Infeksi trematoda monogenea: Pseudorhabdosynochus sp. dapat menyebabkan kematian massal pada ikan kerapu. Prevalensi infeksi trematoda ini mencapai 100%, namun intensitasnya hingga menimbulkan gejala klinis dan kematian ikan belum diketahui. Tujuan dari penelitian ini adalah untuk mengetahui intensitas parasit insang (Pseudorhabdosynochus sp.) pada ikan kerapu hibrida “cantik” melalui infeksi buatan. Ikan uji direndam dalam air tawar dengan 100 mg/L formalin selama satu jam sebelum digunakan. Infeksi buatan dilakukan melalui (A) kohabitasi antara ikan sehat dengan ikan sakit dan (B) penempelan potongan lamella insang ikan yang terinfeksi parasit ke lamella insang ikan sehat. Pada perlakuan (A) sebanyak lima ekor ikan uji dipelihara bersama dengan dua ekor ikan sakit selama 3-4 hari, sedangkan perlakuan (B) penempelan lamella insang ikan sakit (1 g lamella insang/ikan) dilakukan pada lima ekor ikan uji selama lima menit. Masing-masing perlakuan diulang tiga kali. Pada Kontrol kepadatan ikan uji sehat sebanyak enam ekor dan lima ekor. Wadah yang digunakan berupa bak plastik volume 100 L. Pengamatan intensitas parasit dan telurnya pada setiap lamella insang bagian kanan dan kiri dari lima ekor ikan uji dilakukan selama tiga minggu dengan interval waktu satu minggu. Hasil pengamatan menunjukkan bahwa kohabitasi antara ikan sehat dan ikan sakit menyebabkan intensitas parasit Pseudorhabdosynochus sp. dan telurnya lebih tinggi dibandingkan dengan penempelan lamella insang. Pada kontrol, Pseudorhabdosynochus sp. maupun telurnya tidak ditemukan selama tiga minggu pemeliharaan. Hasil ini menunjukkan penyebaran Pseudorhabdosynochus sp. dari ikan sakit ke ikan sehat lebih cepat dibandingkan dengan penempelan dari lamella insang ikan sakit.Monogenetic trematode (Pseudorhabdosynochus sp.) infection often leads to mass mortality in groupers, with prevalency reaching 100%. However, the intensity of this parasite to infect grouper fish has yet to be reported. The purpose of this research was to study the intensity of Pseudorhabdosynochus sp. in hybrid grouper “cantik” through experimental infection. The test fish were soaked with 100 mg/L of formalin in fresh water before used. The experimental infections were performed through: (A) cohabitation between healthy fish with sick fish and (B) infection with attached of gills lamella of sick fish to gill lamella of healthy fish. In treatment (A), a total of five test fish were cohabited with two sick fish for 3-4 days, while in treatment (B), attachment of gills lamella (1 g/fish) was done on five test fish for five minutes. Each treatment was repeated for three times. Six and five test fish were maintened as controls. The containers used were 100 L plastic tanks volume. Observation of intensity of the parasite infection and its egg production in each lamella along the right and left gills of five fish were conducted for three weeks with one week intervals. The result showed that the cohabitation between healthy and sick fish caused an increase in total of Pseudorhabdosynochus sp. and its eggs compared with the attachment of chopped-gills. In the control group, Pseudorhabdosynochus sp. and its eggs were not found for three weeks. These results indicate the spread of Pseudorhabdosynochus sp. from the sick fish to the healthy is fish faster than the attachment of gill lamella from the sick fish.
The aims of this study were to identify and to determine life cycle of marine leech isolated from cultured hybrid grouper “cantik” (Epinephelus fuscoguttatus fx E. polyphekadion m) in the northern Bali waters of Indonesia under laboratory conditions. Observation of the life cycle of the marine leech was done using petri-dishes (9 cm in diameter) arranged into two groups. In group-1, a petri-dish was filled with sterile seawater (with water exchange of 50%-60% every two days) and in group-2, a petri-dish was filled with continuous running water. DNA sequence was aligned with the sequences from GenBank by BLAST program. Results of similarity index with GenBank sequence exhibited that the nucleic acid of the marine leech isolated from the hybrid grouper “cantik” showed high similarity (99%) with Zeylanicobdella arugamensis. One adult leech could produce 1-63 eggs. The eggs were developed into morula, blastula, and gastrula within five days. The early phase of the embryo with daily water exchange treatment started on day-6 and hatched into larvae on day-10. The eggs incubated with continuous running water had hatched faster (eight days). However, not all eggs hatched at the same time. Some of the eggs hatched 1-3 days after the first one. Hatching rate of eggs varied from 2.70% to 100%. The newly hatched Z. arugamensis larva has transparent color and length of 1.0-1.5 mm. On day-6, Z. arugamensis larvae were already seen attaching to the body of the fish. The size of the Z. arugamensis larvae ranged between 3-11 mm on day-9. In that stage, they were able to produce eggs. Therefore, we argue that Z. arugamensis only requires 17 to 22 days to develop into the adult stage.
