Tag: Probiotic bacteria

Reports

Leit að bætibakteríum / Searching for putative probionts in the production system of halibut larvae

Published:

01/09/2008

Authors:

Jónína Þ. Jóhannsdóttir, Eyrún Gígja Káradóttir (MS student), María Pétursdóttir, Jennifer Coe, Heiðdís Smáradóttir, Rannveig Björnsdóttir

Supported by:

Tækniþróunarsjóður Rannís (2006-2008) / Technology Development Fund of Rannís, the Icelandic Center for Research (2006-2008)

Leit að bætibakteríum / Searching for putative probionts in the production system of halibut larvae

The overall goal of the project is to improve the survival and quality of halibut larvae in starter feeding using supplementary bacteria. In the composition of supplementary bacteria for fish, the breeding of warm-water species has often been considered, and the bacterial species that have been used have proved to have a poor foothold in the environmental conditions involved in the breeding of cold-water species, such as halibut. This project seeks out and identifies bacteria that are prevalent in halibut larvae from breeding units that have been successful in terms of larval performance and metamorphosis. Studies were performed on the properties of isolated bacterial strains in terms of growth inhibitory effects on known pathogens for fish as well as predominant bacterial species from halibut larvae in breeding units where the performance and quality of larvae were below average. The predominant bacteria were isolated from larvae in all breeding units of Fiskey hf. in two different periods in addition to which samples were taken from juveniles in export size. The results of studies on the growth inhibitory effect of isolated strains revealed 18 bacterial strains that were found to inhibit the growth of known pathogens and / or bacterial strains that had been isolated from the larval rearing environment. Sequencing results showed a good correlation with 6 different bacterial species. Subsequently, it will be treated with a selected mixture of additive bacteria in the early stages of halibut farming.

The overall aim of this project is to use probiotic bacteria to promote increased survival of halibut larvae during first feeding. Previous studies indicated that the microbial load of larvae and their environment represents a problem and the objective of this project was to search for possible candidates for probiotic bacteria to promote survival and growth of larvae use during the first and most sensitive phase of production. Potential probiotic strains were selected on the basis of dominance in the gut of larvae from production units with successful growth, development and survival. The growth inhibiting activity was tested against known fish pathogens as well as bacteria dominating the intestinal community of larvae from production units with poor overall success. We isolated dominating bacteria in the gut of larvae from all production units of two different spawning groups at Fiskey Ltd. and also from export-size fingerlings. Growth inhibition studies revealed 18 bacterial isolates that inhibited growth of known fish pathogens and / or dominating bacterial isolates from the gut of larvae of an overall poor quality. 16S rRNA sequencing revealed a reasonable correlation to 6 bacterial species and presently. As a next step, halibut eggs and larvae will be treated with selected strains to test their potential as probionts during the first production stages of halibut aquaculture.

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Reports

Treatment of halibut (Hippoglossus hippoglossus L.) eggs and larvae using putative probions isolated from the production system

Published:

01/09/2008

Authors:

Jónína Þ. Jóhannsdóttir, Heiðdís Smáradóttir, Eyrún Gígja Káradóttir, Eydís Elva Þórarinsdóttir, María Pétursdóttir, Rannveig Björnsdóttir

Supported by:

Tækniþróunarsjóður Rannís (2006-2008) / Technology Development Fund of Rannís, the Icelandic Center for Research (2006-2008)

Treatment of halibut (Hippoglossus hippoglossus L.) eggs and larvae using putative probions isolated from the production system

The aim of the project as a whole is to improve the survival and quality of halibut larvae in starter feeding and use environmentally friendly methods where eggs and larvae are treated with a new mixture of additive bacteria that have been isolated from the halibut breeding environment. There will be great losses in the first stages of halibut farming and therefore it is important to create an optimal environment during these first and most sensitive stages of farming. The use of supplemental bacteria is one way of doing this, but supplementary bacteria can in various ways have a positive effect on their host, such as preventing unwanted bacteria from gaining a foothold in its digestive tract, stimulating the immune response and improving the balance in its digestive tract. Three separate experiments were carried out in the fish farm of Fiskey hf. where it was treated with a mixture of additive bacteria at different stages of the culture. The effect of the treatment was assessed in terms of the performance and quality of the eggs and larvae, but the composition of the bacterial flora of the farm was also examined. Supplementary bacteria were added to the breeding environment of eggs, but larvae were treated through the feed animals. The main results suggest that treatment with a new mixture of additive bacteria can affect the composition of the bacterial flora of eggs, larvae and their feed animals, but that treatment needs to be done more frequently than was done in the study if long-term effects are to be maintained. Repeated treatment at the egg stage seemed to reduce the incidence of defective peritoneal larvae, in addition to which treatment from the beginning of the initial feeding seemed to have a positive effect on the larval performance at the end of the initial feeding.

