Probiotic Agents Research Articles

Genomic characterization and probiotic potency of Bacillus velezensis CPA1-1 reveals its potential for aquaculture applications

Biological prevention and control are increasingly applied in sustainable aquaculture, and Bacillus spp. has been revealed to good alternatives to antibiotics. This research examined the probiotic capabilities of Bacillus velezensis CPA1-1 by genomic and phenotypic analysis. The genome sequence showed that B. velezensis CPA1-1 has a 3,925,520 bp chromosome with 46.49 % GC content and 3762 CDSs. And eight clusters of secondary metabolite biosynthesis genes related to antibacterial compounds were predicted in CPA1-1 genome, including surfactin, difficidin, bacillibactin, fengycin, bacilysin, bacillaene, macrolactin H, butirosin A. Besides, the antimicrobial assay indicated that strain CPA1-1 exhibited strong antagonistic capacity against non-O1/O139 Vibrio cholerae GXFL1-4 isolated from diseased Macrobrachium rosenbergii, and MIC of CPA1-1 fermentation broth against GXFL1-4 was 1.0 × 105 CFU/mL. Furthermore, administering CPA1-1 markedly elevated the activities of ACP, AKP, and SOD in M. rosenbergii, and the immune-related genes, including ALF, Crustin, Hemocyanin, Prophenoloxidase, C-type lectin and HSP70, also exhibited higher expression in the CPA1-1 treated groups. Additionally, M. rosenbergii in the test group treated with CPA1-1 could resist non-O1/O139 V. cholerae GXFL1-4 infection by the challenge test. Our study contributed to reveal biocontrol mechanisms of B. velezensis CPA1-1, and demonstrated that CPA1-1 has promise as a probiotic agent for aquaculture.

Effect of Sucrose Concentration on Microbiological, Physicochemical, Antioxidant Activity, and Organoleptic Characteristics of Salak Fruit Juice Beverage Fermented with Lactobacillus Plantarum InaCC B153

Salak is a tropical fruit that has great potential to be made into a healthy fermented beverage. The carbohydrate content and bioactive compounds such as phenolics in salak provide benefits as a source of antioxidants. The fermentation process will produce a probiotic drink that is good for digestive health. The fermentation process involves Lactobacillus plantarum bacteria as probiotic agents. This study aims to determine the effect of sucrose concentration on the characteristics of salak fruit juice probiotic drinks. This study used a completely randomised design (CRD) factorial pattern with sucrose concentration factor (3%, 6%, 9% b/v). The data obtained were analysed using ANOVA followed by DMRT further test at the 5% level. The results showed a significant interaction (p≤0.05). Fermented salak fruit juice using 9% sucrose was the best treatment with characteristics of pH 3.80; total microbes 9.023 log CFU/ml; total acid 1,11%; total sugar 13,88%; viscosity 118,35 mPa.s; DPPH antioxidant activity 89.99%. The resulting organoleptic properties including colour, aroma, and taste, overall were 3.40 (moderately liked), 3.08 (moderately liked), 3.76 (moderately liked), and 3,48 (moderately liked).

Epiphytic Yeasts from South Romania for Preventing Food Microbial Contamination.

Epiphytic yeasts represent an important source for the development of novel strategies aiming to combat food microbial contamination. The present study deals with the characterization of nine yeast strains belonging to Starmerella, Candida, Metschinikowia, Lachancea, Kodamaea and Pichia genera, isolated from the surface of plants from the Botanical Garden "Dimitrie Brandza" (Bucharest, Romania) for use as antimicrobial and probiotic agents. The tests involved the determination of the safe status, cell growth under stress conditions, and activity against pathogenic Candida and bacteria strains, respectively, as well as phytopathogenic filamentous fungi and lipolytic activity. None of the nine strains showed all the characteristics for virulence and pathogenicity, with the rare positive results being explained rather by their adaptability to the habitats of origin. The strains Lachancea thermotolerans CMGB-ST12 and Kodamaea ohmeri CMGB-ST19 grew at 37 °C; Metschnikowia reukaufii CMGB-ST21.2, M. reukaufii CMGB-ST.8.1 and M. reukaufii CMGB ST10 grew in the presence of 10% NaCl, while L. thermotolerans CMGB-ST12 and K. ohmeri CMGB-ST19 tolerated both acidic and alkaline pH values well (3.0 to 12.0). The studied yeast strains showed good antimicrobial activity against Candida krusei, Candida albicans and Gram-negative bacterial strains, with K. ohmeri CMGB-ST19 and Pichia membranaefaciens CMGB-ST53 inhibiting up to 100% the development of filamentous fungi. All the strains produced lipases for tributyrin hydrolysis, the best producer being Starmerella bombi CMGB-ST1, and only Candida magnoliae CMGB-ST8.2 tested positive against other probiotic yeasts. Overall, our nine yeast strains show high potential for industrial applications, for obtaining probiotic products and for preventing the development of a wide range of microbial food contaminants.

