Serum folates in man

In an aseptic microbiological assay of folate compounds and their breakdown compounds, using Lactobacillus casei, Streptococcus faecalis, and Pediococcus cerevisiae, 4a-hydroxy-5methyl-4,5,6,7-tetrahydrofolate and 5-methyl-5,8-dihydrofolate were inactive under all conditions to all three organisms and 5-methyl-5,6-dihydrofolate was inactive unless ascorbate was present in the incubation medium, and then only to L. casei. 5-Methyltetrahydrofolate was active only for L. casei, and activity in purified samples to S. faecalis was due to trace amounts of folic acid. Analysis of S. faecalis values in the serum in normal subjects and in patients with various disorders showed that levels of 10-formyltetrahydrofolate are raised in coeliac disease, leukaemia, rheumatoid arthritis, and schizophrenia. 5-Methyltetrahydrofolate is readily absorbed by normal human subjects and by patients with pernicious anaemia but poorly absorbed by patients with coeliac disease or leukaemia. 5-Methyl-5,6-dihydrofolate was quickly absorbed by normal human subjects, being reflected by a considerably raised level of 5-methyltetrahydrofolate in serum when sodium bicarbonate was given by mouth before the 5-methyl-5,6-dihydrofolate. These higher levels were comparable to those in patients with pernicious anaemia after oral administration of 5-methyl-5,6-dihydrofolate. Oral 5-methyl-5,8-dihydrofolate and 4a-hydroxy-5-methyl-tetrahydrofolate did not appear as microbiologically active folates in the serum. The findings of this study suggest that the availability for biological utilisation of the major dietary folate compounds will depend on the amount of gastric acidity and of ascorbate in the intestinal chyme. Many may be unavailable for metabolic utilization in the body.

Folic acid metabolism in vitamin B12-deficient sheep. Effects of injected methionine on liver constituents associated with folate metabolism

1. The effects of injected l-methionine (2g every second day for 28 days) on liver folates and other constituents of liver associated with folate metabolism were studied in vitamin B(12)-deficient ewes and their pair-fed controls receiving vitamin B(12). The dose rate of methionine used was sufficient to restore almost to normal the elevated excretion in the urine of formiminoglutamate in the deficient animals. 2. Liver folates active for Lactobacillus casei, Streptococcus faecalis R and Pediococcus cerevisiae were severely depressed in deficient livers and were partly restored by methionine. Analysis of the folates after ion-exchange chromatography showed that the major effect of methionine was to increase the concentrations of tetrahydrofolates and formyltetrahydrofolates. Methyltetrahydrofolates were also increased, but there was no effect of methionine on the small amounts of incompletely reduced folates present in deficient livers. The folates present were predominantly penta-, hexa- and hepta-glutamates whether or not animals received vitamin B(12) or methionine. 3. Concentrations of ATP, NAD(+), NADH and NADPH were lower in freeze-clamped liver from vitamin B(12)-deficient sheep than in liver from pair-fed, vitamin B(12)-treated sheep. These changes were not affected by methionine which was also without effect on the elevated K(+)/Na(+) ratios found in deficient livers. 4. The livers of vitamin B(12)-deficient animals contained lower concentrations of choline and higher concentrations of lipid than their pair-fed controls. These effects were reversed by methionine.

Rapid transfer of folic acid from blood to bile in man, and its conversion into folate coenzymes and into a pteroylglutamate with little biological activity

1. [3H]Folic acid infused intravenously into patients with biliary fistulae appeared promptly in bile, coincident with 131I-labelled Rose Bengal injected simultaneously. The radioactivity was distributed among several fractions of biological folates present in bile and was associated with folic acid and with an unidentified folate which chromatographed on DEAE-Sephadex close to 10-formyltetrahydrofolyl monoglutamate.

