Lat. Am. J. Aquat. Res., 41(3): 490-497, The
lactic acid bacteria as growth promoters in fish fed 490
Research Article The use of lactic acid bacteria isolated from intestinal tract of Nile tilapia (Oreochromis niloticus), as growth promoters in fish fed low protein diets Maurilio Lara-Flores1 & Miguel A. Olvera-Novoa2
1Instituto de Ecología, Pesquerías y Oceanografía del Golfo de México, Universidad Autónoma
de Campeche, Av. Agustín Melgar y Juan de la Barrera S/N, Col. Buenavista
C.P. 24039. San Francisco de Campeche, Campeche, México
2Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional
Unidad Mérida Apdo. Postal 73-Cordemex, C.P. 97310, Mérida, Yucatán, México
ABSTRACT. In this study, the effect as growth promoter of five lactic acid strains (Enterococcus faecium, E. durans, Leuconostoc sp., Streptococcus sp. Iand Streptococcus sp. II), isolated from intestinal tract of Nile tilapia (Oreochromis niloticus), was evaluated. Eight isocaloric diets were formulated: one containing 40% of protein as positive control, and seven with 27% protein. Five diets with 27% protein were supplemented with one of the isolated lactic acid bacteria in a concentration of 2.5x106 cfu g-1 of diet. A commercial probiotic based on S. faecium and Lactobacillus acidophilus was added at the same concentration to one 27% protein diet as a comparative diet, and the last diet was not supplemented with bacteria (negative control). Tilapia fry (280 mg basal weight) stocked in 15 L aquaria at a density of two per liter were fed for 12 weeks with experimental diets. Results showed that fry fed with native bacteria supplemented diets presented significantly higher growth and feeding performance than those fed with control diet. Treatment with Streptococcus sp. I isolated from the intestine of Tilapia produced the best growth and feeding efficiency, suggesting that this bacteria is an appropriate native growth promoter. Keywords: probiotics, Nile tilapia, Oreochromis niloticus, growth promoter, lactic acid bacteria. Uso de bacterias ácido lácticas aisladas del tracto intestinal de tilapia nilótica (Oreochromis niloticus) como promotores de crecimiento en peces alimentados con dietas bajas en proteína RESUMEN. Se evaluó el efecto como promotores de crecimiento de cinco cepas de bacterias ácido lácticas (Enterococcus faecium, E. durans, Leuconostoc sp., Streptococcus sp.Iy Streptococcus sp.II) aisladas del tracto intestinal de tilapia nilótica (Oreochromis niloticus). Se formularon ocho dietas isocalóricas: una conteniendo 40% de proteína como control positivo y siete con 27% de proteína. Cinco dietas con 27% de proteína fueron suplementadas con cada una de las bacterias aislada a una concentración de 2,5x106 ufc g-1 de alimento. Un probiótico comercial a base de S. faecium y Lactobacillus acidophilus a la misma concentración de inclusión bacteriana a una dieta con 27% de proteína como dieta comparativa, y la última dieta no fue suplementada con bacterias (control negativo). Juveniles de tilapia (280 mg de peso basal) fueron distribuidos en acuarios de 15 L de capacidad, a una densidad de dos juveniles por litro, alimentados durante 12 semanas con las dietas experimentales. Los resultados mostraron que los organismos alimentados con las dietas suplementadas con bacterias nativas presentaron crecimiento y asimilación del alimento significativamente mayor que las dietas control. El tratamiento con Streptococcus sp. I, aislada del intestino de la tilapia, produjo el mejor crecimiento y la mejor eficiencia alimenticia, sugiriendo que esta bacteria es apropiada como un promotor de crecimiento nativo de tilapia. Palabras clave: probiótico, tilapia nilótica, Oreochromis niloticus, promotor de crecimiento, bacterias ácido lácticas.