Poor survival of larvae during the first feeding phases calls for measures to create optimal environmental conditions during the first and most sensitive phases of the larval production. The overall aim of the project was to promote increased survival and quality of halibut larvae, using putative probionts isolated from halibut production units. Probiotic bacteria can affect their host in various ways, eg by preventing the attachment of unfavorable bacteria, stimulating the immune system and promoting increased stability in the gastrointestinal tract. In this project three separate experiments were carried out at a commercial halibut farm, Fiskey Ltd. in Iceland. Different treatment schedules were used for treatment of eggs from fertilization and larvae throughout first feeding. A mixture of equal concentration of three selected strains was added to the tank water environment of eggs or through grazing of the live feed. The effects of treatment were evaluated with respect to the overall success of eggs and larvae as well as with respect to chances in the bacterial community structure. The results indicate that treatment may affect the bacterial community of eggs, larvae and live feed but more frequent treatments seem to be needed than examined in the present study. Repeated treatment of eggs resulted in reduced incidence of jaw deformation (gaping) amongst yolk sac larvae and treatment from the onset of exogenous feeding resulted in improved survival of larvae compared to sibling tank units.

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Reports

Prevention in aquaculture. Part A - Prevention in cod farming

Published:

01/12/2007

Authors:

Hélène L. Lauzon, Sigríður Guðmundsdóttir, Agnar Steinarsson, Matthías Oddgeirsson, Bergljót Magnadóttir, Ívar Örn Ásgeirsson, Berglind Gísladóttir, Eyjólfur Reynisson, Sólveig K. Pétursdóttir, Þuríður Ragnarsdóttir, Maja Herold Pedersen, Birgitte B. Budde, Bjarnheiður K. Guðmundsdóttir

Supported by:

AVS Fund (R 41-04)

Prevention in aquaculture. Part A - Prevention in cod farming

The aim of Part A was to increase the efficiency of cod farming by increasing the survival of eggs / larvae and promoting increased growth of larvae in starter feeding. The results show that the composition of the microbial flora explained the declines better than the total microbial or Vibrio counts. Extensive analysis of the microflora of aquaculture systems and larval stage results led to the determination of desirable and undesirable bacteria. Chemical measurements in cod farming at the roe and larval stages showed that little accumulation of substances took place in the farmed liquid, except at the beginning of dry feeding. The choice of additive bacteria was decided on the basis of a specific screening process and expected use in cod farming. The use of supplemental bacteria in bathing eggs and / or larvae was examined, but continuous bathing from the egg stage onwards to the larval stage usually led to better results, greater growth and vitality. The use of complementary bacteria also affected the microflora and the development of larvae shortly after hatching, which was confirmed, among other things, by measurements of proteins from the immune system. The use of supplemental bacteria in juvenile farming was investigated and indicated an increase in growth rate. It has not been possible to prove that increased disease tolerance can be achieved with the use of supplementary bacteria in juvenile farming, but there were positive indications of this. The main bottlenecks in the development of prevention methods were the live food animals, which caused a high microbial load. The development of probiotic rodents with other complementary microorganisms did not work well. Investigations into the infectious potential of the cod bacteria in cod fry showed that they did not cause any symptoms or cause death.

The aim was to increase the competitiveness and success of cod aquaculture by increasing survival and development from hatching through the larval stage. This was achieved by developing preventive methods to control important chemical and biological parameters. The results revealed that differences in microbiota composition between different larval treatments explained the success or lack thereof, better observed than total microbial or Vibrio counts of rearing water or larvae. Microbiota analysis and survival rates have hence led to the definition of desirable and undesirable bacteria, the latter being especially Vibrio sp. Assessment of selected chemical parameters was performed at pre- and posthatching periods, indicating NH3 build-up in the rearing water upon dry feeding. The selection of probiotic bacteria was based on a specific screening and their anticipated use in cod farming. Application of selected bacteria was tested for surface treatment of eggs and / or larval bathing, and the continuous use before and after hatching usually led to increased survival, growth and tolerance as well as influencing larval microbiota and immunological development. Application of selected probiotic bacteria was also tested with cod juveniles with increased growth rate. Disease resistance of probiotic-fed juveniles to fish pathogens was not confirmed. Development of probiotic rotifers proved difficult due to their high microbial load. Probiotic strains applied ip to cod juveniles were not found to be virulent

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