A deficiency in aspartate biosynthesis in Lactococcus lactis subsp. lactis C2 causes slow milk coagulation

Hua Wang, Weizhu Yu, Tim Coolbear, Dan O'Sullivan, Larry L. McKay

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

A mutant of fast milk-coagulating (Fmc+) Lactococcus lactis subsp. lactis C2, designated L. lactis KB4, was identified. Although possessing the known components essential for utilizing casein as a nitrogen source, which include functional proteinase (PrtP) activity and oligopeptide, di- and tripeptide, and amino acid transport systems, KB4 exhibited a slow milk coagulation (Fmc-) phenotype. When the amino acid requirements of L. lactis C2 were compared with those of KB4 by use of a chemically defined medium, it was found that KB4 was unable to grow in the absence of aspartic acid. This aspartic acid requirement could also be met by aspartate-containing peptides. The addition of aspartic acid to milk restored the Fmc+ phenotype of KB4. KB4 was found to be defective in pyruvate carboxylase and thus was deficient in the ability to form oxaloacetate and hence aspartic acid from pyruvate and carbon dioxide. The results suggest that when lactococci are propagated in milk, aspartate derived from casein is unable to meet fully the nutritional demands of the lactococci, and they become dependent upon aspartate biosynthesis.

Original languageEnglish (US)
Pages (from-to)1673-1679
Number of pages7
JournalApplied and environmental microbiology
Volume64
Issue number5
DOIs
StatePublished - May 1998

Fingerprint Dive into the research topics of 'A deficiency in aspartate biosynthesis in Lactococcus lactis subsp. lactis C2 causes slow milk coagulation'. Together they form a unique fingerprint.

Cite this