Corresponding author:Maurilio Lara-Flores (firstname.lastname@example.org)
491 Latin American Journal of Aquatic Research
morphology and produce certain enzymes and inhibitory compounds causing improved digestion
Aquaculture is a fast-growing and rapidly expanding
and absorption of nutrients, as well as enhanced
multibillion dollar industry. Marine capture fisheries
immune response (Verschuere et al., 2000). Several
and aquaculture supplied the world with about 104
studies have demonstrated that use of probiotics
million ton of fish in 2004 (FAO, 2007). Of this total,
improves health of larval and juvenile fish, disease
marine aquaculture accounted for about 18%, where
resistance, growth performance and body compo-
shrimp from aquaculture continues to be the most
sition, however, the mode of action in fish species
important commodity traded in terms of value (2.4
may vary between farmed fish species cultured in
million ton). Worldwide, the aquaculture sector has
been expanding at an average compounded rate of
The use of probiotic in feeds to improve growth of
9.2% per year since 1970, compared with only 1.4%
different fish species including African catfish, (Al-
for capture fisheries and 2.8% for terrestrial-farmed
Dohail et al., 2009); Senegalese sole (Sáenz de
meat production systems. During the last decades,
Rodrigáñez et al., 2009), Nile tilapia (Lara-Flores et
antibiotics used as traditional strategy for fish
al., 2003, 2010; El-Haroun et al., 2006), Japanese
diseases management but also for the improvement of
flounder (Taoka et al., 2006), gilthead sea bream and
growth and efficiency of feed conversion. However,
sea bass (Carnevali et al., 2006) has been inves-
the development and spread of antimicrobial resistant
tigated. The effects of probiotics have been linked to
pathogens were well documented (Kim et al., 2004;
modulation of gut microbiota and establish-ment of
the beneficial microorganisms, higher specific and
There is a risk associated with the transmission of
total digestive enzyme activities, in the brush border
resistant bacteria from aquaculture environments to
membrane, which increases the nutrient digestibility
humans, and risk associated with the introduction in
and feed utilization (Verschuere et al., 2000; Balcazar
the human environment of nonpathogenic bacteria,
et al., 2006; Kesarocodi-Watson et al., 2008). In
containing antimicrobial resistance genes, and the
addition, the production of vitamins by these gut
subsequent transfer of such genes to human
microbiota could also increase vitamin synthesis and
pathogens (FAO, 2005). Considering these factors, as
improve fish health (Holzapfel et al., 1998). This
well as the fatal effect of residual antibiotics of
study was carried out to find the effect of isolated
aquaculture products on human health, the European
acid lactic bacteria from intestinal tract of Nile tilapia
Union and USA implemented bans on, or restricted
(Oreochromis niloticus), on feed efficiency and
the use of antibiotics (Kesarcodi-Watson et al.,
growth of fry Nile tilapia fed with low protein diets.
In connection with the ban of antibiotic growth
MATERIALS AND METHODS
promoters new strategies in feeding and health management in fish aquaculture practice have
received much attention (Balcázar et al., 2006). In
Five strains of lactic acid bacteria isolated from Nile
addition, the global demand for safe food has
tilapia intestine were characterized on the basis of
prompted the search for natural alternative growth
morphological, physiological and biochemical test by
promoters to be used in aquatic feeds. There has been
Bergey´s Manual of Systemic Bacteriology (Holt et
heightened research in developing new dietary
al., 1993). Axenic cultures of the purified bacteria
supplementation strategies by promoting various
were tentatively identified, using Mini-API System
health and growth compounds as probiotics (Denev,
Bio-Merieux, as Enterococcus faecium, E. durans, Leuconostoc sp., Streptococcus sp. Iand Strepto-
The importance of probiotics in human and
coccus sp. II. Commercial probiotic containing
animal nutrition is widely recognized (Fuller, 1992;
mixture of Lactobacillus acidophilus and S. faecium
Rinkinen et al., 2003), in recent years, the role of
probiotics in nutrition and health of certain
All bacteria were grown aseptically in 10 mL of
aquaculture species have also been investigated
MRS broth for 24 h at 35 ± 2°C. Five mL were
(Gatesoupe, 1999; Verschuere et al., 2000; Kesarcodi-
transferred under aseptic conditions into 250 mL of
Watson et al., 2008; Ringo et al., 2010; Merrifield et
MRS broth and held on a shaker at 150 rpm for 24-48
al., 2010). It appears that probiotics provide benefits
h at 35 ± 2°C. The cells of each isolate were
by establishing favorable microbial communities,
harvested by centrifugation at 10,000 rpm for 15 min
such as lactic acid bacteria and Bacillus sp. in the
and washed twice with phosphate buffer (PB) having
gastrointestinal track, which may alter gut
The use of lactic acid bacteria as growth promoters in fish fed 492
after which the different treatments were randomly
Eight isocaloric diets were formulated: one
assigned to the aquaria, with four replicates per
containing 40% protein, and the other seven with
27% of protein level. The lower protein inclusion in
Feed was manually administered ad libitum four
the latter diets was used as a stress factor since that
times a day, for 12 weeks. A daily record was kept of
the optimum protein level for fry tilapia is 40%
feed offered. Bulk weight was measured weekly to
(Tacon, 1984). Each one of the lactic acid bacteria
follow growth in weight and calculate survival and
isolates was added to lower protein diets in a
feeding ration. Briefly, the fish were taken from each
concentration of 2.5x106 cfu g-1 of diet. The
tank using a net previously disinfected with a 1%
commercial probiotic was added to one diet with 27%
benzalkonium chloride solution. Initial mean weight
protein in a concentration of 2.5x106 cfu g-1 of diet
(IMW), final mean weight (FMW), specific growth
for comparison. Finally, positive and negative control
rate (SGR), Feed conversion ratio (FCR), survival,
diets were formulated with 40 and 27% of protein
protein efficiency ratio (PER), apparent nitrogen
level, respectively, both diets without bacterial
utilization (ANU), apparent organic matter diges-
supplements. To all diets, 0.5% chromic oxide was
tibility (AOMD) and apparent protein digestibility
added for determining digestibility. Tables 1 and 2
(APD) were measured using the following equations:
shows diet formulation and proximate composition
SGR = 100[(log. final body weight-log initial body
FCR = individual food intake/individual weight gain
PER = individual protein intake/individual weight
Population density was also used as a stress factor,
under the assumption that overpopulation is one of the main growth-inhibiting factors in intensive
ANU = 100(carcass nitrogen deposition/N intake)
aquaculture systems. To this end, 32 glass aquaria of
Beginning in the third week of the experiment,
15 L capacity were stocked at a 30 organisms per
feces were collected by siphoning the aquaria 30 min
aquaria (2 fry per liter). All fry had similar average
after the second daily feeding, to minimize leaching.
