Diacetyl Biosynthesis in<i>Streptococcus diacetilactis</i>and<i>Leuconostoc citrovorum</i>

Speckman, R. A.; Collins, E. B.

doi:10.1128/jb.95.1.174-180.1968

Cited by 159 publications

(57 citation statements)

References 21 publications

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“…However, the exact sequence of reactions leading to the production of these compounds was, until recently, a matter of (heated) debate. Collins and co-workers have presented some evidence that diacetyl can be synthesized directly from two C2-intermediates, hydroxyethyl thiaminpyrophosphate ('active acetaldehyde') and acetyl-CoA, in a reaction catalysed by the enzyme diacetyl synthase [23,24]. Acetoin and butanediol could subsequently be formed by enzymatic re-167 duction of diacetyl.…”

Section: Pyrmate Metabolismmentioning

confidence: 99%

Citrate metabolism in lactic acid bacteria

Hugenholtz¹

1993

FEMS Microbiology Reviews

347

170

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Citrate metabolism plays an important role in many food fermentations involving lactic acid bacteria. Since citrate is a highly oxidized substrate, no reducing equivalents are produced during its degradation, resulting in the formation of metabolic end products other than lactic acid. Some of these end products, such as diacetyl and acetaldehyde, have very distinct aroma properties and contribute significantly to the quality of the fermented foods. In this review the metabolic pathways involved in product formation from citrate are described, the bioenergetic consequences of this metabolism for the lactic acid bacteria are discussed and detailed information on some key enzymes in the citrate metabolism is presented. The combined knowledge is used for devising strategies to avoid, control or improve product formation from citrate.

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Section: Pyrmate Metabolismmentioning

confidence: 99%

Citrate metabolism in lactic acid bacteria

Hugenholtz¹

1993

FEMS Microbiology Reviews

347

170

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“…the only plasmid linked enzyme of this pathway (KEMPLER and MCKAY 1979), was irreversibly alterered under these various conditions whereas the other enzymes were constitutively present. It appears to be the key enzyme which allows the cells to regulate the citrate uptake and consequently to modulate either diacetyl or acetoin production, since data which indicated specific fluctuations in diacetyliacetoin ratio, are consistent with the hypothesis of two separate biosynthetic pathways (SPECKMAN andCOLLINS 1968, SEITZ et NI. 1963).…”

Section: Discussionmentioning

confidence: 57%

“…De carboxylation of alpha-acetolactate following its formation by condensation ofthe acetaldehyde TPP complex with another molecule of pyruvate is one mechanism (SPECKMAN and COLLINS 1968). The other method used by some bacteria consists of reducing part or all of the diacetyl that is formed from condensation of the same complex with acetyl CoA (SPECKMAN and COLLINS, 1968, SEITZ et al 1963. Diacetyl and acetoin formation proceeds for as long as citrate is present.…”

