Phát hiện nhanh Streptococcus agalactiae và Streptococcus iniae từ mẫu mô cá bằng kỹ thuật duplex PCR

Large-scale fish farming faces many environmental stresses, which affect their immune systems, growth performance, and physiological homeostasis, resulting in increase in their susceptibility to infections. Some of the most common bacterial infections of cobia fish (Rachycentron canadum) include streptococcosis, vibriosis, furunculosis and mycobacteriosis, and pastelleurosis. Probiotics could be helpful in reducing or limiting the incidence of severe disease infections or outbreaks. Therefore, the present study aimed to isolate the indigenous bacterial species from healthy cobia fish and then selected 3 strains, including Bacillus sp. RCS1 (MW560712), Pantoea agglomerans RCS2 (MW560713), and Bacillus cereus RCS3 (MW560714) from the gut of juvenile’s cobia having advantageous assets or positive characteristics. Their analysis indicated the presence of similar biochemical profiles and all could effectively utilize carbon sources. The biosafety assessment did not show any pathological symptoms after 10 days of injecting the fish with isolated bacteria. The results showed that all the isolated bacteria in the present study had low auto-aggregation capacity within the first 3 h of incubation. The isolated bacteria showed strong tolerance when exposed to a range of pH. Although asymmetrically, a slow rise in the growth of isolated bacteria was observed within the pH range of 1–8 for RC1, 1–7 for RC2, and 1–6 for RC3. The antagonistic effects of isolated bacterial strains on the development of pathogens, including Vibrio alginolyticus, Vibrio harveyi, Streptococcus iniae, and Streptococcus agalactiae, were investigated using Luria-Bertani (LB) agar plates. All the isolated bacteria exhibited inhibitory effects against the pathogens, including V. alginolyticus, V. harveyi, S. iniae, and S. agalactiae. These isolated bacteria were characterized with a wide range of antagonistic activities, non-hemolytic activities, high survivability after heat-treatments and safety confidence, and antibiotic susceptibility. Generally, the characteristics displayed by these strains indicated that they could be used as potential probiotics in the aquaculture industry.

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Differential PCR detection of Streptococcus agalactiae and Streptococcus iniae in tilapia ( Oreochromis niloticus ) by a single primer pair

Journal of Fish Diseases ◽

10.1111/jfd.13014 ◽

2019 ◽

Author(s):

Miao Cui ◽

Huijie Zhang ◽

Jingjing Li ◽

Ru Liu ◽

Min Wu ◽

...

Keyword(s):

Streptococcus Agalactiae ◽

Oreochromis Niloticus ◽

Pcr Detection ◽

Streptococcus Iniae ◽

Single Primer

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ISOLASI BAKTERIOFAGA ANTI Streptococcus agalactiae DARI IKAN NILA (Oreochromis niloticus)

Jurnal Riset Akuakultur ◽

10.15578/jra.5.2.2010.237-243 ◽

2016 ◽

Vol 5 (2) ◽

pp. 237

Author(s):

Angela Mariana Lusiastuti ◽

Uni Purwaningsih ◽

Tuti Sumiati

Keyword(s):

Causative Agent ◽

Streptococcus Agalactiae ◽

Membrane Filter ◽

Brain Heart Infusion ◽

Fish Mortality ◽

Streptococcus Iniae ◽

Brain Heart Infusion Agar ◽

Physiological Tests ◽

Infusion Agar

Infeksi Streptococcus merupakan salah satu penyakit serius pada ikan yang disebabkan oleh bakteri gram positif. Infeksi oleh streptococcus beta-hemolitik paling sering dilaporkan menginfeksi ikan. Di antara streptococci beta-hemolitik, Streptococcus iniae penyebab septicemia, meningoencefalitis, dan kematian pada ikan budidaya. Selain itu, Streptococcus agalactiae juga menyebabkan streptococcosis parah pada ikan nila. Alternatif yang bisa digunakan untuk terapi infeksi streptococcosis adalah dengan penggunaan bakteriofaga yang merupakan virus yang hidup pada bakteri. Tujuan penelitian ini adalah isolasi bakteriofaga S. agalactiae sebagai kandidat agen terapi yang memberikan efek protektif melawan infeksi streptococcosis. Faga diisolasi dari Brain Heart Infusion Agar (BHIA) yang sudah ditanami dengan 15 isolat S. iniae dan S. agalactiae. Isolat S. iniae dan S. agalactiae diisolasi dari ikan sakit dengan gejala klinis Streptococcosis. Setelah itu diidentifikasi dengan pewarnaan Gram, tes katalase, pertumbuhan pada agar darah dan API 20 Strep System. Pertumbuhan faga ditunjukkan dengan adanya zona lisis pada tempat yang ditetesi dengan sampel cairan usus dari ikan nila sehat. Faga yang tumbuh lalu dikoleksi secara steril, disentrifus dan supernatannya difiltrasi dengan membran filter 0,45 µm dan disimpan pada suhu 4oC. Dari 15 isolat S. iniae dan S. agalactiae hanya satu isolat yaitu PSaT-18 yang menunjukkan zona lisis seperti yang ditunjukkan pada cawan petri isolat kontrol S. iniae. Zona lisis tersebut timbul akibat adanya faga yang memberikan proteksi terhadap S. iniae dan S. agalactiae. Zona lisis yang tidak jernih disebabkan konsentrasi faga yang terlalu rendah akibat dilakukan pengenceran pada proses filtrasi. Faga yang diperoleh selanjutnya akan dilakukan uji in vitro dan in vivo untuk mengetahui efektivitasnya.Streptococcal infection is a serious disease in fish caused by gram positive bacteria. The causative agent is Streptococcus b-hemolytic. Streptococcus iniae, a b-hemolytic bacterium is the main causative agent of septicemia, meningoencephalitis, and fish mortality. Moreover, the other causative agent is S. agalactiae. Bacteriophages which are viruses that live on bacteria can be selected and used as therapy for Streptococcosis. The aim of this research is to isolate bacteriophage of S. agalactiae as therapeutic agent candidate giving protecting effect for Streptococcosis. Phages was isolated from Brain Heart Infusion Agar (BHIA) were obtained from cultures of S. iniae and S. agalactiae. Strains S. iniae and S. agalactiae were isolated from Streptococcosis fish. The predominant types of colonies were subcultured and subjected to biochemical and physiological tests such as Gram staining, catalase test, hemolytic activity in blood agar and API 20 Strep System. Phages were isolated by using a double agar layer method. A zona lysis with plaques was removed from the plate, centrifuged and the supernatant was filtered through a 0.45 µm membrane filter and stored at 4oC. From 15 isolates of S. iniae and S. agalactiae, only one isolate PSaT-18 showed lysis zone. The lysis zone developed because the phages give protection to S. agalactiae. The lysis zone is not clear because the phage concentration is too low and the dilution in filtration process is too high. Later, these phages were used for invitro and invivo test.

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