Studies on biology, pathogenicity and prophylaxis of vibriosis in juvenile tiger shrimp Penaeus monodon (Fabricius)

Studies were carried out to examine the biology, pathogenicity and treatment of Vibrio spp. in cultured shrimp (Penaeus monodon Fabricus). The phenotypic characteristics and the sensitivity to Oxytetracycline (OTC) of bacteria Isolated from diseased shrimp in two areas of Thailand were compared. The areas were Samutsakhon province where shrimp have been cultured for many years and Chanthaburi province, an area in which shrimp culture started after 1988. Thirty-one Vibrio spp. isolates wore obtained from Samutsakhon and hwenty-two Vibrio spp. and one Aeromonas spp. were obtained from Chanthaburi. The most numerous species from both areas was Vibrio parahaemolyticus. Minimal Inhibitory Concentration and Minimal Bacteriocidal Concentration studies were conducted to determine the sensitivity of the isolates to OTC. The isolates from Samutsakhon were found to be more resistant to OTC than those from Chanthaburi. Batches of shrimp were fed with pellets containing different quantities of OTC and their muscle was subsequently analysed to determine its OTC content. In shrimp fed with pellets containing 3 or 5 gOTC/kg of feed, for up to 5 days, the maximum drug in the muscle was approximately 1 ppm. As the OTC was administered for longer periods the concentration and persistence in the muscle increased. A study was conducted to examine the interaction between prophylactic administration of in fed OTC and an Injection challenge with a pathogenic OTC sensitive Vibrio parahaemolyticus. Histological examination revealed that the prophylactically treated shrimp produced a less marked cellular response and healed more rapidly when injected with bacteria. The implication of all these results for the treatment of vibriosis in cultured shrimp is discusse

Effect of Light on the Antibacterial Property of Silver Diamine Fluoride

Objective: The study aimed to evaluate the antibacterial effect of shortened time and lightcuring on the biofilm of silver diamine fluoride (SDF) applied lesions.Materials and methods: Twenty dentin specimens (3 x 3 x 2 mm3) were prepared fromtwenty primary molar teeth with caries extended to the middle third of dentin. The specimens wererandomly allocated into 4 groups (n = 5/group); 1) distilled water (DW, negative control), 2) SDF10 seconds, 3) SDF 10 seconds with light curing (LC) for 20 seconds and 4) SDF 1 minute (AAPDrecommendation) and then were treated following the assigned group. Treated specimens wereindividually placed in 24-well plates with Streptococcus mutans (S. mutans) culture (approximately6 x 108 colony-forming-unit (CFU)/mL) and incubated at 37°C, 5% CO2 for 24 hours to form biofilm.The biofilm was removed from the specimens by a pipette tip and underwent serial 10-fold dilutions.The diluted solutions were then plated on agar. After incubation, the colonies were counted andpresented as CFU/mL.Results: There was no difference in the number of bacteria that remained on the specimenstreated with SDF for 10 seconds, SDF for 10 seconds with LC, and SDF for 1 minute (0, 284 ± 284,and 0 CFU/mL, respectively; mean ± standard error). However, all three groups had significantlyfewer bacterial counts than the DW treatment (8.39 x 106 ± 4.94 x 106 CFU/mL), (p < 0.05).Conclusion: The antibacterial activity of shortening the duration of SDF application with orwithout light curing was not different from the conventional 1-minute application.Keywords: Antibacterial agents, Biofilms, Dental curing lights, Silver diamine fluoride, Streptococcusmutans SWU Dent J. 2021;15(1):86-92

Parâmetros de cultivo e a enfermidade da mancha-branca em fazendas de camarões de Santa Catarina

