteria that metabolize dietary carbohydrate to lactic acid and other organic acids, reducing the intraluminal pH and inhibiting the growth of enteropathogens. 

Tooth decay (dental caries) is one of the most common diseases in humans [8]. It has been defined as a chronic, dietomiaobial, site-specific disease caused by a shift from protective factors favouring tooth remineralization to destructive factors leading to demineralization [9]. The specific factors leading to destruction of the mineral phase of the tooth are the presence of oral bacteria, mainly Streptococcus mutans [10], and the availability of fermentable carbohydrates from the diet. This combination leads to the production of organic acids as a result of the metabolic process of the bacteria, of which the main one is lactic acid, though other weak acids, such as ethanoic and propanoic can also occur [11]. These acids dissolve the mineral component of the tooth, leading to loss of structure. 

Many studies that characterized carbohydrate fermentation patterns applied methods that focused on utilization of single carbohydrates (Davis etal., 1988 Edwards and Jensen, 1992 Edwards etal., 1993 1998a 2000). It is therefore possible that these bacteria can metabolize glycerol to acrolein if other sugars or lactic acid are present. NADH produced as a byproduct of carbohydrate (or lactate) utilization is speculated to be reoxidized to NAD from the reduction of 3-HPA to 1,3-propandiol (Schiitz... 

Like all microorganisms, lactic bacteria cells multiply when conditions are favorable presence of nutritional factors, absence of toxic factors, and adequate temperature. All of the principal reactions of its metabolism are directed towards the biosynthesis of cellular components nucleic acids for the transmission of genetic heritage, carbohydrates, lipids, structure proteins and of course biologically active proteins. To ensure these syntheses, the cell must first find the necessary chemical elements in the medium carbon, nitrogen and minerals—in usable forms. Since aU of these synthesis reactions are endergonic, the medium must... 

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