Probiotics and Antimicrobial Proteins最新文献

Intensive poultry farming has significantly increased the incidence of lipid metabolic disorders, severely compromising the economic benefits of poultry industry. Currently, gamma-aminobutyric acid (GABA) is primarily used to mitigate adverse effects of heat stress in poultry, while the effects and mechanisms of GABA on lipid metabolism disorders remain underexplored. Lactobacillus plantarum (L. plantarum) serves as a significant source of GABA and is widely used in the livestock industry. This study therefore examines the effects of postbiotic GABA and the GABA-producing probiotic L. plantarum 1-2-3 on abdominal adipose tissue of laying hens following corticosterone-induced stress. To this end, hens subjected to corticosterone subcutaneous injections (4 mg/kg of body weight) were respectively received GABA (100 mg/kg BW) or L. plantarum 1-2-3 (1 × 10⁹ CFU/day). Results demonstrated that both GABA and L. plantarum 1-2-3 alleviated corticosterone-induced lipid metabolism disorders and reduced adipocyte size in abdominal fat. Additionally, expression analyses of genes and proteins related to lipid metabolism (PPARγ, C/EBPα, CD36, LPL, ATGL, and HSL) further showed that GABA and L. plantarum 1-2-3 inhibited excessive deposition of abdominal lipids in laying hens by suppressing adipogenesis and lipogenesis, while promoting lipolysis. Moreover, GABA and L. plantarum 1-2-3 both mitigated lipid deposition-induced inflammation and oxidative damage by normalizing macrophage infiltration and improving antioxidative enzyme activities (GSH-Px, T-SOD, CAT). These findings demonstrate the efficacy of GABA and L. plantarum 1-2-3 in alleviating lipid metabolism disorders in the abdominal adipose tissue of laying hens, suggesting their promise as nutritional supplements for counteracting stress-induced metabolic dysfunction.

The widespread use of commercial antibiotics has led to the emergence of multidrug resistance in pathogenic bacteria, posing a significant threat to human health and underscoring the urgent need for alternative antimicrobial agents. In this study, a bacteriocin-producing strain, Bacillus velezensis FS-3 (B. velezensis FS-3), was isolated from soil in Changbaishan, China. Fermentation conditions were optimized to enhance both bacteriocin activity and yield. A novel bacteriocin, PFS-3, was purified from B. velezensis FS-3 using hydrochloric acid precipitation, organic solvent extraction, and preparative reversed-phase high-performance liquid chromatography. Liquid chromatography-mass spectrometry/mass spectrometry analysis determined its molecular weight to be 929.16 Da, and amino acid sequencing of this peptide revealed eight amino acids (STYLFEGL). To date, the biological properties of PFS-3 have not been reported. We demonstrate here that PFS-3 exhibits low toxicity and remarkable stability under diverse conditions, including variations in temperature, pH, and the presence of metal ions or organic reagents. PFS-3 displayed broad-spectrum antimicrobial activity, with particularly strong activity against Gram-negative bacteria. Notably, its minimum inhibitory concentration against multidrug-resistant Escherichia coli B2 (MDR E. coli B2) was 16 μg/mL. Mechanistic investigations revealed that bacteriocin PFS-3 exerts bactericidal effects on MDR E. coli B2 by disrupting cardiolipin in the outer membrane of the cells. Furthermore, in vivo experiments demonstrated that PFS-3 significantly improved survival rates in infection models of MDR E. coli. In conclusion, PFS-3 is a newly identified bacteriocin with strong antibacterial activity, high stability, safety, and a favorable therapeutic index, highlighting its potential applications in the food industry and biopharmaceuticals for combating MDR E. coli infections.

