Rational development of a simple synthetic medium for the sustained growth of Lactococcus lactis

Abstract

The growth of two strains of Lactococcus lactis subsp. lactis from vegetable (NCDO 2118) and dairy origin (IL 1403) were compared on various culture media. Both strains grew more rapidly on a complex organic medium than on a defined synthetic medium. The best growth was obtained under nitrogen gas phase. The single omission technique was applied to each component of a non‐optimized synthetic medium in order to determine the true nutritional requirements. Requirements for macro‐elements, oligo‐elements, bases and vitamins were identical for the two strains. As expected, the dairy strain (IL 1403) was seen to be auxotrophic for some amino acids, whereas the vegetable strain (NCDO 2118) was seen to be prototrophic for all amino acids when using the single omission technique. Growth was then characterized on progressively simplified media and the composition of the absolute minimal media for the growth of both strains was defined. Sustained growth of the vegetable strain was only possible in minimal media supplemented with six amino acids (Glu, Met, Ile, Leu, Val, Ser), indicating that the definition of prototrophy/auxotrophy is partly dependent upon the medium composition. The dairy strain showed a requirement for Arg, His and Thr in addition to the six amino acids necessary for growth of the vegetable strain. The removal of ammonium salt from the medium did not affect the growth, illustrating that the amino acids may satisfy the totality of the nitrogen requirement for biomass synthesis.

Complete Genome Sequence of the Prototype Lactic Acid Bacterium Lactococcus lactis subsp. cremoris MG1363

“…Jensen et al (52) observed in vivo activity of threonine aldolase in L. lactis MG1363, while 95% of the threonine was taken up from the medium. Growth of L. lactis IL1403 was reduced by 25% in the absence of threonine (19). A threonine aldolase gene is not present in the genome of L. lactis MG1363, L. lactis SK11, or L. lactis IL1403, implying that all threonine biosynthesis occurs through aspartate or that a cryptic gene specifies the activity measured by Jensen and coworkers (52).…”

Transcriptional, translational and metabolic regulation of glycolysis in Lactococcus lactis subsp. cremoris MG 1363 grown in continuous acidic cultures

“…cremoris MG 1363 was used throughout this work; this bacterium lacks the lactose plasmid (Gasson, 1983). The strain was grown on simplified synthetic medium MS10 (Cocaign-Bousquet et al, 1995) supplemented with glucose (10 g l 21 ) as carbon source.…”

Response of the central metabolism of Escherichia coli to modified expression of the gene encoding the glucose‐6‐phosphate dehydrogenase

“…For this purpose, cells were grown in minimal medium containing a mixture of 80% [1-13 C] glucose and 20% [U-13 C] glucose. The specifically labelled [1-13 C] glucose was used, in addition to the uniformly labelled glucose, to obtain direct data concerning flux through the oxidative PPP since CO 2 loss within this pathway involves specific loss of [1][2][3][4][5][6][7][8][9][10][11][12][13] C] glucose [21]. Thus, the M0 abundances will reflect the extent to which glucose is catabolized via PPP.…”