Prebiotic administration is one method to increase growth performance, improve intestinal microbiota composition, inhibit pathogen growth and induce immunity in fishes. Honey consists of oligosaccharides as the major content that can be used as a prebiotic. This study investigated the effects of administration of dietary prebiotic from honey at different doses on growth performance, digestive enzyme activities, intestinal microvilli, short‐chain fatty acid contents and microbiota diversity in the digestive tract of Nile tilapia (Oreochromis niloticus). Four diet treatments were applied, namely control (without honey administration) and honey administration at 0.25%, 0.5% and 1% doses (g/kg diet). Nile tilapia weighing 20 ± 1.72 g were reared with these diet treatments for 30 days. Results demonstrated that honey prebiotic administration could increase growth performance; provide a lower feed conversion ratio; induce digestive enzyme activities (amylase, protease and lipase); increase microvilli length, perimeter ratio, density of intestinal microvilli and short‐chain fatty acid contents (propionate, iso butyrate, iso‐valerate and N‐valerate); and improve microbiota diversity in the digestive tract of Nile tilapia at the best dietary dose of 1%.
Streptococcosis is one of bacterial diseases in the culture of Tilapia, Oreochromis niloticus and has caused significant economic losses. Streptococcus iniae, is known as pathogen to marine and freshwater fishes whereas Streptococcus agalactiae is known as pathogen to Tilapia. The isolation and characterization of four isolates of S. agalactiae, were described from an infected Tilapia from Cirata Reservoir, West Java, in July 2008. Conventional and rapid identification systems were used to determine isolates of S. agalactiae from brain and kidney tissues. In this paper, we have characterized S. agalactiae and this was the first isolation of this bacteria from fish. The isolates were gram positive, catalase-negative, oxidase-negative, haemolytic cocci colonies on blood agar. All of the of isolates were biochemically characterized with the API 20 Strep System (bioMerieux). Bacterial chromosomal DNA used in PCR assay was extr acted by heating method. The forward primer is Sdi 61: 5'-AGGAAACCTGCCATTTGCG-3' and the r ever se pri mer is Sdi 252: 5'-CAATCTATTTCTAGATCGTGG-3' with gene target 16S intergenic spacer and it has 192 bp in length. These primers were designed by Alpha DNA (Montreal, Quebec). The biochemical patterns of four isolates were rather different although almost all traits were similar with the exception of pyroglutamic acid (pyra) and L-arginin (ADH), for which we observed negative and positive reaction in this study. Therefore, some of the biochemical characteristics of the four isolates did not fit 100% with the typical patterns of S. agalactiae. However, the PCR result showed that this PCR assay is an effective tool for rapid and specific detection of S. agalactiae, the main pathogens involved in warm-water streptococcosis, obtained from pure culture of naturally infected fish. Therefore, it could be a useful alternative for culture-based routine diagnosis of warm-water streptococcal infections in fish.
The multiple-pathogen infection causes severe economic impact to shrimp industry in Indonesia and worldwide due to mass mortality and multiple abnormalities of the survived infected shrimps. However, multiple-pathogen detection tools in shrimp diseases have not yet widely used. The purpose in this study was to develop and applied simultaneous detection system using multiplex polymerase chain reaction (PCR) assay from natural infections caused by white spot syndrome virus (WSSV), infectious hypodermal and haematopoietic necrosis virus (IHHNV) and monodon baculovirus (MBV) in Black tiger shrimp culture. To analyze multiple-pathogen infections in the shrimp, the study designed and used three pairs of specific primers targeting DNA virus from the shrimp diseases. All amplifications used a specific master mix for multiplex PCR assay and standardized extracted nucleic acid from the samples. This mPCR assay successfully amplified the DNA of three viruses in a single tube-run by multiplex PCR for each virus. Based on the results, the study confirms that multiple-pathogen infection contributes the highest mass mortality rather than from single infection by either WSSV, IHHNV or MBV. This study also confirms that the mPCR assay is a faster, cheaper, and efficient method to detect and subsequently prevent the spreading of multi-pathogen shrimp diseases.
The research aims are to observe the effect of vaccination in microbial profiles and gut microbiome composition. The treatments were as follows: the fishes were injected with PBS and challenged (A); the fishes were injected with freeze–dried vaccine dissolved in 100 ml 0.85% NaCl and challenged (B); the fishes were injected with freeze–dried vaccine dissolved in 50 ml 0.85% NaCl and challenged (C), and the fishes were injected with liquid vaccine and challenged (D). Microbiome composition measurements were carried out on the 21st–day post–vaccination and the 7th day after the challenge test. Fish intestine samples from three replications were tested by Next Generation Sequencing (NGS). Two significant phyla were identified from all treatments, namely Proteobacteria and Firmicutes. Cetobacterium, Candidatus Bacilloplasma, and Clostridium sensu stricto were the genera classified as good bacteria in vaccinated fish. It can be concluded that vaccination can increase the diversity of the gut microbiome, especially bacteria beneficial to the fish host. Chitosan as a coating antigen in freeze–dried vaccine increases gut microbiome's number and diversity better than a liquid vaccine.
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