Dietary Administration of Probiotic Aeromonas veronii V03 on the Modulation of Innate Immunity,Expression of Immune-Related Genes and Disease Resistance Against Aeromonas hydrophila Infection in Common Carp (Cyprinus carpio)

This study investigates the effects of dietary Aeromonas veronii V03 supplementation on growth performances, innate immunity, and expression of immune-related genes in lymphoid organs of Cyprinus carpio and resistance to Aeromonas hydrophila infection. Fish were fed for 4 weeks with basal diet (BD; without probiotic), and experiment diet containing different doses of A. veronii V03 at 3.2 × 10⁷ (DI) and 3.5 × 10⁹ (DII) CFU g⁻¹ of diet. At the end of the probiotic feeding trial, fish were challenged with A. hydrophila, and the percentage of survival rates was recorded over 7 days. Results revealed that fish fed with A. veronii V03 demonstrated a significant improvement in growth and enhancement of innate immunity, including respiratory burst, myeloperoxidase, and lysozyme activities, and total immunoglobulin level compared with BD fed to fish. Relatively, expression of cytokines (MyD88, IL-1β1, IL-8, and IL-10) and c- and g-type lysozymes were significantly up- and downregulated in lymphoid organs of fish. Moreover, dietary supplementation of A. veronii V03 exhibited significantly (p < 0.001) higher survival rates of DI (90%) and DII (96.66%) compared with BD (53.33%) fed fish against A. hydrophila infection. These findings help to understand the effects of probiotic A. veronii V03 administrated feed influences on growth and ailment resistance to A. hydrophila infection by regulating innate and systemic immunity in common carp fish.

     

Isolation and characterization of new potential probiotic bacteria based on quorum-sensing system

Aims: This work was aimed at identifying strains which can degrade quorum‐sensing (QS) molecules from fish gut, with properties suitable for use as probiotic in aquaculture. Methods and Results: A total of 200 strains were obtained from the intestine gut of Carassius auratus gibelio after enrichment in KG medium contained 500 μg l^?1 of C6‐HSL as the sole source of carbon and nitrogen; one strain named QS inhibitor (QSI)‐1 was identified as the genus Bacillus spp. by morphological phenotypes, and the strain also possessed an aiiA homologue gene using PCR amplification. In vitro, QSI‐1 strongly interfered with violacein production by Chromobacterium violaceum. Coculture of QSI‐1 with fish pathogen effectively reduced the amount of acyl‐homoserine lactones (AHLs) and the extracellular proteases activity of Aeromonas hydrophila YJ‐1. The oral LD50 of QSI‐1 to fish was more than 10¹¹ CFU shown that it was avirulent to fish. Fish fed diet supplemented with QSI‐1 had good survival, suggesting that QSI‐1 showed protection against Aer. hydrophila infection. Conclusions: The results indicate that the isolate QSI‐1 might have the potential possibility to be used as a probiotic in aquaculture. Significance and Impact of the Study: This is the first report to describe a bacterium isolated from the intestine gut of C. auratus gibelio which can degrade AHLs and has the probiotic characteristics for its use in aquaculture.     

Evaluation of the Impacts of Long-Term Enriched Artemia with Bacillus subtilis on Growth Performance,Reproduction, Intestinal Microflora,and Resistance to Aeromonas hydrophila of Ornamental Fish Poecilia latipinna

The present study investigated the effect of enriched Artemia with Bacillus subtilis on growth performance, reproductive factors, proximate composition, intestinal microflora, and resistance to Aeromonas hydrophila of ornamental fish, Poecilia latipinna. Using a completely randomized design, the experiment included three groups. The first group was fed with commercial food without any probiotic. The second group was fed with unenriched Artemia, and the last group consumed long-time enriched Artemia with Bacillus subtilis. The bacteria B. subtilis with a density of 1 × 10⁵ CFU mL⁻¹ was added daily to Artemia culture medium. The total microflora and Bacillus subtilis counts were significantly increased in enriched Artemia compared to the unenriched group (P < 0.05). In fish fed groups, growth factors did not show any significant difference (P > 0.05). The maximum relative fecundity (28.65 ± 2.52 egg number g⁻¹), fry production (62.93 ± 4.6 individual per female), and fry survival (70.97 ± 1.56%) obtained in the third group were found to be significantly more than those in the first and the second groups. Moreover, intestinal bacterial count for Bacillus revealed that the higher concentration of bacteria was significantly related to the third group (6.24 ± 0.11 log CFU g⁻¹) (P < 0.05). Maximum protein and fat contents were observed in fish fed with Bacillus-enriched Artemia; however, no significant difference was found between control and unenriched Artemia groups (P > 0.05). The highest amount of ash was observed in fish fed with commercial food without any probiotic (P < 0.05). At the end of the feeding period, each of the three groups along with positive group (oxytetracycline 100 mg kg⁻¹ of commercial food) was exposed to A. hydrophila (BCCM5/LMG3770) bacteria intraperitoneally. Based on the results, the lowest cumulative mortality was significantly found in group three (68.75 ± 3.6%) and positive group (62.5 ± 7.0%) compared to control and unenriched Artemia groups (P < 0.05). Hence, B. subtilis with a concentration of 1 × 10⁵ CFU mL⁻¹ during the period of Artemia culturing can improve the reproductive parameters, intestinal microflora, and resistance to pathogenic bacteria of Poecilia latipinna.

