This study evaluated the performance, immunology, and survival of the Pacific white shrimp Litopenaeus vannamei to experimental challenge to Vibrio alginolyticus based on the use of the probiotic Lactobacillus plantarum and the combined use of probiotic and butyrate. Four different diets resulted from the addition of additives: butyrate, probiotic, butyrate + probiotic, and control (no additives). The attractiveness of the diets was assessed by the percentage of positive choices and rejections, using a dual-choice Y-maze format aquarium. The shrimps were fed during four weeks and performance parameters, intestinal microbiota, and immunological parameters were all evaluated. Subsequently, the shrimps were challenged with V. alginolyticus and after 48 h, survival and immunological parameters were evaluated. The results showed increased attractiveness and intake, but only with diets supplemented with sodium butyrate. However, other diets were not rejected. No difference in performance or immunological parameters was observed among the different diets. Also, among the treatments, no difference in Vibrio spp., or total heterotrophic bacteria counts, was found in the intestinal tract. However, the lactic acid bacteria count was higher in the intestinal tract of shrimps fed diets supplemented with probiotic. After bacterial challenge, shrimp fed all diets had a greater survival when compared with the control group. Lactobacillus plantarum and sodium butyrate increase the resistance of shrimp to infection with V. alginolyticus, but do so without affecting performance, immunological parameters, or Vibrio spp., and total heterotrophic bacteria counts in the intestinal tract.

The objective of this study was to evaluate the effect of different stocking densities and the presence/absence of two artificial substrates on water quality and production rates of marine shrimp in a biofloc shrimp nursery culture. Two experiments were performed: different stocking densities with mosquito netting substrate and the presence/absence of polyestertype substrate. The first experiment lasted 38 days, and shrimp at an initial weight of 0.013±0.010 g were stocked in 24 tanks. The second experiment lasted 35 days, and shrimp at an initial weight of 0.037±0.002 g were stocked in six tanks. Weekly biometric measurements were performed to adjust the amount of feed. Suspended solids were higher at a density of 6000 PL m −3 and mosquito netting substrate. Final weight and specific growth rate were higher in treatments with mosquito netting substrate. However, survival was significantly lower with this substrate. Yield was significantly higher at a density of 6000 PL m −3. Polyester-type substrate had no significant effect on production rates or variables of water quality. However, this substrate could reduce the production of sludge. The results indicate that it is possible to culture shrimp in nursery stage up to 6000 PL m −3 in a biofloc system.

This study aimed to evaluate the combined and isolated effect of sodium butyrate and the probiotic Lactobacillus plantarum on the performance and midgut microbiological parameters of Litopenaeus vannamei post-larvae reared on biofloc technology, as well as the water quality of the system. Feed additives were added at the concentrations of 200 mL of probiotic (1.0x107 CFU mL-1) and 2.0% of organic salt (w/w) in the diet, as follows: 1) Probiotic; 2) Butyrate; 3) Probiotic+Butyrate; 4) Control. Each treatment was composed of three replicates. Biometric measurements were performed once a week, as well as analysis of water quality. At the end of the experiment, statistical difference was observed in the counts of lactic acid bacteria from the intestinal tract of shrimp fed diets containing probiotic. Therefore, while the addition of probiotic and sodium butyrate had no effect on the productive parameters of shrimp or water quality, the inclusion of the probiotic L. plantarum in the diet did increase the counts of lactic acid bacteria in the intestine of L. vannamei without altering the counts of Vibrio spp. or total heterotrophic bacteria in the intestine.

The objective of this work was to evaluate the effect of Lactobacillus plantarum on the preservation of fresh mussels and its effect on the attractiveness, consumption, and midgut bacterial microbiota of Pacific white shrimp broodstock. The experiment evaluated mussels stored with L. plantarum at 4ºC. The controls were: mussels stored at -18ºC without L. plantarum; mussels stored at -18ºC with L. plantarum; and mussels stored at 4ºC without L. plantarum. Microbiological analyses on mussels were performed on days 1, 7, 15, 30, 45, and 60 after processing. Additionally, mussels preserved with L. plantarum and stored at 4ºC, and mussels stored at -18ºC without L. plantarum were evaluated after 15 days for attractiveness, consumption, and midgut bacterial microbiota of shrimps. Mussels preserved with L. plantarum showed higher lactic acid bacteria counts and lower counts of Vibrio spp., as well as of total heterotrophic bacteria, after 60 days of storage. No differences were observed for attractiveness or consumption between treatments. The bacterial microbiota of midgut in shrimp fed mussels preserved with L. plantarum showed higher lactic acid bacteria count and lower Vibrio spp. The use of L. plantarum inhibits Vibrio spp. and preserves feed without changing attractiveness or consumption for shrimp.

