Our preliminary results showed that the water of shrimp tanks fed
bioflocs inoculated with Bacillus had an on average 5 times lower Vibrio
load when compared to the shrimp tanks fed an artificial feed
(Crab, 2010). These results indicate that inoculating biofloc reactors
with probiotic bacteria might have biocontrol effect toward Vibrio
spp., but the inoculation of biofloc systems with specific desired microorganisms
needs further investigation in order to confirm these
beneficial effects. Other interesting fields of research regarding this
subject are possible immunostimulatory features of the bioflocs. Enhancement
of the innate immunity of cultured organisms may provide
broad-spectrum resistance to infections. Existing immunostimulants
include bacteria and bacterial products, complex carbohydrates, nutritional
factors, animal extracts, cytokines, lectins, plant extracts and
synthetic drugs such as levamisole (Wang et al., 2008). Bioflocs
might also contain immunostimulatory compounds since biofloc technology
deals with bacteria and bacterial products.