2. Based on affinity for DEAE-Sephadex and support of growth of Lactobacillus casei, Streptococcus faecalis and Pediococcus cerevisiae, we have tentatively identified some of the folates of human bile as 10-formyltetrahydrofolate, 10-formylfolate, 5-formyltetrahydrofolate, 5-methyltetrahydrofolate and tetrahydrofolate or 5,10-methylene tetrahydrofolate. After infusion of folic acid, the formyltetrahydrofolates increased more rapidly than did 5-methyltetrahydrofolate.

3. The unidentified radioactive folate contained both the pteridine and p-aminobenzoate portions of folate. It appeared not to support growth of the test microorganisms and not to be bound to a protein or a chain of γ-glutamates. It was present in the bile of a dog injected with [3H]folic acid but was absent from extracts of liver. This material may be a transport form of folate or a special modification imposed on folic acid during transport across the liver.

Identification and measurement of the folates in sheep liver

1. Methods are described for the extraction, separation by ion-exchange chromatography and estimation by microbiological assay of the folates in sheep liver. 2. Injection of [2-(14)C]-pteroylglutamate into a sheep fed on a stock diet led to extensive labelling of chromatographically separable liver folates. About 12% of the label in the liver could not be extracted by the method used. 3. Liver folates were examined in five ewes fed on restricted amounts of a diet of wheaten hay-chaff and gluten and injected weekly with vitamin B(12). Chromatographic separation was followed by microbiological assay with Lactobacillus casei, Streptococcus faecalis R. and Pediococcus cerevisiae both before and after treatment of fractions with conjugase (gamma-glutamylcarboxypeptidase). Evidence was obtained that the folates present were predominantly polyglutamate forms of tetrahydropteroylglutamate, 5-methyltetrahydropteroylglutamate and 5- (and 10-) formyltetrahydropteroylglutamates. Differences in the responses of the assay organisms permitted quantitative distinction between these three main classes of folates. 4. Methyltetrahydrofolates were eluted in seven successive peaks that were separated by constant increments in the logarithm of eluant [P(i)]. A similar relationship existed for seven successive peaks of tetrahydrofolate and may also have existed for each of the two series of formyltetrahydrofolates. 5. Based on these and other observations it is proposed that sheep liver folates consist predominantly of the mono- to hepta-glutamates of each of the reduced pteroates identified. The methods employed allowed quantitative determinations to be made of most of the folates present. The predominant forms were hexaglutamates. 6. Four components active for L. casei were detected that could not be identified. Three of them were polyglutamates.

Folic acid metabolism in vitamin B12-deficient sheep. Depletion of liver folates

1. Metabolism of folate was studied in six ewes in an advanced state of vitamin B(12) deficiency as judged by voluntary food intake and in their pair-fed controls receiving vitamin B(12). A group of four animals that were maintained throughout the experiment at pasture was also studied. 2. After 34-40 weeks on the cobalt-deficient diet urinary excretion of formiminoglutamate by four deficient animals was about 3.2mmol/day and this was not significantly decreased by injection of three of them with about 4.5mug of [2-(14)C]folate/kg body weight per day for 5 days. Three days after the last injection retention of [2-(14)C]folate by the livers of the deficient animals (5.5% of the dose) was lower than that of their pair-fed controls (26% of the dose) but there was no evidence of net retention of injected folate in the livers of either group. Urinary excretion of (14)C indicated that renal clearance of folate may have been impaired in very severe vitamin B(12) deficiency. 3. As estimated by microbiological assays total folates in the livers of animals at pasture (12.9mug/g) included about 24% of 5-methyltetrahydrofolate as compared with about 72% of a total of 12.5mug/g in three further ewes fed on a stock diet of wheaten hay-chaff and lucerne-chaff. Liver folates of vitamin B(12)-deficient animals (0.5mug/g) included about 88% of 5-methyltetrahydrofolate as compared with about 51% of a total of 5.2mug/g in pair-fed animals treated with vitamin B(12). 4. Chromatography of liver folates of the pair-fed animals permitted quantitative estimates of the pteroylglutamates present. The results showed that the vitamin B(12)-deficient livers were more severely depleted of tetrahydrofolates and formyltetrahydrofolates than of methyltetrahydrofolates and that as the deficiency developed they were more severely depleted of the higher polyglutamates than of the monoglutamate within each of these classes. Results from animals injected with [2-(14)C]folate indicated an impairment of the exchange between pteroylmonoglutamates and pteroylpolyglutamates in the livers of deficient animals. 5. In vitamin B(12)-deficient animals with food intakes below 200g/day some of the liver folates were not completely reduced and some degradation of pteroylpolyglutamates was detected. The latter condition may have been associated with fatty liver. 6. The results are discussed in relation to current theories of vitamin B(12)-folate interactions.