Effect of period supplementation of Saccharomyces boulardii in humoral immune response of sheep immunized with recombinant chimera of Paeniclostridium sordellii

Saccharomyces boulardii has emerged as a promising probiotic agent in bolstering the immune system. In vaccinology, its application can be explored to optimize vaccine efficacy by augmenting host immune response and consequently enhancing the immunogenicity of antigenic formulations. However, it is imperative to conduct further research to comprehend the effectiveness of this probiotic in novel vaccines targeting significant pathogens affecting animal health. Hence, this study investigated the effects of a short (3 - 5 days) or continuously (56 days) S. boulardii supplementation (3 × 108 CFU/mL) on the adaptive immunity of sheep immunized with a recombinant antigen against Paeniclostridium sordellii (rAPS). Four immunized groups (G1-G4) were evaluated, varying the regimen of S. boulardii supplementation. Elevated levels of anti-rAPS IgG immunoglobulins were detected in all vaccinated animals. Daily supplementation with S. boulardii (G1) resulted in higher IgG levels, reaching antibody titers of up to 25,600, which were 16 times higher than those observed in not supplemented group (G4) and 4 times higher than in the group supplemented for 3 days (G3) or 5 days (G2) before each immunization. These findings demonstrate that S. boulardii can enhance vaccine-induced immune responses against P. sordellii, particularly IgG-mediated immune responses in sheep. The possibility of a short supplementation for 5–3 days is a very important finding for animal husbandry, considering the supplementation and supply management cost.

Screening of the Lipid-Lowering Probiotic Lactiplantibacillus Plantarum SDJ09 and its Anti-Obesity Mechanism.

In this study, 39 strains of lactic acid bacteria were screened from several fermented foods. Based on the evaluation of functional and prebiotic properties, Lactiplantibacillus plantarum SDJ09 was selected as a promising candidate. It gave a 48.16% cholesterol reduction and 33.73% pancreatic lipase inhibition in cells; exhibited high resistance to acid, bile salts, and gastrointestinal fluid; and had strong antibacterial activity and high adhesion capabilities. More importantly, the lipid-lowering effect of L. plantarum SDJ09 was also investigated using 3T3-L1 mature adipocytes and HepG2 nonalcoholic fatty liver disease models. L. plantarum SDJ09 effectively decreased triglyceride accumulation by more than 50% in both cell models, in which the expression of PPARγ, C/EBPα, aP2, and LPL in 3T3-L1 cells was significantly downregulated by L. plantarum SDJ09. L. plantarum SDJ09 also improved lipid metabolism by downregulating the expression of HMGCR, SREBP-1c, ACC, and FAS and upregulating the expression of CYP7A1 in HepG2 nonalcoholic steatohepatitis cells. Therefore, L. plantarum SDJ09 has the potential to effectively decrease obesity and non-alcoholic fatty liver disease (NAFLD) by inhibiting lipid accumulation, providing a prospective probiotic agent for anti-obesity.

