Live Feeds: Microbial Assemblages, Probiotics and Prebiotics - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 430

were observed despite the biochemical analysis revealing that the probiotic preparation was
a nutritionally poor food, lacking essential fatty acids. The authors suggested the activation
of digestive enzymes or a supply of specific nutrients (e.g. vitamins, proteins, amino acids or
other metabolites) as possible mechanisms.
16.6 BIOENCAPSULATION OF PROBIOTICS IN LIVE FOOD
AND DELIVERY TO LARVAE
As discussed, probiotics have been used in live feed to enhance growth and to control oppor-
tunistic bacteria in live feed, but they are also applied to live feeds as a way to efficiently deliver
probiotic bacteria to larvae. The addition of probiotics to the water of the rearing system may
not be an effective way to incorporate probiotics (Suzer et al. 2008). Bioencapsulation has
been demonstrated to be a more effective way to introduce the probiotic bacteria to the larval
gut, and in the case of some allochthonous bacteria (e.g. LAB of tellurian origin, with a low
survival in seawater) it can be the only efficient route (Gatesoupe 1994). Studies of probiotic
bacteria bioencapsulated in live feed are summarized in Table 16.1.
16.6.1 Bioencapsulation of probiotics in microalgae
The feasibility of co-culturing microalgae and beneficial bacteria has been demonstrated by
several authors (Suminto and Hirayama 1997; Fukami et al. 1997; Rico-Mora et al. 1998),
but assays on the use of microalgae as a vector to deliver probiotics to larvae are still scarce.
Avendaño and Riquelme (1999) studied the incorporation of bacteria, isolated from scallop
Argopecten purpuratus cultures and with inhibitory activity against the pathogen V. anguil-
larum , into axenic cultures of Isochrysis galbana . The microalgae cultures were subsequently
used as a vector of the probiotic into cultures of scallop larvae. The results demonstrated a
stimulation of microalgae growth and a significant ingestion by scallop larvae of the strain
delivered in conjunction with the microalgae. Moreover, the addition of the bacteria bioencap-
sulated in the microalgae promoted a higher maintenance of the probiotic in the larvae (10 2
CFU larva -1 ) than when the bacteria were added to the water of the rearing tanks (10 1 CFU
larva -1 ). Although the effect of the probiotic on growth, survival or bacterial microbiota of
scallop was not reported, the effectiveness of the bioencapsulation in the microalgae as a way
to introduce the probiotic to larvae was demonstrated.
16.6.2 Bioencapsulation of probiotics in rotifers and Artemia
The first studies, conducted by Gatesoupe (1990), reported that LAB resembling Lactobacillus
or Carnobacterium and isolated from rotifers can be effectively bioencapsulated in rotifers.
Feeding turbot ( Scophthalmus maximus L.) larvae with those rotifers subsequently improved
growth rate and significantly reduced mortality rate in first-feeding larvae challenged with
pathogenic Vibrio sp. (Gatesoupe 1994).
Strains previously isolated from healthy fish or larvae have also been bioencapsulated in
rotifers. Olsson et al. (1992) screened bacteria from the turbot intestine (gut content and
mucus) or skin mucus, and selected isolates based on inhibition of the growth of V. anguil-
larum and of adhesion to turbot intestinal mucus. The incorporation into rotifers of a bac-
terial strain (strain 4:44) isolated in the study, along with others isolated from turbot larvae,