Lacticaseibacillus paracasei fermentation broth identified peptide, Y2Fr, and its antibacterial activity on Vibrio parahaemolyticus

Probiotic modulation of key immune macromolecules in shrimp

The rapid expansion of shrimp aquaculture has been accompanied by significant disease challenges, driving the need for innovative prevention strategies. Probiotics, which are live microorganisms that confer health benefits to the host, have shown promise in controlling diseases in aquatic environments. Shrimp rely on their innate immune system, including physical barriers, and cellular and humoral defenses, for protection against pathogens. Physical barriers include the exoskeleton and the digestive tract, while cellular defenses involve hemocytes that engage in encapsulation, phagocytosis, and nodulation. Humoral defenses include the prophenoloxidase (proPO) system, lectins, agglutinins, and antimicrobial peptides (AMPs). Recent studies suggest that shrimp innate immunity can exhibit immunological memory, primarily through the actions of phagocytic cells. This review explores the use of probiotics in shrimp aquaculture, with a focus on their interaction with the shrimp immune system and their potential role in probiotic selection, either through environmental adaptation or as feed additives. Probiotics that enhance shrimp immunity by boosting phagocytosis, modulating the proPO system, and interacting with key signaling pathways such as Toll, IMD, and JAK/STAT offer a promising means of improving disease resistance. Probiotics play a critical role in modulating the infection process, influencing pathogen virulence factors, and shaping host-pathogen interactions. Further research into emerging immune pathways in shrimp could deepen our understanding of crustacean immunity and its applications in aquaculture.

Enhancing the quality of mango juices through Lacticaseibacillus paracasei fermentation: unveiling aroma and taste characteristics

BACKGROUND

Lacticaseibacillus paracasei, widely recognized for its safety, is frequently used as a starter culture in fermented foods. In the present study, the differences in the physicochemical properties, antioxidant activities, volatile compounds and non-volatile compounds of mango juice fermented with L. paracasei FJG2339 were evaluated.

RESULTS

The results displayed that L. paracasei FJG2339 significantly reduced the total sugar content of mango juice, but slightly increased the contents of polyphenols and flavonoids. Meanwhile, the ABTS [i.e. 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)], DPPH (i.e. 2,2-diphenyl-1-picrylhydrazyl) and OH radical scavenging abilities of mango juice were increased by 28%, 29% and 48%, respectively, after L. paracasei FJG2339 fermentation. Flavor profiles analysis suggested that L. paracasei FJG2339 facilitated the production of acids, alcohols and esters in mango juice, which endow it with a distinct aroma. Untargeted metabolomics analysis displayed that L. paracasei FJG2339 fermentation significantly shifted 207 non-volatile compounds (containing 123 up-regulated non-volatile substances and 84 down-regulated non-volatile substances) of mango juice, which are mainly involved in animo acid metabolism (such as alanine, aspartate and glutamate metabolism, tyrosine metabolism, tryptophan metabolism, phenylalanine metabolism, phenylalanine, and tyrosine and tryptophan biosynthesis).

CONCLUSION

These results indicate that L. paracasei FJG2339 fermentation enhances the physicochemical properties, antioxidant capacity and metabolic profiles of mango juices. This study has important implications for the application of fermentation technology of fruit juices. © 2025 Society of Chemical Industry.

Assessment of Multifunctional Activity of a Postbiotic Preparation Derived from Lacticaseibacillus paracasei Postbiotic-P6

