Effects of Thiamin on Vitamin B6 Synthesis in Yeasts

Abstract

The effects of exogenous thiamin on the growth yield and vitamin B, content of 18 strains of yeasts and a few strains of bacteria were examined. The addition of thiamin hardly affected the growth yield of the yeasts tested, except for two strains Saccharomyces uvarurn strain 4228 and Saccharomyces uvarum IF0 0751. In contrast, the vitamin B, content of all the yeasts tested, except Pichia membranaefaciens I F 0 0189, decreased markedly in the presence of thiamin. In S . uvarum IF0 1265, the synthesis of vitamin B, was maximally inhibited by the addition of thiamin (1.5 nmol ml-l) to the growth medium without affecting cell growth, whereas the amounts of cellular vitamin B, increased in the presence of the thiamin antagonist, pyrithiamin or oxythiamin, at concentrations that did not affect growth. When [4'-14C]pyridoxine. HC1 (0*5pgml-') was added to the growth medium at least 54% of the added isotope was incorporated into the cells during 24 h incubation, In the presence of thiamin (15 nmol ml-'), at least 32% of the added isotope was incorporated. The metabolism of [4'-14C]pyridoxine. HC1 to inactive forms having no vitamin B, activity was not stimulated by the addition of thiamin. Thus, vitamin B6 synthesis in many yeasts was affected by thiamin, whereas, in bacteria, growth yield and vitamin B, content were not affected by thiamin. I N T R O D U C T I O NThe relation between added thiamin in the growth medium and vitamin B, requirements for yeast growth has been studied in detail in Saccharomyces uuarum strain 4228 (Saccharomyces carlsbergensis strain 4228), an organism widely used in the assay of vitamin B, (Atkin et a/., 1943;Rabinowitz & Snell, 1947;Fukui, 1953). This yeast does not require vitamin B, as an essential growth factor, except when thiamin is added to the culture medium (Rabinowitz & Snell, 1951; Chiao & Peterson, 1956). Exogenous thiamin greatly depresses the vitamin B, content of this yeast, possibly by inhibiting biosynthesis (Kawasaki & Yamada, 1965;Kishi, 1969); the severe deficiency of vitamin B, in the yeast was manifest in a marked reduction in the rate of nicotinic acid biosynthesis by inhibiting the synthesis of 3-hydroxyanthranilic acid from 3-hydroxykynurenine (Kawasaki et al., 1969). Nakamura et al. (1974) reported that thiamin depressed the respiratory activity, the content of unsaturated fatty acids, especially palmitoleic acid (Nishikawa et al., 1974a) and the level of sterols (Nishikawa et al., 1974b) in the yeast, and that these effects of thiamin were abolished by the addition of pyridoxine to the growth medium. Haskell & Snell (1965) have also observed that deficiency of vitamin B, caused a marked decrease in the content of palmitoleic acid of the yeast, Hanseniaspora ualbyensis. The facts strongly support the presumption that the externally added thiamin causes primarily the inhibition of vitamin B6 biosynthesis, followed by various abnormalities in vitamin B, metabolism, so that S . uuarurn 4228 cannot grow normally without the addition of pyridoxine, pyridoxal, and pyrid...

Hydrogen sulphide production bySaccharomyces cerevisiaeUCD 522 in a synthetic grape juice medium deficient of thiamin (vitamin B1) and/or pyridoxine (vitamin B6)

“…As thiamin and pyridoxine are metabolically linked in S. cerevisiae , it was not surprising that both vitamins affected evolution of H 2 S. Although imported from media (Singleton ), thiamin can also be synthesized through an intermediate [(4‐amino‐5‐hydroxyethyl)‐4‐methythiazole phosphate] which, itself, is produced from histidine and pyridoxal‐5‐phosphate (Li et al ). Thiamin can also interfere with yeast synthesis of pyridoxine (Minami et al ), a vitamin whose deficiency results in production of H 2 S (Wainwright ). Here pyridoxine serves as a co‐factor for homocysteine/cysteine synthase which is involved in the synthesis of methionine and cysteine, the latter using H 2 S and O ‐acetyl‐L‐serine as substrates (Tokuyama et al, ; Yamagata and Takeshima, ).…”

Biosynthesis of Vitamin B1 in Yeast. Derivation of the Pyrimidine Unit from Pyridoxine and Histidine. Intermediacy of Urocanic Acid

“…The existence of a possible metabolic relationship between thiamin and pyridoxine (Vitamin B 6 ) in yeasts had been noted more than half a century ago, and interaction of the two vitamins in Saccharomyces sps. and in Neurospora sps. has been repeatedly studied since then.…”

“… has been repeatedly studied since then. Several possible rationalizations for this apparent relationship have been advanced, among them the notion “that one of the vitamins might serve as the precursor of an intermediate from which the other may be synthesised”,8a but no conclusive interpretation has been offered.…”

Industrial fuel ethanol yeasts contain adaptive copy number changes in genes involved in vitamin B1 and B6 biosynthesis

“…Indeed, several reports have shown significant up-regulation of thiamin metabolism genes in fermenting yeast cells in various industrial settings including wine, sake, and bread dough (Rossignol et al 2003;Tanaka et al 2006;Wu et al 2006), and in yeast cells cultivated in sugarcane molasses (Shima et al 2005), indicating that there is a high demand for thiamin (and its precursors) under these industrial conditions. However, it is well known that for S. cerevisiae, as well as for other members of the Saccharomyces sensu stricto complex, the presence of thiamin in the medium has a negative effect on the initial growth phase of the yeast cells, although it does not affect the final cell density (Minami et al 1982;Nakamura et al 1982;Kamihara and Nakamura 1984). This thiamin-induced growth inhibition has been extensively studied in yeast, and is a consequence of the repressing effect of this vitamin on PLP biosynthesis (Minami et al 1982;Nakamura et al 1982;Kamihara and Nakamura 1984;Hohmann and Meacock 1998;RodriguezNavarro et al 2002;Mojzita and Hohmann 2006;Nosaka 2006).…”

“…This thiamin-induced growth inhibition has been extensively studied in yeast, and is a consequence of the repressing effect of this vitamin on PLP biosynthesis (Minami et al 1982;Nakamura et al 1982;Kamihara and Nakamura 1984;Hohmann and Meacock 1998;RodriguezNavarro et al 2002;Mojzita and Hohmann 2006;Nosaka 2006). Due to the resultant marked decrease in cellular vitamin B6 (e.g., pyridoxine) content, many metabolic pathways are repressed, including a pronounced lowering of d-aminolevulinate synthase activity and decreased synthesis of heme, with consequent lowering of respiration and a significant alteration in membrane lipid composition due to inhibition of sterol and unsaturated fatty acids biosynthesis (Minami et al 1982;Nakamura et al 1982;Kamihara and Nakamura 1984).…”