Probiotics have increasingly gained interest as alternatives to antibiotics in controlling infectious diseases in aquaculture. This research aimed to isolate and evaluate lactic acid bacteria (LAB) ...for potential use as probiotics for Pangasius bocourti. A total of 656 LAB isolates were obtained from fish gut and fermented beef samples, of which 367 isolates displayed antagonistic activity against Aeromonas hydrophila FW52 and/or Streptococcus agalactiae F3S which were employed as indicator fish pathogens. Among these antagonistic LAB, only 18 isolates produced bacteriocin-like activity. These were further evaluated in vitro for other probiotic properties. After in vitro screening, the isolate L34b-2 obtained from Thai indigenous fermented beef was chosen as a suitable probiotic LAB for in vivo studies based on its remarkable probiotic characteristics. These included broad-spectrum bacteriocin-like activity, tolerance to simulated gastrointestinal tract conditions, mucin adhesion ability, co-aggregation ability with fish pathogens tested, non-blood hemolysis, antibiotic susceptibility and protease enzyme production. Identification of the isolate L34b-2 using conventional methods together with 16S rDNA analysis revealed that it belonged to Lactobacillus paraplantarum. Then, the effects of 60-day-dietary administration of L. paraplantarum L34b-2 on fish growth, innate immune responses and disease resistance were investigated in Pangasius bocourti. In feed-trial studies, after feeding for both 30 and 60 days it was found that the Pangasius fish fed with basal diet containing 107 CFU g−1 L. paraplantarum L34b-2 had significantly (p < 0.05) higher weight gain and specific growth rate, and the lowest feed conversion ratio, compared to the control fish that received only basal diet. For immune response studies, it was found that the fish fed with the probiotic strain L34b-2, when compared to the control fish, had significantly higher lysozyme, alternative complement and bactericidal activities but no significant differences (p > 0.05) in phagocytic and respiratory burst activities. After 60-day feeding, fish were subjected to challenge tests by intraperitoneal injection with 106 CFU of a virulent Aeromonas hydrophila FW52 and rearing was continued for two more weeks. As expected, fish that received L34b-2 had a significantly higher (p < 0.05) post challenge survival rate than the control group. These results clearly show that L. paraplantarum L34b-2 displayed beneficial effects on P. bocourti as a probiotic by which it not only promoted growth but also enhanced innate immunity and disease resistance against A. hydrophila.
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•A probiotic Lactobacillus paraplantarum L34b-2 was derived from indigenous fermented beef.•L. paraplantarum L34b-2 exhibited a broad spectrum bacteriocin-like activity.•L. paraplantarum L34b-2 enhanced growth and disease resistance in Pangasius fish.•L. paraplantarum L34b-2 stimulated fish innate immunity.•A novel strain L34b-2 displayed beneficial roles in fish cultivation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Infectious diseases have been found to be a major cause of mortality in fish hatcheries. Probiotics have been introduced to replace antibiotics commonly used for treatment of bacterial infection in ...aquaculture. This study was conducted to isolate, screen, and evaluate the probiotic Bacillus spp. for potential use as a feed supplement to enhance fish growth, disease resistance and innate immunity of Pla-mong Pangasius bocourti. Bacillus aerius strain B81e was selectively isolated from the intestine of healthy catfish and chosen based on its probiotic properties both in vitro and in vivo. This bacterium produced a bacteriocin-like substance and exhibited a broad-spectrum antibacterial activity inhibiting both Gram-positive and Gram-negative bacteria especially the fish pathogens Aeromonas hydrophila and Streptococcus agalactiae. The susceptibility to all 8 antibiotics tested implies that it is unlikely to be an antibiotic-resistant bacterium. B. aerius strain B81e possessed interesting adhesion properties as shown by its high percentages of hydrophobicity, auto-aggregation, co-aggregation with fish pathogens A. hydrophila FW52 and S. agalactiae F3S and mucin binding. The strain B81e survived simulated gastrointestinal conditions, producing protease and lipase but not β-haemolysin. The study also evaluated the effects of dietary supplementation with strain B81e on growth performance, innate immunity, and the disease resistance of P. bocourti against A. hydrophila infection. Fish with a mean body weight of 69 g were fed strain B81e at 0 (control) and 107 CFU g−1 feed (test) for 60 days. Various growth and immune parameters were examined at 30 and 60 days post-feeding. Fish were challenged with A. hydrophila 60 days post-feeding and mortalities were recorded over 14 days post-infection. Results showed that the administration of strain B81e for 60 days had significant effects (p < 0.05) on weight gain, specific growth rate and feed utilization efficiency of P. bocourti. Dietary administration of strain B81e increased the serum lysozyme and bactericidal activities of P. bocourti significantly throughout the experimental period whereas the alternative complement, phagocytic and respiratory burst activities were significantly (p < 0.05) higher in the test fish compared to the control fish after 60 days of feeding. In addition, the fish fed a strain B81e supplemented diet had a significantly higher (p < 0.05) post-challenge survival rate than the control fish. The results in this study indicate that B. aerius B81e has beneficial effects on growth performance, innate immunity and disease resistance of P. bocourti. This is the first report on the probiotic roles of B. aerius in aquaculture.
