Freshwater fish culture has traditionally been dominated by various carp species but recently tilapia production has increased significantly; as a result tilapia are currently being cultured in 74 countries with an estimated annual output of over three million tonnes (FAO, 2010).

1. November | December 2011
Feature title: Evaluation of probiotic bacteria in tilapia production
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2. F: Probiotic bacteria F: Probiotic bacteria
Ferguson et al. (2010) used more accu- Lactobacillus plantarum, Bacillus pumilus, tilapia can obtain their essential amino acid
rate and reliable molecular techniques to Lactobacillus acidophilus and Streptococcus requirements from GI microbiota alone
Figure 1: de Man,
Rogosa & Sharpe demonstrate that diets supplemented with faecium as well as various mixtures of these when dietary sources are low or absent.
(MRS) plates of digesta Pediococcus acidilactici exhibited altera- candidates. Other authors have isolated gut microbes
from fish fed a control tions in GI microbiota. PCR-DGGE revealed However, other studies have failed to that can produce other enzymes involved in
diet (top plates) direct antagonism of P. acidilactici with an show a difference in growth parameters with digestion (carbohydrases, esterases, lipases,
Evaluation and a P. acidilactici
supplemented diet
(bottom plates)
uncultured bacterium (closest known rela-
tive was a bacterial clone isolated from the
the use of various probiotics. Contradictory
results may reflect the differences in rearing
phosphatases, peptidases, cellulases), some
of which are being assessed as potential
of probiotic intestine of Atlantic salmon) during a period
of reverting to nonsupplemented feeding.
Recent work conducted at the
conditions and diet where fish reared under
near optimal conditions are unlikely to
benefit from probiotic applications.
probiotics.
Anaerobic microbes can produce short-
chain fatty acids (which can elevate gut
bacteria in tilapia Aquaculture and Fish Nutrition Research
Aquarium, University of Plymouth supports
Probiotics can improve growth perform-
ance by increasing nutrient utilisation and
motility and be used for energy purposes
or further lipid synthesis) by fermenting
production this (see Figure 1). Here fish fed a P. acidilac-
tici supplemented diet exhibited consider-
uptake, production of enzymes, amino acids,
short-chain fatty acids and vitamins.
dietary carbohydrates. Obligate anaerobes,
primarily Cetobacterium somereae and
ably higher LAB populations in their digesta, However, the specific mechanisms in Chlostridium spp. can produce large amounts
which, were identified as P. acidilactici. This scientific evaluations are often hard to of vitamin B12, thus tilapia do not require
by Benedict Standen & Ali Abid, Aquatic colonisation of the GI tract (at least during elucidate, due in part to the ethical and a dietary source of this vitamin because of
Animal Nutrition and Health Research Group, continual supplementation) is thought to be methodological limitations of animal stud- the microbial production capability. Another
The University of Plymouth, United Kingdom a major advantage for potential probionts. ies, together with complex relationships mechanism which may improve digestive
between possible modes of action. function is the enhancement of the mor-
Growth performance and Bacteria commonly found in the gut, phology of the GI tract.
effect on digestion and including Aeromonads, are known to pro-
nutrient utilisation Morphological effects
F
duce proteases and other gut microbes
reshwater fish culture has when administered in adequate amounts colonisers of the intestine followed by Improved growth performance has been produce amino acids which could be used on the intestine
traditionally been dominated can enhance the growth and health of the Pleisomonas spp., Enterobacteriaceae, observed in tilapia fed diets supplemented by the host. It has been reported that probiotics can
by various carp species but host, as well as the quality of its ambient Micrococcus spp., Actinobacter spp., Clostridium with a number of probiotics including This helps to explain the findings of affect fish GI function and morphology. In
recently tilapia production environment beyond inherent basic nutri- spp., Bacteroides spp. and Fusarium spp. . Also S. cerevisiae, Micrococcus luteus, B. subtilis, Newsome et al. (2011) who showed that this respect, a study by Pirarat et al (2011)
has increased significantly; as a result tion (Fuller, 1989; Merrifield et al., 2010a). present in tilapia intestine are Burkholderia
tilapia are currently being cultured in These measures help facilitate consumer spp., Chromobacterium spp., Citrobacter spp.
over 70 countries with an estimated perceptions of bio-security and eco-friendly and Flavimonas spp. (Molinari et al., 2003).
annual output of over three million aquaculture. Despite being prevalent in mammalian and
tonnes (FAO, 2010). Aquatic animals are constantly in contact avian intestines lactic acid bacteria (LAB)
with the composition and changes in their are present, but generally sub-dominant,
AquaStar ®
This rapid growth suggests that tilapia surrounding environment. in fish.
