salmonicida

Evaluation of Different Nutritional Sources in Lactic Acid Bacteria Fermentation for Sustainable Postbiotic Production

In recent years, interest in postbiotics has grown due to their potential health benefits and applications in food systems. This study evaluated various nutritional sources for lactic acid bacteria (LAB) fermentation to enhance postbiotic production. Three LAB strains were tested: Pediococcus acidilactici CECT 9879 (PA), Weissella cibaria CECT 30731 (WC), and Lactococcus lactis CECT 30734 (LL). Fermentation experiments assessed bacterial growth, pH levels, and antibacterial activity against E. coli using different carbon and nitrogen sources. Fructose and xylose significantly improved growth in WC (9.39 ± 0.16 log CFU/mL) and LL (9.37 ± 0.22 log CFU/mL) compared to glucose. Ribose enhanced antimicrobial activity in PA (41.67 ± 2.89%) and WC (50.00 ± 0.00%) relative to glucose. Additionally, plant-based nitrogen sources, such as soy (LL: 8.93 ± 0.12 log CFU/mL and 81.67 ± 2.89%) and wheat (WC: 9.40 ± 0.17 log CFU/mL and 65.00 ± 0.00%), along with microbial sources like yeast (PA: 9.57 ± 0.12 log CFU/mL and 40.00 ± 0.00%), effectively supported growth and antibacterial activity. These findings highlight the potential of developing animal-free fermentation media that meet nutritional, safety, and sustainability criteria while making a significant contribution to the optimization of postbiotic production.

Microalgae and cyanobacteria as microbial substrate and their influence on the potential postbiotic capability of a bacterial probiotic

Postbiotics are metabolic by-products from microorganisms that provide health benefits to the host. Their secretion can be influenced by various conditions affecting bacterial metabolism. This study presents a novel approach for producing potential postbiotics, specifically extracellular products (ECPs), from the probiotic strain Shewanella putrefaciens SpPdp11, grown under different culture conditions. These conditions include aquafeed media, with partial or total microalgae/cyanobacteria replacement as the microbial substrate, as well as variations in temperature and growth phase. The use of microalgae/cyanobacteria as substrates may represent a valuable strategy for generating novel postbiotics with unique properties. The ECPs assessed were evaluated for their in vitro cytotoxic, hydrolytic and antimicrobial activities. Three conditions (ECPs derived from aquafeed media with partial (FM2324 and FM1548) or total (M2324) microalgae/cyanobacteria replacement) were non-cytotoxic to various fish cell lines and hydrolysed key nutritional compounds (casein, lipids, amylase and gelatin). Proteomic analysis of these ECP conditions revealed common structural and regulatory DNA-associated proteins, while differentially expressed proteins were associated with amino acid metabolism and antioxidant system (FM2324 and FM1548) and chemotaxis system (M2324). The results highlight the potential of the selected postbiotics as feed additives for future in vivo studies, aligning with sustainable development for aquaculture.

Microbial Contamination of Food: Probiotics and Postbiotics as Potential Biopreservatives

Microbial contamination of food and alimentary toxoinfection/intoxication in humans are commonly caused by bacteria such as Salmonella spp., Escherichia coli, Yersinia spp., Campylobacter spp., Listeria monocytogenes, and fungi (Aspergillus, Fusarium). The addition of probiotic cultures (bacterial strains Lactobacillus and Bifidobacterium and the yeast Saccharomyces cerevisiae var. boulardii) to food contributes primarily to food enrichment and obtaining a functional product, but also to food preservation. Reducing the number of viable pathogenic microorganisms and eliminating or neutralizing their toxins in food is achieved by probiotic-produced antimicrobial substances such as organic acids (lactic acid, acetic acid, propionic acid, phenylacetic acid, and phenyllactic acid), fatty acids (linoleic acid, butyric acid, caproic acid, and caprylic acid), aromatic compounds (diacetyl, acetaldehyde, reuterin), hydrogen peroxide, cyclic dipeptides, bacteriocins, and salivabactin. This review summarizes the basic facts on microbial contamination and preservation of food and the potential of different probiotic strains and their metabolites (postbiotics), including the mechanisms of their antimicrobial action against various foodborne pathogens. Literature data on this topic over the last three decades was searched in the PubMed, Scopus, and Google Scholar databases, systematically presented, and critically discussed, with particular attention to the advantages and disadvantages of using probiotics and postbiotics as food biopreservatives.