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This study aimed to evaluate the in vitro effect of carvacrol on different microorganisms of importance in shrimp farming, as well as its in vivo effect on zootechnical, immunological and microbiological performance, as well as resistance, of Litopenaeus vannamei challenged with Vibrio parahaemolyticus. In particular, the antimicrobial activity of carvacrol was evaluated in vitro by analysis of the minimum inhibitory concentration (MIC) and by agar diffusion disc with Gram-negative and Gram-positive bacteria. The in vivo experiment was conducted using different concentrations of carvacrol (1, 3, 4 and 6 mg mL-1) added to shrimp feed, together with a control diet without carvacrol. After four weeks, zootechnical, immunological and microbiological parameters, as well as resistance, of animals challenged with V. parahaemolyticus were evaluated. The MIC of Vibrio alginolyticus and Vibrio harveyi was 0.078 mg mL-1, while for the other bacteria, it was 0.156 mg mL-1 of carvacrol. The greatest halos of inhibition were observed in V. parahaemolyticus and Vibrio harveyi with significant differences demonstrated for the other microorganisms, except Escherichia coli. The in vivo results showed no significant differences among treatments. In conclusion, the antimicrobial activity of carvacrol was confirmed with Gram-negative and Gram-positive bacteria, and it is suggested that its antimicrobial potential is more effective against Vibrio spp. However, the concentrations of carvacrol used in vivo did not affect the parameters evaluated.

RESUMO O presente trabalho teve como objetivo investigar a atividade antimicrobiana dos extratos metanólicos das algas Haematococcus pluvialis, Kappaphycus alvarezii, Sargassum filipendula e Undaria pinnatifida em cepas padrão e em bactérias patogênicas de organismos aquáticos. O método de microdiluição em caldo foi utilizado para determinação da concentração inibitória mínima (CIM) dos extratos. Além disso, foi determinado o perfil de suscetibilidade das bactérias frente a 12 antimicrobianos pelo método de disco-difusão em ágar. Os testes de atividade antimicrobiana mostraram que apenas os extratos de S. filipendula e U. pinnatifida inibiram todas as bactérias testadas, sendo U. pinnatifida o extrato com maior eficiência contra os patógenos. Também os testes mostraram predileção da atividade antimicrobiana da microalga de água doce H. pluvialis por microorganismos de ambientes marinhos, enquanto as algas marinhas, K. alvarezii, S. filipendula e U. pinnatifida, mostraram-se mais eficazes na inibição do crescimento de cepas patogênicas de água doce. A multirresistência foi verificada em todas as cepas patogênicas isoladas testadas (Pseudomonas sp., S. agalactiae, V. alginolyticus and V. anguillarum). Os resultados sugerem que os extratos das algas exerceram atividade antimicrobiana frente as cepas de bactérias patogênicas da aquicultura, sendo o extrato da U. pinnatifida o que inibiu o crescimento dos micro-organismos com as menores concentrações.

The present study evaluated the use of the indigenous probiotic Lactobacillus plantarum and commercial probiotic containing Bacillus spp. in the culture of L. vannamei in a biofloc system. Shrimp were fed with four diets: L. plantarum, Bacillus spp., L. plantarum + Bacillus spp. and feed with no additives. Growth performance, water quality variables and microbiological counting of water and digestive tract of shrimp were determined. The control group and L. plantarum treatment showed better growth performance. The highest feed conversion ratio (FCR) and the lowest survival were obtained in the L. plantarum + Bacillus spp. treatment, which had significantly higher nitrite values. Vibrio spp. counts in the water were lower in the L. plantarum and L. plantarum + Bacillus spp. treatments and were lower in the intestinal tract in the L. plantarum treatment. Lactic acid bacteria (LAB) was higher in the L. plantarum treatment in the water and digestive tract. The count of total heterotrophic bacteria (THB) deferred only among Bacillus spp. and L. plantarum + Bacillus spp. treatment, being higher in the latter group. In Bacillus spp. treatment, no presence of LAB was detected in the water or intestinal tract. We conclude that the use of L. plantarum combined with Bacillus spp. negatively affected survival, FCR and water quality, but that the use of L. plantarum alone reduced the presence of Vibrio spp., even though it did not change the growth performance of L. vannamei.