Bakteri merupakan mikroorganisme yang secara alami berada dalam ekosistem perairan laut dan beberapa spesiesnya bersifat patogen. Penelitian ini bertujuan untuk menentukan pola fluktuasi populasi bakteri secara umum dan Vibrio spp. secara khusus di perairan pantai dan teluk sebagai dampak dari aktivitas baik panti pembenihan, tambak udang, maupun karamba jaring apung (KJA) di pesisir Bali Utara. Sampel air diperoleh dari tiga lokasi sentra budidaya laut dan satu lokasi ekowisata yang berada di Kecamatan Gerokgak Kabupaten Buleleng. Sampel air diambil dari tiga titik sampling di perairan dengan jarak 50 m, 100 m, dan 300 m dari garis pantai di Desa Gerokgak dan Desa Penyabangan. Sampling air dilakukan pada tiga titik sampling di sekitar KJA di Teluk Kaping, Desa Sumberkima, dan satu titik sampling di perairan dengan jarak 100 m dari garis pantai di Desa Pemuteran. Sampling air dilakukan sekali dalam sebulan dari bulan Februari hingga November 2018. Hasil penelitian menunjukkan bahwa total bakteri dan Vibrio spp. di empat lokasi perairan di Kecamatan Gerokgak, Bali menunjukkan populasi tinggi pada bulan Maret hingga Mei dan menurun pada bulan berikutnya. Dan meningkat kembali pada bulan Oktober hingga November. Total bakteri dan Vibrio spp. tertinggi terjadi di perairan pantai Desa Gerokgak hingga 9.067 ± 7.481 CFU/mL dan 1.147 ± 689 CFU/mL dibandingkan dengan dua lokasi sentra budidaya lainnya (Desa Penyabangan dan Teluk Kaping). Total bakteri dan Vibrio spp. teramati pula di perairan Desa Pemuteran hingga 500 ± 52 CFU/mL dan 65 ± 7 CFU/mL yang kemungkinan merupakan dampak dari aktivitas budidaya ikan. Pola fluktuasi populasi bakteri di perairan pantai Kecamatan Gerokgak, Bali dipengaruhi oleh musim dan kegiatan budidaya perikanan. Tingginya populasi bakteri Vibrio spp. pada perairan pantai dapat memengaruhi kesehatan ikan budidaya.Bacteria are a group of microorganisms naturally present in aquatic ecosystems. Some of the bacteria are pathogenic to other organisms and cause severe diseases. This study aimed to determine the fluctuation patterns of bacterial populations, with specific interest to Vibrio spp. in coastal and bay areas of North Bali which constantly receive effluents from nearby mariculture activities. Water samples were collected from three locations in a clustered marine fish farming area and one location in an ecotourism area as a control. Water samples were taken from three sampling points in the coastal area of Gerokgak and Penyabangan villages at a distance of 50 m, 100 m, and 300 m from the coastline. Water samples were also collected at three sampling points around floating net cages (KJA) in Kaping Bay, Sumberkima Village, and one sampling point in Pemuteran Village located 100 m from the coastline. Water sampling was carried out each month from February to November 2018. Results of the study showed that total bacteria and Vibrio spp. were notably higher between March-May and October-November. The total bacteria and vibrio reached the peak number at 9,067 ± 7,481 CFU/mL and 1,147 ± 689 CFU/mL, respectively, which occurred in the coastal waters of Gerokgak Village. The total bacteria and Vibrio spp. of up to 500 ± 52 CFU/mL and 65 ± 7 CFU/mL, respectively, were also observed in the waters of Pemuteran Village which are likely to be the effects of aquaculture activities in these of three locations. This study concludes that the fluctuation pattern of bacterial population in the coastal waters of Gerokgak District, Bali is primarily influenced by the season and activities of the fish farming. The high population of Vibrio spp. in the coastal waters could lead to a fish disease oubreak related to the pathogenic bacterium.
Infection of Megalocytivirus cause serious mass mortality in marine fish in South East Asian countries. The aim of this study was to produce recombinant of GSDIV capsid protein and its protection to humpback grouper Cromileptes altivelis against grouper sleepy disease iridovirus (GSDIV). A major capsid protein (MCP) was selected for use as a crude subunit vaccines. This gene target (MCP) was inserted to the protein expression system vector of pET SUMO and cloned in cells bacteria Escherichia coli strain BL-21. The MCP was succeded to be induced using 1 mM of IPTG. Results of protein analysis using MALDI TOF-TOF indicated that the MCP has measurement of 49.566 kDa with PI index of 6.00, and contained 453 amino acids. BLAST homology analysis exhibited that the amino acid sequence of the MCP showed high similarity with MCP of Red Sea Bream Iridovirus (RSIV). E. coli expressing MCP protein was inactivated using 0.03% formalin overnight and washed using PBS. The inactivated E. coli as a crude subunit vaccine was then injected intramuscularly to humpback grouper juveniles. Subsequently, the juveniles were challenged tested with GSDIV. The juveniles vaccinated with the MCP recombinant bacteria showed significantly higher survival rates than control those vaccinated with PBS. Thus, the MCP fusion protein is considered as a potential vaccine against GSDIV infections in grouper.
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