O objetivo deste trabalho foi avaliar a relação entre parâmetros físico-químicos e biológicos do cultivo de camarão com a enfermidade causada pelo vírus da síndrome da mancha-branca (WSSV). Foram avaliadas a mortalidade, as características físicas e químicas da água e do solo, e foram realizados os exames e as análises microscópicas a fresco, presença de víbrios na hemolinfa, além do diagnóstico histopatológico e molecular (PCR) do WSSV, em viveiros de oito fazendas de Santa Catarina, entre 2008 e 2009. O vírus foi detectado em cinco fazendas com registros da enfermidade em ciclos anteriores. A temperatura da água foi semelhante entre as fazendas com e sem WSSV, e a mortalidade ocorreu a intervalos ascendentes entre 24,6 e 29,3ºC. Não foram encontradas diferenças significativas nos parâmetros de análises microscópicas a fresco, tempo de coagulação e presença de víbrios na hemolinfa e sinais clínicos, entre viveiros com e sem WSSV. As concentrações de nitrito, sílica, fenol e alcalinidade na água e pH do solo apresentaram diferenças significativas entre os viveiros afetados ou não por WSSV. Os valores de nitrito, sílica e pH do solo estavam dentro dos limites recomendados para o cultivo de camarões, no entanto, isto não ocorreu com a alcalinidade e a concentração de fenol, o que sugere uma relação dos últimos com a manifestação da enfermidade da mancha-branca

The importance of behaviour in improving the production of shrimp in aquaculture

There is an increasing recognition within the aquaculture industry that understanding the behaviour of farmed animals can help provide solutions to feeding problems. However, most studies have focused on finfish production, with fewer behavioural studies on feeding processes in commercially produced crustaceans. More than 60% of crustacean aquaculture is attributed to the production of penaeids, particularly the Pacific white‐leg shrimp (Litopenaeus vannamei Boone). The profitability of the Pacific white‐leg shrimp for aquaculture stems from its ability to survive in a wide range of environments and its fast growth at high densities. However, there are significant setbacks within their farming. In particular, while they can move rapidly to take food pellets, they can be slow to consume them leading to food wastage and subsequent economic losses for the industry. Understanding shrimp behaviour provides a starting point for refinements to feeding practices. Here, we review the different influences on shrimp behaviour which are likely to influence productivity such as individual‐level effects (e.g. moulting, sex), environmental influences (e.g. photoperiod, conspecific presence) and water quality (e.g. salinity, temperature). Although work on feed management has been conducted, providing information on nutrition, feeding frequency and schedules, here we demonstrate that such advances must be accompanied by behavioural approaches to allow the development of optimal feeding efficiencies and to support the continued growth of the crustacean aquaculture industry

Studies on biology, pathogenicity and prophylaxis of vibriosis in juvenile tiger shrimp Penaeous monodon (Fabricius)

SIGLEAvailable from British Library Document Supply Centre- DSC:D174257 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Growth promotion and enhancement of vibriosis resistance in penaeid shrimp after oral administration of lactic acid bacteria and marine bacteria

Vibriosis is one of the most serious problems in the shrimp culture industry worldwide. Antibiotic treatment is becoming less and less effective, as new strains of pathogens evolve, which are resistant to commonly used antibiotics. Use of probiotics is an alternative method for controlling bacteria in shrimp culture. In this experiment, lactic acid bacteria (Peddiococcus sp, Lactobacillus sp, and L. acidophilus) and marine bacteria (Alteromonas sp. and Vibrio alginolyticus) were mixed with pellet feed and used to feed juvenile shrimp. The growth and survival rate of the shrimp were monitored during the experiment. After feeding the shrimp for 60 days, all the surviving shrimp were bath-challenged with Vibrio harveyi (105-106 CFU/ml) for 7 days. Mortality of the shrimp was recorded. The result shows that the total biomass and survival rate of the shrimp fed with probiotics were significantly higher than the control group (p<0.05). However, there were no significant differences in the mean growth rate of shrimp between treatments. The results of the challenge test shows that the groups fed with lactic acid bacteria had the highest survival rates (Peddiococcus sp., 86.4%; Lactobacillus sp., 90.5% and L. acidophilus, 93.8%), followed by the treatments fed with marine bacteria (Alteromonas sp, 74.6% and Vibrio alginolyticus, 61.8%) and the control treatment had the lowest survival rate (59%)