In vitro assessment of probiotic potentials of yeast strains isolated from a cereal-based (Ogi)) traditional fermented food

This present research focused on the isolation of yeast strains from fermented African cereal-based food with promising probiotic attributes. Yeast isolates were obtained from a locally produced cereal-based food “Ogi” also known as Akamu. The yeast was evaluated for their stress tolerance (pH, bile, temperature, NaCl, gastric juice), adhesion properties (auto-aggregation, hydrophobicity) and susceptibility to antibiotics. The strains performed well at 37 °C and exhibited strong ability to tolerate acid (pH 3) and bile salt (1.5%) environment with a percentage survival range of 60-82.61% and 62.96-83.67% respectively. Candida tropicalis (A4) gave the highest salt tolerance at 1% (89.29) and 4% (92.86), while Saccharomyces cerevisiae (A2) showed greater ability to survive the stimulated gastrointestinal conditions at 42.86%. The strains exhibited high auto-aggregation (68.8-94.9%) and a good hydrophobicity to chloroform and toluene. Susceptibility profile of the yeast strains to antibacterial antibiotics showed that all the yeasts presented a resistance pattern. These results indicate that C. tropicalis and S. cerevisiae both have the capability to serve as probiotic agents and can be proposed for various applications. Also, fermented cereal-based Ogi with its wide array of health benefits can serve as a carrier for the delivery of probiotics to both animals and humans as food supplements.

Fermented Ananas comosus and Carica papaya harbour putative probiotic Limosilactobacillus fermentum and Lacticaseibacillus paracasei strains with inhibitory activity against α-glucosidase and α-amylase

Diabetes mellitus (DM) is the condition represented by persistent hyperglycaemia, owing to the altered glucose metabolism. The current research aims to assess the capabilities of strains of lactic acid bacteria (LAB) that were obtained from fermented Ananas comosus (A. comosus) and Carica papaya (C. papaya) (non-dairy sources) as probiotics for the prevention of DM. The capacity of the strains to endure or survive extreme conditions was evaluated using bile tolerance using oxgall at varying concentrations, hydrophobicity, coaggregation ability, adhesion ability, and hemolytic activity, and their survival rate in gastric and intestinal juices. The LAB strains demonstrated the following results: phenol (>7 Log CFU/mL), acid-bile conditions (6.53–7.11 Log CFU/mL), gastric and intestinal juice tolerance (6.18–7.33 Log CFU/mL), thereby fulfilling the requirements to be a prospective probiotic agent. The LAB strains showed characteristics of cell surface hydrophobicity (≥ 40 %), autoaggregation (≥ 70 %), and coaggregation (≤ 48 %). Furthermore, they demonstrated antioxidant activity (≥ 59 %) as well as the ability to lower blood sugar levels by inhibiting α-glucosidase (≤ 57 %) and α-amylase (≤ 64 %). The development of antidiabetic probiotics from fermented papaya and pineapple has several potential uses. These probiotics may be used as functional foods or supplements to improve glycemic control in individuals with DM. They may also be used as adjunct therapies to conventional diabetes treatments to enhance their efficacy. The results of this research may pave way for creating probiotic products that function as food additives or supplements, with the aim of enhancing health and preventing long-term illnesses like diabetes. Additionally, probiotics have been proven to boost intestinal health, regulate the immune system, and decrease inflammation.

Post Natal Microbial and Metabolite Transmission: The Path from Mother to Infant.

The entero-mammary pathway is a specialized route that selectively translocates bacteria to the newborn's gut, playing a crucial role in neonatal development. Previous studies report shared bacterial and archaeal taxa between human milk and neonatal intestine. However, the functional implications for neonatal development are not fully understood due to limited evidence. This study aimed to identify and characterize the microbiota and metabolome of human milk, mother, and infant stool samples using high-throughput DNA sequencing and FT-ICR MS methodology at delivery and 4 months post-partum. Twenty-one mothers and twenty-five infants were included in this study. Our results on bacterial composition suggest vertical transmission of bacteria through breastfeeding, with major changes occurring during the first 4 months of life. Metabolite chemical characterization sheds light on the growing complexity of the metabolites. Further data integration and network analysis disclosed the interactions between different bacteria and metabolites in the biological system as well as possible unknown pathways. Our findings suggest a shared bacteriome in breastfed mother-neonate pairs, influenced by maternal lifestyle and delivery conditions, serving as probiotic agents in infants for their healthy development. Also, the presence of food biomarkers in infants suggests their origin from breast milk, implying selective vertical transmission of these features.

Pichia kudriavzevii UNJCC Y-137 and Candida tropicalis UNJCC Y-140 isolated from Durio kutejensis as potential probiotic agents.

