The production of a bacteriocin-like substance with antimicrobial activity, named peocin, by the probiotic Paenibacillus ehimensis NPUST1 was previously reported by our laboratory. The present study aimed to identify peocin and increase the peocin yield by heterologous expression in Escherichia coli BL21(DE3). Peocin was identified as a DNA starvation/stationary phase protection protein, also called DNA-binding protein from starved cells (Dps), by gel overlay and LC-MS/MS analysis. For mass production of peocin, fed-batch cultivation of E. coli was performed using a pH-stat control system. Purification by simple nickel affinity chromatography and dialysis yielded 45.3 mg of purified peocin from a 20-mL fed-batch culture (49.3% recovery). The biological activity of the purified peocin was confirmed by determination of the MIC and MBC against diverse pathogens. Purified peocin exhibited antimicrobial activity against aquatic, food spoilage, clinical and antibiotic-resistant pathogens. In an in vivo challenge test, zebrafish treated with purified peocin exhibited significantly increased survival rates after A. hydrophila challenge. The present study is the first to show the antimicrobial activity of Dps and provides an efficient strategy for production of bioactive peocin, which will aid the development of peocin as a novel antimicrobial agent with potential applications in diverse industries.

Abstract. Serdiati N, Arfiati D, Widodo MS, Lelono TJ, Ndobe S, Saranga R. 2020. Morphological variations and phylogenetic analysis of Oryzias nigrimas Kottelat, 1990 (Rice fish) from Lake Poso, Central Sulawesi, Indonesia. Biodiversitas 21: 882-888. Rice fish (Oryzias nigrimas Kottelat, 1990) is a well-studied species endemic to Lake Poso, Sulawesi and identified as scarce. This study aims to identify the Rice fish of Lake Poso, Central Sulawesi based on morphological characters (15 morphometric characters and 5 meristic counts) and phylogenetic analysis using maximum-likelihood (ML) method based on mtDNA, CO1 gene. Based on the morphological analysis, it was showed that the meristic counts show significantly different only on the lateral line scale. However, the morphometric measurements show significantly different characteristics on postorbital distance, body depth, and length of jaw. Our phylogenetic analysis also showed that our samples are indeed a species of O. nigrimas. We suggest that the endemicity of this Rice fish on Lake Poso is greatly influenced by the well-maintained genetic structure of the population.

Abstract. Sofarini D, Herawati EY, Mahmudi M, Hertika AMS, Arfiati D, Musa M, Amin M, Supriharyono. 2019. Analysis of stomach content of piscivorous fishes caught in Danau Panggang Peatland, South Kalimantan, Indonesia. Biodiversitas 20: 3788-3793. The purpose of this study was to analyze the stomach content profile of piscivorous fishes caught at the reservaat station and the station without activity as The control station, in the Danau Panggang peatland. Sampling was carried out four times and the index of preponderance stomach content was determined in piscivorous fishes. The results showed there were nine fish species in the reservaat area, including Cryptopterus spp., Pangasius nieuwenhuisii, Chana striata, Anabas testudineus, Pangasius sp., Mastecembelus erythrotaenia, Macrognathus aculeatus, Mystus nigriceps, and Mystus nemurus. Their gut was dominated 89% by Chrysophyta, and 37.5% by Diatom and Navicula. In the area without activity, six species of fish were caught, including Cryptopterus spp, Pangasius nieuwenhuisii, Anabas testudineus, Pangasius sp, Mystus nigriceps, and Mystus nemurus, with 83% of their gut dominated by Diatom. The water temperature was 28.07-33.25º C, brightness (6-115 cm), pH of 4.23-6.97, dissolved oxygen (DO) (1.4-6.5 mg/L) and BOD (7.52-24.92 mg/L) i.e., water quality parameters that tend to be incompatible with the persistence of fishes. These limiting factors of peatland water and extreme conditions led to a limitation at availability of natural food for piscivorous fishes.

