Influence of a fish bacterium Lactobacillus sp. on the production of swordtail xiphophorus helleri (Heckel 1848)

The influence of a fish gut bacterium Lactobacillus sp on the production of swordtail Xiphophorus helleri was studied for a period of one year. The Lactobacillus sp P21 produced bacteriocin-like inhibitory substance and exhibited wide spectrum of action against Aeromonas hydrophila, Bacillus spp, Pseudomonas spp and Citrobacter freundi in vitro. The growth performance of X. helleri reared in the presence of Lactobacillus P21 at 106/ml rearing water was better than the control. The total plate counts, total MRS agar counts and the counts of motile aeromonads, presumptive pseudomonads, lactose fermenters and lactose non-fermenters in the gut of probiotic group were comparatively low than the control. On day 60 the count of Lactobacillus sp P21 was observed to be log 5.28/g in the gut of X. helleri indicating colonization of this bacterium in the gastrointestinal tract. The fecundity of X. helleri was in the range of 9-134. On average, it produced from 39.42±18.72 fry/female in control group to 53.00±23.57 fry/female in probiotic group. The increase in average fecundity in probiotic group over the control group was about 25%. There existed significant difference between probiotic group and control in respect of average fecundity/female (p<0.02), average number of fry survived /female (p<0.006) and average number of fry dead/female (p<0.029). The results of the present study demonstrated that the rearing of X. helleri in probiotic-enriched water have growth inducing ability and favourably influenced the reproductive performance in terms of high fecundity, high fry survival, reduced fry mortality and reduced fry deformity

Inactivation of luminous Vibrio spp. by free chlorine

In vitro inactivation of penaeid shrimp larval pathogens, Vibrio iiarveyi and V splendidus biovar 1, by free chlorine and the influence of organic matter on the bactericidal activity of chlorine were assessed. More than 5 log unit (>99.99%) reduction in luminous bacteria from >= log 6.00/ml within the first 60 sec of exposure to free chlorine at 1 ppm level was observed. Chlorine was ineffective at <50 ppm levels to inhibit luminous Vibrio spp in the presence of 0.1% peptone as interfering organic agent. These results revealed that luminous bacteria are highly susceptible to chlorine but the bactericidal activity of chlorine is affected by organic substance

Effect of feeding bioencapsulated Lactobacillus sp. in live Tubifex sp. on the growth performance of gold fish Carassius auratus (Linnaeus, 1758)

An attempt was made to feed bioencapsulate Lactobacillus sp. in live fish food organism Tubifex for use in the culture of gold fish Carassius auratus. The C. auratus fries when fed with bioencapsulated Lactobacillus sp. in Tubifex showed significant improvement in total wet weight gain (p0.05) in bioencapsulated Tubifex fed group. None of the bacteriological parameters of the fish gut between the experimental and control groups differed significantly (p>0.05). Lactobacillus sp. was recorded at a level of log 5.11/g on the 90th day of experimentation. When the experimental C. auratus fries were infected with Pseudomonas fluorescents, the bioencapsulated Tubifex fed group resisted the infection. The survival was significantly higher (p<0.05) in bioencapsulated Tubifex fed group (44%) than in control (22%). The C. auratus fed with bioencapsulated Tubifex showed less (55%) signs of tail/fin rot. Likewise, a significant improvement in total wet weight gain (p<0.009), FCR (p<0.01) and SGR (p<0.04) of C. auratus brooder fed with bioencapsulated Tubifex was seen compared to control group fed with depurated Tubifex

Microcosm evaluation of indigenous microflora of traditional shrimp farming system as bioremediators

The ability of indigenous microflora of traditional shrimp farming system to remove ammonia was evaluated under laboratory conditions. The indigenous microflora in combination were capable of removal of total ammoniacal nitrogen (TAN) to the tune of 85 - 99% within a week. The activity of nitrifying bacteria was observed to be substrate dependent. The results revealed that the TAN removal rate was affected by high initial TAN concentration and varied microbial activity. The results of the present study would release new avenues for future research and refinement of techniques on bioremediation in shrim

Efficacy of commercial shrimp farm bioremediators in removing ammonia in microcosm experiments

The efficacy of two commercial aquaculture bioremediators to remove ammonia was tested under laboratory conditions. The bioremediators were capable of removal of total ammoniacal nitrogen (TAN) to the tune of 86 - 90% (max) at 1-3 ppm initial level of ammonia (NH3) and the removal rate decreased thereafter. Significant differences in nitrite (NO2) levels in treated and control tanks were observed probably due to the differences in the levels of resident nitrifying bacteria that utilize NH3 and oxidize it to NO2. The nitrate levels increased in all the treatment tanks, but showed a general decreasing trend in control tanks. Among the tanks with varied NH3 concentrations, the levels of NO3 between the control and treatment tanks differed insignificantly (P>0.05). The results of the present study revealed that the commercial bioremediators failed to remove majority of the total ammoniacal nitrogen when the NH3 level is high initially

Effects of dietary supplementation of commercial human probiotic and antibiotic on the growth rate and content of intestinal microflora in ornamental fishes