     

E. coli Nissle microencapsulation in alginate-chitosan nanoparticles and its effect on Campylobacter jejuni in vitro

Microencapsulation enhances the oral delivery of probiotic bacteria. In this study, the probiotic Escherichia coli Nissle 1917 (EcN) was microencapsulated using alginate and chitosan nanoparticles. The result showed 90% encapsulation yield of EcN, and the encapsulated EcN displayed significantly (P < 0.05) increased survival in low pH (1.5), high bile salt concentration (4%), and high temperature (70 °C). The most effective cryopreservatives of EcN during freezing and thawing was skim milk and sucrose. Exposure to microencapsulated EcN significantly (P < 0.05) reduced the Campylobacter jejuni growth by 2 log CFU. The rate of EcN release from microcapsule was 9.2 × 10⁵ cell min⁻¹, and the appropriate model to describe its release kinetics was zero order. Importantly, the entrapment of EcN inside the microcapsule did not eliminate the exterior diffusion of EcN produced antioxidant compounds. In addition, the EcN microcapsule efficiently adhered to intestinal HT-29 cells and the pre-treatment of HT-29 cells with EcN-microcapsule for 4 h significantly (P < 0.05) reduced the invasion (1.9 log) of C. jejuni; whereas, completely abolished the intracellular survival. Furthermore, HT-29 cells pre-treated with encapsulated EcN in PCR array showed decreased expression (> 1.5-fold) of genes encoding chemokines, toll-like receptors, interleukins, and tumor necrosis factors. In conclusion, the alginate-chitosan microcapsule can provide effectual platform to deliver probiotic EcN and thereby can reduce the Campylobacter infection in chickens and humans.

     

Therapeutic Prospective of a Spore-Forming Probiotic—Bacillus clausii UBBC07 Against Acetaminophen-Induced Uremia in Rats

To screen Bacillus clausii UBBC07 as a putative probiotic strain and to examine the protective effect of probiotic—B. clausii UBBC07 spore on uremia on rats induced by acetaminophen. In vitro tests performed to screen potential probiotic strains were gastric and bile acid resistance and ability to reduce pathogen adhesion to surfaces. An in vivo study was performed on rats (n = 18) which were randomly divided into three groups: group I, control—receives normal food and water, groups II and III receive acetaminophen i.p. at the dose of 550 mg/kg/day for 10 days, groups III was treated with B. clausii UBBC07 at a dose of 1 × 10⁹ CFU/day for 15 days. Urea, creatinine, malondialdehyde (MDA), and GSH levels and antioxidant enzymes like super oxide dismutase (SOD) and catalase activity were considered to analyze renal failure. Plasma urea and creatinine levels (p < 0.05) significantly increase and SOD, catalase, and GSH activity level significantly decrease in group II as compared with the control group. After treatment with probiotic, there was a significant increase in SOD and catalase (p < 0.05) and a significant decrease in serum urea, creatinine, and MDA (p < 0.05) in group III in response to group II. The results also revealed that probiotic was able to tolerate pH 3.0–9.0 and 0.3% bile salt. The present study suggests that B. clausii UBBC07 could be used as a novel alternative natural therapy for uremia, a major syndrome of CKD.

