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Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/4623

Title: 
  • is The bacterial community during early production stages of intensively reared halibut (Hippoglossus hippoglossus L.)
Other Titles: 
  • is Bakteríuflóra á fyrstu stigum lúðueldis
Abstract: 
  • is

    High bacterial numbers and the establishment of an unfavourable bacterial community has been identified as possible causes of the high mortalities commonly observed during early life stages of intensively reared Atlantic halibut (Hippoglossus hippoglossus L.). The impact of particular bacterial species is, however, poorly defined and still remains disputable.
    Highly variable larval survival and overall success were observed and analysis of the bacterial community revealed a high variation in the cultivable part as well as the bacterial community structure as analysed by denaturing gradient gel electrophoresis (DGGE) of PCR amplified 16S ribosomal DNA fragments. The effects of different treatments on the bacterial community and the quality of eggs and larvae were analysed. The treatments involved shading of the culture environment of larvae using either marine algae or inorganic clay, bioencapsulation of the live prey using a fish protein hydrolysate and treatment of eggs and bioencapsulation of the live prey using a mixture of three bacteria, Pseudoalteromonas elyakovii, Vibrio spp. and V. splendidus that were selected from the dominating bacterial community of overall successful larvae.
    Analysis of the bacterial community of unfed yolk sac larvae revealed a higher diversity than previously reported, with a positive relationship commonly observed between jaw deformation and the numbers of cultivable bacteria in unfed yolk sac larvae. Vibrio spp. dominated the bacterial community of larvae after the onset of exogenous feeding and α-Proteobacteria, not previously reported in halibut, were observed as a part of the intestinal microbiota. The bacterial community structure of the live prey was only partly reflected in larvae after one week of feeding, and the diverse bacterial community was only partly reflected in the cultivable part which may, however, reflect the dominating bacterial microbiota of larvae and their live prey.
    Higher bacterial numbers were observed in the tank water of larvae with environmental shading provided by marine algae as compared with inorganic clay. Manipulation of the bacterial community using isolates dominating the cultivable gut community of overall successful larvae did not affect egg survival, while bioencapsulation of the live prey resulted in enhanced larval survival, and improved larval growth was observed in one of the two experiments that were carried out. Bioencapsulation of the live prey using a fish protein hydrolysate resulted in stimulation of an innate immune response, with enhanced production of lysozyme, and more widespread distribution of complement factor C3 in larval tissues observed. Treatment was, however, neither found to affect the bacterial community associated with surface sterilized larvae nor larval survival and development. Low concentrations of IgM detected in larvae at the onset of feeding indicated maternal origin, not previously reported in halibut larvae.
    Mikil og skyndileg afföll verða á fyrstu stigum eldis sjávartegunda fiska og gefa
    rannsóknir vísbendingar um að bakteríuvöxtur hafi víðtækari áhrif á vöxt og afkomu lirfa
    en áður er þekkt. Bakteríur nærast á lífrænum efnum og úrgangi í eldiskerfunum og geta
    óæskilegar tegundir því náð miklum fjölda á skömmum tíma. Áhrif einstakra tegunda eru
    þó lítt þekkt en mikilvægt er að eldisumhverfi lirfanna sé stöðugt og sem minnstar
    breytingar verði á þessum viðkvæmu stigum eldisins.
    Bakteríuflóra hrogna og lirfa lúðu (Hippoglossus hippoglossus L.), eldisumhverfis þeirra
    og fæðudýra var kortlögð með ræktun á næringarætum svo og með sameindalíffræðilegum
    aðferðum (denaturing gradient gel electrophoresis, DGGE), sem ekki krefjast
    ræktunar bakteríanna. Ennfremur voru könnuð áhrif mismunandi meðhöndlunar á
    samsetningu bakteríuflóru svo og gæði hrogna og lirfa. Þetta var gert með samanburði á
    áhrifum skyggingar eldisvökva í kerjum ýmist með þörungum eða leir, meðhöndlun
    fóðurdýra lirfa með vatnsrofnum fiskipróteinum og meðhöndlun hrogna og fóðurdýra
    lirfa með blöndu þriggja baktería (Pseudoalteromonas elyakovii, Vibrio spp. og V.
    splendidus), sem einangraðar voru úr meltingarvegi lirfa í kerjum með góða afkomu.
    Bakteríuflóra kviðpokalirfa reyndist fjölbreyttari en áður hefur verið sýnt fram á og
    samband fannst á milli kjaftgalla og fjölda ræktanlegra baktería í lirfum. Vibrio tegundir
    voru ríkjandi í meltingarvegi lirfa eftir að frumfóðrun hófst. Einnig voru _-Proteobacteria
    einangraðar sem hluti af ríkjandi flóru lirfa en þessi hópur hefur ekki áður verið staðfestur
    í lúðu. Bakteríuflóra í lifandi fóðurdýrum lirfa reyndist aðeins endurspeglast að hluta til í
    meltingarvegi lirfa eftir fyrstu vikuna í fóðrun. Einungis lítill hluti tegunda í ákaflega
    fjölbreyttri bakteríuflóru lirfa og fóðurdýra þeirra reyndist vera ræktanlegur en
    vísbendingar eru um að ríkjandi hluti flórunnar geti að stórum hluta verið ræktanlegur.
    Notkun leirs í stað þörunga við nauðsynlega skyggingu eldisumhverfis lirfa hafði ekki
    áhrif á vöxt, gæði eða afkomu lirfa í startfóðrun en veruleg fækkun varð á fjölda baktería
    í eldisumhverfi lirfa. Meðhöndlun með stofnum sem einangraðir voru úr ríkjandi flóru í
    meltingarvegi lirfa úr kerum með góða afkomu hafði ekki áhrif á lifun eða gæði hrogna
    ii
    en fóðrun með bakteríumeðhöndluðum fæðudýrum leiddi til aukinnar lifunar og marktæk
    aukning var í vexti lirfanna í annarri af tveimur tilraunum sem framkvæmdar voru.
    Meðhöndlun fæðudýra með vatnsrofnum fiskipróteinum örvaði ósérhæft ónæmi lirfa, þar
    sem framleiðsla lysósíms var aukin og meiri dreifing var á C3 þætti komplement kerfisins
    í vefjum. Meðhöndlunin hafði hins vegar hvorki áhrif á bakteríuflóru né lifun lirfa.
    Meðfætt IgM greindist í lirfum við upphaf startfóðrunar rúmum mánuði eftir klak en
    meðfætt IgM hefur ekki áður verið greint í lúðulirfum.

ISBN: 
  • 978-9979-9918-6-1
Accepted: 
  • Apr 6, 2010
URI: 
  • http://hdl.handle.net/1946/4623


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The bacterial community during early production stages of intensively reared halibut _Hippoglossus hippoglossus L.pdf1.6 MBOpenHeildartextiPDFView/Open
The bacterial community during early production stages of intensively reared halibut (Hippoglossus hippoglossus L.)_Paper I.pdf617.69 kBOpenPaper IPDFView/Open
The bacterial community during early production stages of intensively reared halibut (Hippoglossus hippoglossus L.)_Paper II.pdf148.07 kBOpenPaper IIPDFView/Open
The bacterial community during early production stages of intensively reared halibut (Hippoglossus hippoglossus L.)_Paper IV.pdf1.36 MBOpenPaper IVPDFView/Open
The bacterial community during early production stages of intensively reared halibut (Hippoglossus hippoglossus L.)_Paper III.pdf317 kBOpenPaper IIIPDFView/Open