L. casei

In the case of xylitol efflux in L. casei, is the only route for xylitol transport. 

Fig. 13.2 Cellular morphology of Lactobacillus (L. delbrueckii subsp. bulgaricus and L. casei), Streptococcus thermophilus and Bifidobacterium sp.

Recently, radioassay methods have been refined to measure folates in biological samples. These techniques use radioactively labeled folates and competitive protein binding.80 Johnson et al.81 compare this method with traditional microbiological assay with L. casei. 

The assay for pantothenic acid in whole blood, serum, urine, and cerebrospinal fluid is described here. Lactobacillus plantarum ATCC No. 8014 (formerly L. arabinosus) is used for the assay. The basal medium for assay (Table 2) is made up in double strength 2.5-ml portions of the medium are distributed into 10-ml borosilicate micro-Fembach flasks provided with aluminum caps (H18). Solutions to be assayed are added and distilled water used to bring the volume to 5 ml. The techniques for maintenance and assay are the same as those for L. casei (B12). Full growth at 37° takes 3 days. 

The organism is L. casei ATCC No. 7469. The basal medium (J6) has been modified it contains twice the concentration listed in Table 10a, and is stable when stored in an amber bottle in the cold. It is kept free from contamination with a volatile preservative. L. casei was maintained in medium given in Table 10b 10 ml of this medium is dispensed into screw-capped tubes and autoclaved for 30 minutes at 118°, 16 psi. It should be transferred every 2 weeks one drop of an 18-hour culture into 10 ml of maintenance medium suffices with subsequent 18-hour incubation at 37°. Cultures should be stored at 4°. 

Because of the multiplicity of folic acid factors reported in whole blood (Ul), the microbiologic assay for folic acid in whole blood and serum was regarded as valueless (C2, L8, W9) results based on S. faecalis methods (C2, C3) did not contradict this view. Streptococcus faecalis is inferior to L. casei in its utilization of the PGA polyglutamates... 

H20, S7). In fact, the ability to utilize PGA polyglutamates may be responsible for the superiority of L. casei over S. faecalis. 

The L. casei method described here can also be used to determine absorption of folic acid. Five milligrams of folic acid is given by mouth samples are obtained at 0, 2, 4, 6, and 8 hours. In cases of deficient folic acid absorption, normal peak levels are not obtained in the malabsorption syndrome, a flat curve indicates no absorption. Normal peak levels are maintained during 2-4 hour intervals (B3). 

This data shows a noticeable drop in binding affinity for trimethoprim and chicken liver DHFR. Figure 8 illustrates steric interaction between the 5-OMe of trimethoprim (green) with the sidechain of Tyr 31 of native chicken liver DHFR (red). There is no steric interaction seen between the 5-OMe of trimethoprim (green) and the sidechain of Phe 30 of L. casei DHFR (red). (Right view chicken liver DHFR Left View L. casei DHFR) It is known from x-ray crystallographic results that the sidechain of Tyr 31 of chicken liver DHFR rotates to accommodate trimethoprim. ( ... 

The NADH-forming activity described here is different from the classical malic enzyme activity found by London et al. (95) in Lacto-badUus casei. In their system, NADH is a major end product and detectable by spectrophotometry while lactic acid is only a minor product. L. casei uses malic acid as an energy source with carbon dioxide, acetate, and ethanol as the main fermentation products. The optimal pH... 

Antibacterial Spectrum. Hawley reported that various species and strains of the genera Staphylococcus, Streptococcus, Neisseria, Bacillus, Clostridium, and Corynebacterium are inhibited by nisin (Hawley 1957A, B). Mattick and Hirsch (1947) added actinomycetes, pneumococci, mycobacteria, and Erysipelothrix to this list. The nisin concentration required for complete inhibition is organism specific and ranges from 0.25 to 500 units per milliliter. Inhibition of L. casei by antibiotics from S. lactis and S. cremoris was observed by Baribo and Foster (1951). Inhibition of Propionibacterium by nisin but not of coliform bacteria was reported by Galesloot (1957). 

Laboratory-scale experiments which used L. casei symbiotically with Propionibacterium freudenreichii in the fermentation of whey gave an average yield of 2.2 mg of vitamin per liter the maximum was 4.3 mg/liter. Production of vitamin Bi2 is not species-specific. All species of Propionibacterium, when cultivated under the same conditions, produce active substances, but in different quantities. P freudenreichii and P zeae synthesized sufficient quantities to warrant their consideration for commercial exploitation. Because propionic acid bacteria are active during Swiss cheese ripening, it was anticipated, and actually demonstrated, that production of vitamin Bi2 in Swiss cheese is influenced by the same factors that influence its production in pure culture, particularly by the cobalt content of milk (Hargrove and Leviton 1955). 

Because of its significance in cancer therapy and its small size, dihydrofolate reductase is one of the most studied of all enzymes. Numerous NMR studies385 387 and investigations of catalytic mechanism and of other properties388 have been conducted. Many mutant forms have been created 389-391 For example, substitution of Asp 27 (Asp 26 in L. casei) of the E. coli... 

Lactic Fermentation—in which lactic acid is produced. This is an important fermentation for the preservation of food. Ixtclohacillits bitlgaricus. L, casei. and Streptococcus lartis are used for the manufacture of dairy products, such as sour cream. Lactobacillus plunlariim is used in lhe preservation of certain vegetables, such as the production of pickles and kraut. 

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