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Antibiotic resistance in shrimp farms has emerged as an extremely serious situation worldwide. The main aim of this study was to optimize the cultural conditions for producing new antibiotic agents from marine Streptomyces species. Streptomyces SK3 was isolated from marine sediment and was identified by its 16S rDNA as well as biochemical characteristics. This microbe produced the highest concentration of bioactive secondary metabolites (BSMs) when cultured in YM medium (YM/2). It produced the maximum total protein (41.8 ± 6.36 mg/ml) during the late lag phase period. The optimum incubation temperature was recorded at 30 °C; BSMs were not produced at ≤10 °C within an incubation period of 3–4 days. The suitable agitation speed was found to be 200 rpm with pH 7.00. The proper carbon, nitrogen, and trace elements supplementation consisted of starch, malt extract, calcium carbonate (CaCO3), and magnesium sulfate (MgSO4). The ethyl acetate extract was found to act strongly against three vibriosis pathogens, Vibrio harveyi, Vibrio parahaemolyticus, and Vibrio vunificus, as indicated by the inhibition zones at 34.5, 35.4, and 34.3 mm, respectively. The extract showed the strongest anti-V. harveyi activity, as indicated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 0.101 ± 0.02 and 0.610 ± 0.04 mg/ml, respectively. Basic chemical investigation of the crude extract using thin layer chromatography (TLC), bioautography, liquid chromatography tandem mass spectrometry (LC‒MS/MS), Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (1H-NMR) revealed that the active components were the terpenoid and steroid groups of compounds. They showed carboxylic acid and ester functions in their molecules.

The experiment was in completely randomized design. Seven iso-nitrogenous and iso-lipidic diets were formulated having soybean and palm oil, an equal combination, to replace fish oil (FO) in diets at 0%, 25%, 37.5%, 50%, 62.5%, 75%, and 100%, respectively. Each diet was fed twice daily to Asian seabass juvenile (3.00±0.26g) in quintuplicate for eight weeks and performances were investigated. Finally, the fish were challenged with 30 ppt salinity to observe osmoregulatory responses. Zero mortality was observed in all feeding groups. Fish growth responses, diet consumption and feed conversion ratio were significantly affected (p

In recent years, countries around Japan and especially in Southeast Asia, white spot disease (WSD) is highly infectious and severely damages shrimp aquaculture. At the same time, the various diseases are occurring in shrimp farms. In the early stages of infection, shrimp shows three abnormal behaviors: (1) they appear in the shallow waters of the farm, (2) they do not move and do not eat even when feeding, and (3) they suddenly stop moving. Currently, infected shrimps are found by visual inspection, which places a burden on the farmers and delays the discovery. Therefore, in this paper, we proposed a system for detecting infected shrimp by using image processing technology in order to eliminate the delay of discovery and reduce the burden of farmers. According to our experimental results, the proposed system has 95% precision, 100% recall rate and an accuracy of 96.4% by using hold-out evaluation method.

An experiment was conducted using factorial (3×4) in completely randomized design to examine incorporation of vegetable oils in diets on seabass growth, fatty acid profile, digestive enzyme activity and immune responses. Ten isonitrogenous and iso-lipidic diets were formulated to have soybean, palm and sunflower oil replacing fish oil (FO) at 0%, 25%, 50% and 75%, respectively. Each diet was fed to quadruplicate fish groups (3.29±0.30g initial weight) for eight weeks. Results revealed interaction effects between oil types and replacement levels on diet consumption among the feeding groups. Fish growth and immune parameters were not affected by oil types (p˃0.05), but final weight, specific growth rate, white blood cell and serum protein were altered by replacement levels (p

The present study report on epizootiology, pathogenicity and haemato-immunological aspects of Streptococcus agalactiae (Group B Streptococcus, GBS) serotype Ib (GBS-Ib) affecting climbing perch (Anabas testudineus) in southern Thailand. Study on growth of GBS-Ib under various conditions indicated that this bacterium grew from 25 to 35C, pH 5 to 9 and 0.5 to 4.0% NaCl. Climbing perch inoculated by intraperitoneally injected GBS-Ib at concentrations of 101 to 104 CFU/mL exhibited 60.00-96.67% mortality, with 60 h-LD50 and 72 h-LD50 at 4.5x102 CFU/mL and 6.3x101 CFU/mL inoculums, respectively. Study of the haemato-immunological changes in the fish infected with GBS-Ib revealed declines of haematocrit, haemoglobin, serum protein, red blood cells, and respiratory burst activity. On the other hand, white blood cells, lysozyme activity, phagocytic index, and average beads per cell, were significantly increased in the infected fish. Study on the effect of environmental factors on the susceptibility of fish to GBS-Ib infection indicated that high water temperature and low dissolved oxygen levels proved to increase mortality of climbing perch. These findings indicate that GBS-Ib is a pathogenic bacterium responsible for fish mortality in Thailand.

