The objective of this study was the characterisation of the S-layer protein (SlpA) and its functional role in the probiotic activity of
Lactobacillus helveticus
M92. SlpA was isolated and identified ...by SDS-PAGE LC-MS/MS analysis. The
slpA
gene encoding the SlpA from
L. helveticus
M92 was sequenced and compared with other well characterised
slpA
genes. Sequence similarity searches revealed high homology with the SlpA of
Lactobacillus
strains. Purified SlpA showed significantly better immunomodulatory effects in orally immunised mice than
L. helveticus
M92 cells after SlpA removal. SlpA is involved in the autoaggregation of
L. helveticus
M92 cells and coaggregation of
L. helveticus
M92 with
S.
Typhimurium FP1 as these processes were negatively affected after SlpA removal from the cell surface. Therefore, the influence of oral treatment with
L. helveticus
M92 on an oral infection of mice by
S.
Typhimurium FP1 was investigated. Following the oral immunization of mice, with viable
L. helveticus
M92 and
S.
Typhimurium FP1 cells, the concentration in the luminal contents of total S-IgA and specific anti-
Salmonella
S-IgA antibodies, from all immunized mice was significantly higher compared to the control group or a group of mice infected only with
S.
Typhimurium FP1. These results demonstrate that the observed reduced infection by
S.
Typhimurium FP1 in mice with
L. helveticus
M92 is associated with competitive exclusion in the intestinal tract and enhanced immune protection conferred by the
L. helveticus
M92 and its SlpA.
► Significant variation is detected in antioxidant content of white cabbage cultivars. ► Developmental stage significantly influences the accumulation of phenolics in cabbage. ► Seed selection causes ...intracultivar variations in the phytochemical content of cabbage plants.
The accumulation of total phenols (TP, Folin-Ciocalteu method) and total flavonoids (TF, colorimetric assay with AlCl
3) and the evolution of antioxidant capacity (FRAP assay, DPPH and ABTS radical scavenging assays) have been monitored in juices of Croatian white cabbage (
Brassica oleracea var.
capitata) cultivars Varaždinski and Ogulinski, as well as Chinese cabbage (
Brassica rapa var.
pekinensis), at various developmental stages. Measurements were performed every four weeks, starting from planting to full maturity, throughout the course of eight months. In the first 8–12 weeks, the TP and TF contents as well as antioxidant capacity increased significantly in all analyzed juice samples and in most even doubled. This rapid increase was followed by a gradual decrease in values derived from all assays, over the course of 12–30 weeks, to the final values which were in all cases lower than the values measured at week 4. The results also point to significant variability in TP and TF contents and antioxidant capacity at the fully mature stage between white and Chinese cabbage juices and between juices extracted from cultivars Ogulinski and Varaždinski.
The antimicrobial activity of industrially important lactic acid bacteria as starter cultures and probiotic bacteria is the main subject of this review. This activity has been attributed to the ...production of metabolites such as organic acids (lactic and acetic acid), hydrogen peroxide, ethanol, diacetyl, acetaldehyde, acetoine, carbon dioxide, reuterin, reutericyclin and bacteriocins. The potential of using bacteriocins of lactic acid bacteria, primarily used as biopreservatives, represents a perspective, alternative antimicrobial strategy for continuously increasing problem with antibiotic resistance. Another strategy in resolving this problem is an application of probiotics for different gastrointestinal and urogenital infection therapies. Key words: antimicrobial activity, bacteriocins, lactic acid bacteria, probiotics, starter cultures
Glavna je tema ovoga rada antimikrobno djelovanje industrijski važnih bakterija mliječne kiseline što se koriste kao starter kulture i probiotičke bakterije. Njihovo antimikrobno djelovanje potječe ...od proizvedenih metabolita, kao što su organske kiseline (mliječna i octena kiselina), vodikov peroksid, etanol, diacetil, acetaldehid, acetoin, ugljikov dioksid, reuterin, reutericiklin i bakteriocini. Primjena bakteriocina bakterija mliječne kiseline, u prvom redu kao biokonzervansa, može biti alternativa rješavanju sve većeg problema antibiotičke rezistencije. Druga je mogućnost u rješavanju toga problema primjena probiotika u terapiji različitih gastrointestinalnih i urogenitalnih infekcija.
