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ABSTRAKBakteri Streptococcus agalactiae tipe -hemolitik dan non-hemolitik menjadi agen penyebab infeksi streptococcosis yang mengakibatkan kematian dan kerugian besar pada budidaya ikan nila. Penelitian ini bertujuan untuk membandingkan toksisitas sel utuh dan extracellular product (ECP) bakteri -hemolitik dan non-hemolitik yang diinjeksikan pada ikan nila. Karakterisasi S. agalactiae berdasarkan SNI dan API 20 STREP, serta pemisahan protein dengan metode SDS-PAGE. Pengujian toksisitas dilakukan dengan cara menginjeksikan sel utuh dan ECP S. agalactiae secara intraperitoneal (IP) dengan dosis 0,1 mL ekor -1 . Hasil uji biokimia, dan konfirmasi dengan API 20 STREP menunjukkan bahwa semua isolat positif S. agalactiae. Fraksinasi protein pada sel utuh bakteri diperoleh pita protein masing-masing sebanyak sembilan dan tujuh pita pada tipe -hemolitik dan non-hemolitik. Fraksinasi ECP teridentifikasi pada -hemolitik sebanyak tujuh pita dan non-hemolitik empat pita protein. Konsentrasi protein sel utuh dan ECP -hemolitik lebih besar dibandingkan bakteri non-hemolitik. Gejala abnormalitas lebih cepat terjadi pada ikan nila yang diinjeksi ECP bakteri -hemolitik dan berbanding lurus dengan kematian sebanyak 91%-100% pada jam ke-13 pascainjeksi. Hasil ini menunjukkan bahwa ECP bakteri S. agalactiae -hemolitik lebih virulen dibandingkan tipe non-hemolitik. Hingga akhir pemeliharaan tidak ada kematian pada ikan yang diinjeksi sel utuh bakteri S. agalactiae -hemolitik dan non-hemolitik. Studi histopatologi ikan yang diinjeksi ECP S. agalactiae pada organ hati, limpa, otak, dan ginjal menunjukkan adanya kongesti, hemoragi, dan nekrosis. KATA KUNCI: fraksinasi; gejala klinis; Streptococcus agalactiae; sintasan; ikan nila ABSTRACT: Toxicity of whole cells and extracelluar product (ECP) of -hemolytic and non-hemolytic Streptococcus agalactiae in tilapia (Oreochromis niloticus).The -hemolytic and non-hemolytic biotype of Streptococcus agalactiae are the agents that cause streptococcosis infection which resulted in high mortality and major losses in tilapia culture. This study aimed to compare the toxicity of whole cell and extracellular product (ECP) -hemolytic and non-hemolytic bacteria from injected tilapia. Characterization of S. agalactiae was based on SNI and API 20 STREP and protein separation by SDS-PAGE method. Toxicity test was carried out by injecting whole cells and ECP S. agalactiae intraperitoneally with a dose of 0.1 mL fish-1. The results of biochemical tests, with confirmation by API 20 STREP showed that all isolates were positive for S. agalactiae. Protein fractionation of whole bacterial cells obtained as many as nine and seven bands of protein in -hemolytic and non hemolytic biotype, respectively. ECP fractionation was identified in b-hemolytic biotype as many

Streptococcosis is a significant fish disease impacting tilapia culture in Indonesia, causing losses estimated up to IDR 15.0 billion annually. This study aims to assess the efficacy of bivalent and trivalent vaccines containing Streptococcus agalactiae bacteria on tilapia. The formula of the bivalent vaccine contains 75% of S01-196-16 and 25% of N14G isolates (v/v). Trivalent vaccine contains 30%, 35%, and 35% of N14G, NP1050, and SG01-16 isolates (v/v), respectively. A challenge test assessed the efficacy of the vaccines, and it was carried out at 30, 90, and 150 days post-vaccination by artificially infection at LD60. Selected bacteria isolate to be appointed in the challenge test are N14G (biotype 2) and S01-196-16 (biotype 1). Relative Percentage of Survival (RPS) was used as the main indicator of vaccine efficacy. The results revealed that the highest RPS of a bivalent vaccine against S. agalactiae (S01-196-16) was achieved at the first challenge (61.84%), and trivalent vaccine against S. agalactiae (N14G) and S. agalactiae (S01-196-16) was achieved at the first challenge (61.53% and 76.20%, respectively). Bivalent and trivalent S. agalactiae bacteria vaccines are promising “tools” to control streptococcosis on tilapia.

Abstract. Sofian A, Suhermanto A, Saidin, Sayuti M, Novianto D, Widyasari F. 2021. Short communication: Environment and morphometric of sea hare Dolabella auricularia from shrimp pond, Sorong West Papua, Indonesia. Biodiversitas 22: xxxx. Dolabella auricularia is a herbivorous marine biota living on the shallow seabed, which is found mostly in Indo-Pacific waters. The purpose of this study was to analyze the environmental and morphometric characteristics of Dolabella auricularia which live in vaname shrimp pond, Sorong, West Papua, Indonesia. Samples were collected from April to June 2020. From the measurement of pond waters environmental conditions, the following data were obtained: temperatures ranging from 31.47 ± 1.08oC, salinity ranging from 31.91 ± 2.29 ppt, pH ranging from 8.02 ± 0.20, brightness 108.00 ± 45.63 cm, and Dissolved Oxygen (DO) ranging from 4.10 ± 0.22 mg/L. The morphometrics of D. auricularia consisted of R-Anterior resp distances with sizes ranging from 38.9 ± 17 mm, wet weight ranging from 170 ± 34 g total lengths ranging from 112 ± 57.83 mm, posterior diameters ranging from 71 ± 41 mm. D. auricularia was found in pond waters as a pest for shrimp culture. However, D. auricularia also has biomedical and economic potentials as raw materials for the pharmaceutical industry. So, further studies are needed for their development.

Streptococcosis caused by Streptococcus agalactiae has become a major disease problem in tilapia culture in Indonesia. This study aimed to detect virulence genes of S. agalactiae during streptococcosis disease outbreaks in several tilapia farms in Indonesia and evaluate the correlation between biotype and virulence genes to bacterial virulence. The presence of virulence genes was determined in 10 strains of S. agalactiae isolated from farm-raised tilapia. Polymerase chain reaction (PCR) protocol was used to determine genes for cylE, hylB, lmb, bib A, PI-2b, fbs A, fbs B, gap, PI-1, and cfb in the template DNA. Pathogenicity test was carried out by intraperitoneal injection of 24 hour-cultured S. agalactiae to tilapia with 108 CFU/fish. Four isolates have seven of virulence genes (cylE, hylB, bibA, PI-2b, fbs A, fbs B, and gap genes), three isolates have six virulence genes (hylB, bib A, fbs A, fbs B, gap, cfb genes), one isolate has four virulence gene (hyl B, bib A, fbs, and cfb genes), and one isolate has one virulence gene (PI-2b gene). None of the isolates has lmb or PI-1 genes. Bacteria with more virulence genes showed higher pathogenicity post injection. Mortality of tilapia injected with b-hemolytic bacteria was 100% within the period of 14-19 hours, while non-hemolytic bacteria was 53.3%-86.6% on 14 days post-injection. Pathological changes associated with the infection by either isolate included melanosis, slow response, anorexia, ocular opacity, gasping, erratic, C-shape, and whirling. It can be concluded that S. agalactiae with more virulence genes show a higher level of pathogenicity. The presence of a virulent gene has the potential to be used as a basis for selecting candidate isolates and designing vaccine compositions as an effort to prevent streptococcosis infection in tilapia in Indonesia.