Extent of Genetic Lesions of the Arginine and Pyrimidine Biosynthetic Pathways in Lactobacillus plantarum , L. paraplantarum, L. pentosus , and L. casei : Prevalence of CO 2 -Dependent Auxotrophs and Characterization of Deficient arg Genes in L. plantarum
ABSTRACT Lactic acid bacteria require rich media since, due to mutations in their biosynthetic genes, they are unable to synthesize numerous amino acids and nucleobases. Arginine biosynthesis and pyrimidine biosynthesis have a common intermediate, carbamoyl phosphate (CP), whose synthesis requires C...
Saved in:
Published in | Applied and environmental microbiology Vol. 69; no. 5; pp. 2674 - 2683 |
---|---|
Main Authors | , |
Format | Journal Article |
Language | English |
Published |
01.05.2003
|
Online Access | Get full text |
Cover
Loading…
Summary: | ABSTRACT
Lactic acid bacteria require rich media since, due to mutations in their biosynthetic genes, they are unable to synthesize numerous amino acids and nucleobases. Arginine biosynthesis and pyrimidine biosynthesis have a common intermediate, carbamoyl phosphate (CP), whose synthesis requires CO
2
. We investigated the extent of genetic lesions in both the arginine biosynthesis and pyrimidine biosynthesis pathways in a collection of lactobacilli, including 150 strains of
Lactobacillus plantarum
, 32 strains of
L. pentosus
, 15 strains of
L. paraplantarum
, and 10 strains of
L. casei
. The distribution of prototroph and auxotroph phenotypes varied between species. All
L. casei
strains, no
L. paraplantarum
strains, two
L. pentosus
strains, and seven
L. plantarum
strains required arginine for growth. Arginine auxotrophs were more frequently found in
L. plantarum
isolated from milk products than in
L. plantarum
isolated from fermented plant products or humans; association with dairy products might favor arginine auxotrophy. In
L. plantarum
the
argCJBDF
genes were functional in most strains, and when they were inactive, only one gene was mutated in more than one-half of the arginine auxotrophs. Random mutation may have generated these auxotrophs since different
arg
genes were inactivated (there were single point mutations in three auxotrophs and nonrevertible genetic lesions in four auxotrophs). These data support the hypothesis that lactic acid bacteria evolve by progressively loosing unnecessary genes upon adaptation to specific habitats, with genome evolution towards cumulative DNA degeneration. Although auxotrophy for only uracil was found in one
L. pentosus
strain, a high CO
2
requirement (HCR) for arginine and pyrimidine was common; it was found in 74 of 207
Lactobacillus
strains tested. These HCR auxotrophs may have had their CP cellular pool-related genes altered or deregulated. |
---|---|
ISSN: | 0099-2240 1098-5336 |
DOI: | 10.1128/AEM.69.5.2674-2683.2003 |