Citrate metabolism in starved cells of Streptococcus lactis subsp. diacetylactis

✍ Scribed by F. Vilchez; C. Petit; Dr. R. Marczak

• Book ID: 102387574
• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 371 KB
• Volume: 30
• Category: Article
• ISSN: 0233-111X
• DOI: 10.1002/jobm.3620300821

✦ Synopsis

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.