Durio kutejensis, commonly known as Lai durian, has a unique characteristics of a creamy texture and a combination of sweet and bitter tastes. This study aimed to isolate and screen yeast from fruits as a potential probiotic agent. The tests consisted of tolerance to bile salt and gastric acid at pH 2, antibacterial activity against Listeria monocytogenes and Salmonella enteriditis, and hemolytic activity on blood agar medium. The results showed that 40 yeasts isolated from Lai durian fruit and 34 of these isolates grew on YMA medium. The two isolates showed high significance in the probiotic tests. These two isolates were able to grow on bile salt up to a concentration of 2% and gastric acid for up to 6h, with survival rates of 99.06% and 100%, respectively. Two isolates were identified as Pichia kudriavzevii UNJCC Y-137 and Candida tropicalis UN-JCC Y-140 Therefore, these two yeast isolates can be used as potential probiotic agents.

Screening of Probiotic Candidates Bacteria as Biocontrol of Aeromonas Hydrophila Pathogen Isolated from Mina Padi Cultivation Area

The agricultural activities in rice-farming system can have an impact on fish farming and the characteristics of bacterial community, especially pathogenic bacteria. Utilization of probiotics as environmentally friendly biotechnology products can be used to improve environmental quality and suppress the presence of pathogenic bacteria. This study aimed to select bacteria as probiotic agents from aquaculture ponds with the Rice-fish farming system. A total of 22 bacterial isolates were isolated from the water and sediment contained in the culture ponds. Based on the screening results, 15 isolates were confirmed as general non-pathogenic bacteria (Aeromonas sp.), 9 isolates had antibacterial activity against Aeromonas hyrophylla and 4 isolates showed high antibiotic sensitivity and were able to synergize. The results showed the Proteus mirabilis, Proteus penneri, Kurthia gibsonii and Bacillus cereus strains. Bacillus cereus strain LB8 has antibacterial activity that can inhibit the pathogen Aeromonas hydrophila with an inhibition zone of 8mm and has a very high sensitivity to antibiotics. These four isolates are able to work together synergistically and can be used as consortium probiotic bacterial agents to suppress the growth of pathogens.

TREM2 deficiency reprograms intestinal macrophages and microbiota to enhance anti-PD-1 tumor immunotherapy.

The gut microbiota and tumor-associated macrophages (TAMs) affect tumor responses to anti-programmed cell death protein 1 (PD-1) immune checkpoint blockade. Reprogramming TAM by either blocking or deleting the macrophage receptor triggering receptor on myeloid cells 2 (TREM2) attenuates tumor growth, and lack of functional TREM2 enhances tumor elimination by anti-PD-1. Here, we found that anti-PD-1 treatment combined with TREM2 deficiency in mice induces proinflammatory programs in intestinal macrophages and a concomitant expansion of Ruminococcus gnavus in the gut microbiota. Gavage of wild-type mice with R. gnavus enhanced anti-PD-1-mediated tumor elimination, recapitulating the effect occurring in the absence of TREM2. A proinflammatory intestinal environment coincided with expansion, increased circulation, and migration of TNF-producing CD4+ T cells to the tumor bed. Thus, TREM2 remotely controls anti-PD-1 immune checkpoint blockade through modulation of the intestinal immune environment and microbiota, with R. gnavus emerging as a potential probiotic agent for increasing responsiveness to anti-PD-1.

Examination of the Bactericidal and Fungicidal Activity of Bacillus amyloliquefaciens M Isolated from Spring Waters in Bulgaria