     

Dietary probiotic supplementation improves growth and the intestinal morphology of Nile tilapia

Probiotic administration can be a nutritional strategy to improve the immune response and growth performance of fish. The current study aimed to evaluate the effects of a probiotic blend (Bacillus sp., Pediococcus sp., Enterococcus sp., Lactobacillus sp.) as a dietary supplement on growth performance, feed utilization, innate immune and oxidative stress responses and intestinal morphology in juvenile Nile tilapia (Oreochromis niloticus). The probiotic was incorporated into a basal diet at three concentrations: 0 g/kg (A₀: control), 3 g/kg (A₁: 1.0×10⁶ colony forming unit (CFU)/g) and 6 g/kg (A₂: 2.3×10⁶ CFU/g diet). After 8 weeks of probiotic feeding, weight and specific growth rate where significantly higher in fish-fed A₁ diet than in fish-fed A₀. Alternative complement in plasma was significantly enhanced in fish-fed A₂ when compared with A₀. The hepatic antioxidant indicators were not affected by probiotic supplementation. Villi height and goblet cell counts increased significantly in the intestine of fish-fed A₁ and A₂ diets compared with A₀. The dietary probiotic supplementation was maintained until 20 weeks of feeding. Then the selected immune parameters, digestive enzymes and apparent digestibility of diets were studied. No effect of probiotic feeding was observed after that longer period supplementation. The dietary supplementation of mixed species probiotic may constitute a valuable nutritional approach towards a sustainable tilapia aquaculture. The improvement of the immune responses and intestinal morphology play an important role in increasing growth performance, nutrient absorption and disease resistance in fish, important outcomes in such a competitive and developing aquaculture sector.     

The Effect of Lactococcus lactis subsp. lactis PTCC 1403 on the Growth Performance,Digestive Enzymes Activity,Antioxidative Status,Immune Response,and Disease Resistance of Rainbow Trout (Oncorhynchus mykiss)

The effect of Lactococcus lactis subsp. lactis strain PTCC 1403 as a potential probiotic was investigated on the growth, hematobiochemical, immune responses, and resistance to Yersinia ruckeri infection in rainbow trout. A total of 240 fish were distributed into 12 fiberglass tanks representing four groups (× 3 replicates). Each tank was stocked with 20 fish (average initial weight: 11.81 ± 0.32 g) and fed L. lactis subsp. lactis PTCC 1403 at 0 (control, T0), 1 × 10⁹ (T1), 2 × 10⁹ (T2), and 3 × 10⁹ (T3) CFU/g feed for 8 weeks. The results showed enhanced protein efficiency ratio and reduced feed conversion ratio in the fish-fed T2 diet. Further, fish-fed T2 and T3 diets showed a significantly higher survival rate than the control (p < 0.05). Trypsin, lipase, and protease activities were increased in fish-fed L. lactis subsp. lactis PTCC 1403 compared to the control (p < 0.05). Fish fed with a T2 diet showed significantly (p < 0.05) lower glucose content than other groups. The blood lysozyme activity and IgM showed significantly (p < 0.05) higher values in fish-fed T2 and T3 diets than in other groups. The antioxidative responses were increased in fish-fed T2 and T3 diets (p < 0.05). After 7 days post-Y. ruckeri challenge, the cumulative mortality rate showed the lowest value in fish fed with T1 and T2 diets, while the highest value was recorded in the control group. In conclusion, the results revealed beneficial effects of L. lactis subsp. lactis PTCC 1403 on the feed efficiency, immune response, and resistance to Y. ruckeri infection in rainbow trout.

     

The Effects of Probiotic Supplementation on Genetic and Metabolic Profiles in Patients with Gestational Diabetes Mellitus: a Randomized,Double-Blind,Placebo-Controlled Trial