Metal halide (MH) lamp is applied in light fishing purse seine (PS). This lamp have weaknesses like wasteful energy, it is necessary to replace with energy saving lamp. Light emitting diode (LED) is potential to replace the MH. The experimental method in order to obtain data on different light intensity, fuel consumption, and number of catch in PS fishing using MH and LED lamps as fish attractor. Light intensity observations were done on each of 6 MH and LED lamps in the distance of 0-17 m. The LED lamp had focus more onto the front that enabled to reach farther distance, MH lamp had dispersed illumination distance. The LED lamp is more efficient in directing the lamp into the water. The number addition of MH lamps on different side of vessel does not increase the total amount of light intensity significantly. The ratio of the number captures of MH and LED lamps is 3.57:1 is much lower than the electric power ratio of both lamps (40:1). So that if the electric power LED lamps increased 6.2 times from 600 W to 3,875 W then the total number of fish from the LED lamps will approach the MH lamps.

Ekosistem lamun di wilayah Paciran, Lamongan, Jawa Timur, merupakan habitat bagi komunitas makrozoobentos. Tujuan dari penelitian ini adalah untuk mengetahui struktur komunitas makrozoobentos di wilayah pesisir Paciran dengan metode survei. Sampel makrozoobentos diamati dengan menggunakan transek saat air laut surut di tiga stasiun yang telah ditentukan. Stasiun 1 merupakan wilayah tempat bersandarnya kapal; stasiun 2 adalah daerah dekat pemukiman penduduk dan stasiun 3 di dekat daerah pembenihan ikan atau udang. Hasil penelitian ditemukan 3 filum organisme, yaitu Mollusca, Echinodermata, dan Annelida. Kelimpahan makrozoobentos di tiga stasiun berkisar 486-608 ind/m 2 , dengan indeks keanekaragaman (H') sedang (1,68-1,71), indeks keseragaman (E) tinggi (0,70-0,73) dan indeks dominasi (C) rendah (0,23-0,25) dengan kelimpahan relatif tertinggi yaitu pada gastropoda Cerithium granosum dan tidak ditemukan makrozoobenthos yang mendominasi. Berdasarkan hasil penelitian dapat disimpulkan bahwa perlu adanya pemantauan dan penyuluhan bagi warga sekitar lingkungan pantai agar ketersediaan makrozoobentos tersebut tetap lestari.

Ikan-ikan dari Famili Bagridae di Indonesia mencapai 60 jenis dan salah satunya dari genus Msytus. Metode yang digunakan untuk identifikasi ikan yang sangat cepat dan akurat sangat diperlukan. DNA barcoding adalah teknik identifikasi baru dengan pendekatan molekular. Gen CO1 diamplifikasi dan produk PCR disekuensing serta dianalisis dengan menggunakan software bioinformatika. Pengeditan hasil sekuensing dan penentuan komposisi nukleotida dianalisis dengan software Mega5. Urutan DNA disejajarkan dengan ClustalW vers. 1.4. Sekuens dibandingkan dengan data GenBank menggunakan BLAST (Basic Local Aligment Search Tools) dan BOLDSystems. Pohon filogenetik dibuat dengan menggunakan metode Neighbor_Joining. Salah satu contoh identifikasi ikan dari genus Mystus yang telah dikonfirmasi adalah Mystus nigriceps menjadi Mystus singaringan.

The purpose of study is to determine the type of plankton found in cultivation pond of nile tilapia infected by VNN. The method is to identify the plankton in the water pond and testing the VNN that infects nile tilapia related to plankton eaten using Polymerase Chain Reaction (PCR). VNN identification results on the nile tilapia digestive tract stomach and intestines as well as plankton found in the stomach and intestines indicate VNN positively. Plankton found in the digestive tract of fish is division of Chlorophyta, Bacillariophyta, phylum Rotifera, and Crustacea. It indicates that nile tilapia infected by VNN both on the gastrointestinal tract organs, stomatch or intestines and plankton were found with positive VNN digestive duct, while plankton found in water pond is VNN negative. The VNN infection depends on the nature of specifications VNN on nile tilapia and the plankton in the nile tilapia digestive duct.

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