38 Aquaculture Microbiology and Biotechnology
and also provided both cellular and humoral immune defense responses
(Rengpipat et al., 1998; Rengpipat et al., 2000).
Streptococcaceae
Streptococcus phocae (PI80) was isolated from the intestine of shrimp
(Penaeus indicus) and conferred protection to Penaeus monodon postlarvae
(PL-55, 55 d after they molted from the last mysis stage) when challenged
with a V. harveyi strain (Swain et al., 2009). The survival attained with this
strain was 92% against 60% in the control (V. harveyi, only). However, this
strain did not protect the postlarvae against a strain of V. parahaemolyticus.
The authors speculated that the mode of action is the production of
bacteriocins and other substances capable of making a pore in the cell
membrane of pathogens, which leads to the effl ux of K + ions, although no
evidence is presented.
PROBIOTIC IN LARVAL CULTURE: GRAM-NEGATIVE
BACTERIA
Vibrios (Vibrionaceae)
Turbot larvae often experience mass mortalities apparently caused by
different pathogenic vibrios and other Gram-negative bacteria (Hjelm et
al., 2004). To control these pathogens, several Gram-negative and positive
bacteria have been tested. A strain of Vibrio pelagius introduced in the
rearing water improved the survival of larvae compared to fi sh exposed
to Aeromonas caviae, a species associated with high larval mortalities, and
with the control group (Ringo and Vadstein, 1998). This result might point
out that V. pelagius served more as a feed additive than a true probiont. A
very desirable and maybe indispensable requirement for a probiotic strain
to function as such is its ability to colonize the gut of the host. A strain of
V. mediterranei (Q40) was observed as a fi rst colonizer of the gut of turbot
larvae and thus be able to prevent the colonization of potential pathogens
(Huys et al., 2001). Larvae treated this way also showed improved
survival, but since no infection challenges were done, it is diffi cult to say
that this strain is indeed a probiont. “Vibrio E” (phenotypically close to
V. alginolyticus) was challenged against the pathogenic strain “Vibrio P”
described previously (Gatesoupe, 1997). In this case, a higher survival
percentage was observed when a higher density of the probiont was
inoculated, but in any case, signifi cantly lower than uninfected larvae.
Vibrio E is a siderophore producing strain that can grow in iron-chelating
media and it was proposed that both strains competed for iron, and since
and also provided both cellular and humoral immune defense responses
(Rengpipat et al., 1998; Rengpipat et al., 2000).
Streptococcaceae
Streptococcus phocae (PI80) was isolated from the intestine of shrimp
(Penaeus indicus) and conferred protection to Penaeus monodon postlarvae
(PL-55, 55 d after they molted from the last mysis stage) when challenged
with a V. harveyi strain (Swain et al., 2009). The survival attained with this
strain was 92% against 60% in the control (V. harveyi, only). However, this
strain did not protect the postlarvae against a strain of V. parahaemolyticus.
The authors speculated that the mode of action is the production of
bacteriocins and other substances capable of making a pore in the cell
membrane of pathogens, which leads to the effl ux of K + ions, although no
evidence is presented.
PROBIOTIC IN LARVAL CULTURE: GRAM-NEGATIVE
BACTERIA
Vibrios (Vibrionaceae)
Turbot larvae often experience mass mortalities apparently caused by
different pathogenic vibrios and other Gram-negative bacteria (Hjelm et
al., 2004). To control these pathogens, several Gram-negative and positive
bacteria have been tested. A strain of Vibrio pelagius introduced in the
rearing water improved the survival of larvae compared to fi sh exposed
to Aeromonas caviae, a species associated with high larval mortalities, and
with the control group (Ringo and Vadstein, 1998). This result might point
out that V. pelagius served more as a feed additive than a true probiont. A
very desirable and maybe indispensable requirement for a probiotic strain
to function as such is its ability to colonize the gut of the host. A strain of
V. mediterranei (Q40) was observed as a fi rst colonizer of the gut of turbot
larvae and thus be able to prevent the colonization of potential pathogens
(Huys et al., 2001). Larvae treated this way also showed improved
survival, but since no infection challenges were done, it is diffi cult to say
that this strain is indeed a probiont. “Vibrio E” (phenotypically close to
V. alginolyticus) was challenged against the pathogenic strain “Vibrio P”
described previously (Gatesoupe, 1997). In this case, a higher survival
percentage was observed when a higher density of the probiont was
inoculated, but in any case, signifi cantly lower than uninfected larvae.
Vibrio E is a siderophore producing strain that can grow in iron-chelating
media and it was proposed that both strains competed for iron, and since