Lactose utilization

McKay, L. L., Miller, A., Sandine, W. E. and Elliker, P. R. 1970. Mechanism of lactose utilization by lactic acid streptococci Enzymatic and genetic analyses. J. Bacteriol. 120, 804-809. 

In exponentially growing liquid cultures, the spontaneous mutation rate to lactose utilization (lac+) is high (Table II), which may explain the early appearance of Lac+ papillae. However, neither L-gulonic acid-utilizing nor L-arabitol-utilizing mutants were ever obtained by plating liquid cultures directly onto selective media. 

Some of the earlier publications were particularly concerned with the fact that lactose is utilized faster than either of its component monosaccharides, D-glucose or D-galactose, by Kluyveromyces (Saccharomyces) fragilis,221,579 Candida pseudotropicalis (Torula cre-moris), Candida kefyr (Torula lactosa),579 and other yeasts.589 This was held to show that hydrolysis is not the first step in lactose utilization. However, after Gottschalk s critical review,222 later authors could explain these and other observations by suggesting that the /3-... 

Friedl et al [3.70] studied ABE production in an integrated process using C. acetobutylicum immobilized onto a packed bed of bonechar coupled with continuous product removal by pervaporation. Using a concentrated feed solution containing lactose at 130 g/1, a lactose utilization value of 98.7 % was observed. The PVMBR system showed low acid loss, a high solvent yield of 0.39 g solvents/g lactose utilized, and a solvent productivity of 3.5 g/1. 

Bacteria respond rapidly to changes in their environment. Genes for lactose utilization are activated once E. coli cells sense the presence of lactose or a similar compound... 

Operon composition/induction - The lactose operon consists of three linked structural genes that encode enzymes of lactose utilization, plus adjacent regulatory sites. The three structural genes—z, y, and a—encode / -galactosidase, / -galactoside permease (a transport protein), and thiogalactoside transacetylase (an enzyme of still unknown metabolic function), respectively. 

Multistabihty in the Lactose Utilization Network of Escherichia coli. 

It has also been demonstrated that culture-containing dairy products, such as sweet acidophilus milk (Lactobacillus acidophilus cells added to unfermented milk and refrigerated), may be useful in the management of lactose intolerance. Kim and Gilliland (1983) investigated the effect of added Lactobacillus acidophilus cells of human origin on lactose utilization from milk by lactose malabsorbers. Three cell levels (2.5 x 10, 2.5 x 10, and 2.5 x 10 /ml) were used. The test subjects consumed 5 ml/kg... 

Gilliland, S. E., and Kim, H. S., 1984, Effect of viable starter culture bacteria in yogurt on lactose utilization in humans, J. Dairy Scl 67 1. 

Rehberger TG and Glatz BA (1987a) Characterization of plasmid DNA in Propionibacterium freudenreichii subsp. globosum P93 evidence for plasmid-hnked lactose utilization. J Dairy Sci (Suppl 1) 70, D73... 

Let us first discuss modern concepts about the genetic regulatory systems of bacteria and phage. The basic ideas were proposed by Jacob and Monod (Jacob and Monod, 1961 Jacob and Wollman, 1962 for review see Benzer, 1963 Kumar et al., 1970 Szybalski, 1972 Ratner, 1975 Flint, 1977 Smith, 1977 Nover et al., 1978). It was demonstrated that in bacteria there are blocks of contiguous structural genes which code for specific proteins and which are assembled into functional units or operons. These units participate for instance in the regulation of the synthesis of enzymes which in turn participate in lactose utilization (Fig. 94). 

Fig. 94. Jacob and Monod s scheme of lactose utilization, z, a galactozidase gene y, permease gene ac, transacetylase gene O, operator P, promotor. (After Bresler, 1973)...

Galactose permease (M protein) activity abolished, blocking lactose utilization... 

Francl, A.L., Hoeflinger, J.L., and Mflla-, M.J. (2012) Identification of lactose phosphotransferase systems in Lactobacillus gasseri ATCC 33323 required fa- lactose utilization. Microbiology 158,944-952. 

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