Regulation of C metabolism by L-methionine in Saccharomyces cerevisiae

1. The concentrations of folate derivatives in aerobic cultures of Saccharomyces cerevisiae (A.T.C.C. 9763) were determined by microbiological assay employing Lactobacillus casei (A.T.C.C. 7469) and Pediococcus cerevisiae (A.T.C.C. 8081). Cells cultured in media lacking l-methionine contained higher concentrations of folate derivatives than cells grown in the same media supplemented with 2.5mumol of l-methionine/ml. The concentrations of highly conjugated derivatives were also decreased by supplementing the growth medium with l-methionine. 2. DEAE-cellulose column chromatography of extracts prepared from cells grown under these conditions revealed that the concentrations of methylated tetrahydrofolates were drastically decreased by the methionine supplement. Smaller decreases were also observed in the concentrations of formylated and unsubstituted derivatives. 3. The concentrations of four enzymes of C(1) metabolism were compared after 6h of growth in the presence and in the absence of l-methionine (2.5mumol/ml). The specific activities of formyltetrahydrofolate synthetase, methylenetetrahydrofolate reductase and serine hydroxymethyltransferase were not altered by this treatment but that of 5-methyltetrahydrofolate-homocysteine methyltransferase was decreased by approx. 65% when l-methionine was supplied. The activities of 5-methyltetrahydrofolate-homocysteine methyltransferase, serine hydroxymethyltransferase and formyltetrahydrofolate synthetase were not appreciably altered by l-methionine in vitro. In contrast this amino acid was found to inhibit the activity of methylenetetrahydrofolate reductase. 4. Feeding experiments employing sodium [(14)C]formate indicated that cells grown in the presence of exogenous methionine, although having less ability to convert formate into methionine, readily incorporated (14)C into serine and the adenosyl moiety of S-adenosylmethionine. 5. It is suggested that exogenous l-methionine controls C(1) metabolism in Saccharomyces principally by regulation of methyl-group biogenesis within the folate pool.

The formation of rhizopterin and formylated folate polyglutamates during the growth of Staphylococcus epidermidis

The distribution of various folate forms during the growth of Staphylococcus epidermidis is described. Cellular-free folate activity (pteroate-like substances and mono- and di-glutamate folates) was quite prevalent in the early and mid-log phase of growth, but subsequently reached a minimal level in the stationary phase of growth. This free folate activity was identified as rhizopterin, with an extremely small amount of folic acid per se also being found. Cellular polyglutamate folates (folate conjugates with three or more glutamic acid units) were found in relatively high amounts throughout growth, and for any cellular sample constituted most of the total folate activity. The polyglutamate folate compounds were identified as formylated derivatives. A biosynthetic pathway from rhizopterin to the formylated polyglutamate folates is proposed.