This study was carried out to evaluate the effects of probiotic supplementation on genetic and metabolic profiles in patients with gestational diabetes mellitus (GDM) who were not on oral hypoglycemic agents. This randomized, double-blind, placebo-controlled clinical trial was conducted in 48 patients with GDM. Participants were randomly divided into two groups to intake either probiotic capsule containing Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, Lactobacillus fermentum (2 × 10⁹ CFU/g each) (n = 24) or placebo (n = 24) for 6 weeks. Probiotic intake upregulated peroxisome proliferator-activated receptor gamma (P = 0.01), transforming growth factor beta (P = 0.002) and vascular endothelial growth factor (P = 0.006), and downregulated gene expression of tumor necrosis factor alpha (P = 0.03) in peripheral blood mononuclear cells of subjects with GDM. In addition, probiotic supplementation significantly decreased fasting plasma glucose (β, − 3.43 mg/dL; 95% CI, − 6.48, − 0.38; P = 0.02), serum insulin levels (β, − 2.29 μIU/mL; 95% CI, − 3.60, − 0.99; P = 0.001), and insulin resistance (β, − 0.67; 95% CI, − 1.05, − 0.29; P = 0.001) and significantly increased insulin sensitivity (β, 0.009; 95% CI, 0.004, 0.01; P = 0.001) compared with the placebo. Additionally, consuming probiotic significantly decreased triglycerides (P = 0.02), VLDL-cholesterol (P = 0.02), and total-/HDL-cholesterol ratio (P = 0.006) and significantly increased HDL-cholesterol levels (P = 0.03) compared with the placebo. Finally, probiotic administration led to a significant reduction in plasma malondialdehyde (P < 0.001), and a significant elevation in plasma nitric oxide (P = 0.01) and total antioxidant capacity (P = 0.01) was observed compared with the placebo. Overall, probiotic supplementation for 6 weeks to patients with GDM had beneficial effects on gene expression related to insulin and inflammation, glycemic control, few lipid profiles, inflammatory markers, and oxidative stress.

     

Quantitative and qualitative study of the bacterial flora of farmed freshwater prawn (Macrobrachium rosenbergii) larvae

Quantitative and qualitative studies of the bacterial flora of farmed freshwater prawn (Macrobrachium rosenbergii) larvae in Saudi Arabia were performed, and isolates identified where possible. Physico‐chemical characteristics, bacterial counts, and the nature of the bacterial flora of larvae rearing tank water, sediment, tank wall surfaces, larval surface, supplied water, and feed were investigated. Bacterial counts ranged from 2.1 ± 1.3 × 10⁵ to 2.2 ± 0.8 × 10⁷ colony forming units (CFU) ml^?1 in tank water; 4.4 ± 0.9 × 10⁷ to 8.3 ± 1.7 ×10⁹ CFU g^?1 in tank sediment; 8.6 ± 1.0 × 10² to 9.8 ±0.7 × 10⁴ CFU cm^?2 on the tank wall surface; 1.3 ± 1.1 × 10⁴ to 7.7 ± 1.6 × 10⁶ CFU per larva surface, 7.9 ± 1.2 × 10⁵ to 5.0 ± 1.5 × 10⁷ CFU g^?1 in washed larval tissue slurries, 9.1 ± 0.7 × 10³ CFU ml^?1 in supplied water, and 2.4 ± 1.9 ×10¹⁰ CFU g^?1 in mixed feed. Fourteen bacterial genera were identified, including Chryseomonas sp., Vibrio spp., Cellulomonas sp., Aeromonas hydrophila, and Pasteurella sp. The tank water and sediment had similar bacteria to those on the prawn larvae. Chryseomonas sp., Cellulomonas sp. and Vibrio sp. were the most dominant species (prevalence >10%) in tank water; Chryseomonas sp., Pseudomonas alcaligenes and Shewanella putrefaciens in the sediment; Ps. alcaligenes and Cellulomonas sp. on the tank wall surface; Chryseomonas sp., and Cellulomonas sp. on the larval surface; and Chryseomonas sp., Vibrio vulnificus, Sh. putrefaciens and V. alginolyticus in the washed larval tissue slurries (prevalence 10%). Pseudomonas alcaligenes, Moraxella sp., Serratia liquefaciens, Gordona sp. and Burkholderia glumae were absent in larvae but identified in the culture water, tank sediment, and tank wall surface. Pseudomonas sp., Chryseomonas sp., Pasteurella sp. and V. alginolyticus were the prevalent bacteria (>12%) in supplied water. The feed contained V. alginolyticus, A. hydrophila and Cellulomonas sp. as the dominant bacteria (>13%). In the culture water and larvae samples, 83% of the feed and supplied water bacteria were identified.     