Postbiotics possess various functional activities, closely linked to their source bacterial strains and preparation methods. Therefore, the functional activities of postbiotics need to be evaluated through in vitro and in vivo methods. This study aims to prepare a postbiotic and explore its antihemolytic, anti-inflammatory, antioxidant, and antibacterial activities. Specifically, a postbiotic preparation named PostbioP-6 was prepared by intercepting 1-5 kDa of Lacticaseibacillus paracasei Postbiotic-P6 fermentation broth. The results demonstrate that PostbioP-6 exhibited notable biological activities across multiple assays. It showed significant antihemolytic activity, with a 4.9-48.1% inhibition rate at 10-50% concentrations. Anti-inflammatory effects were observed both in vitro, where 8-40% PostbioP-6 was comparable to 259.1-645.4 μg/mL diclofenac sodium, and in vivo, where 3.5 and 4.0 μL/mL PostbioP-6 significantly reduced neutrophil counts in inflamed zebrafish (p < 0.05). Antioxidant properties were evident through increased reducing power (OD700 increased from 0.279 to 2.322 at 1.25-12.5% concentrations), DPPH radical scavenging activity (38.9-92.4% scavenging rate at 2.5-50% concentrations), and hydroxyl radical scavenging activity (4.66-10.38% scavenging rate at 0.5-4% concentrations). Additionally, PostbioP-6 demonstrated antimicrobial activity against two Gram-positive bacteria, eight Gram-negative bacteria, and one fungus. Furthermore, PostbioP-6 significantly inhibited the increase in peroxide value and malondialdehyde content in cookies, highlighting its potential application in food preservation. In conclusion, we prepared a novel postbiotic, termed PostbioP-6, which proved to have prominent anti-hemolytic, anti-inflammatory, antioxidant, and broad-spectrum antimicrobial activities. The multifunctional properties of PostbioP-6 position it as a potentially effective functional food supplement or preservative. In the future, further research is necessary to elucidate the precise mechanisms of action, identify the active components, and validate its biological activities in animal models or clinical trials.

Antimicrobial Activity, Genetic Relatedness, and Safety Assessment of Potential Probiotic Lactic Acid Bacteria Isolated from a Rearing Tank of Rotifers (Brachionus plicatilis) Used as Live Feed in Fish Larviculture

Aquaculture is a rapidly expanding agri-food industry that faces substantial economic losses due to infectious disease outbreaks, such as bacterial infections. These outbreaks cause disruptions and high mortalities at various stages of the rearing process, especially in the larval stages. Probiotic bacteria are emerging as promising and sustainable alternative or complementary strategies to vaccination and the use of antibiotics in aquaculture. In this study, potential probiotic candidates for larviculture were isolated from a rotifer-rearing tank used as the first live feed for turbot larvae. Two Lacticaseibacillus paracasei and two Lactiplantibacillus plantarum isolates were selected for further characterization due to their wide and strong antimicrobial activity against several ichthyopathogens, both Gram-positive and Gram-negative. An extensive in vitro safety assessment of these four isolates revealed the absence of harmful traits, such as acquired antimicrobial resistance and other virulence factors (i.e., hemolytic and gelatinase activities, bile salt deconjugation, and mucin degradation, as well as PCR detection of biogenic amine production). Moreover, Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR) analyses unveiled their genetic relatedness, revealing two divergent clusters within each species. To our knowledge, this work reports for the first time the isolation and characterization of Lactic Acid Bacteria (LAB) with potential use as probiotics in aquaculture from rotifer-rearing tanks, which have the potential to optimize turbot larviculture and to introduce novel microbial management approaches for a sustainable aquaculture.

Antibacterial activity and mechanism of cell-free supernatants of Lacticaseibacillus paracasei against Propionibacterium acnes

Propionibacterium acnes (P. acnes) is an anaerobic and gram-positive bacterium involved in the pathogenesis and inflammation of acne vulgaris. This study particularly focuses on the antimicrobial effect of Lacticaseibacillus paracasei LPH01 against P. acnes, a bacterium that causes acne vulgaris. Fifty-seven Lactobacillus strains were tested for their ability to inhibit P. acnes growth employing the Oxford Cup and double dilution methods. The cell-free supernatant (CFS) of L. paracasei LPH01 demonstrated a strong inhibitory effect, with an inhibition zone diameter of 24.65 ± 0.27 mm and a minimum inhibitory concentration of 12.5 mg/mL. Among the CFS, the fraction over 10 kDa (CFS-10) revealed the best antibacterial effect. Confocal laser scanning microscopes and flow cytometry showed that CFS-10 could reduce cell metabolic activity and cell viability and destroy the integrity and permeability of the cell membrane. A scanning electron microscope revealed that bacterial cells exhibited obvious morphological and ultrastructural changes, which further confirmed the damage of CFS-10 to the cell membrane and cell wall. Findings demonstrated that CFS-10 inhibited the conversion of triglycerides, decreased the production of free fatty acids, and down-regulated the extracellular expression of the lipase gene. This study provides a theoretical basis for the metabolite of L. paracasei LPH01 as a potential antibiotic alternative in cosmeceutical skincare products.