Biofloc technology is a sustainable aquaculture production system which uses microorganisms
to maintain water quality and to increase productivity. In this system, probiotics
can enhance the positive effects of bioflocs on the cultured species. The objective
of this research is to study the role of the probiotic bacterium Bacillus amyloliquefaciens
during the formation of a biofloc system for the culture of Litopenaeus vannamei.
Two doses of probiotic were assayed and applied directly to the water. The experiment
was developed in nine tanks distributed as follows: Three control tanks with no probiotic,
three tanks with a probiotic dose of 10(3) cfu/mL, and three tanks with a dose of
10(4) cfu/mL. Water quality, microbial activity, growth parameters and the immune
system state of shrimps were monitored throughout the maturation process. The results
indicate a positive effect upon the shrimp immune system throughout the study period,
where specifically there was an increase in granular hemocytes in the shrimp hemolymph.
During the immature biofloc phase, granular hemocytes were 5% higher in tanks supplemented
with the probiotic. During the mature biofloc phase, granular hemocytes were 7% higher
in those same tanks. During the maturation of the biofloc, environmental conditions
are more unfavorable for shrimp growth, due to the accumulation of nitrites. So, the
effect of the probiotic is especially important during this stage when the shrimp
are stressed and are more vulnerable to diseases. However, the effects on microbial
activity, water quality and Litopenaeus vannamei growth did not increase the benefits
of the biofloc system.