An ex vivo Approach in European Seabass Leucocytes Supports the in vitro Regulation by Postbiotics of Aip56 Gene Expression of Photobacterium damselae subsp. piscicida

Shewanella putrefaciens Pdp11 (SpPdp11) is a probiotic strain assayed in aquaculture; however, its postbiotic potential is unknown. Postbiotics are bacterial metabolites, including extracellular products (ECPs) that improve host physiology and immunity. Their production and composition can be affected by different factors such as the growing conditions of the probiotics. Photobacterium damselae subsp. piscicida strain Lg 41/01 (Phdp) is one of the most important pathogens in marine aquaculture. The major virulent factor of this bacterium is the exotoxin aip56, responsible for inducing apoptosis of fish leucocytes. Viable SpPdp11 cells have been reported to increase resistance to challenges with Phdp. This work aimed to evaluate the effect of two ECPs, T2348-ECP and FM1548-ECP, obtained from SpPdp11 grown under different culture conditions that previously demonstrated to exert different degradative and non-cytotoxic activities, as well as the effect on pathogens biofilm formation. These SpPdp11-ECPs were then analyzed by their effect on the viability, phagocytosis, respiratory burst and apoptogenic activity against European sea bass leucocytes infected or not with Phdp supernatant. Both ECPs, T2348-ECP and FM1548-ECP, were not cytotoxic against leucocytes and significantly reduced their apoptosis. Phagocytosis and respiratory burst of leucocytes were significantly reduced by incubation with Phdp supernatant, and not influenced by incubation with T2348-ECP or FM1548-ECP. However, both activities were significantly increased after leucocyte incubation with combined T2348-ECP and FM1548-ECP with Phdp supernatant, compared to those incubated only with Phdp supernatant. Finally, both T2348-ECP and FM1548-ECP significantly reduced the relative in vitro expression of the Phdp aip56 encoding gene.

A Novel Postbiotic Product Based on Weissella cibaria for Enhancing Disease Resistance in Rainbow Trout: Aquaculture Application

Postbiotics are innovative tools in animal husbandry, providing eco-friendly solutions for disease management within the industry. In this study, a new postbiotic product was evaluated for its impact on the health of rainbow trout (Oncorhynchus mykiss). In vivo studies were conducted to assess the safety of the Weissella cibaria strains used in postbiotic production. Additionally, this study evaluated the impact of diet supplementation with 0.50% postbiotics on growth performance during a 30-day feeding trial; the gut microbial communities, immunomodulation, and protection against Yersinia ruckeri infection were evaluated. The strains did not harm the animals during the 20-day observation period. Furthermore, the effect of postbiotics on growth performance was not significant (p < 0.05). The treated group showed a significant increase in acid-lactic bacteria on the 30th day of the feeding trial, with counts of 3.42 ± 0.21 log CFU/mL. Additionally, there was an up-regulation of the pro-inflammatory cytokine IL-1β in head kidney samples after 48 h of feed supplementation, whereas cytokines IL-10, IL-8, INF-γ, and TNF-α were down-regulated. The findings indicate that rainbow trout fed with postbiotics saw an improvement in their survival rate against Y. ruckeri, with a 20.66% survival improvement in the treated group. This study proves that incorporating postbiotics from two strains of W. cibaria previously isolated from rainbow trout into the diet of fish has immunomodulatory effects, enhances intestinal microbial composition, and improves fish resistance against Y. ruckeri.

New Evidence for the Role of Pituitary Adenylate Cyclase-Activating Polypeptide as an Antimicrobial Peptide in Teleost Fish

Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) is a multifunctional neuropeptide that is widely distributed and conserved across species. We have previously shown that in teleost fish, PACAP not only possesses direct antimicrobial properties but also immunomodulatory effects against the bacterial pathogens Flavobacterium psychrophilum and Pseudomonas aeruginosa using in vitro and in vivo experiments. These previous results suggest PACAP can be used as an alternative to antibiotics to prevent and/or treat bacterial infections in the aquaculture industry. To accomplish this goal, more studies are needed to better understand the effect of PACAP on pathogens affecting fish in live infections. In the present study, the transcripts PACAP, PRP/PACAP, and VPAC2 receptor were examined in rainbow trout (Oncorhynchus mykiss) naturally infected with Yersinia ruckeri, which exhibited an increase in their expression in the spleen when compared to healthy fish. Synthetic Clarias gariepinus PACAP-38 has direct antimicrobial activity on Y. ruckeri and inhibits up to 60% of the bacterial growth when the peptide is at concentrations between 50 and 100 µM in TSB. The growth inhibition increased up to 90% in the presence of 12.5 µM of PACAP-38 when salt-free LB broth was used instead of TSB. It was also found to inhibit Y. ruckeri growth in a dose-dependent manner when the rainbow trout monocyte/macrophage-like cell line (RTS11) was pre-treated with lower concentrations of the peptide (0.02 and 0.1 µM) before going through infection. Differential gene expression was analyzed in this in vitro model. Overall, the results revealed new evidence to support the role of PACAP as an antimicrobial and immunomodulatory peptide treatment in teleosts.

From probiotics to postbiotics: Concepts and applications

In recent years, the important role of gut microbiota in promoting animal health and regulating immune function in livestock and poultry has been widely reported. The issue of animal health problems causes significant economic losses each year. Probiotics and postbiotics have been widely developed as additives due to their beneficial effects in balancing host gut microbiota, enhancing intestinal epithelial barrier, regulating immunity, and whole‐body metabolism. Probiotics and postbiotics are composed of complex ingredients, with different components and compositions having different effects, requiring classification for discussing their mechanisms of action. Probiotics and postbiotics have considerable prospects in preventing various diseases in the livestock industry and animal feed and medical applications. This review highlights the application value of probiotics and postbiotics as potential probiotic products, emphasizing their concept, mechanism of action, and application, to improve the productivity of livestock and poultry.