Root colonisation of Pseudomonas aeruginosa strain UPMP3 and induction of defence‐related genes in oil palm (Elaeis guineensis)

Pseudomonas aeruginosa strain UPMP3 labelled with β‐glucuronidase (gusA) and green fluorescent protein (gfp) by electrotransformation yielded ca 1 × 10⁷ transformants µg^?1 DNA. The data obtained from the dilution plate count showed that over 28 days both epiphytic and endophytic populations of P. aeruginosa strain UPMP3 increased from 5.76 log₁₀ [colony forming unit (CFU) + 1] g^?1 fresh weight (FW) to 8.19 log₁₀ (CFU + 1) g^?1 FW and 4.10 log₁₀ (CFU + 1) g^?1 FW to 6.23 (CFU + 1) g^?1 FW, respectively. Confocal laser scanning microscopic analysis of oil palm roots treated with gusA:gfp‐tagged P. aeruginosa strain UPMP3 showed intense root colonisation over the sampling period. The root surface colonisation by P. aeruginosa strain UPMP3 was followed by a second stage, characterised by cortical infection, and a third stage, which involves xylem ingression. The colonisation of oil palm roots by the gusA:gfp‐tagged strain was concentrated on root areas potentially rich in nutrients such as the elongation zones, ridges between epidermal cells and points of secondary adventitious root emergence. Different expression levels of defence‐related genes, namely, chitinase and β‐1,3‐glucanase in the strain UPMP3–host interaction recorded over 28 days, suggested the potential role of P. aeruginosa strain UPMP3 in triggering the defence mechanism in oil palm. This is the first report on root colonisation and upregulation of defence‐related genes on oil palm roots by P. aeruginosa strain UPMP3 and shows the potential of this strain to be used as a biocontrol agent in oil palm.     

Replication of <Emphasis Type="Italic">Legionella pneumophila</Emphasis> in Floating Biofilms

Biofilms are a major source of human pathogenic Legionella pneumophila in aquatic systems. In this study, we investigated the capacity of L. pneumophila to colonize floating biofilms and the impact of Acanthamoeba castellanii on the replication of biofilm-associated Legionella. Biofilms were grown in Petri dishes and consisted of Aeromonas hydrophila, Escherichia coli, Flavobacterium breve, and Pseudomonas aeruginosa. Six hours following inoculation, Legionella were detected in floating biofilms in mean concentrations of 1.4 × 10⁴ cells/cm² (real-time polymerase chain reaction) and 8.3 × 10² CFU/cm² (culture). Two-way analysis of variance tests and fluorescent in situ hybridization clearly proved that increased biofilm-associated L. pneumophila concentrations were the result of intracellular replication in A. castellanii. Forty-eight hours after the introduction of A. castellanii in the Petri dishes, 90 ± 0.8% of the amoebae (infection rate) were completely filled with highly metabolic active L. pneumophila (mean infection intensity).     

The Effects of Probiotic Honey Consumption on Metabolic Status in Patients with Diabetic Nephropathy: a Randomized,Double-Blind,Controlled Trial

To the best of our knowledge, this study is the first evaluating the effects of probiotic honey intake on glycemic control, lipid profiles, biomarkers of inflammation, and oxidative stress in patients with diabetic nephropathy (DN). This investigation was conducted to evaluate the effects of probiotic honey intake on metabolic status in patients with DN. This randomized, double-blind, controlled clinical trial was performed among 60 patients with DN. Patients were randomly allocated into two groups to receive either 25 g/day probiotic honey containing a viable and heat-resistant probiotic Bacillus coagulans T11 (IBRC-M10791) (10⁸ CFU/g) or 25 g/day control honey (n = 30 each group) for 12 weeks. Fasting blood samples were taken at baseline and 12 weeks after supplementation to quantify glycemic status, lipid concentrations, biomarkers of inflammation, and oxidative stress. After 12 weeks of intervention, patients who received probiotic honey compared with the control honey had significantly decreased serum insulin levels (− 1.2 ± 1.8 vs. − 0.1 ± 1.3 μIU/mL, P = 0.004) and homeostasis model of assessment-estimated insulin resistance (− 0.5 ± 0.6 vs. 0.003 ± 0.4, P = 0.002) and significantly improved quantitative insulin sensitivity check index (+ 0.005 ± 0.009 vs. − 0.0007 ± 0.005, P = 0.004). Additionally, compared with the control honey, probiotic honey intake has resulted in a significant reduction in total-/HDL-cholesterol (− 0.2 ± 0.5 vs. + 0.1 ± 0.1, P = 0.04). Probiotic honey intake significantly reduced serum high-sensitivity C-reactive protein (hs-CRP) (− 1.9 ± 2.4 vs. − 0.2 ± 2.7 mg/L, P = 0.01) and plasma malondialdehyde (MDA) levels (− 0.1 ± 0.6 vs. + 0.6 ± 1.0 μmol/L, P = 0.002) compared with the control honey. Probiotic honey intake had no significant effects on other metabolic profiles compared with the control honey. Overall, findings from the current study demonstrated that probiotic honey consumption for 12 weeks among DN patients had beneficial effects on insulin metabolism, total-/HDL-cholesterol, serum hs-CRP, and plasma MDA levels, but did not affect other metabolic profiles. http://www.irct.ir: IRCT201705035623N115.

