Lactic acid from bacteria fermentation

Lactic acid bacteria have the property of producing lactic acid from sugars by a process called fermentation. The genera bacillus, leuconostoc, pediococcus and streptococcus are important members of this group. The taxonomy of lactic acid bacteria has been based on the gram reaction and the production of lactic acid from various fermentable carbohydrates. 

In discussing the studies of Brechot et al. (24) and Peynaud et al. (25), Kunkee (I) found it odd that bacteria which ordinarily produce d or DL-lactic acid from glucose produce L-lactic acid in wine as a result of malo-lactic fermentation. Peynaud et al. (26) reported that organisms which produced only D-lactic acid from glucose produced only L-lactic acid from L-malic acid. He postulated further that the malo-lactic fermentation pathway has no free pyruvic acid as an intermediate because the optical nature of L-malic acid would be lost when it was converted to pyruvic acid since pyruvic acid has no asymmetric carbon atom. Therefore, if pyruvic acid were the intermediate, one would expect d, l, or DL-lactic acid as the end product whereas L-lactic acid is always obtained. These results lend considerable support to the hypothesis that free pyruvic... 

You can tiy working the other way, from the configurational label to the structure. Take lactic acid as an example. Lactic acid is produced by bacterial action on milk it s also produced in your muscles when they have to work with an insufficient supply of oxygen, such as during bursts of vigorous exercise. Lactic acid produced by fermentation is often racemic, though certain species of bacteria produce solely (R)-lactic acid. On the other hand, lactic acid produced by anaerobic respiration in muscles has the S configuration. 

The fermentative production of lactic acid from carbohydrates has repeatedly been reviewed recently [36, 41, 42]. Two classes of lactic acid producers are discerned the homofermentative lactic acid bacteria, which produce lactic acid as the sole product, and the heterofermentative ones, which also produce ethanol, acetic acid etc. [43]. Recently, the focus has been on (S)-L-lactic acid producing, homofermentative Lactobacillus ddbrueckii subspecies [42]. 

Persson A, Jonsson A-S, and Zacchi G. Separation of lactic acid-producing bacteria from fermentation broth using a ceramic microfiltration membrane with constant permeate flow. Biotechnol. Bioeng. 2001 72(3) 269-277. 

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 ... 

In addition to lactic acid producing bacteria, a few mycelial molds belonging to Rhizopus are good lactic acid producers. The ability of Rhizopus to produce only L-(-I-)-lactic acid aerobically under nitrogen-limited environments has been studied [25-28]. Compared to bacterial fermentation, Rhizopus requires only inorganic salts. In addition, Rhizopus cultures are more tolerant to a low pH environment. Consequently, pH maintenance is not as stringent as bacterial culture during lactic acid fermentation. Furthermore, Rhizopus molds are amy-lolytic that can produce lactic acid from starchy materials directly. For example, R. oryzae NRRL 395 was used to ferment starch derived from barley, cassava, corn, oat, and rice to L-lactic acid [25]. 

The cream used for butter may be fresh ( pH 6.6) or ripened (fermented pH 4.6), yielding sweet-cream and ripened cream (lactic) butter, respectively. Sweet-cream butter is most common in English-speaking countries but ripened cream butter is more popular elsewhere. Traditionally, the cream for ripened cream butter was fermented by the natural microflora, which was variable. Product quality and consistency were improved by the introduction in the 1880s of cultures (starters) of selected lactic acid bacteria, which produce lactic acid from lactose and diacetyl (the principal flavour component in ripened cream butter) from citric acid, A flavour concentrate, containing lactic acid and diacetyl, is now frequently used in the manufacture of ripened cream butter, to facilitate production schedules and improve consistency. 

Homofermentative lactic acid bacteria (such as Lactococcus lactis and Streptococcus lactis) produce (-l-)-L-lactic acid (e.g. in sour cream). Both isomers, (-l-)-L-lactic acid and (-)-D-lactic acid (8-65), are formed during milk fermentation by heterofermen-tative bacteria (lactic acid bacteria are mostly heterofermentative bacteria) and lactic acid thus also occurs as a racemate in sauerkraut, pickled cucumbers, olives and silage. For example, bacteria of the genus Leuconostoc produce d-lactic acid, while bacteria Pediococcus acidilactici and other bacteria produce racemic lactic acid. The content of lactic acid in dairy products is 0.5-1.0%. L-Lactic acid in yoghurt represents about 54% and in sour cream 96% of the total lactic acid content. The total lactic acid content in sauerkraut is 1.5 2.5%, in fermented cucumbers it ranges from 0.5 to 1.5% and fermented green olives contain 0.8 to 1.2% lactic acid. 

Two species of Lactobacillus that utilize starch as a substrate are listed inO Table 1.8. Although starch is not normally utilized by lactic acid bacteria, two species, L. amylophilus (Mercier et al. 1992) and L. amylovorus (Cheng et al. 1991 Zhang and Cheryan 1994), have been isolated and are able to produce a high yield of lactic acid from liquefied starch in experimental fermenters. 

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