Merrill N. Camien

Saturated fatty acids as bacterial antimetabolites

Abstract Inhibitory effects of saturated fatty acids of from 7 to 24 carbons in length on nine species of lactic acid bacteria have been investigated. The inhibitions due to the acids of from approximately 12 to 20 carbons in length (depending on the test organism) have been shown to be the result of a potent antimetabolite effect, readily reversible by any of the six unsaturated fatty acids (oleic, linoleic, ricinoleic, vaccenic, licanic, and erucic acids) and the one cyclopropane acid (lactobacillic acid) tested. The inhibitions due to saturated fatty acids of longer chain length (22 and 24 carbons) nearly equal those of the most active saturated acids in the 12- to 20-carbon range, but the mechanism of these inhibitions has not been investigated. The short-chain fatty acids (12 and fewer carbons) are relatively feeble inhibitors and appear to act primarily according to the physicochemical hypotheses which have been proposed by earlier investigators. A scheme of metabolic pathways suggested by the present findings and correlating the latter with earlier data concerning bacterial lipide metabolism is proposed.

Relationship of Renal “Net Acid” Excretion to Titratable Ash-Acidity (Ash-TA) in Diet and Feces.

Summary Titratable ash-acidity (ash-TA) has been described as an acid-base parameter which is based solely on mineral composition and may therefore be defined strictly in terms of biologically stable chemical elements. Renal “net acid” values were shown to consist of two components: 1) the urinary ash-TA value, which varies markedly with diet composition and remains generally equal to the value for net absorption of dietary ash-TA, and 2) a relatively small and essentially constant quantity equal to the urinary organic anions value minus the values for urinary organic sulfur, organic phosphorus and organic cations. Most of the second component was accounted for by the organic anions value, so that the renal “net acid” values were generally slightly higher than the corresponding urinary ash-TA values. The renal “net acid” values nevertheless remained closely correlated with the corresponding urinary ash-TA values and hence with the values for net absorption of dietary ash-TA. No basis was found for relating either ash-TA intake or excretion to true endogenous acid production; however, it was shown that both ash-TA values and renal “net acid” values correspond theoretically to approximate evaluations of “potential” acid.

Determination of Total Cation-Forming Mineral Elements in Feces And Urine and Its Relation to Renal “Net Acid” Excretion.

Summary A relatively simple titrimetric method for determining total cation-forming mineral elements in urine and feces is described and demonstrated to yield dependable values. Addition of fecal minerals to an otherwise constant diet in rats is shown to effect an increased urinary excretion of total cation-forming mineral elements together with a correspondingly decreased renal “net acid” excretion. The theoretical basis for this result and for analogous results of others is discussed. It is concluded that the extent to which cation-forming mineral elements are excreted in the feces rather than in urine can considerably influence the extent of renal “net acid” excretion. Addendum: While the preceding report was in press, studies by Lennon, Lemann and Litzow(13,14) appeared, in which collective values for Na+, K+, Ca++ and Mg++ (ions derivable from cation-forming elements) in diet and feces, respectively, are calculated as a negative and positive component, respectively, of “total effective acid production” (”TEAP”) in the organism, a value which is shown normally to be balanced by renal “net acid” excretion (13). The value for fecal excretion of the cation-forming mineral elements therefore appears as a positive component of the “TEAP” value, and since the latter is normally balanced by the renal “net acid” value, it appears that the described calculation of “TEAP”(13) takes into account the influence of fecal excretion of cation-forming mineral elements on renal “net acid” excretion. However, the nature of the calculation suggests that the authors (13) are unaware of the relationships shown in Equation 2, which account for this influence. The complete operational definition proposed (13) for “TEAP” may be expressed by the following equation, in which “absorbed” designates values obtained by subtracting fecal from dietary values:

Response of lactic acid bacteria to amino acid derivatives. II. Glycine.

Abstract The response of five lactobacilli (for which glycine is an essential nutrient) to two tripeptides, five dipeptides, and seventeen other glycine derivatives has been tested over a range of concentrations and at four or five incubation times from 18 to 229 hours. In general the activities decreased with increasing concentrations and incubation times although in some cases they remained nearly constant, increased, or increased and then decreased. Hippuric acid, all of the dipeptides, and the tripeptide, l -leucylglycylglycine, exhibited greater activity than glycine for one or more of the organisms. These results may be interpreted to signify that ( a ) the apparent decrease in apparent glycine in hydrolyzed urines may be accounted for in part by the higher activity of hippuric acid in unhydrolyzed urines, and ( b ) some peptides may be utilized directly by lactic acid bacteria under some conditions.