     

The Effects of Limosilactobacillus reuteri LR-99 Supplementation on Body Mass Index,Social Communication,Fine Motor Function,and Gut Microbiome Composition in Individuals with Prader–Willi Syndrome: a Randomized Double-Blinded Placebo-Controlled Trial

Prader–Willi syndrome (PWS) is a rare genetic disorder associated with developmental delay, obesity, and neuropsychiatric comorbidities. Limosilactobacillus reuteri (Lactobacillus reuteri, Lact. reuteri) has demonstrated anti-obesity and anti-inflammatory effects in previous studies. In the present study, we aim to evaluate the effects of Lact. reuteri supplementation on body mass index (BMI), social behaviors, and gut microbiota in individuals with PWS. We conducted a 12-week, randomized, double-blind, placebo-controlled trial in 71 individuals with PWS aged 6 to 264 months (64.4 ± 51.0 months). Participants were randomly assigned to either receive daily Lact. reuteri LR-99 probiotic (6 × 10¹⁰ colony forming units) or a placebo sachet. Groupwise differences were assessed for BMI, ASQ-3, and GARS-3 at baseline, 6 weeks, and 12 weeks into treatment. Gut microbiome data was analyzed with the QIIME2 software package, and predictive functional profiling was conducted with PICRUSt-2. We found a significant reduction in BMI for the probiotic group at both 6 weeks and 12 weeks relative to the baseline (P < 0.05). Furthermore, we observed a significant improvement in social communication and interaction, fine motor function, and total ASQ-3 score in the probiotics group compared to the placebo group (P < 0.05). Altered gut microbiota was observed in the probiotic group to favor weight loss and improve gut health. The findings suggest a novel therapeutic potential for Lact. reuteri LR-99 probiotic to modulate BMI, social behaviors, and gut microbiota in Prader–Willi syndrome patients, although further investigation is warranted.

Trial registration Chinese Clinical Trial Registry: ChiCTR1900022646

     

Effects of Dietary Lactiplantibacillus plantarum subsp. plantarum L7, Alone or in Combination with Limosilactobacillus reuteri P16, on Growth,Mucosal Immune Responses,and Disease Resistance of Cyprinus carpio

Skin mucosal lymphoid tissues of fish are the first line of defence against pathogen invasion. We investigated the effects of Lactiplantibacillus plantarum subsp. plantarum L7, singularly or in combination with Limosilactobacillus reuteri P16, on mucosal immunity and diseases resistance of carp Cyprinus carpio. C. carpio (average weight: 26.28 ± 1.02 g) were divided into five experimental groups. Fish in each group were fed with one of the following potential probiotic-supplemented diets: control (0 – basal diet), D1 (10⁷ CFU/g L7), D2 (10⁸ CFU/g L7), D3 (10⁹ CFU/g L7), and D4 (10⁸ CFU/g L7 + 10⁸ CFU/g P16). Eight weeks post-feeding, growth performance was higher in D4, with a final weight gain of 67.18 ± 1.47 g. Results showed a significantly higher skin mucosal lysozyme, alkaline phosphatase, mucus protein level, superoxide dismutase, and catalase activities in D2 and D4 compared to the control. However, potential probiotics had no significant effect on skin mucosal immunoglobulin level. Skin mucus of D4 exhibited stronger inhibition zones against pathogenic bacterial strains. Moreover, digestive enzyme activities (protease, lipase) were highest in D4. Intesinal lactic acid bacterial counts of fish fed combind probiotics (i.e. D4) was significantly higher than the control. Further, supplementation of potential probiotics altered the expression of IL-1β, TNF-α, and IL-10 cytokines. Fish from D4 exhibited significantly higher relative post-challenge survival (69.7%) against Aeromonas hydrophila, followed by D2 (66.67%). Therefore, the inclusion of L. plantarum subsp. plantarum L7 at 10⁸ CFU/g or in combination with L. reuteri P16 could enhance the growth performance, mucosal immune responses, and disease resistance of C. carpio.

