The Synthesis of Vitamin B6 by some Mutant Strains of Escherichia coli

Morris, James G.

doi:10.1099/00221287-20-3-597

Cited by 20 publications

(15 citation statements)

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“…In particular, it cannot be decided whether serine + glycine and glycolaldehyde decrease the need for vitamin B, or take part in its synthesis. An attempt to discriminate between these two possibilities by a direct study of vitamin B, synthesis in the light of the present results will be described in the following paper (Morris, 1959).…”

Section: Discussionmentioning

confidence: 99%

“…If the same substance had still further functions in these mutants, their growth in its presence together with serine + glycine and either pyridoxine or glycolaldehyde might reach the maximum attained by the prototroph. A fuller appraisal of the growth characteristics of these mutants has been attempted elsewhere (Morris, 1958). It is considered that Escherichia coli M2 alone of all the mutants studied is a true vitamin B6 auxotroph in that its requirement for the vitamin is absolute and its growth response to pyridoxine maximal.…”

Section: Discussionmentioning

confidence: 99%

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Inter-relationships of Serine, Glycine and Vitamin B6 in the Growth of Mutants of Escherichia coli

Morris

Woods

1959

Journal of General Microbiology

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SUMMARY: Five mutants of Escherichia coli which grow to a greater or less extent when the minimal medium is supplemented with vitamin B, have been studied. They fall into two groups according to the further effect of serine + glycine on growth.(1) Two strains showed full and rapid growth with pyridoxine alone and serine + glycine neither replaced this vitamin nor enhanced growth in its presence. (2) Three strains showed delayed and suboptimal growth with pyridoxine alone. With these serine + glycine had two effects: (a) it decreased the lag and enhanced the final extent of growth when added with pyridoxine ; (b) it permitted suboptimal growth in the absence of pyridoxine. The second effect was dependent on (two strains), or greatly increased by (one strain), the concurrent addition of glycolaldehyde.Nothing is known of the pathway of synthesis of vitamin B, by organisms not requiring an external source of it for growth. Mutant strains of Escherichia coli which multiply only when vitamin B, is supplied are more rare than those which respond to vitamin B, or serine or glycine. The simplest explanations of the apparent replacement of the vitamin by these amino acids are: ( a ) the amino acids are end products of reactions catalysed by vitamin B, derivatives; consequently, when provided preformed, they decrease or abolish the need for the vitamin; ( b ) the synthesis of serine and glycine by the organism is limited, and one or other is a reactant a t some step in the biosynthesis of vitamin B,.A detailed study was made of the properties of mutants of this type in an attempt to discover an immediate biochemical lesion resulting from the mutation and possibly to obtain some conception of the route of synthesis of vitamin B, and its derivatives by normal strains of Escherichia coli. METHODSEscherichia coli. Stock cultures were maintained on tryptic meat agar slopes and were subcultured monthly (16 hr. a t 37" , 1955) which required vitamin B, for growth a t 37" but responded also to certain mixtures of amino acids at lower temperatures.Strain B166 was used for most of the work to be described.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Inter-relationships of Serine, Glycine and Vitamin B6 in the Growth of Mutants of Escherichia coli

Morris

Woods

1959

Journal of General Microbiology

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“…By testing the growth effects of varying in gredients of the media on which a series of vitamin B6-requiring mutants of E. coli were grown, Woods and Morris came to the con clusion that seriee, glycine and glycolaldehyde are possible precursors in the biosynthesis of vitamin B6 in E, coli. However, no isotopic experiments have yet been performed to con firm the hypothesis that any or all of these compounds are true precursors of vitamin B6 (5,6). Recently, Lunan and West isolated the 14C -labeled pyridoxamine from Candida utilis , Serine-3-14C, acetate-l-14C, alanine-1-14C and acetate-2-14C gave rise to 14C-labeled pyridoxa mine.…”

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confidence: 99%

Biosynthesis of Vitamin B6

Suzue

Haruna

1970

J. Vitaminol

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“…Although some vitamin B, is synthesized under these conditions (Morris, 1959) the organisms may be expected to be at least relatively deficient in the vitamin. Growth with the supplement used (a mixture of DL-serine, glycine and DL-alanine) was only half that attained if pyridoxal were also present.…”

Section: Resultsmentioning

confidence: 99%