Studies on the Nutrition of Leptospira canicola

Summary Nutritional. experiments with Leptospira conicola have been described A semisynthetic medium containing dialyzed rabbit serum, salts, vitamins, amino acids, and purine and pyridine bases was developed and appeared to be adequate as a basis for determining amino acid and vitamin requirements of this organism.

Production of α-hydroxy fatty acids by two strains of Lactobacillus casei☆

Abstract The principal α-hydroxy acids other than lactic acid produced by L. casei strains 7469 and 280-16A were isolated by countercurrent extraction and identified as α-hydroxyisocaproic acid and α-hydroxyisovaleric acid. The amount of these acids and of lactic acid were estimated from counter-current distribution data, and the degrees of racemization were estimated from specific rotation values and from the results of optically specific microbiological assays. The maximal concentrations of α-hydroxyisocaproic and α-hydroxyisovaleric acids produced by L. casei were approximately 0.6 and 0.2 μeq./ml., respectively. The lactic acid, α-hydroxyisovaleric acid, and α-hydroxyisocaproic acid produced by L. casei 7469 were approximately 16%, 62%, and 97% racemic (the rest l -), respectively, whereas the same acids produced by L. casei 280-16A were much less racemic. This was particularly true of the L. casei 280-16A lactic acid, which appeared to be 99.3% l -lactic acid. Racemization of the α-hydroxy acids appears to be of importance in L. casei since strain 280-16A, which produces only slightly racemized acids, fails to grow in the usual media unless provided with a d -α-hydroxy acid source.

The preparation of γ-aminobutyric acid by enzymatic decarboxylation of l-glutamic acid

Abstract A method has been described for the preparation of γ-aminobutyric acid hydrochloride by isolating it from the reaction mixture obtained by the action of a specific l -glutamic acid decarboxylase on l -glutamic acid.

Amino Acid Composition of Mycobacterial Cell Wall.

Summary The amino acid composition of cell walls from 4 strains of mycobacteria has been determined by quantitative column chromatography. Glutamic acid, alanine and diaminopimelic acid were major components in each of the cell wall preparations. Aspartic acid, serine, threonine, glycine, isoleucine, leucine and valine were present at probably significant levels in cell walls of one or more, but not all of the mycobacteria. chromatographically detectable amounts of arginine, cystine, histidine, lysine, methionine, phenylalanine, proline and tyrosine were absent from all cell wall preparations.

“Back-mutation” of Lactobacillus casei 280-16 and 1-tetradecene sensitivity in a “back-mutant” strain☆

“Back-mutant” organisms were found to accumulate within 3 years in normally maintained stock cultures of Lactobacillus casei 280-16, a d-α-hydroxy acid dependent mutant. A typical “back-mutant” strain differed from the wild strain in that a) its rate of growth was lower in d-α-hydroxy acid-free medium than was that of the wild strain and b) its growth, but not that of the wild strain, was markedly inhibited by 1-tetradecene in d-α-hydroxy acid-free medium, but only slightly in medium containing d-lactic acid. It was suggested that since 1-tetradecene apparently neither inhibits d-lactic acid production by the wild strain nor seriously interferes with d-lactic acid utilization, d-lactic acid is probably not an intermediary metabolite in the “back-mutant” strain when the latter is grown in d-α-hydroxy acid-free medium.

Utilization of L-,D- and Dl-forms of asparagine and aspartic acid by Leuconostoc mesenteroides P-60.

Summary The utilization of the optically active and racemic forms of asparagine and aspartic acid by Leuconostoc mesenteroides has been studied under a variety of test conditions. D-asparagine was found to be entirely inactive, and DL-asparagine was found to have 50% the activity of L-asparagine. Conditions were described under which D-aspartic acid was essentially inactive and under which DL-aspartic acid had 50% the activity of L-aspartic acid. Under other conditions acid with Leuconostoc mesenteroides were suggested