Bacterial Interactions in Early Life Stages of Marine Cold Water Fish

Abstract

> Abstract The intensive rearing of various fish species in aquaculture has revealed intimate relationships between fish and bacteria that eventually may affect establishment of a "normal" mucosal microflora or result in disease epizootics. Interactions between bacteria and mucosal surfaces play important roles both at the egg and larval stages of marine fish. Bacterial adhesion and colonization of the egg surface occur within hours after fertilization. The diverse flora which eventually develops on the egg appears to reflect the bacterial composition and load of the ambient water, but species-specific adhesion at the egg surface may also play a role in development of the egg epiflora. Proteolytic enzymes produced by members of the adherent epiflora may cause serious damage to the developing egg and may also affect further adhesion of the epiflora. Ingestion of bacteria at the yolk sac stage results in establishment of a primary intestinal microflora which seems to persist beyond first feeding. Establishment of a gut microflora is likely to undergo several stages, resulting in an "adult" microflora weeks to months after first feeding. Ingested bacteria may serve as an exogenous supply of nutrients or essential factors at an early life stage. Early exposure to high bacterial densities is probably important for immune tolerance, and thus for the establishment of a protective intestinal microflora. Successful rearing of early life stages of several marine fish species depends on knowledge of the complex interactions among the cultured organisms and the bacterial communities which develop at the mucosal surfaces and in the ambient water and rearing systems. The routine use of antibiotics during rearing of fish larvae is not advisable, since it may increase the risk of promoting antibiotic resistance and adversely affect the indigenous microflora of the larvae. The use of probiotics has proven advantageous in domestic animal production, and the search for effective probiotics may have a great potential in aquaculture of marine organisms. Bacteria with antagonistic effects against fish pathogens have been successfully administered to several fish species, resulting in decreased mortality or increased growth rate.http://link.springer-ny.com/link/service/journals/00248/bibs/38n1p1.html

Deciphering microbial landscapes of fish eggs to mitigate emerging diseases

“…Here, we showed a significant correlation between the incidence of Saprolegniosis and the richness and evenness of specific bacterial genera associated with salmon eggs. These results indicate that along with established factors influencing disease susceptibility, such as genetic inheritance (broodstock effect), developmental stage of the salmon eggs, environmental and other stress conditions (Hansen and Olafsen, 1999), the microbiota are also a determining factor in health and disease of fish eggs that have an immature adaptive immune system and depend on other defences for protection. In terms of genetic inheritance, components of the complement immune system were shown to be maternally transferred to the eggs for rainbow trout, zebrafish and amphibian eggs (Lovoll et al, 2006;Poorten and Kuhn, 2009;Wang et al, 2009;Walke et al, 2011), and a paternal genetic component contributed to resistance against Saprolegnia in frog eggs (Sagvik et al, 2008).…”

“…Over the past years, several studies have unequivocally shown that microbes play a pivotal role in the protection of eukaryotes (humans, plants and insects) against pathogens (Round et al, 2010;Mendes et al, 2011;Weiss and Aksoy, 2011;Everard et al, 2013;Stecher et al, 2013;Turner et al, 2013). For fish and amphibians, microbiome studies have only been initiated recently (Cahill, 1990;Hansen and Olafsen, 1999;Schulze et al, 2006;McKenzie et al, 2012). Several studies have indicated that specific bacteria can contribute to the protection of fish and amphibians against fungal and oomycete pathogens.…”

Dietary input of microbes and host genetic variation shape among-population differences in stickleback gut microbiota

“…Microbial colonization of the vertebrate gut begins at birth through contact with parents and the external environment (Bergh, 1995;Hansen and Olafsen, 1999;Dominguez-Bello et al, 2010;Pantoja-Feliciano et al, 2013). Colonization continues throughout life by microbes from ingested materials, such as food and liquid, or via contact with microbes on other organisms or abiotic surfaces (Liston, 1956;Campbell and Buswell, 1983;Meadow et al, 2013).…”

Enterovibrio norvegicus gen. nov., sp. nov., isolated from the gut of turbot (Scophthalmus maximus) larvae: a new member of the family Vibrionaceae.

“…Recently, there have been several reports showing that the intestinal microflora of sea-water fish is dominated by members of the family Vibrionaceae and that the gut microflora plays an important role in the health of early life stages of fish (Hansen & Olafsen, 1999 ;Ring & Birkbeck, The EMBL accession numbers for the 16S rDNA sequences of strains LMG 19839 T , LMG 19840 and LMG 19842 are respectively AJ316208, AJ316207 and AJ437193.…”

“…It is likely that phenotype-based fingerprinting techniques applied in many previous studies have hampered the correct taxonomic identification of several taxa (Cerda ' -Cue! llar et al Hansen & Olafsen, 1999 ;Onarheim et al, 1994 ;Ring & Birkbeck, 1999). The usefulness of genomic fingerprinting techniques such as amplified fragment length polymorphism (AFLP), pulsed-field gel electro-F. L. Thompson and others phoresis and repetitive elements palindrome PCR for studies on bacterial evolution, phylogeny and taxonomy have recently been recognized (Rademaker et al, 2000 ;Van Belkum et al, 2001).…”