The Effect of Temperature on the Nutritional Requirements of Pasteurella pestis

Abstract

SUMMARY:The nutrition of three virulent and three avirulent strains of Pasteurella pestis has been studied at temperatures between 23 and 37" on a basal medium containing glucose, ammonium and other inorganic salts. The organism has considerable synthetic powers and the distinction between essential nutrients and non-specific stimulants of growth is not always definite. At 32" and below, the optimal medium contained phenylalanine, valine, isoleucine, cysteine, methionine and haemin. Five out of the six strains utilized leucine in place of valine, but the maximum count was then delayed. At 36" the optimal medium contained in addition, alanine, leucine, serine, threonine, biotin and pantothenate. Omission of alanine or leucine delayed growth without reducing the maximum population. When biotin and pantothenate were omitted the organism required a mixture of twenty amino-acids.The nutrition of Pasteurella pestis has been studied with conflicting results by Rao (1939, 1940b), Berkman (1942), Doudoroff (1943) and Herbert (1949). Rao (1939), using large washed inocula (c. 107 cells/ml.) at 2 7 ' , claimed that the only amino-acids for which there was a specific requirement were phenylalanine, proline and cystine, but that glycine was stimulatory and a t least two of the four comprising alanine, leucine, lysine and arginine were also required. Metabolic experiments (Rao, 1940 a) showed that arginine and lysine were not appreciably oxidized and these were then omitted from media used for investigating the stimulatory effects of some of the then-known growth factors (Rao, 1940b), but other amino-acids oxidizable by the organism were also added, viz. valine, isoleucine, methionine, serine, tyrosine and glutamate. Doudoroff (1943), working a t 29", claimed that only cystine and phenylalanine were essential on first transfer from blood agar, although proline stimulated two pathogenic strains. A non-pathogenic strain was able to utilize thiosulphate, sulphite, thiolacetic acid or homocystine, but not methionine, in place of cystine. Large inocula were necessary, however. Berkman (1942), using an inoculum of 1-2 x 104 cells/ml. and a temperature of 37", found that four out of five strains grew in 1-2 days on a mixture of 18 a-amino-acids or a gelatin hydrolysate medium, but the fifth strain failed to grow under these conditions. Using a similar medium containing 20 a-aminoacids, Herbert (1949), also working a t 37O, found growth to be irregular even with as large an inoculum as lo6 organisms/ml., but the addition of haemin led to consistent growth from as few as 10 cells/ml.Rao (1939) and Doudoroff (1943), working below 30" in the neighbourhood of the recognized optimum temperature, agree in claiming simpler nutritional requirements than those observed at 37' by Berkman (1942) and Herbert (1949). The observations of the two former authors are of little value, however, owing to the use of large inocula. It was considered desirable therefore to

The Nutritional Requirements of some Pasteurella Species

“…All three Pasteurella species were similar in having additional requirements for growth at 37" over those required at 28", as was first shown for Pasteurella pestis by Hills & Spurr (1952). Impaired thiamine-synthesis was noted with all representatives.…”

Temperature Sensitivity of Mutants of Bacillus anthracis Caused by a Block in Thymine-Nucleotide Synthesis

“…In this respect B. anthracis appears to be similar to PaSteureZZa pestis, a pathogen having a definitely higher nutritional requirement a t 87" than below 3 2 ' (Hills & Spurr, 1952). It has been found (Iviinovics, Varga & Marjai, to be published) that the adverse effect of incubation at 57' on B. unthracis, strain VC-, was very much diminished by the presence of thiamine.…”

Current Topics in Microbiology and Immunology

“…For example, inocula greater than 10 8 cells per ml are necessary to initiate growth at 37° C in the rich synthetic media of CARLIN (1958) andHIGUCHI et al (1959) but these media eventually yield over 10 10 cells per ml. In contrast, an inoculum of 10 4 to 10 5 cells per ml is sufficient to initiate growth in the well-balanced medium of BROWNLOW and WESSMAN (1960) Hemin and mercaptoacetate, shown by HERBERT (1949) to favor the formation of colonies on solid media, can be replaced by a number of other reducing agents (HILLS and SPURR, 1952;BURROWS and GILLETT, 1966) and, in liquid medium, by potential precursors of hemin (BROWNLOW and WESSMAN, 1960). Oxidizable organic acids have been employed in synthetic media with favorable results (JACKSON and BURROWS, 1956a;HIGUCHI and CARLIN, 1958;BRUBAKER, 1970) and high concentrations of Fe H (0.5 mM) stimulate cell division in the medium of HIGUCHI and CARLIN (1957).…”

“…Oxidizable organic acids have been employed in synthetic media with favorable results (JACKSON and BURROWS, 1956a;HIGUCHI and CARLIN, 1958;BRUBAKER, 1970) and high concentrations of Fe H (0.5 mM) stimulate cell division in the medium of HIGUCHI and CARLIN (1957). At 26° C, cells of Y. pestis typically exhibit a nutritional requirement for L-methionine and L-phenylalanine; growth is enhanced by addition of L-isoleucine, L-valine (HILLS and SPURR, 1952;ENGELSBERG, 1952) and glycine (BURROWS and BACON, 1954). According to BURROWS and GILLETT (1966), strains of the variety mediaevalis lack the requirement for L-phenylalanine but it should be noted that all phenylalanine-independent isolates examined by these workers were of this variety.…”