In order for a strain to be considered a probiotic or suitable plant bioprotective agent, it must have proven antimicrobial activity against pathogenic bacteria and phytopathogenic fungi. Bacillus amyloliquefaciens M exhibited significantly high antifungal activity against pathogenic fungi of the genera Aspergillus, Penicillium, Fusarium, and Sclerotinia; yeasts of the genera Candida and Saccharomyces; as well as high antibacterial activity against pathogens of the genera Escherichia, Salmonella, Staphylococcus, Listeria, Pseudomonas, and Bacillus. The manifested antimicrobial activity was influenced by the composition of the growth medium. The antifungal activity of the strain was investigated at growth temperatures of 30 °C and 37 °C, and at different pH values in aerobic and anaerobic cultivation, under static and dynamic culturing conditions. High antifungal activity was observed at the 24th h on both growth media (LBG broth and MPB broth) at pH = 6 and pH = 7 in aerobic and anaerobic cultivation. Bacillus amyloliquefaciens M produced antibiotic substances at pH > 5.0, and the antibiotic substances were either secreted into the medium or associated with the cell surface. Four compounds with different antifungal activity and different Rf values were registered through thin-layer chromatography (Rf1 = 0.47; Rf2 = 0.55; Rf3 = 0.67; and Rf4 = 0.75), two of the compounds were ninhydrin-positive. Bacillus amyloliquefaciens M was cultured in a bioreactor with stirring, and the parameters of the growth kinetics and the sporulation kinetics have been modeled. A spore concentrate of Bacillus amyloliquefaciens M has been obtained. In further research, the efficiency of the concentrate as a plant bioactive agent will be tested.

FEASIBILITY OF USING A PROBIOTIC BACTERIAL COMPLEX IN THE FORM OF A THROAT SPRAY IN THE LOCAL TREATMENT OF ACUTE VIRAL TONSILLITIS

The aim of the study was to determine the feasibility of using a probiotic bacterial complex in the form of a throat spray in the local treatment of acute viral tonsillitis based on the analysis of its clinical and microbiological efficacy.
 Materials and methods. The randomized controlled trial involved 46 people with acute tonsillitis diagnosed on the basis of clinical and pharyngoscopic signs. According to the treatment received, patients were divided into 2 groups. Patients in the control group (23 people) were treated according to the unified clinical protocol "Tonsillitis". The main group included 23 patients who, in addition to the protocol treatment, received a probiotic agent in the form of a throat spray containing a complex of bacteria of the genus Bacillus. To exclude the bacterial etiology of acute tonsillitis, a modified Centor scale (McIsaac scale) was used. Evaluation of the effectiveness of treatment was based on the study of the dynamics of clinical and pharyngoscopic signs of the disease, as well as the establishment of quantitative and qualitative changes in the microbiota of the palatine tonsils during treatment.
 Results. The analysis of the dynamics of the main clinical and pharyngoscopic parameters indicates a more significant and rapid normalization in patients of the main group. The results of microbiological studies show that the use of a probiotic bacterial complex in the treatment of acute tonsillitis in patients of the main group contributed to the elimination of dysbiotic changes, restoration of the population level of the main representatives of the palatine tonsils microbiome and colonization resistance of the oropharynx.
 Conclusions. It has been established that acute viral inflammation of the palatine tonsils occurs under conditions of quantitative and qualitative changes in the species composition of the microbiota of this biotope and is accompanied by an increase in dysbiotic disorders during the course of the disease. It has been confirmed that the use of a probiotic bacterial complex in the form of a spray in the local treatment of acute viral tonsillitis is appropriate due to its proven clinical and microbiological efficacy, and also makes it possible to refrain from premature administration of antibacterial chemotherapy.

Dual effects of a bacteriocin-producing Lactiplantibacillus pentosus CF-6HA, isolated from fermented aloreña table olives, as potential probiotic and antimicrobial agent

The probiotic potential of Lactiplantibacillus pentosus CF-6HA isolated from traditionally fermented Aloreña table olives was analyzed in vitro and in silico. Results obtained suggested that this strain can be catalogued as “talented” bacterium exhibiting bacteriocin production with antimicrobial activity against human/animal and plant pathogens, such as Pseudomonas syringae and Verticillium dahliae. The robustness, safety and probiotic potential of L. pentosus CF-6HA was confirmed by in silico analysis. In addition, a plethora of coding genes for defense and adaptability to different life styles besides functional properties were identified. In this sense, defense mechanisms of L. pentosus CF-6HA consist of 17 ISI elements, 98 transposases and 13 temperate phage regions as well as a CRISPR (clustered regularly interspaced short palindromic repeats)/cas system. Moreover, the functionality of this strain was confirmed by the presence of genes coding for secondary metabolites, exopolysaccharides and other bioactive molecules. Finally, we demonstrated the ability of L. pentosus CF-6HA to biotransform selenite to nanoparticles (SeNPs) highlighting its potential role in selenium bioremediation to be exploited in foods, agriculture and the environment; but also for the bio-enrichment of fermented foods with selenium.