     

Inhibitory Activity of Probiotic <Emphasis Type="Italic">Bacillus subtilis</Emphasis> UTM 126 Against <Emphasis Type="Italic">Vibrio</Emphasis> Species Confers Protection Against Vibriosis in Juvenile Shrimp (<Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>)

The bacterial strain Bacillus subtilis UTM 126 produced antimicrobial activity against pathogenic Vibrio species, including V. alginolyticus, V. parahaemolyticus, and V. harveyi. The probiotic effect of B. subtilis was tested by feeding juvenile shrimp (Litopenaeus vannamei) food supplemented with B. subtilis (10⁵ CFU/g) for 28 days before an immersion challenge with V. harveyi at 10⁵ CFU/mL for 24 h. The treatment with B. subtilis UTM 126 decreased final mortality to 18.25%, compared with 51.75% in the control group. Bacillus subtilis UTM 126 has potential applications for controlling pathogenic V. harveyi in shrimp aquaculture.     

三株海洋木霉的应用潜力

【目的】探索3株海洋生境木霉的应用潜力。【方法】经过筛选和诱变,获得高抑菌活性及产孢量的木霉突变株;通过优化培养基、温度、初始p H考察其产孢量及最适培养条件;综合抑菌谱、重寄生及抑菌相关基因考察其抑菌活性;采用特殊培养基法考察其产纤维素酶、植酸酶、铁载体以及降解磷钾的能力,高效液相色谱法测定其产吲哚乙酸能力。【结果】3株木霉菌的产孢量分别为3.45×108、3.10×108和2.55×108 CFU/cm2,与野生型相比分别提高了88.52%、63.16%和180.22%;且均可产生厚垣孢子,其中XG20-1厚垣孢子产量最高,达到3.56×108 CFU/m L。3株木霉菌具有较广抑菌谱及对番茄早疫病菌的重寄生作用,同时扩增得到Tex1、Nag1、Eg1基因,生物学测试显示其均具有产纤维素酶、几丁质酶以及铁载体的能力,证明其抑菌活性是多种机制共同作用的结果;菌株可以降解磷钾,且吲哚乙酸产量分别为2.61、1.57和1.92 mg/L,具有促进植物生长的潜力。【结论】本文中3株木霉菌在开发为生防菌与生物肥料方面展现出良好的应用潜力。     

Evaluation of Paenibacillus spp. isolates for the biological control of black rot in Brassica oleracea var. capitata (cabbage)

The ability of isolates of Paenibacillus spp. to protect Brassica oleracea var. capitata (cabbage) against the black rot pathogen, Xanthomonas campestris pv. campestris (Xcc),was evaluated. Twenty-four isolates of Paenibacillus spp., isolated from New Zealand-grown brassica hosts or soil, were evaluated for in vitro antagonism towards six Xcc isolates. Seven Paenibacillus spp. isolates with different levels of in vitro suppressive activity against Xcc were screened in pot experiments for their capacity to reduce black rot symptoms on cabbage. Two Paenibacillus isolates (P10 and P16) exhibited biocontrol activity against Xcc, and four isolates (P1, P6, P9, and P24) reduced cabbage seed germination and seedling emergence. The dependence of bioactivity on inoculum rate was investigated with three Paenibacillus isolates (P6, P10, and P16) at three different concentrations (5?×?10⁸, 5?×?10⁹, and 5?×?10¹⁰?CFU?ml^?1). Negative effects on seedling emergence were detected with isolate P6 at concentrations?≥5?×?10⁹?CFU?ml^?1. All three isolates applied at the three concentrations reduced black rot symptoms on the cotyledons and true leaves. There was poor or no relationship between the inhibitory effect of Paenibacillus spp. isolates on the growth of Xcc in vitro, and their biocontrol activity in vivo. Paenibacillus isolate P16 was identified as a potential biological control of black rot in cabbage.     