In this study, an in silico screening approach was employed to mine potential bacteriocin clusters in genome-sequenced isolates of Lacticaseibacillus zeae UD 2202 and Lacticaseibacillus casei UD 1001. Two putative undescribed bacteriocin gene clusters (Cas1 and Cas2) closely related to genes encoding class IIa bacteriocins were identified. No bacteriocin activity was recorded when cell-free supernatants of strains UD 2202 and UD 1001 were tested against Listeria monocytogenes. Genes encoding caseicin A1 (casA1) and caseicin A2 (casA2) were heterologously expressed in Escherichia coli BL21 (DE3) using the nisin leader peptide cloned in-frame to the C-terminal of the green fluorescent gene (mgfp5). Nisin protease (NisP) was used to cleave caseicin A1 (casA1) and caseicin A2 (casA2) from GFP-Nisin leader fusion proteins. Both heterologously expressed peptides (casA1 and casA2) inhibited the growth of L. monocytogenes, suggesting that casA1 and casA2 are either silent in the wild-type strains or are not secreted in an active form. The minimum inhibitory concentration (MIC) of casA1 and casA2, determined using HPLC-purified peptides, ranged from < 0.2 µg/mL to 12.5 µg/mL when tested against Listeria ivanovii, Listeria monocytogenes, and Listeria innocua, respectively. A higher MIC value (25 µg/mL) was recorded for casA1 and casA2 when Enterococcus faecium HKLHS was used as the target. The molecular weight of heterologously expressed casA1 and casA2 is 5.1 and 5.2 kDa, respectively, as determined with tricine-SDS-PAGE. Further research is required to determine if genes within Cas1 and Cas2 render immunity to other class IIa bacteriocins.

The mammalian gut microbiota plays a crucial role in promoting host health, and lactic acid bacteria (LAB) are commonly employed as probiotics for their beneficial effects. The Hangul deer (Cervus hanglu hanglu), a critically endangered red deer subspecies found in the Indian subcontinent, requires meticulous health management for its conservation. This pioneering study aimed to isolate, identify, and evaluate the in-vitro probiotic functional properties of LAB strains from the faeces of Hangul deer. A total of 27 LAB strains were isolated and identified using 16S rDNA gene sequencing, followed by comprehensive probiotic characterization and safety assessment. Remarkably, four species exhibited robust resistance and survivability against varying pH levels and bile salts, along with high aggregation and co-aggregation capacities. Notably, Lactobacillus acidophilus and Enterococcus mundtii strains displayed antibacterial activities. Safety assessment revealed the absence of hemolytic activity and virulence genes in all four strains. Antibiotic susceptibility testing showed that Lactobacillus acidophilus and Enterococcus casseliflavus were susceptible to all tested antibiotics, while Enterococcus mundtii exhibited resistance to clindamycin, and Enterococcus gallinarum exhibited resistance to erythromycin. These findings suggest that the isolated LAB strains possess advantageous probiotic characteristics and hold potential as dietary supplements for promoting the health and disease management of Hangul deer.

The aim of the study was the preliminary genetic and phenotypic characterization of a potential probiotic strain of Lactiplantibacillus pentosus (strain krglsrbmofpi2) obtained from traditionally fermented rice. Genome sequencing revealed that the strain has a 3.7-Mb genome with a GC content of 46 and a total of 3192 protein-coding sequences. Using bioinformatic methods, we have successfully identified phage genes, plasmids, pathogenicity, antibiotic resistance and a variety of bacteriocins. Through comprehensive biochemical and biophysical analyses, we have gained valuable insights into its auto-aggregation, co-aggregation, antibiotic resistance, hydrophobicity, antioxidant activity and tolerance to simulated gastrointestinal conditions. The safety evaluation of the isolated L. pentosus was performed on the basis of its haemolytic activity. Our studies have shown that this strain has a strong antagonistic activity against the priority pathogens identified by the World Health Organization such as Vibrio cholerae, Clostridium perfringens, Salmonella enterica subsp. enterica ser. Typhi, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus. It is essential to fully understand the genetic and functional properties of the L. pentosus strain before considering its use as a useful probiotic in the food industry.

The study aimed to evaluate the effects of supplementation with Lacticaseibacillus casei CSL3 in Swiss mice immunosuppressed with cyclophosphamide on immunological, biochemical, oxidative stress, and histological parameters. The animals were distributed into four groups (control, CSL3, cyclophosphamide, and CSL3 + cyclophosphamide), where two groups were treated with L. casei CSL3 (10 log CFU mL^-1) for 30 days, and two groups received chemotherapy (days 27 and 30-total dose of 250 mg kg^-1). Counts of lactic acid bacteria (LAB) and bile-resistant LAB in stool samples; blood count (erythrogram, leukogram, and platelets); serum total cholesterol levels; catalase enzyme activity; and thiobarbituric acid reactive substances (TBARS) levels in liver, kidney, and brain; IL-4 expression; IL-23, TNF-α, NF-κβ in the spleen; and histological changes in the liver, kidneys, and intestine were evaluated. The CSL3 + cyclophosphamide group showed a significant increase in bile-resistant LAB counts in feces (p = 0.0001), leukocyte counts, and expression of IL-23, TNF-α, and NF-κβ (p < 0.05) significantly reduced total cholesterol levels (p = 0.001) and protected liver damage of supplemented animals. For oxidative stress damage, the bacterium did not influence the results. It is concluded that the bacterium is safe at a concentration of 10 log CFU mL^-1 and has probiotic potential due to its positive influence on the immune response and lipid metabolism.