Screening of Amylolytic Bacteria from Mina Padi Aquaculture in Panembangan Village, Cilongok District, Banyumas, Central Java

Amylolytic bacteria play an important role in the ecosystem, especially as probiotic and bioremediation agents in cultivation, as examples can be found in Mina Padi culture. The purpose of this study was to determine the amylolytic bacteria in the waters of the Mina Padi pond. Bacterial isolation began with bacterial sampling, inoculation and isolation of bacteria, calculation of the total abundance of bacteria, observation of bacterial morphology and bacterial purification, and isolation of amylolytic bacteria. The results of the isolation of amylolytic bacteria obtained 3 bacterial isolates capable of producing amylolytic enzymes, namely BA5, BA6, and BA7. The highest index of amylolytic activity was obtained by isolates of BA6 with a medium category of 2.3 cm, and the lowest index was obtained by BA5 with a weak category of 0.3 cm. The average bacterial abundance from each dilution was 2.5 x 103 CFU/mL.

The alleviating effect of Akkermansia muciniphila PROBIO on AOM/DSS-induced colorectal cancer in mice and its regulatory effect on gut microbiota

Emerging evidence indicates that Akkermansia muciniphila (AKK) may be a potential probiotic agent for ameliorating colorectal cancer (CRC). Thus, we utilized the azoxymethane (AOM)/ dextran sodium sulfate (DSS)-induced mouse model of colorectal cancer to evaluate the intervention effect of AKK PROBIO. The results showed that AKK PROBIO significantly improved mouse colon health, decreased the serum pro-inflammatory cytokines levels, as well as downregulated the mRNA levels of p50, p52, p65, and IκBβ, upregulated the expressions of Bid, Bim, and caspase-9 in the colon. In addition, AKK PROBIO modulated the gut microbiota composition, as characterized by the increased abundance of Muribaculaceae and Akkermansia and the decreased levels of Bacteroides, and Parasutterella. Notably, the high-dosage group was better than that of low-dosage. In conclusion, AKK PROBIO has the potential to modulate colorectal cancer by alleviating intestinal inflammation through the NF-κB pathway and promoting cell apoptosis, thereby intervening in the development of colorectal tumors.

Rumen microbes: Exploring its potential for productivity and commercial use

Ruminant animals are known for their dairy and meat products worldwide. They are the best converters of poor quality fibrous feed ingredients, and presence of rumen, the anaerobic chamber that harbours vast category of microbes, is attributable to this phenomenon. The microbes include bacteria, fungi, protozoa, archaea and bacteriophages that work on synergistically for optimal performance of ruminant animals. These microbes help not only in digestion of fibrous materials, but also involved in various biological functions, such as probiotic activity, antimicrobial metabolite production, synthesis of health promoting bioactive fatty acid molecules, biomass conversion, etc. Earlier, the probiotic organisms used in food animals (calves, sheep, goat, swine and poultry) were mainly originated from dairy products but today organisms of autochthonous origin are being used, as they show better adaptability. Since, rumen do possess organisms with probiotic and fibre utilising activity, these organisms are now explored for their suitability as a probiotic and fibrolytic agent in monogastric food animals. Diversity of rumen microbes was not properly understood through the conventional culture methods, however with advancement in ‘Omic’ technologies, researchers could identify new class of organisms from the rumen and their potential use for the commercial and industrial purposes.

Resistance of Lactobacillus Sp. SKG 34 in The Digestive Tract of Rats Detected Using Random Amplified Polymorphic DNA Technique

In recent years, interest in probiotics, particularly Lactobacillus strains like Lactobacillus sp. SKG34, isolated from Sumbawa mare milk, has surged due to their potential health benefits. This strain holds promise as a probiotic agent, but understanding its behavior in the gastrointestinal (GI) tract is essential for effective application. This study aimed to investigate the resistance and persistence of Lactobacillus sp. SKG34 in the GI tract of rats. Rats were orally administered the strain at a concentration of 10^8 cells for 30 days. The probiotic’s ability to modulate gut microbiota and improve host health is a key area of interest. By utilizing techniques like PCR-RAPD, this research sought to elucidate the fate of Lactobacillus sp. SKG34 in the complex environment of the rat GI tract. Results revealed a significant increase in LAB population in cecal contents, from 3.06 x 10^9 cfu/g in the control group to 1.25 x 10^10 cfu/g in the probiotic group. RAPD analysis also detected Lactobacillus sp. SKG34 in approximately 23% of the total population of lactic acid bacteria in cecal contents, indicating its resistance and proliferation within the GI tract. Further investigation is warranted to fully understand the potential of Lactobacillus sp. SKG34 as a beneficial probiotic strain for human application.