Effects of the Use of a Combination of Two Bacillus Species on Performance,Egg Quality,Small Intestinal Mucosal Morphology,and Cecal Microbiota Profile in Aging Laying Hens

Sixty-week-old Hy-Line brown laying hens were randomly divided into five groups and fed different diets over a period of 84 days. Experimental treatments included a basal diet (control); the basal diet supplemented with 1.0 × 10⁶B. licheniformis yb-214245; the basal diet supplemented with 1.0 × 10⁶B. subtilis yb-114246; a combination of both strains in a 2:1 ratio (6.6 × 10⁵:3.3 × 10⁵B. licheniformis yb-214245:B. subtilis yb-114246); and the latter, added with 5 mg/kg flavomycin. Basal diet supplementation with the combined Bacillus species improved egg-laying performance in aging hens significantly (P < 0.05). Eggshell strength improved significantly with this treatment, compared to the control or the antibiotic-supplemented groups (P < 0.05). The levels of total cholesterol, triglycerides, and very low-density lipoprotein cholesterol in egg yolk declined significantly more in the Bacillus-treated group than in the control or the antibiotic-supplemented groups (P < 0.01). Small intestinal morphology was better in the hens treated with the Bacillus combination than in the hens in the control group (P < 0.05). The total number of aerobic bacteria (Bacillus, Lactobacillus, and Bifidobacterium) in the cecum was significantly higher in all the Bacillus-supplemented hens than either in the control or the antibiotic-supplemented hens (P < 0.01); additionally, the number of E. coli and Salmonella was significantly lower than in the control group (P < 0.01). In conclusion, diet supplementation with the combination of Bacillus species used here for aging laying hens improved their growth performance, cecal bacterial composition, egg quality, and small intestine morphology.

     

Antagonistic Activity of Cellular Components of Potential Probiotic Bacteria, Isolated from the Gut of Labeo rohita, Against Aeromonas hydrophila

The objective of this study was to characterise the antagonistic activity of cellular components of potential probiotic bacteria isolated from the gut of healthy rohu (Labeo rohita), a tropical freshwater fish, against the fish pathogen, Aeromonas hydrophila. Three potential probiotic strains (referred to as R1, R2, and R5) were screened using a well diffusion, and their antagonistic activity against A. hydrophila was determined. Biochemical tests and 16S rRNA gene analysis confirmed that R1, R2, and R5 were Lactobacillus plantarum VSG3, Pseudomonas aeruginosa VSG2, and Bacillus subtilis VSG1, respectively. Four different fractions of cellular components (i.e. the whole-cell product, heat-killed whole-cell product [HKWCP], intracellular product [ICP], and extracellular product) of these selected strains were effective in an in vitro sensitivity test against 6 A. hydrophila strains. Among the cellular components, the ICP of R1, HKWCP of R2, and ICP of R5 exhibited the strongest antagonistic activities, as evidenced by their inhibition zones. The antimicrobial compounds from these selected cellular components were partially purified by thin-layer and high-performance liquid chromatography, and their properties were analysed. The ranges of pH stability of the purified compounds were wide (3.0–10.0), and compounds were thermally stable up to 90 °C. Considering these results, isolated probiotic strains may find potential applications in the prevention and treatment of aquatic aeromonosis.     

Evaluation of Pseudomonas aeruginosa Z5 for biocontrol of cotton seedling disease caused by Fusarium oxysporum

Plant growth-promoting bacteria-mediated biocontrol of plant pathogens is renowned to enhance the growth of the plants using different direct or indirect mechanisms. The goal of the present investigation was the evaluation of Pseudomonas aeruginosa Z5 isolated from cotton grown in Pakistani soils for the suppression of Fusarium oxysporum associated with cotton seedling disease. In dual culturing techniques, four bacterial strains inhibited fungal pathogens, i.e. F. oxysporum, Fusarium moniliforme, Fusarium solani and Rhizoctonia solani, significantly with percent inhibition ranging from 25% to 91.5%. P. aeruginosa Z5 showed maximum suppression of all the tested pathogens. Net-house experiments showed that the application of P. aeruginosa Z5 both separately and in combination with Bacillus fusiformis S10 significantly reduced the disease incidence by suppressing F. oxysporum (the causal agent of cotton seedling disease) up to 64–65% and improved the percent germination as compared to the infected control plants. The production of antibiotics, proteases and siderophores may be the contributing factors for its antagonistic properties. Highest bacterial population (8.9 CFU/g root) observed on roots of cotton plants inoculated with P. aeruginosa Z5 showed its good colonisation aptitudes even in the presence of high inoculation of soil with F. oxysporum. Confocal laser scanning microscopy supported the root colonisation of cotton plants with fluorescently labelled P. aeruginosa Z5. Because of innate fungicidal potential, growth promoting P. aeruginosa Z5 can be used as a bioinoculant and an antagonist to suppress the growth of cotton root-associated fungal pathogen.