I don't think the e-coli is synthesising citrate, rather it is metabolising it.
From the newscientist.com
Excess ammonium ferric citrate and potassium ferricyanide are then washed away.
From the en.wikipedia.org
The paper is impregnated with a solution of ammonium ferric citrate and dried.
From the en.wikipedia.org
Researchers measured the citrate and malate content of 15 popular diet sodas.
From the sciencedaily.com
Calcium phosphate costs more than calcium carbonate, but less than calcium citrate.
From the en.wikipedia.org
Citrate and lactate are vital for our bodies'metabolism for normal function.
From the sciencedaily.com
If you take a supplement, calcium citrate is better absorbed than calcium carbonate.
From the express.co.uk
AcsD catalyzes enantioselective citrate desymmetrization in siderophore biosynthesis.
From the sciencedaily.com
Alternatively, citrate is exported back to the cytosol to be used for lipid synthesis.
From the nature.com
More examples
Cause to form a salt or ester of citric acid
(citration) The act of citrating
A citrate is a compound of citric acid and a base; in the body it is involved in blood coagulation (clotting) and the synthesis of fatty acids.
An important urinary acid neutralizer and inhibitor of kidney stone formation. It is excreted by the kidneys and will be reduced if there is too great an acid load in the body. ...