Localization and interconversion of tetrahydropteroylglutamates in isolated pea mitochondria

1. Mitochondria were extracted from 4-day-old pea cotyledons and purified on a sucrose density gradient. 2. Microbiological assay of the purified mitochondrial fraction with Lactobacillus casei (A.T.C.C. 7469), Streptococcus faecalis (A.T.C.C. 8043) and Pediococcus cerevisiae (A.T.C.C. 8081) revealed a discrete pool of conjugated and unconjugated derivatives of tetrahydropteroylglutamic acid. 3. Solubilization and chromatographic studies of the mitochondrial fraction demonstrated the presence of formylated and methylated derivatives, 10-formyltetrahydropteroylmonoglutamic acid, 5-formyltetrahydropteroylmonoglutamic acid and 5-formyltetrahydropteroyldiglutamic acid being the major derivatives present. 4. The principal mitochondrial pteroylglutamates were labelled when dry seeds were allowed to imbibe [2-(14)C]pteroylglutamic acid and 5-[methyl-(14)C]-methyltetrahydropteroylmonoglutamic acid. 5. The ability of isolated mitochondria to catalyse oxidation and reduction of tetrahydropteroylglutamic acid derivatives was demonstrated in feeding experiments in which [(14)C]formaldehyde, [3-(14)C]serine, sodium [(14)C]formate, 5-[methyl-(14)C]methyltetrahydropteroylmonoglutamic acid or [2-(14)C]-glycine served as C(1) donor. In addition, (14)C was incorporated into free amino acids related to C(1) metabolism.

Pteroylglutamate derivatives in Pisum sativum L. Biosynthesis of cotyledonary tetrahydropteroylglutamates during germination

1. The concentrations of pteroylglutamate derivatives in the cotyledons of pea (Pisum sativum L.) seedlings were determined by microbiological assay by using Lactobacillus casei (A.T.C.C. 7469), Streptococcus faecalis (A.T.C.C. 8043) and Pediococcus cerevisiae (A.T.C.C. 8081). During germination the pteroylglutamate content of the cotyledons increased rapidly from 0.2mug/g dry wt. to 4.0mug/g dry wt., the maximum values being reached approx. 120h after imbibition. 2. Approx. 50% of the pteroylglutamate pool of 3-day-old seedlings was accounted for by highly conjugated derivatives. The concentrations of such derivatives were greatest when precautions were taken to inactivate endogenous enzymes before extraction of the tissues. 3. Individual derivatives present in the tissue extracts were separated by chromatography on DEAE-cellulose. Synthesis of the major derivative, 5-methyltetrahydropteroylmonoglutamate, was inhibited by administration of 0.1mm-aminopterin and -amethopterin solutions during imbibition. Under these conditions pteroylglutamic acid accumulated in the tissues. 4. Feeding experiments employing [2-(14)C]pteroylglutamic acid and 5[(14)C]-methyltetrahydro-pteroylmonoglutamic acid revealed that both compounds were incorporated into conjugated and unconjugated derivatives of the pteroylglutamate pool.

Effect of excision and benzimidazole treatment on folate content of wheat leaves and wheat leaf chloroplasts

Crude extracts were prepared from freshly harvested wheat leaves, and from leaves floated on water or on solutions of benzimidazole. Extracts were also prepared from chloroplasts isolated with non-aqueous solvents from similar leaves. All extracts were fractionated on DEAE-cellulose columns. Folate content was determined with Lactobacillus casei, Streptococcus faecalis, and Pediococcus cerevisiae as assay organisms.Total folates increased in leaves after excision whether benzimidazole was present or not. The increase was mainly due to an increase of conjugates of 5-methyltetrahydrofolate. Similar folate drifts were observed in chloroplasts isolated from these samples. Peak fraction analyses indicated that methylated folate conjugates were converted to 5-methyltetrahydrofolate, and formylated folates disappeared in leaves floated on water. Benzimidazole treatment arrested the degradation of conjugated folates, except that of a formylated folate found only in chloroplasts.