may become one of the most important Potential pathogens are able to maintain
cultured fish species in the future. themselves in the external medium and Modification of microbial
Although tilapia are relatively resistant proliferate independently of the host caus- composition
to infection and disease compared to other ing disease or rendering aquatic animals The GI tract is available to microbial Fast growth in clean water!
finfish, intensification of tilapia production immunocompromised. colonisers upon opening of the mouth of
has resulted in an increase of bacterial infec- The gastrointestinal (GI) tract is one larval fish. AquaStar product line
®
tions which frequently causes mass mor- of the key sites of interaction with the In this sense the commensal microbiota
talities, leading to severe economic losses external world and is considered one of reflects the microbiota of the eggs, rearing • Probiotic strains to support gut health
in major fish producing countries. the major portals for pathogenic invasion in water and the microbiota of any dietary • Biodegrading strains to stabilize water
Traditional practices involve using fish (Ringø et al., 2007). The GI microbiota intake during the first-feeding. It has been quality and pond bottom
antimicrobial compounds to treat disease provide a number of functions that benefit proposed that any probiotic supplementa-
outbreaks and control infections in aquatic the health of the host by promoting nutri- tion at this stage has a significant advantage,
animals. ent and enzyme supply, enhancing innate whereby good microbes ‘get there first’.
• Im
pr
However, a number of issues exist with immune function, preventing colonisation of However, at any developmental stage the heal oved gu
these measures, namely the increasing pathogenic microbes (by either competition microbiota can shift as a result of farming perf th and t
orm
or production of inhibitory compounds), • Im a
prov nce
problem of emerging antibiotic resistant practices, rearing environment, seasonality
pathogens with the threat of resistance energy homeostasis and are also involved in and diet. Furthermore, the administration qual ed wa
ity ter
transfer to human pathogens as well as food localised morphological development and of a probiotic may also cause a shift in the • Co
ntro
and environmental contamination. maturation of the intestine. microbial composition. path l of
Consequently, in recent years there Culture dependent and independent bact ogenic
For example, Oreochromis niloticus fed eria
has been considerable effort to evaluate studies indicate that bacteria are the main a diet supplemented with a mixture of
the feasibility of using alternative methods, colonisers of the GI tract with early studies Saccharomyces cerevisiae and Bacillus subtillus
particularly probiotics to enhance growth, recording the predominance of anaerobes showed an altered composition, lacking
stimulate the innate immune system and/or in the GI tract of tilapia (Sugita et al., 1989). Escherichia coli, Salmonella spp., Klebsiella aquastar.biomin.net
prevent disease in the host. We now know that in freshwater fish, spp. and Pseudomonas fluorescens which
Probiotics are live microorganisms, Vibrio spp., Aeromonas spp., Pseudomonas were present in control fish (Marzouk et
including many yeasts and bacteria, which spp. and Cetobacterium somereae are major al., 2008). Naturally ahead
Biomin_Anzeige_AquaStar_01.indd 1 31.10.11 11:17
16 | InternatIonal AquAFeed | november-December 2011 november-December 2011 | InternatIonal AquAFeed | 17

3. F: Probiotic bacteria
demonstrated that L. rhamnosus application response of Nile tilapia were positively conditions, farming practices and stocking
as a dietary supplement encouraged the affected by P. acidilactici. The authors found densities.
development of the intestinal structure of that the serum lysozyme activity was sig- Therefore, in order for the probiotics
Nile tilapia. nificantly higher in the fish fed the probiotic concept to be beneficial and cost-effective,
The authors found the length of villous diet in comparison with the control fish; future work must address these issues
in the proximal and middle sections of the furthermore, the total number of circula- associated with the application methods
intestine were greater in the group of fish tory leucocytes was also elevated. In addi- and must be used in concert with suitable
fed the probiotic. On the contrary, Nile tion, another study examined the potential farm management.
tilapia that were fed P. acidilactici at 107 probiotic effect of Lactobacillus rhamnosus
CFU /g for 32 days (Ferguson et al., 2010) GG on tilapia immunity. After being fed a References
showed no gross morphological differences probiotic supplemented diet for 30 days,
FAO (2010) The State of World Fisheries
in the intestine of fish fed the probiotic in nonspecific parameters were significantly and Aquaculture 2010 (Food and Agricultural
enhanced in the probiotic Organization of the United Nations, Rome,
group (Pirarat et al., 2011). It is 2010).
noteworthy that the activity of
"The intensification of tilapia innate immune parameters can
Ferguson RM, Merrifield DL, Harper GM,
Rawling MD, Mustafa S, et al. (2010) The effect
be affected by several external
production has caused an increase and internal aspects, including
of Pediococcus acidilactici on the gut microbiota
and immune status of on-growing red tilapia
in bacterial infections and issues handling, crowding stress and (Oreochromis niloticus). J Appl Microbiol 109:
temperature changes. 851-862.
associated with the over usage of The dietary supplementa-
Fuller R (1989) Probiotics in man and animals. J
tion of probiotics can enhance
antibiotics has highlighted the need both systematic and localised
Appl Bacteriol 66: 365-378.