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confidence: 99%

Citrate metabolism in starved cells of Streptococcus lactis subsp. diacetylactis

Vilchez¹,

Petit²,

Marczak³

1990

J. Basic Microbiol.

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The effect of starvation on citrate metabolism by fully grown cells of S/wp~o(~occus lactis subsp. diace/>,/ar/is was studied by three different procedures. An 8-hour starvation period in fermented medium decreased citrate uptake rate but diacetyl and acetoin levels remained constant over a fermentation without starvation period: about 19 mg I-' diacetyl and 130 mg 1-I acetoin were produced after utilization of 8.8 m~ citrate. When fermentation products were discarded from the medium before starvation, diacetyl and acetoin levels reached 30 mg I-' and 240 mg I-*, respectively.When the cells were allowed to rest on an isotonic diluent, citrate uptake rate slowed down, but the diacetyl plus acctoin yield remained higher sincc the cells accumulated as much acetoin (1 20 mg I ~ ') and more diacetyl (50 mg 1-1). Peak production of diacetyl still coincided with citrate exhaustion whereas a delay in acetoin production was observed.Stwprocotcus lactis subsp. cliucetylactis produces little diacetyl and acetoin from carbohydrate mctabolisrn, unless an additional source of pyruvate (e.g. citrate) is present (DRINAN P / a/. 1976).Excess pyruvate, not needed for coenzyme regeneration, becomes toxic towards bacteria, which turn it into neutral compounds such as diacetyl (2-3 butane dione) or acetoin (3 hydroxy 2-butanone) (HARVEY and COLLINS 1963).The biosynthesis of acetoin from pyruvate in bacteria proceeds by two mechanisms. De carboxylation of alpha-acetolactate following its formation by condensation ofthe acetaldehyde TPP complex with another molecule of pyruvate is one mechanism (SPECKMAN and COLLINS 1968). The other method used by some bacteria consists of reducing part or all of the diacetyl that is formed from condensation of the same complex with acetyl CoA ( SPECKMAN and COLLINS, 1968, SEITZ et al. 1963). Diacetyl and acetoin formation proceeds for as long as citrate is present. Once citrate is exhausted, reduction of both compounds may occur (WALSH and COGAN 1973, leading in some bacteria to the production of 2-3 butane diol (THORNILL and COGAN 1984).In Strepcoccus Iuctis subsp. diacrtylactis, strain DRC1, the enzymes involved in these pathways are constitutively present. Diacetyl and acetoin reductases are partly repressed and acetolactate synthase partly induced by growth on a citrate-containing medium (COGAN 198 I). There is also evidence that citrate permease is a plasmid-linked enzyme (KEMPLER and MCKAY 1979). Diacetyl is produced at a much lower concentration than acetoin but it is of greater interest as regards the flavour of several fermented dairy products. For these reasons, our main aim was to enhance diacetyl production by changing physiological cell conditions during citrate metabolism.19 J B m c Microbiol 30 (1990) 8

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“…It should be pointed out that pyruvate formed through the citrate fermentation pathway joins the common acetoin-forming pathway with pyruvate as a central intermediate [74]. Therefore the carbon from which diacetyl is formed originates from citrate and lactose [67,69,75]. An inducible transport system has been demonstrated in S. lactis ssp.…”

Section: Physiology and Enzyrnology Of Citrate Metabolismmentioning

confidence: 99%

Citrate metabolism in anaerobic bacteria

Antranikian

Giffhorn

1987

FEMS Microbiology Letters

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The regulation of anaerobic citrate metabolism is very diverse among different groups of bacteria. In organisms like Streptococcus lactis and Clostridium sporosphaeroides which lack citrate synthase, the activity of its antagonistic enzyme, citrate lyase, need not be regulated. Many anaerobes like Rhodocyclus gelatinosus and Clostridium sphenoides are able to synthesize their own l‐glutamate and contain citrate synthase. In these bacteria the activity of citrate metabolizing enzymes which are involved in a cascade system are under strict control. In Rc. gelatinosus activation/inactivation of citrate lyase is controlled by acetylation/deacetylation which is catalyzed by its corresponding regulatory enzymes, citrate lyase ligase and citrate lyase deacetylase. In C. sphenoides inactivation of citrate lyase is accomplished by deacetylation as well as by changing in the enzyme conformation. Activation of citrate lyase is catalyzed by citrate lyase ligase whose activity in addition is modulated by phosphorylation/dephosphorylation. Further, electron transport process also seems to play a role in the inactivation of citrate metabolizing enzymes in enteric bacteria.

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Diacetyl Biosynthesis inStreptococcus diacetilactisandLeuconostoc citrovorum

Cited by 159 publications

References 21 publications

Citrate metabolism in lactic acid bacteria

Citrate metabolism in lactic acid bacteria

Citrate metabolism in starved cells of Streptococcus lactis subsp. diacetylactis

Citrate metabolism in anaerobic bacteria

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