Folate derivatives in healthy and rust-infected primary leaves of wheat

Six days after inoculation, crude extracts were prepared from healthy and rust-infected wheat leaves of a susceptible line and from healthy and rust-infected wheat leaves of a resistant line. Extracts from rust-infected leaves of both lines contained 50% more folates, active as growth factors for Lactobacillus casei, than did those from healthy leaves. Rust-infected leaves did not differ from healthy leaves in their content of folates active as growth factors for Streptococcus faecalis and Pediococcus cerevisiae.All extracts were fractionated on DEAE-cellulose columns. The eluate fractions were treated with chicken pancreas conjugase and assayed with L. casei. All extracts yielded similar folate profiles consisting of five major and three minor peaks. Conjugase treatment and differential assay of the peak fractions with L. casei, S. faecalis, and P. cerevisiae indicated that the eluates contained folates methylated at N-5 and folates formylated at N-10 in various states of oxidation and conjugation. The eluates also contained a compound believed to be 5-formyltetrahydropteroylglutamate, small amounts of pteroylglutamate, traces of tetrahydropteroylglutamate, and several unidentified folates.The increase of folate levels in rust-infected leaves was due almost entirely to increases of 5-methyl-tetrahydropteroylgiutamate and its conjugates. The folate composition of resistant-reacting leaves did not differ appreciably from that of susceptible-reacting leaves.Radioactivity was not incorporated into either 5-methyltetrahydropteroyltriglutamate or into methionine when 5-[methyl-14C]-tetrahydropteroylglutamate was fed to wheat leaves.

5-Methyltetrahydrofolic acid and other folate derivatives in germinating pea seedlings

The folate derivatives present in germinating pea seedlings were isolated by chromatography on DEAE-cellulose and assayed with Lactobacillus casei, Streptococcus faecalis, and Pediococcus cerevisiae. The major folate derivative in the cotyledons, developing embryos, and young leaves was identified as 5-methyltetrahydrofolate. Smaller amounts of 10-formyltetrahydrofolate were also present in these tissues. Synthesis of these derivatives in the cotyledons was inhibited by aminopterin. Feeding experiments showed that the 5-methyl derivative was rapidly synthesized from folic acid-2-14C.

Chemical characterization of wines fermented with various malo-lactic bacteria

Six malo-lactic strains of lactic acid bacteria were isolated from California wines and identified as Lactobacillus delbrueckii, L. buchneri, L. brevis, Leuconostoc citrovorum, and two strains of Pediococcus cerevisiae. Malo-lactic fermentation was induced in separate lots of wine by inoculation of each lot with one of the strains of bacteria. Malo-lactic fermentation had occurred in each inoculated wine within 2 months. The resultant wines were subjected to chemical analysis, including gas chromatographic examination of concentrated extracts of the wines. Only a few differences in composition were found when the malo-lactic wines were compared one with another. The differences that were found were in volatile acidity and in concentrations of acetoin (plus diacetyl) and probably diethyl succinate.

Distribution and Characteristics of the Catalases of Lactobacillaceae

Johnston , M. A. (Cornell University, Ithaca, N.Y.), and E. A. Delwiche . Distribution and characteristics of the catalases of Lactobacillaceae. J. Bacteriol. 90: 347–351. 1965.—Certain strains of lactobacilli and pediococci incorporated hematin during growth, with the concomitant formation of cyanide- and azide-sensitive catalase. Three of five strains of lactobacilli and five of 25 strains of pediococci were capable of this biosynthesis. The pediococci required the heme component of blood, whereas the lactobacilli could incorporate the heme component in the form of purified and solubilized hemin or from blood. In all cases where inhibitor-sensitive enzyme was produced, it was accompanied by the production of inhibitor-insensitive enzyme. In the absence of hematin, only insensitive enzyme was obtained. Two catalase-positive strains of Streptococcus faecalis were found incapable of the synthesis of a heme-type enzyme, as was one member of the genus Leuconostoc . Iron and manganese in the growth medium stimulated the production of the insensitive catalase, but significant quantities of these metals could not be found in a purified enzyme preparation obtained from Lactobacillus plantarum . Aeration had little or no effect on growth, but it consistently doubled the amount of cyanide- and azide-resistant catalase. By means of conventional enzyme fractionation techniques, it was possible to separate the two different enzymes present in the cell-free extract of a strain of Pediococcus homari which had been grown in the presence of blood.

