Imaging Mass Spectrometry and Genome Mining Reveal Antimicrobial Peptides of Novel Pediococcus acidilactici CCFM18.

The mechanism of metabolites produced by lactic acid bacteria in mediating microbial interactions has been difficult to ascertain. This study comparatively evaluated the antimicrobial effect of the novel bacterium Pediococcus acidilactici CCFM18 and explored the global chemical view of its interactions with indicator bacteria. P. acidilactici CCFM18 had sufficiently strong antimicrobial activity to effectively inhibit the growth of the indicator bacteria and enhance their intracellular reactive oxygen species (ROS) level. The emerging technique of matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) imaging mass spectrometry indicated that P. acidilactici CCFM18 increased the production of pediocin PA-1 and the penocin A profile during its interaction with the indicator bacteria, thus differing from P. acidilactici CCFM28 (a commonly used laboratory strain). Strikingly, the production of coagulin A was triggered only by signaling molecules made by the competing strain L. thermophilus, suggesting an idiosyncratic response from P. acidilactici CCFM18. Bioinformatic mining of the P. acidilactici CCFM18 draft genome sequence revealed gene loci that code for the complex secondary metabolites analyzed via MSI. Taken together, these results illustrate that chemical interactions between P. acidilactici CCFM18 and indicator bacteria exhibit high complexity and specificity and can drive P. acidilactici CCFM18 to produce different secondary metabolites.

Digestive properties and prebiotic activity of garlic saccharides with different-molecular-weight obtained by acidolysis.

Garlic saccharides have prebiotic activity, but the association between their function and structure is still poorly known. In present study, four different garlic saccharides were obtained from garlic polysaccharides (GPs) after acidolysis by ultrafiltration. Obtained GPs were constituted by different monosaccharides, among which fructose and glucose were the main components, while galactose was a major component of GPs-U6. All four saccharides were partly degraded by the simulated digestive system, and most could reach the large intestine to be utilized by the gut microbiota. Except for GPs-U6, the other three garlic saccharide fractions had good prebiotic activity in vitro and in vivo. Furthermore, GPs-U0.3 with lower molecular weight (Mw) showed better prebiotic activity, including promoting the production of short-chain fatty acids (SCFAs), increasing the abundance of beneficial bacteria such as Bifidobacterium, Lachnospiraceae NK4A136 group and Phoscolarctobacterium, and inhibiting the growth of potentially harmful bacteria. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway enrichment analysis showed that GPs-U0.3 could reduce the risk of cancer and cardiovascular diseases. Overall, this findings of the present study revealed the digestive properties of GPs, as well as the potential association between their chemical structures and fermentation characteristics by gut microbiota. Thus, it can be stated that GPs-U0.3 can be used as potential prebiotics in functional foods, which provides a theoretical basis for the targeted preparation of functionalized garlic saccharides.

Bioactive polysaccharides and oligosaccharides from garlic (Allium sativum L.): Production, physicochemical and biological properties, and structure-function relationships.

Garlic is a common food, and many of its biological functions are attributed to its components including functional carbohydrates. Garlic polysaccharides and oligosaccharides as main components are understudied but have future value due to the growing demand for bioactive polysaccharides/oligosaccharides from natural sources. Garlic polysaccharides have molecular weights of 1 × 103 to 2 × 106  Da, containing small amounts of pectins and fructooligosaccharides and large amounts of inulin-type fructans ((2→1)-linked ß-d-Fruf backbones alone or with attached (2→6)-linked ß-d-Fruf branched chains). This article provides a detailed review of research progress and identifies knowledge gaps in extraction, production, composition, molecular characteristics, structural features, physicochemical properties, bioactivities, and structure-function relationships of garlic polysaccharides/oligosaccharides. Whether the extraction processes, synthesis approaches, and modification methods established for other non-garlic polysaccharides are also effective for garlic polysaccharides/oligosaccharides (to preserve their desired molecular structures and bioactivities) requires verification. The metabolic processes of ingested garlic polysaccharides/oligosaccharides (as food ingredients/dietary supplements), their modes of action in healthy humans or populations with chronic conditions, and molecular/chain organization-bioactivity relationships remain unclear. Future research directions related to garlic polysaccharides/oligosaccharides are discussed.