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•Bacillus aerius strain B81e was isolated from the intestine of healthy catfish.•B. aerius B81e possesses prominent probiotic properties.•B. aerius B81e improved growth and feed utilization of Pangasius bocourti.•B. aerius B81e enhanced immunity of P. bocourti.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The use of probiotic bacteria to control bacterial infection in farmed fish is of clear practical interest. The aims of this study were to isolate and select a probiotic Bacillus sp. and to evaluate ...the effects of its supplementation on the growth and disease resistance of hybrid catfish. Bacillus siamensis strain B44v, selectively isolated from Thai pickled vegetables (Phak-dong), displayed a high potential as a probiotic in catfish culture. This bacterium produced a bacteriocin-like substance and exhibited a broad-spectrum antibacterial activity inhibiting both Gram-positive and Gram-negative bacteria, especially the fish pathogens Aeromonas hydrophila and Streptococcus agalactiae. The susceptibility to all 14 antibiotics tested implies its less possibility to be the antibiotic-resistant bacterium. Bacillus siamensis strain B44v possessed interesting adhesion properties, as shown by its high percentages of hydrophobicity (64.8%), auto-agglutination (73.8%), co-aggregation (67.2% with A. hydrophila FW52 and 63.5% with S. agalactiae F3S), and mucin binding (88.7%). The strain B44v survived simulated gastrointestinal conditions and produced protease and cellulase enzymes. Hybrid catfish (C. macrocephalus × C. gariepinus) were employed in the feed-trial experiments. Fish fed diet containing strain B44v (107 CFU/g feed) displayed not only no mortality but also growth improvement. At the end of the feed trial, fish were challenged by an intraperitoneal injection of Aeromonas hydrophila FW52. The Bacillus siamensis strain B44v fed fish survived (75.0%; p < 0.05) better than the controls (36.7%; p < 0.05) after a two week challenge. These collective results present for the first time the potential of Bacillus siamensis strain B44v for use as a bacterial probiotic in aquaculture.
A mixed culture of probiotics, one from the genus Bacillus and one lactic acid bacterium (LAB), was developed to be used as a feed additive for enhancing growth, innate immunity and disease ...resistance in Pangasius bocourti. From our earlier work, three probiotic Bacillus species, Bacillus siamensis B44v, Bacillus sp. B51f and Bacillus aerius B81e, and three probiotic LABs, Streptococcus lutetiensis L7c, Lactiplantibacillus paraplantarum (synonym. Lactobacillus paraplantarum) L34b-2 and Lactiplantibacillus plantarum (synonym. Lactobacillus plantarum) L42g, were selected for comparison. These bacteria, which express probiotic properties including bacteriocin-like activity against Aeromonas hydrophila, were subjected to in vivo screening in hybrid catfish (Clarias macrocephalus × Clarias gariepinus). A 30-day feed-trial followed by a challenge test in screening experiments resulted in the prominent B. aerius B81e and L. paraplantarum L34b-2 being selected. A mixture of these bacteria was added to a diet for P. bocourti. After 60-day feeding, the fish fed with mixed probiotics had weight gain, specific growth rate and feed conversion ratio improved significantly (p < 0.01) when compared to the control. Both humoral and cellular immunity were significantly higher in probiotic-fed fish. Following the 60-day feeding experiment, P. bocourti fed with the diet containing mixed probiotics had a higher survival rate than the control fish after injection with a virulent A. hydrophila. It can be concluded that a combination of B. aerius strain B81e and L. paraplantarum strain L34b-2 markedly improved growth performance, innate immunity and disease resistance of P. bocourti.