During October 2015 to December 2016, eight marine sponge-associated bacteria (PSU-KSAAHRC MS1-8) with red, reddish orange, yellow, reddish pink, and dark red pigments were isolated from five species of marine sponge, namely Callyspongia sp., Callyspongia diffusa, Haliclona sp., Dysidea sp. and Stylissa carteri, sampled from Satun and Phang-Nga provinces on the Andaman coast of Thailand. These bacteria produced pigments in the range 55.65-5,619.67 µg/g. The highest pigment content was found in the dark red-pigmented bacterial isolate PSU-KSAAHRC MS2 isolated from Haliclona sp. sampled in Satun province. Thin layer chromatography of a red amorphous pigment extract from the bacterial isolate PSUKSAAHRC MS2 revealed two fractions with respective Rf value of 0.65 and maximum absorbance at 535, and Rf value of 0.57 and maximum absorbance at 539 nm. Analyses of each TLC fraction by liquid chromatograph quadrupole time of flight mass spectrometer revealed the molecular weights of 323 (m/z 324, [M+H]+ ) and 321 (m/z 322, [M+H]+ ), in the same order. Comparing to published data, the compound with maximum absorbance at 535 and molecular weight of 323 (m/z 324, [M+H]+ ) was identified as prodigiosin while the compound with maximum absorbance at 539 nm and molecular weight of 321 (m/z 322, [M+H]+ ) was identified as cycloprodigiosin. Based on morphological and biochemical characteristics as well as phylogenetic analysis obtained from the present study, the bacterial isolate PSU-KSAAHRC MS2 was identified as Zooshikella sp. To our knowledge, this is a first report on identification of prodigiosin and cycloprodigiosin from Zooshikella sp. isolated from marine sponge, Haliclona sp., in Thailand.

To evaluate water quality and growth performance of butter catfish under temperature manipulation, 15 fish were cultured in 16 fiberglass tanks for ten weeks in three temperatures of 29 °C, 31 °C, 33 °C, and in ambient temperature as control (25.1-29.5 °C). The growth performance and water quality parameters (temperature, DO, pH, TAN and NO2-N) in culture were investigated. Water quality seemed not to be controlled by temperature but by feed consumption. DO concentration decreased (8.27+0.10 mg/l) in the 33 °C tank (P0.05). Results reveal that the maximum thermal tolerance for growth is best in water temperature which does not exceed 31 °C.

The solid-state fermentation by effective microorganisms (containing photosynthetic bacteria, lactic acid bacteria, nitrogen-fixing bacteria, yeast and Bacillus sp.) improved the nutritive values of palm kernel meal (PKM). Increased crude protein (20.79%), nitrogen-free extract (40.07%) and gross energy (19.58%) were observed in fermented PKM (FPKM) relative to raw PKM while crude lipid (15.65%), crude fiber (36.45%) and ash (29.54%) were decreased. Replacement of soybean meal (SBM) with FPKM as a protein source was investigated for its effects in sex-reversed red tilapia (Oreochromis niloticus × O. mossambicus). The two-month-old fish (14.85 ± 0.28 g initial weight) were fed fish meal-SBM-based diets with replacement by FPKM at 25% (25FPKM), 50% (50FPKM), 75% (75FPKM) and 100% (100FPKM), while an FPKM-free diet (0FPKM) was used as a control. The five treatments, comprising triplicate cement ponds and forty fish each, were conducted in a recirculating system over 12 weeks. At the end of the feeding trial, fish fed the 50FPKM diet were superior in growth performance, while the feed utilization parameters were similar across all five treatments. Physiological adaptation of the protein-digesting (pepsin and trypsin) and lipid-digesting (lipase) enzymes was detected at all protein replacement levels (except for 25FPKM), as well as of the enzyme for cellulose digestion (cellulase), but not of the carbohydrate-digesting enzymes (amylase). Protein synthesis capacity in flesh was improved in fish fed the 50FPKM diet, while the quality of the main flesh proteins, actin and myosin, showed no significant differences across the five treatments. No differences in carcass composition and no negative effects on hematological parameters or liver histoarchitecture at the 50% replacement level of SBM by FPKM also support this alternative. Findings from the current study indicate the low-cost FPKM-containing diet for tilapia in comparison with control diet.