The contamination of food with Listeria monocytogenes threatens food safety and human health, and developing a novel, green, and safe antimicrobial substance will offer a new food preservation strategy. FengycinA-M3 is a novel lipid peptide with low cytotoxicity and resistance and has effective antibacterial activity against L. monocytogenes with a minimum inhibitory concentration (MIC) of 4 µg/mL. Further combined transcriptomics and proteomics analysis yielded 20 differentially expressed genes (DEGs). The MICs of the combined use of FengycinA-M3 and Cefalexin on L. monocytogenes were further determined as FengycinA-M3 (2 µg/mL) and Cefalexin (8 µg/mL) using the checkerboard method. In addition, FengycinA-M3 was found to play a role in delaying pork deterioration. This study explored the inhibitory effect of FengycinA-M3 on L. monocytogenes and its mechanism of action. FengycinA-M3 interacted with penicillin-binding protein 2B on the cell membrane of L. monocytogenes, destroying the permeability of the membrane, causing cell membrane rupture, thereby inhibiting the growth of L. monocytogenes. Overall, FengycinA-M3 is a promising candidate for preventing the emergence and spread of L. monocytogenes with potential applications in food processing.

The increase in the prevalence of asthma, particularly in urban communities, has encouraged investigations into preventive strategies. The hygiene theory proposes that early exposure to infections and unhygienic conditions during childhood influences immune system development, potentially protecting against allergic diseases. The mechanisms involved are related to alterations in the intestinal microbiota, such as with probiotics. This study aimed to evaluate the preventive effect of Lacticaseibacillus rhamnosus, Lacticaseibacillus paracasei, and Bifidobacterium animalis ssp. lactis, administered isolated or in combination, at various concentrations, on asthma in an animal model. Mice received two concentrations (1 × 10⁹ and 1 × 10¹⁰ CFU/ml) of three probiotics, isolated and in combination, over 26 consecutive days, initiating 10 days before sensitizing and challenging with ovalbumin. In vivo bronchial hyperresponsiveness and airway and lung inflammation were assessed. The administration of L. paracasei, L. rhamnosus, and B. animalis spp. lactis in different concentrations, isolated or in combination, did not reduce hyperresponsiveness and airway and lung inflammation. As probiotic effects are strain and dose-dependents, specific studies are necessary to assess the effect of different probiotic strains, doses, and regimes.

Eubacterium rectale (E. rectale) has the ability to attenuate systemic and intestinal inflammation. Its naturally secreted membrane vesicles (MVs) likely play a crucial role in this process. The objective of this study is to investigate the anti-inflammatory effects of E. rectale and its membrane vesicles (MVs). An inflammation model was established by inducing an inflammatory response in Raw 264.7 cells using lipopolysaccharide (LPS). Subsequently, the cells were pre-treated with E. rectale and its MVs, and the expression levels of IL-1β, IL-6, TNF-α, and IL-10 in the cells were then detected using RT-qPCR. ELISA was used to measure the secretion levels of IL-1β, while western blot analysis was employed to assess the expression of key proteins in the IL-1β pathway, specifically ASC, Caspase 1, and NLRP3. The results revealed that both E. rectale and its MVs significantly reduced the expression of the inflammatory cytokines IL-1β and TNF-α in Raw 264.7 cells, which were induced by LPS. Additionally, they markedly upregulated the expression of the anti-inflammatory cytokine IL-10 and suppressed IL-1β expression via the NLRP3-Caspase 1-ASC signaling pathway. These findings suggest that E. rectale, through its membrane vesicles, can attenuate LPS-induced NLRP3 inflammasome activation, thereby mitigating the inflammatory response in Raw 264.7 cells.