Temporal gene expression and probiotic attributes of Lactobacillus acidophilus during growth in milk

Temporal clusters of orthologous groups (COG; Tatusov et al., 1997) classification of differentially expressed genes at 4, 8, and 12h. Genes were classified according to the main COG domain present in the potentially encoded protein sequence. The COG functional category codes are indicated on the right.

Temporal expression patterns of genes of the proteolytic system identified by the quadratic regression method (Liu et al., 2005). Patterns obtained included: Flat (not shown; no significant differential expression over time), linear up-regulated regression pattern (LU), quadratic concave regulated regression pattern (QC), quadratic convex regulated regression pattern (QV), quadratic linear concave up-regulated regression pattern (QLCU), and quadratic linear convex up-regulated regression pattern (QLVU).

Mean gene expression of oligopeptide transport 1 (opp1, continuous line), opp2 (dashed line), and LBA1524HPK-LBA1525RR 2-component regulatory system (dotted line) over time during growth of L. acidophilus NCFM in milk.

Correlation between tm (time in minutes necessary to reach the maximum acidification rate in milk) and K (death rate) values corresponding to acidification rates in milk and survival in acidified milk, respectively.

Adherence abilities of 6 L. acidophilus NCFM derivatives grown in skim milk, to mucin (■), and to Caco-2 cells (□). The results are expressed as a percentage of the wild-type strain. Values represent the mean of 3 independent experiments and error bars represent the standard deviation. The asterisks represent statistically significant (P<0.05) differences between mutant and control strains.