SILAGE BACTERIOLOGY. II. INFLUENCE OF TEMPERATURE DIFFERENCES ON THE COMPOSITION OF THE LACTIC MICROFLORA

At temperatures upwards of 36�C pediococci become increasingly prominent among the lactic microfiora of ryegrass silage and at 44�C lactobacilli are rarely found. This effect is not peculiar to the silage environment since it has been demon-strated in common laboratory media also. It may be explained simply on the basis of the greater capacity of pediococci for growth at the higher temperatures within the range studied. A possible significance of this phenomenon in relation to practical silage making is not presently apparent.

BEER-SPOILAGE BACTERIA AND THEIR CONTROL WITH A PHOSPHORIC ACID – AMMONIUM PERSULFATE WASH

Flavobacterium proteus, Acetobacter aceti, Acetobacter capsulatum, Pediococcus cerevisiae, and Lactobacillus pastorianus were isolated from contaminated yeast in certain Canadian breweries. F. proteus was most prevalent in ale yeast, while L. pastorianus and P. cerevisiae were most prevalent in lager yeast but the plant also affected the prevalence of the species.A phosphoric acid – ammonium persulfate wash was developed which has proved very effective in the breweries in which it has been used since 1960. Treatment time is very short (2 hours) and consequently a great saving in plant equipment and labor has resulted.The fermentative ability and viability of Saccharomyces cerevisiae is not affected nor is it killed even when it is treated with a phosphoric acid – ammonium persulfate wash that is six times as strong as the one recommended for use in the brewery.

INDUCTION AND REPRESSION OF L-ARABINOSE ISOMERASE IN PEDIOCOCCUS PENTOSACEUS

Dobrogosz, Walter J. (University of Illinois, Urbana) and Ralph D. DeMoss. Induction and repression of l-arabinose isomerase in Pediococcus pentosaceus. J. Bacteriol. 85:1350-1355. 1963.-The inducible l-arabinose isomerase of Pediococcus pentosaceus can be rapidly and conveniently measured in whole-cell preparations by use of a standard colorimetric procedure originally developed for studies with cell-free enzyme preparations. The enzyme is measured by its ability to catalyze the isomerization of l-arabinose to l-ribulose. Whole cells suspended in a suitable buffer and pretreated with toluene were shown to exhibit this isomerase activity at a level comparable with that observed in cell-free enzyme preparations. Conditions for optimal induction of l-arabinose isomerase are described. In addition, it was determined that the formation of this enzyme is subject to repression by glucose, i.e., via catabolite repression.

INTERRELATIONSHIP BETWEEN TEMPERATURE AND SODIUM CHLORIDE ON GROWTH OF LACTIC ACID BACTERIA ISOLATED FROM MEAT-CURING BRINES

Goldman, Manuel (American Meat Institute Foundation, Chicago, Ill.), R. H. Deibel, and C. F. Niven, Jr . Interrelationship between temperature and sodium chloride on growth of lactic acid bacteria isolated from meat-curing brines. J. Bacteriol. 85: 1017–1021. 1963.—An elevation of the temperature limit for growth of some Pediococcus homari ( Gaffkya homari ) and motile Lactobacillus strains could be effected by the addition of sodium chloride to the growth medium. At the optimal temperature for growth, sodium chloride was stimulatory, and as the temperature of incubation was increased a mandatory requirement for sodium chloride was manifested. At the optimal temperature for growth (30 C), the highest sodium chloride concentrations were tolerated; as the temperature was increased, this tolerance decreased, although the optimal sodium chloride concentration increased. No other substances were found that would replace the sodium chloride requirement at higher temperatures of incubation.