Indigenous Lactic Acid Bacteria in Fish and Crustaceans - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 129

Pediococcus sp. as indigenous species. In warm water fish species (e.g. sturgeon, zebrafish,
carp, tilapia, grouper and cobia etc.), members of the genera Lactobacillus , Lactococcus ,
Enterococcus , Pediococcus , Leuconostoc and Weissella have commonly been identified as the
indigenous GI populations, while Carnobacterium species have rarely been identified. The
dominant LAB in shellfish belong to the Pediococcus and Lactobacillus genera, including
the species Lb. plantarum , Lb. acidophilus , Lb. bulgaricus , Lb. sporogenes , Lb. casei , Lb.
brevis , Lb. helveticus and P. acidilactici . Although Bifidobacterium are commonly reported
in the GI tract of mammals and terrestrial organisms, they are seldom reported in fish. Future
experiments should attempt to quantify these bacterial groups using qPCR, FISH, metagenetic
and metagenomic approaches. The importance of these bacteria in mediating host benefits,
how they respond to dietary and environmental changes, and their potential to antagonize
enteric pathogens, should be topics of future investigations.
6.1 INTRODUCTION
At the time of hatching, the digestive tract of fishes is a simple tube, histologically and
functionally undifferentiated (Govoni et al . 1986). Early differentiation of the intestinal tube
includes a proliferation of intestinal cells and the gut lengthens and twists as is essential for
the intestine-specific functions; the anatomy and functions may eventually stabilize during
larval development but then change again significantly at metamorphosis, especially if there
is a major change in the diet.
In fish the initial intestine microbiota establishes at the yolk sac stage (Hansen and Olafsen
1999) and is initially composed of only few taxa within the digestive tract of sac fry (Yoshimizu
et al . 1976; 1980). At this stage bacteria become ingested, leading to the establishment of an
initial intestinal microbiota. Data on bacterial genera in the different regions of the GI tract
show a progressive increase in the number of aerobic heterotrophic bacteria in adult yellow-
tail ( Seriola quinqueradiata ) (Sakata et al . 1978) and in the juvenile and adult Dover sole
( Solea solea L.) (MacDonald et al . 1986). Contrasting results on the changes of the intesti-
nal microbiota have been reported comparing these data with cold water species such as the
farmed Arctic charr ( Salvelinus alpinus L.) (Ringø 1993a) and rainbow trout ( Oncorhynchus
mykiss Walbaum) (Austin and Al-Zahrani 1988). In turbot ( Scophthalmus maximus L.) lar-
vae, bacterial colonization of the GI tract coincides with the start of feeding and at this stage
the microbiota is reportedly dominated by Aeromonas and Vibrio (Munro et al . 1994; Ringø
et al . 1996). Readers with a specific interest on the overall composition of the gut microbiota
of fish and the factors that modulate these communities are referred to Ringø et al . (2012a;
2012b) and Chapter 4 , and readers with special interest in the importance of host-microbiota
interactions within the fish GI tract are referred to the review of Pérez et al . (2010).
The aim of the present chapter is to present information on LAB reported in the GI tract of
different fish and crustaceans. The results cited in the present review include works published
in peer-reviewed international scientific journals, national journals, and abstracts presented in
topics from international conferences. The information presented is organized by ish families
according to the current recognized taxonomical structure (FishBase 2012).
Readers with special interest on LAB in fish and crustaceans beyond what is presented in
this chapter are referred to previous published reviews discussing this topic (Ringø et al . 1995;
Ringø and Gatesoupe 1998; Ringø 2004; Ringø et al . 2005; Gatesoupe 2008; Merrifield et al .
2010a; Ringø et al . 2010; Lauzon and Ringø 2012).