Gómez GD, Balcázar JL (2008) A review on the
to fight disease using more robust immunity in a wide range of fish
including tilapia, rainbow trout, interactions between gut microbiota and innate
and sustainable methods, namely gilthead seabream, European immunity of fish. FEMS Immunol Med Mic 52:
145-154.
seabass and grouper.
the administration of probiotics" The effectiveness of pro- Magnadóttir B (2006) Innate immunity of fish
biotics in terms of protection (overview). Fish Shellfish Immun: 20: 137-151.
against infectious pathogens Marzouk MS, Moustafa MM, Mohamed NM
is often attributed to elevated (2008) The influence of some probiotics on the
comparison with the control group of fish. immunity. In tilapia, numerous probiotics growth performance and intestinal microbial flora
However, a study with rainbow trout have shown increased protection against of Oreochromis niloticus. Proceedings of 8th
showed that dietary P. acidilactici may Edwardsiella tarda and Aeromonas hydrophi- International Symposium on Tilapia in Aquaculture,
improve microvilli length and enterocyte la infections. In other aquaculture species, Cairo, Egypt, pp. 1059-1071.
endocytic activity (Merrifield et al. 2010b), protection against enteric red mouth Merrifield DL, Dimitroglou A, Foey A, Davies
which has yet to be studied in tilapia. disease, edwardsiellosis, furunculosis, SJ, Baker RT et al. (2010a). The current status
lactococcosis and several other diseases and future focus of probiotic and prebiotic
Stimulating the innate have been documented with probiotic applications for salmonids. Aquaculture 302:
immune response feeding. 1-18.
It is well documented that the modula-
tion of the nonspecific immune system is
one of the most important modes of action
Furthermore, probiotic treatment may
provide ‘herd immunity’ from multiple dis-
eases. Protection against viral and protozoan
Merrifield, DL, Harper, GM, Dimitroglou, A,
Ringø, E, Davies, SJ (2010b) Possible influence
of probiotic adhesion to intestinal mucosa on
Amino Acids
for probiotics. infections has also shown some successes in the activity and morphology of rainbow trout Headquarters Choosing the right nutrients for your Aquafeed
In general, growth inhibitors, natural the fight to control Ichthyophthiriasis in (Oncorhynchus mykiss) enterocytes. Aquacult Res Evonik Industries AG
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chemokines, various lytic enzymes and Molinari LM, Scoaris D, Pedroso RB, Bittencourt Rodenbacher Chaussee 4 • replace costly and scarce raw materials
components of the complement pathways Conclusion N, Nakamura CV, et al. (2003) Bacterial microflora 63457 Hanau-Wolfgang, Germany
• improve protein balance and production efficiency
in the gastrointestinal tract of Nile tilapia, phone +49 6181 59-2256
are considered to be components of The intensification of tilapia production
Oreochromis niloticus, cultured in a semi-intensive
fax +49 6181 59-6734 • reduce environmental pollution
humoral parameters of the innate immune has caused an increase in bacterial infec-
system whereas nonspecific cytotoxic cells tions and issues associated with the over system. Acta Sci Biol Sci Mar 25: 267-271. Europe & Middle East Africa +49 6181 59-6766
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Previous studies, have generally dem- tion of probiotics. synthesis in Nile tilapia. Funct Ecol (in press).
onstrated some visible benefits on either Current literature clearly demonstrates Ringø E, Myklebust R, Mayhew TM, Olsen RE
the immune function, disease resistance, that probiotics can benefit tilapia production. (2007) Bacterial translocation and pathogenesis in
or both. Contrary results may stem from differ- the digestive tract of larvae and fry. Aquaculture
In order to explore an improvement of ences in the species and strain of probiont, 268: 251-264.
the immune system due to probiotic appli- dosage, species and age/size of host fish, Sugita H, Oshima K, Tamura M, Deguchi Y (1989)
cation, Ferguson et al (2010) confirmed that mode of application, feeding management, Bacterial flora of gastrointestine of freshwater
some aspects of the nonspecific immune duration of supplementation, environmental fishes in river. B Jpn Soc Fish 49: 1387-1395.
18 | InternatIonal AquAFeed | november-December 2011

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