The effects of dietary supplementation of commercial human probiotic, Lactobacil and antibiotic, oxytetracycline on the growth, survival, disease resistance and content of intestinal microflora in two ornamental fishes, viz., goldfish, Carassius auratus and swordtail, Xiphophorus helleri were studied. The total wet weight gain, food conversion ratio and specific growth rate of C. auratus did not vary significantly (p>0.05) among treatments. While in X. helleri, significant differences existed in the total wet weight gain, survival, food conversion ratio and specific growth rate among treatment groups (p<0.05). The counts of antibiotic resistant bacteria in fish gut increased with days of culture in all the treatments and the increase was more in antibiotic fed fishes. A reduction in the development of antibiotic resistance among the bacterial flora of fish gut was noticed in probiotic fed groups of C auratus and X. helleri. The results of the present study revealed that the effects of human probiotic on the growth, survival and disease resistance of ornamental fishes are variable and difficult to reproduce the similar effect on different species

Virulence of Vibrio harveyi possessing a transferable chloramphenicol resistance determinant to larvae of Indian white shrimp Fenneropenaeus indicus (Decapoda)

275-278The virulence of luminous Vibrio harveyi possessing a transferable chloramphenicol-resistance determinant to Indian white shrimp, Fenneropenaeus indicus larvae was studied. The V. harveyi strains isolated from luminous F. indicus larvae produced extracellular virulence factors such as haemolysin, chitinase, proteinase, lipase and phospholipase were resistant to at least four of six antibiotics tested. The chloramphenicol-resistance determinant was transferred from V. harveyi to Escherichia coli at frequencies of 6.69 10⁻⁴ - 4.27 10⁻³. The concentration of V. harveyi cells capable of causing 50% mortality differed significantly (P<0.05) and the 72 h LD₅₀ values ranged between 273 and 3,040 cells/ml. The chloramphenicol-resistant strains were more virulent to shrimp larvae compared to chloramphenicol-sensitive strain. Prevalence of highly virulent V. harveyi strains harbouring a transferable chloramphenicol-resistance determinant together with other extracellular virulence factors may hamper the hatchery production of penaeid shrimp larvae

Food Safety Hazards Related to Emerging Antibiotic Resistant Bacteria in Cultured Freshwater

Abstract: Association of opportunistic human bacterial pathogens in cultured freshwater fishes of Kolkata, India and their sensitivity to broad spectrum antibiotics was investigated. Both indigenous and non-indigenous human bacterial pathogens such as Aeromonas hydrophila, A. caviae, Edwardsiella tarda, Escherichia coli, Pseudomonas spp. and Vibrio parahaemolyticus were isolated from freshwater fishes of Kolkata. These strains were highly resistant to oxytetracycline (62%) and nitrofurantoin (46%), and sensitive to ciprofloxacin (91%) and chloramphenicol (89%). Multiple Antibiotic Resistance (MAR) was high in catfishes (76%) followed by miscellaneous fishes (66%) and sewage-fed farm grown carps (55%). Among the bacterial species, the MAR was high in Ed. tarda (86%). More than 50% of the strains of A. hydrophila, A. caviae, E. coli, Pseudomonas spp., V. parahaemolyticus and unidentified Gram positive rods exhibited MAR. The results suggested that there is added risk of antibacterial resistance developing in the emerging human bacterial pathogens from freshwater aquaculture and of such antibiotic resistant bacterial pathogens entering the food chain

Antibiotic susceptibility of luminous bacteria from shrimp farm environs of West Bengal

334-336 Sensitivity of 175 isolates of luminous bacteria from various shrimp farming systems of West Bengal was tested against six antibiotics, viz., chloramphenicol (30µg), ciprofloxacin (5µg), co-trimoxazole (25µg), gentamycin (10µg), nitrofurantoin (300µg) and oxytetracycline (30µg). Besides, the minimum inhibitory concentration (MIC) of the antibiotics was determined against 60 isolates of Vibrio harveyi. The isolates were least susceptible to oxytetracycline followed by ciprofloxacin and nirofurantoin, and highly susceptible to chloramphenicol. Vibrio harveyi was the most resistant species. About 56% of the luminous isolates exhibited multiple antibiotic resistance. The MIC of oxytetracycline was observed to be in the range of 1.56->200 µg/ml. Majority of the isolates were inhibited at a concentration of 0.10-0.78 µg/ml of ciprofloxacin and 0.20-6.25 µg/ml of chloramphenicol. The observations on the antibiotic resistance did not indicate that the luminous bacteria of certain shrimp culture systems of West Bengal is developing resistance to broad-spectrum antibiotics. </smarttagtype

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Not AvailableThe ability of indigenous microflora of traditional shrimp farming system to remove ammonia was evaluated under laboratory conditions. The indigenous microflora in combination were capable of removal of total ammoniacal nitrogen (TAN) to the tune of 85 - 99% within a week. The activity of nitrifying bacteria was observed to be substrate dependent. The results revealed that the TAN removal rate was affected by high initial TAN concentration and varied microbial activity. The results of the present study would release new avenues for future research and refinement of techniques on bioremediation in shrimpNot Availabl