Use of Probiotic Bacteria in the Nursery and Grow-Out Phases of Pacific White Shrimp Penaeus vannamei in Biofloc and Clear Water Systems
Author: Aline da Costa Bezerra (Currículo Lattes)
Advisor: Dr. Wilson Francisco Britto Wasielesky Junior
Abstract
With the intensification of aquaculture production, productivity success is closely related to farming conditions, management practices, and the production environment. In this context, probiotic bacteria emerge as a sustainable alternative, defined as live microorganisms that provide benefits to the host through the modulation of intestinal and environmental microbiota, resulting in improved zootechnical performance, immune response, and water quality. This thesis aimed to evaluate different commercial probiotic bacteria at various production stages—nursery and grow-out—under different culture conditions (clear water and biofloc systems) and production intensities (super-intensive and intensive). Strains of Bacillus subtilis, Lactobacillus plantarum, and Pediococcus acidilactici were used, both individually and in a commercial mix. The study was structured into three chapters. The first chapter aimed to assess the effects of different isolated probiotic bacteria and application strategies on water quality and zootechnical performance of Penaeus vannamei during the grow-out phase in a super-intensive system, as well as their antagonistic effects against pathogenic bacteria and their influence on shrimp immune response. The experiment lasted 49 days. No significant differences were observed in water quality; however, zootechnical performance data (final weight and productivity) showed significant differences, particularly in treatments with B. subtilis added to both feed and water, which presented the highest values (8.75 g and 0.81 kg/m²). L. plantarum and P. acidilactici showed satisfactory results, although lower than Bacillus spp. All probiotics tested were able to grow at a salinity of 30 and temperature of 30 °C. The use of mixed bacterial strains proved effective against several common aquaculture pathogens. The second chapter aimed to evaluate the efficacy of the probiotic mix in marine shrimp nurseries cultured in biofloc systems, considering different application routes and their relationships with microbial community structure, water quality, and zootechnical performance. Fluorescent in situ hybridization (FISH) was used to analyze bacterial abundance in both culture water and shrimp intestines. Treatments were divided into two systems: clear water (CW) and biofloc (BFT), with probiotics applied only in feed (PR), only in water (PA), or in both (PRA). The nursery phase lasted 35 days. Microbial diversity and abundance were higher in biofloc treatments with dual probiotic application routes. Intestinal colonization by probiotic bacteria was evidenced by hybridized, quantified, and classified microorganisms, showing a direct relationship with culture water. Zootechnical performance was significantly higher (p < 0.05) in the treatment with probiotics added to both feed and water in the biofloc system (BFT-PRA), where all performance indices surpassed other treatments. Survival rates were above 89%, except for the control (79%). Treatments with at least one probiotic application route showed satisfactory results compared to the control, including the clear-water system, which performed similarly to the biofloc system without probiotics (BFT-CTL). The third chapter aimed to evaluate the efficiency of the commercial probiotic mix in super-intensive and semi-intensive grow-out systems of P. vannamei, assessing its interactions with water quality, zootechnical performance, microbial community structure, and bacterial abundance. Experiments were conducted in two grow-out phases—semi-intensive (20 shrimp/m²) and super-intensive (300 shrimp/m²)—each lasting 63 days. Treatments were divided into Grow-out 1 and Grow-out 2, with different probiotic application routes in clear-water systems. Significant differences were observed in all zootechnical parameters when comparing probiotic treatments with the control group. Probiotic supplementation promoted greater microbial diversity and intestinal colonization by beneficial bacteria. In the super-intensive phase, differences were also observed in water quality parameters. Zootechnical performance was superior when probiotics were applied both in feed and water within the biofloc system. Greater microbial diversity and bacterial abundance were also recorded in biofloc systems compared to clear water. However, the treatment with dual probiotic application in clear water showed performance similar to the control in the BFT system. In conclusion, the use of probiotics contributes to improved zootechnical performance, enhanced microbial diversity, and increased colonization by beneficial bacteria in both culture water and shrimp intestines, demonstrating the feasibility of probiotic application under different cultivation conditions and production challenges.