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•A mixture of Bacillus aerius B81e and Lactobacillus paraplantarum L34b-2 probionts exert beneficial effects in fish.•Mixed probiotics improve growth, immunity and disease resistance in Pangasius fish.•First report of the beneficial effects of mixed probiotics in Pangasius bocourti.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The experiment was performed to examine the effect of Lactobacillus paracasei l61‐27b (LP) isolated from Nile tilapia intestine on the growth rate, skin mucus and serum immune parameters and disease ...resistance. Fish (25.40 ± 0.33 g) were distributed into glass tank (150 litres tank−1) at 20 fish tank−1 and fed with different levels of dietary L. paracasei l61‐27b: 0 (LP1), 106 (LP2), 107 (LP3), 108 (LP4) and 109 CFU mL−1 (LP5) for 8 weeks. The results indicated that SGR, WG and FW significantly improved, while FCR significantly decreased, in fish fed LP supplemented. Dietary L. paracasei significantly increased SMLA and SMPA with the highest values recorded for fish in LP4 and LP5 groups. Similarly, SL, SP, ACH50, PI and RB were significantly stimulated in fish fed LP diet compared with fish fed control diet. Challenge study showed that in comparison with the control diet (20% survival), the survival rates of fish fed the L. paracasei were significantly (p < 0.05) higher; by 63.33% (LP2), 66.67% (LP3), 80.00% (LP4) and 83.33% for LP5. The relative per cent survival (RSP) was 54.17%, 58.33%, 75% and 79.17% in LP2, LP3, LP4 and LP5, respectively. In conclusion, the dietary inclusion of L. paracasei can be potentially used in Nile tilapia to improve its growth and health status.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
This investigation was performed to assess the influences of the host‐associated probiotic Bacillus altitudinis B61‐34b (BAA) on growth, immune response and disease resistance to Streptococcus ...agalactiae in Nile tilapia (Oreochromis niloticus). Fish (25.50 ± 0.52 g fish−1) were distributed into 15 aquaria (150 litres tank−1) at density of 20 fish tank−1. The fish were fed basal diets with BAA inclusions in different concentrations: 0 (BAA1—Control), 106 (BAA2), 107 (BAA3), 108 (BAA4) and 109 (BAA5) CFU ml−1 for 8 weeks. A completely randomized design with three replications was used. The results indicated that BAA administration generated greater (p < 0.05) skin mucus and peroxidase activities compared to the control, with maximum levels recorded in BAA4 and BAA5. Higher serum immunities, such as serum lysozyme, serum peroxidase, complement, phagocytosis and respiratory burst activities were observed in the BAA4 and BAA5 dietary groups compared to the control, BAA1, BAA2 and BAA3 diets. The relative percentage of survival, growth performance and FCR were also significantly higher (p < 0.05) in the BAA4 and BAA5 groups. In conclusion, dietary supplementation of B. altitudinis at 108 CFU ml−1 can improve Nile tilapia's growth performance, skin mucus and serum immunities, and disease resistance.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
By applying non-sterile open fermentation of food waste, various thermotolerant l-lactic acid-producing bacteria were isolated and identified. The predominant bacterial isolates showing higher ...accumulation of l-lactic acid belong to 3 groups of Bacillus coagulans, according to their 16S rRNA gene sequence similarities. B. coagulans strains M21 and M36 produced high amounts of l-lactic acid of high optical purity and lactic acid selectivity in model kitchen refuse medium and glucose–yeast extract–peptone medium. Other thermotolerant isolates resembling to Bacillus humi, B. ruris, B. subtilis, B. niacini and B. soli were also identified. These bacteria produced low amounts of l-lactic acid of more than 99% optical purity. All isolated strains showed the highest growth rate at temperatures around 55–60°C. They showed unique responses to various oxygen supply conditions. The majority of isolates produced l-lactic acid at a low overall oxygen transfer coefficient (KLa); however, acetic acid was produced instead of l-lactic acid at a high KLa. B. coagulans M21 was the only strain that produced high, consistent, and reproducible amounts of optically pure l-lactic acid (>99% optical purity) under high and low KLa conditions in a homo-fermentative manner.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this study, 119 bacterial strains were isolated from various samples such as healthy tilapia fish (Oreochromis niloticus), water and sediment around the culture fish-cages, and several kinds of ...traditional fermented foods. These bacterial isolates were screened for antibacterial activities against bacterial fish pathogens i.e. Aeromonas hydrophila, A. caviae and Streptococcus agalactiae using an agar well diffusion assay. The isolate CR1T5 derived from fermented rice showed the highest antibacterial activity against all three fish pathogens tested. It was identified as Lactobacillus plantarum by using both conventional and molecular methods. The other probiotic properties were evaluated in vitro which revealed that strain CR1T5 tolerated the simulated gastrointestinal conditions well, showed high capacity to adhere intestinal mucosa and did not lyse red blood cells. The efficiency of L. plantarum CR1T5 was also examined in vivo. O. niloticus were employed in the feed-trial experiments. Fish fed a diet containing strain CR1T5 (108 CFU g-1 feed) displayed not only no mortality but also growth improvement. At the end of feed-trial, fish were challenged by intramuscularly injection of A. hydrophila (3.1x105 CFU) The L. plantarum CR1T5-fed fish survived (87.5%) better than the fish fed a control diet (12.5%) after a two week-challenge. This study clearly shows that L. plantarum strain CR1T5 is a promising probiotic candidate for farmed fish.
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