The protective efficacy of formalin-killed Streptococcus agalactiae (Group B Streptococcus, GBS) serotype Ia (GBS-Ia) and III (GBS-III) vaccines were assessed in Nile tilapia (Oreochromis niloticus). The fish with an average weight of 34.45± 0.08 g were immunized by intraperitoneal (i.p.) injection with 4 different formalin-killed vaccines prepared from GBS-Ia (1x1010 CFU/mL), GBS-III (1x1010 CFU/mL), and combined GBS-Ia and GBS-III in an equal volume at final concentrations 1x1010 CFU/mL and 2x1010 CFU/mL in comparison with the non-immunized control group. At 2 and 4 weeks post vaccination, no significant differences were observed (p>0.05) among treatments in growth performance or haemato-immunological parameters, except the increased red blood cell at 2 weeks. Significantly increased antibody titers (p

Streptococcus agalactiae (Group B Streptococcus, GBS) infections cause serious worldwide damage to fish farming. Here, we evaluated the pathological manifestations and immune responses of Nile tilapia (Oreochromis niloticus) infected with GBS serotype Ia (GBS-Ia) and GBS serotypes III (GBS-III). Experimental infection of fish with GBS by intraperitoneal injection indicated the severity of GBS-Ia infection as shown by the LD50 of GBS-Ia and GBS-III, being 1.58106 CFU/fish and 2.10108 CFU/fish, respectively. The onset of disease and clinical observation revealed notable differences between the GBS-Ia and GBS-III infections. Histological findings showed severe changes of the liver, pancreas, kidney and brain of fish infected with GBS. In addition, significantly different haemato-immunological parameters were observed between GBS-Ia and GBS-III infected fish. Differences in the pathological manifestations and immune responses of GBS-Ia and GBS-III infections in tilapia are of practical use for fish pathologists who monitor tilapia mortality resulting from GBS infections.

The study on diplomonad flagellates infection in some ornamental fishes in the family cichlidae i.e., angelfish(Pterophyllum scalare), oscar (Astronotus ocellatus), blue mbuna (Labeotropheus fuelleborni) and the family osphronemidaei.e., Siamese fighting fish (Betta splendens) revealed that this parasite infected three out of four ornamental fish species,angelfish, oscar and blue mbuna. The highest infection was recorded in angelfish (90%) followed by oscar (75.4%) and bluembuna (61%), respectively. Identification of diplomonad flagellates from angelfish by means of morphological studies underlight and electron microscopes indicated that the parasite was Spironucleus vortens. The 14–days LD50 of S. vortens inangelfish was 2.99x103 cells. Histopathological changes of infected angelfish revealed granulomatous liver, numerousnumbers of melanomacrophage in the spleen and inflammation of the intestine. Susceptibility study of S. vortens to goldfish(Carassius auratus), guppy (Poecilia reticulata) and platy (Xiphophorus maculatus) indicated that they were resistant toartificial infection. In vitro examination of the growth inhibition assay of S. vortens indicated that dimetridazole and metronidazolewere effective in inhibiting parasite growth after 48 hrs exposure at concentrations of >4.0 μg/ml and >6.0 μg/ml,respectively. Magnesium sulfate at a concentration of >60 mg/ml inhibited the parasite growth after 72 hrs exposure. In vivoexamination of the dimetridazole efficiency on S. vortens infection indicated that dimetridazole at 4.0 μg/ml provided thehighest efficiency which could be used for treatment of spironucleosis in angelfish.