initial weights (280 ± 10 mg). The different diet
Scales were removed from the collected feces, the
formulations were assigned within the aquaria. The
feces were oven dried at 105°C for 24 h, and then
animals were allowed to adapt to the experimental
stored in hermetic containers under refrigeration to
system for a week, and fed with a conventional diet,
Table 1. Formulation of experimental diets.
CON 40: Positive control, CON 27: Negative control, ED: Diet supplemented with E. faecium, B2: Diet supplemented with E. durans, B3: Diet supplemented with Leuconostoc sp., A1: Diet supplemented with Streptococcus sp. I, A2: Diet supplemented with Streptococcus sp. II; ALL 27: Diet supplemented with commercial probiotic. 1Jauncey & Ross, (1982). 2Tacon, (1984).
493 Latin American Journal of Aquatic Research
Table 2. Proximate composition of experimental diets (% dry matter).
Gross energy (MJ kg-1) 19.95 19.75 20.09
For water quality control, temperature and
dissolved oxygen were measured daily, and weekly analyses were done of total ammonium, nitrite, nitrate
The growth performance including IMW, FMW,
and pH levels, using standard methods (APHA,
SGR, FCR, PER, ANU, AOMD, APD and survival
1989). The following values (±SD), appropriate for
rate of Nile tilapia are shown in Table 3. No
tilapia cultivation, were used: temperature, 28.83 ±
significant differences were observed in IMW among
0.45°C; dissolved oxygen, 5.71 ± 1.16 mg L-1; pH
treatments. Fish fed with CON 27 diet showed significantly lower survival (66.7%) than those fed
7.98 ± 0.45; ammonia, 0.09 ± 0.04 mg L-1; nitrite,
with bacteria-supplemented and positive control diets
0.08 ± 0.02 mg L-1 and nitrate, 5.93 ± 0.61 mg L-1.
(P < 0.05). The highest survival was recorded for
Every third day, each aquaria was partially cleaned
CON 40 and diet supplemented with E. durans
and the water partially changed (1:l). Once a week,
(100%). The treatment CON 27 presents the lower
the same day bulk weight measurement was done, the
FMW (5.95 g). Fish fed with diets supplemented with
aquaria were completely cleaned and a total change
native bacteria exhibited higher FMW compared to
The ALL 27 treatment resulted with the signifi-
cantly higher FCR (2.02) among the bacteria-
Proximate chemical analyses of diet ingredients were
supplemented diets, thought all the other bacteria-
made and a sample of fish, at the beginning and end
containing diets showed FCR significantly lower than
of the experiment, according to standard methods
those for the controls diets (P < 0.05). The best FCR
(AOAC, 1995). Gross energy in the feed was
determined by combustion in a Parr adiabatic
The PER was significantly higher in treatment A1
calorimeter. To evaluate digestibility, the chromic
(2.53) than in the others treatments. The lower PER
oxide content of each diet and the collected feces
was recorded for the CON 40 treatment (1.36). Fish
were analyzed using the acid digestion method
from A1 treatment presented ANU significantly
(Furukawa & Tsukahara, 1966). Protein content was
greater (48.4%), in comparison with the other
also determined for the feces, to assess protein
treatments. The lowest biological value was observed
In general, AOMD and APD were variable among
treatments. The maximum value were obtained in the
Growth performance and feed utilization efficiency
A2 treatment (AOMD = 95.08%; APD = 94.28%),
parameters were statically compared using one-way
which was statically different from the rest of the
ANOVA (P < 0.05), and differences among means
were identified using Duncan Multiple Range Test.