Whole genome sequencing of Lacticaseibacillus casei KACC92338 strain with strong antioxidant activity, reveals genes and gene clusters of probiotic and antimicrobial potential.

Lacticaseibacillus casei KACC92338 was originally isolated from Korean raw milk. The antioxidant activities and protective effect in vitro of this strain were evaluated extensively. The results showed that KACC92338 can tolerate hydrogen peroxide up to 2 mM and cell-free supernatant (CFS) had higher scavenging rates for DPPH, hydroxyl radical, reducing power, and iron chelating activities with 95.61 ± 1.59%, 34.10 ± 1.93%, 2.220 ± 0.82 and 81.06 ± 1.06%, respectively. Meanwhile, the CFS showed a protective effect on yeast cells against 10 mM hydrogen peroxide with a survival rate of 76.05 ± 5.65%. To explore the probiotic potential of KACC92338, whole genome assembly and gene clusters with probiotic properties were further analyzed. The genome size was 3,050,901 bp with a 47.96% GC ratio, and 63 contigs. The genome contains 3,048 genes composed of 2,981 coding sequences and 67 RNAs (including 57 tRNAs +9 rRNAs +1 tmRNA). Average Nucleotide Identity and genome-based taxonomy showed that the KACC92338 genome had close similarity with L. casei strains with 96% ANI. Functional annotation by EggNOG and KEGG revealed the presence of numerous genes putatively involved in carbohydrate- and amino acid-transport and metabolism, genetic information processing, and signaling and cellular processes. Additionally, several genes conferring probiotic characteristics such as tolerance to stress, heat, cold, acid, bile salts, oxidative stress, immunomodulation, and adhesion to intestinal epithelium were identified. Notably absent were acquired antibiotic resistance genes, virulence, and pathogenic factors, that prove KACC92338 is a safe strain. Besides, the defense mechanisms of KACC92338 include six prophage regions and three clustered regularly interspaced short palindromic repeat (CRISPR) arrays as acquired immune systems against mobile elements. Further, the BAGEL4 database determined antimicrobial bacteriocin clusters of class IIb: sakacin-P, Enterolysin_A, sactipeptides, and Enterocin X, which suggests the strain could exhibit a wide range of antimicrobial functions. Together, these findings show that the L. casei KACC92338 strain can be a potential probiotic candidate in producing functional fermented foods-, health care- and skin care products- with antioxidant properties. However, a few more mechanistic studies are necessary on the safety assurance and potential application of the strain as a probiotic agent.

Prospection of strains of Bacillus sporogenes in the digestive tract of native crustaceans and characterization of the probiotic potential.

The cultivation of marine shrimp is one of the fastest growing activities in the world. However, the emergence of diseases has resulted in a decrease in production and losses for the sector. Probiotics emerged as an option to the use of antibiotics to control these pathogens. The efficiency of applying this technology depends on the characteristics of the bacterial agents and their bioavailability in the shrimp intestine. The objective is to evaluate the viability and efficiency of bacteria isolated from the digestive tract of healthy crustaceans as probiotic agents in the cultivation of shrimp Litopenaeus vannamei. Eighteen strains of the genus Bacillus belonging to the following species were tested: Bacillus sp., B. cereus, B. thuringiensis, B. circulans, B. megaterium, B. subtilis and B. agaridevorans. Bacterial isolates were subjected to characterization as potential probiotics. The test results were considered satisfactory; thus, the tested strains have potential for use as probiotics in shrimp culture. Treatments that used of the genus Bacillus had reduced growth of the genus Vibrio after infection, both in the intestinal contents and in the intestine. With the results obtained, it can be suggested that further research be carried out on the probiotic potential of Bacillus sp.