A multiplex PCR (m-PCR) technique was developed for simultaneous detection of the causative agents responsible forstreptococcosis of cultured fish in Thailand i.e., Streptococcus agalactiae, Streptococcus iniae, and Lactococcus garvieae.The study on the sensitivity of the technique indicated that the minimum detected DNA concentration was 9.76, 39.06, and19.53 pg for S. agalactiae, S. iniae and L. garvieae, respectively. Detection of streptococcosis in healthy and diseased Niletilapia (Oreochromis niloticus) and red tilapia (Oreochromis niloticus x Oreochromis mossambicus) cultured in Paphayomand Bangkaew District, Phatthalung Province and Sichon and Hua Sai District, Nakhon Si Thammarat Province, Thailand, bym-PCR technique showed positive results for S. agalactiae from tilapia cultured in Bangkaew and Hua Sai and negativeresults for samples from Paphayom and Sichon. The m-PCR results were in accordance with microbiological culture techniques,which detected S. agalactiae from tilapia cultured in Bangkaew and Hua Sai indicating that our m-PCR assay is a sensitiveand specific diagnostic tool for simultaneous detection of streptococcosis caused by S. agalactiae, S. iniae and L. garvieaein cultured fish in Thailand.

Streptococcus iniae infections are becoming an increasing problem in aquaculture and have been reported worldwidein a variety of fish species. Our previous study showed that S. iniae infection in tilapia Oreochromis sp. and Asian sea bassLates calcarifer cause serious damage in fish farm in Thailand. To prevent streptococcosis caused by S. iniae, a formalinkilledvaccine was applied in red tilapia Oreochromis niloticus x O. mossambicus by injection, immersion and oral vaccination.At 1 week post vaccination, levels of antibody titer and some blood parameters response to different routes of administrationwere significantly different. The best disease resistance was found in the group injected with vaccine plus -(1,3/1,6)–glucan with the relative percent survival (RPS) of 95.12% followed by pure vaccine injection (RPS = 80.49%), immersion(RPS = 41.46%) and oral vaccination (RPS = 9.75%).No difference in blood parameters of tilapia after vaccination for 4 weeks was observed. However, antibody titer ofthe group received vaccine plus -(1,3/1,6)–glucan and vaccine alone were significantly higher than the other groups. RPS offish at week 4 post vaccination showed the same trend as the highest disease resistance recorded in the group injected withvaccine plus -(1,3/1,6)–glucan (RPS=76.00%) which significantly differ from vaccine alone (RPS=54.00%). Immersion andoral vaccination showed less effect on disease protection at week 4 post vaccination. The result from the present studyindicated that formalin-killed S. iniae vaccine provided excellent efficacy against S. iniae infection in tilapia by intrapertonealinjection and -(1,3/1,6)–glucan increased the effectiveness of vaccine produced from S. iniae.

Streptococcal infections are becoming an increasing problem in aquaculture and have been reported worldwide in avariety of fish species. Here we describe the isolation and characterization of Streptococcus iniae from Asian sea bass (Latescalcarifer) and red tilapia (Oreochromis sp.) cultured in southern Thailand. Conventional and rapid identification systems,as well as the polymerase chain reaction (PCR), were used to determine that the isolate was S. iniae. The virulence of thisS. iniae was higher in Asian sea bass than in red tilapia, as shown by the 10 day-LD50 in Asian sea bass and red tilapia, being1.08x104 and 1.14x107 CFU, respectively. Histopathological changes in Asian sea bass are more severe than those observedin red tilapia. The changes can be found in several organs including liver, pancreas, heart, eye and brain. Histopathologicalfindings included cellular necrosis, infiltration of lymphocytes and granuloma formation in the infected organs.

Streptococcal infections are becoming an increasing problem in aquaculture and have been reported worldwide in a variety of fish species. Here we describe the isolation and characterization of Streptococcus iniae from Asian sea bass (Lates calcarifer) and red tilapia (Oreochromis sp.) cultured in southern Thailand. Conventional and rapid identification systems, as well as the polymerase chain reaction (PCR), were used to determine that the isolate was S. iniae. The virulence of this S. iniae was higher in Asian sea bass than in red tilapia, as shown by the 10 day-LD in Asian sea bass and red tilapia, being 50 4 7 1.08x10 and 1.14x10 CFU, respectively. Histopathological changes in Asian sea bass are more severe than those observed in red tilapia. The changes can be found in several organs including liver, pancreas, heart, eye and brain. Histopathological findings included cellular necrosis, infiltration of lymphocytes and granuloma formation in the infected organs. [ABSTRACT FROM AUTHOR]