Whole body composition data are presented in
Analyses were carried out with the StatGraphics Plus
Table 4. The moisture content showed no significant
Version Centurion XV computer software. Arcsin
difference among fish fed with the experimental
transformation of raw data were made when
diets, and it ranged from 72.9 to 76.4%. The
uppermost two values (18.7 and 18.4%) of crude
The use of lactic acid bacteria as growth promoters in fish fed 494
Table 3. Growth and feeding performance of fish feed with diets supplemented with bacteria.
1Values with the same superscript in the same row are not statistically different (P > 0.05), 2Standar error, calculated from mean-square error of the ANOVA, 3Specific Growth Rate, 4Food Conversion Ratio, 5Protein Efficiency Ratio, 6Apparent Nitrogen Utilization, 7Apparent Organic Mater Digestibility, 8Apparent Protein Digestibility.
Table 4. Body composition of fish fed diets supplemented with bacteria.
1Values with the same superscript in the same row are not statically different (P > 0.05).
protein were achieved for fish fed diets A1 and
promotion (Gatesoupe, 2002; Lara-Flores et al.,
ALL27, with no significant difference. Fish from B2
treatment showed lower lipid content (4.7%) in
In this study, groups administered diets with lactic
comparison with the other treatments. Statistical
acid bacteria showed similar and superior survival
differences were observed also in the body ash
results when compared with positive and negative
content among fish fed with the different diets, with
control groups. Similar results were observed by
significantly lower content in fish from ALL 27
Suyanandana et al. (2002) when administered Lacto-bacillus sp. isolated from the intestine of Nile tilapia.
Probiotics are biopreparations containing living
microbial cells that optimize the colonization and composition of the growth and gut micro flora in
Many studies on probiotics in aquaculture have used
animals, and stimulate digestive processes and
in vitro models of specific bacteria as antagonists of
immunity (Bomba et al., 2002). The results of the
pathogens (Vine et al., 2004, 2006), measured the
present study confirm the results from other studies
survival of probiotic in fish gut (Andlid et al., 1998),
that the incorporation of probiotic in the diets can
or evaluated the beneficial effect of probiotic on
improve growth performance in terms of SGR, FCR
health management, disease resistance and immune
and PER. Gatesoupe (1991) reported increased
response of fish (Li & Gatlin III, 2004; Shelby et al.,
weight gain in Scophital mus larvae fed a diet
2006). Other important effect of the use of probiotic,
incorporating lactic acid bacteria and Bacillus toyoi.
that it is not extensively study, but demonstrated an
In the present study, fish fed lactic acid bacteria grew
important effect, is the feed efficiency and the growth
faster than those fed a control. It has been reported
495 Latin American Journal of Aquatic Research
that the improvement of growth by using probiotics is
The present investigation showed that the addition
related to an enhancement of nutrition (El-Haroun et
of native bacteria in Nile tilapia fry diets improved
al., 2006), as some probiotic strains may serve as a
animal growth and mitigated the effect of stress
supplementary source of food and their activity in the
factors, such as the low protein level in diets. All
digestive tract may be a source of essential nutrients
native bacterial strains used in the present study were
(Balcazar et al., 2006). According with Ghosh et al.
effective in stimulating fish performance. Strepto-
(2007), most of this enhancement is reflected in the
coccus sp. I produced the best results, and it could be
whole body proximal composition of fish. In the
a good candidate for optimizing growth and feed
present experiment, and regardless of the treatments
utilization in intensive tilapia culture.
with lactic acid bacteria, the whole body composition of O. niloticus showed a trend of higher values of
protein, which might indicates a better utilization of diet nutrient provided by the probiotic cells.
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rainbow trout Onchorhynchus mykiss, fry. Aqua-
Received: 13 November 2012; Accepted: 9 June 2013
Gemeng Leideleng • Commune de Leudelange Aus de Betrieber/Syndikater Attraktives „Petro-Center“ eröffnet Verwaltungssitz Mittelstandsministerin Françoise Hetto-Gaasch, Bürgermeister Rob Roemen mit „Petro-Center“ Chef Paul Kaiser und Gemahlin. Madame la ministre des Classes moyennes Françoise Hetto-Gaasch et le bourgmestre Rob Roemen avec le chef de «Petro-Center» Paul Kai
Is Mandatory Testing of Newborns for HIV in the United States a Good Idea? Rodney Richards, PhD is a bio/organic chemist who worked for many years for Amgen, the world’s largest biotechnology company. Richards worked specifically in the area of HIV test development. In the following letter Richards questions the wisdom of Illinois legislation HB4306 that would mandate an HIV test for infan