Effect of blend oil on the volatile aroma profile and storage quality of garlic paste.

The aim of this study was to evaluate the effect of edible oil on the volatile aroma profile and storage quality of garlic paste, and to explore the underlying mechanisms. The administration of blend oil at 40 °C in a garlic to oil ratio of 1.8 had a higher overall acceptance by affective sensory test. Compared with the original garlic paste, the sensory aroma profile of the oil-immersed garlic paste was characterized by suppressed pungency, garlic scent and garlic odor, and enhanced oil scent. SPME-GC-MS and HS-GC-IMS showed that the application of blend oil caused great changes in the level of some compounds, which could explain its role in the oil-immersed garlic paste. Furthermore, the blend oil also reduced the growth rate of the total number of colonies and browning intensity, and inhibited the loss of allicin. Therefore, the application of blend oil in garlic paste improved the sensory aroma and delayed the deterioration of the product quality.

Pediococcus acidilactici Strains Improve Constipation Symptoms and Regulate Intestinal Flora in Mice.

Constipation is a prevalent gastrointestinal disorder that seriously reduces the quality of life. Clinical studies have shown that a great change or severe imbalance occurs in the intestinal microbiota of people with constipation. This study explored whether bacteriocin-producing and non-bacteriocin-producing Pediococcus acidilactici strains resulted in differences in the alleviation of constipation and changes in the fecal flora in BALB/c mice. The constipation-related indicators, gastrointestinal regulatory peptides and gut microbiota were identified to evaluate their alleviating effects and underlying mechanisms. The time to the first black-stool defecation and the gastrointestinal transit rate in constipated mice were found to be somewhat improved by four P. acidilactici strains (P > 0.05). Moreover, there were significant differences in the level of most gastrointestinal regulatory peptides in the serum, as well as in the composition and abundance of intestinal microbiota in different groups (P < 0.05). At the phylum level, the relative abundance of Firmicutes was significantly increased, but those of Bacteroidetes and Proteobacteria were significantly reduced after the administration of four P. acidilactici strains for 14 d (P < 0.05). The levels of Bacteroides and genera from Enterobacteriaceae were significantly decreased, whereas Bifidobacterium and Lactobacillus were upregulated when bacteriocin-producing P. acidilactici CCFM18 and CCFM28 strains were provided in the diet (P < 0.05). The results indicated that although constipation-related symptoms were alleviated to only a limited degree, the administration of four P. acidilactici strains effectively regulated the gut flora and provided a potential health benefit to the host, especially the bacteriocin-producing P. acidilactici strains.

Structural characterization and antioxidant activities of one neutral polysaccharide and three acid polysaccharides from the roots of Arctium lappa L.: A comparison.

In this work, we comparatively analyzed the structure and antioxidant activities of different polysaccharide fractions from Arctium lappa L. A total of four water-soluble polysaccharide fractions (ALP-1, ALP-2, ALP-3 and ALP-4) were obtained from the roots of Arctium lappa L. They differed in monosaccharide composition, molecular weight and linkage mode. ALP-1 and ALP-2 mainly consisted of fructose, with average molecular weights of 2.676 × 103 and 2.503 × 104 g/mol, respectively. ALP-3 and ALP-4 were mainly composed of fructose, arabinose and galactose, with average molecular weights of 9.709 × 104 and 6.790 × 104 g/mol, respectively. Furthermore, Fourier transform infrared spectrometry, methylation analysis and nuclear magnetic resonance spectroscopy suggested that the main polysaccharide ALP-1 had a linear chain of (1 → 2)-linked ß-D-Fructofuranosyl backbone (n ≈ 15) linked to a terminal (1 → 2)-linked α-d-Glucopyranosyl at the non-reducing end. All five polysaccharides displayed high antioxidant ability, especially ALP-4 in H2O2-induced HepG2 cell model and ALP-1 in metronidazole [MET]-induced zebrafish model. These findings provided comparative information on the structure and biological activity of different burdock polysaccharides and highlighted their potential as antioxidants in functional foods.