Judul: Selection of probiotic bacteria for controlling vibriosis on tiger grouper (Epinephelus fuscoguttatus)
Abstrak: Vibriosis is a bacterial disease affecting farmed fish including grouper. Disease control usually uses antibiotic but can lead to ecological inbalance and antibioticresistant pathogens. The use of probiotic bacteria is one of the methods in aquaculture that is used to control infectious diseases. The aims of this study were to obtain and isolate pathogenic Vibrio in the tiger grouper, to select bacterial probiotic candidates in controlling vibriosis, to evaluate efficacy of probiotic bacterial administration in controlling vibriosis in tiger grouper fry, and to evaluate probiotic bacterial candidates in enhancing immune responses. The first step was isolation and characterization of pathogenic bacteria as causative agent of vibriosis on grouper. Secondly, selection of probiotic candidate bacteria was conducted from the coral reef and tiger grouper fish farming environment including isolation of probiotic candidates, selection of probiotic candidates using inhibition test, co-culture method, and pathogenicity test of selected probiotic candidates. The third and fourth steps were administration of probiotic candidate bacteria on tiger grouper fry and juvenile, respectively, on feed for 28 days, and challenge test was performed at day-29. The result indicated that V6 isolate was the most pathogenic among isolates. Moreover, from 124 isolates, based on selection of probiotic candidates bacteria using inhibition zone and co-culture methods, there were found four potential isolates namely K7, K8, K21, T41, and K15, K55, K68, T36, respectively. Four isolates, namely K7, K8, T36 and T41, had high survival rate of fish in pathogenicity test. Furthermore, T36 isolate may decrease pathogenic Vibrio population, increase immune response, survival rate and growth rate of tiger grouper. According to gene sequencing analysis using 16S-rRNA, V6 dan T36 were Vibrio parahaemolyticus and Bacillus cereus, respectively.
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Judul: : Seleksi Bakteri Kandidat Probiotik Potensial Asal Air Laut dan  Sedimen Tambak Udang sebagai Penghambat Vibrio  parahaemolyticus
Abstrak: Vibrio parahaemolyticus merupakan salah satu bakteri patogen penyebab penyakit vibriosis. V. parahaemolyticus strain tertentu yang mengekspresikan toksin PirA dan PirB merupakan penyebab utama penyakit Acute Hepatopancreatic Necrosis Disease pada udang. Upaya pencegahan infeksi bakteri pada udang yaitu melalui aplikasi probiotik dengan diawali proses seleksi kandidat probotik potensial. Penelitian ini bertujuan mendapatkan isolat dan melakukan karakterisasi bakteri probiotik potensial yang berasal dari air laut dan sedimen tambak sebagai upaya penghambat V. parahaemolyticus. Penelitian dilakukan secara eksperimental menggunakan Rancangan Acak Lengkap (RAL) dengan 3 perlakuan dan 2 ulangan pada uji antagonistik in vitro (kultur bersama) dan uji non patogenisitas. Hasil penelitian berhasil mendapatkan 37 isolat kandidat probiotik dengan 10 isolat memiliki aktivitas enzim terbesar. Uji antagonistik in vitro dengan metode Kirby-Bauer dan uji kultur bersama didapatkan 2 isolat terbaik dengan kode LAZ-2 dan SAZ-22. LAZ-2 dan SAZ 22 merupakan bakteri kandidat probiotik terpilih yang memiliki aktivitas enzimatik, mampu menghambat pertumbuhan bakteri patogen V. parahaemolyticus serta tidak bersifat patogen terhadap udang vaname., Vibrio parahaemolyticus is one of the pathogenic bacteria that cause vibriosis. V. parahaemolyticus strain that express the PirA and PirB toxin is the main causative agent of Acute Hepatopancreatic Necrosis Disease in shrimp. The effort to prevent bacterial infections in shrimp is through the application of probiotics, which begins with the process of screening for potential probiotic candidates. This study aims to obtain isolates and characterize the potential probiotic bacteria isolated from seawater and pond sediments as an inhibition effort V. parahaemolyticus. The study was carried out experimentally using a completely randomized design (CRD) with 3 treatments and 2 replications in an antagonistic test (co culture) and in the non-pathogenicity test. The results of the study succeeded in obtaining 37 probiotic candidate isolates with 10 isolates having the greatest enzyme activity. Antagonistic test in vitro with the Kirby Bauer method and co-culture, the 2 best isolates with the LAZ-2 and SAZ-22 codes. LAZ-2 and SAZ-22 are selected probiotic candidates have enzymatic activity, capable of inhibiting the growth of V. parahaemolyticus and are not pathogenic to vannamei shrimp.
Keyword: probiotic, vannamei shrimp, Vibrio parahaemolyticus

Judul: Analisis keamanan konstruksi fungsi hash berbasis sandi blok kunci simetrik (Kajian Teoritik)
Abstrak: Hash function is used to secure the integrity and authenticity of a massege, so that the message is save. The message which will be secured, will be attached to hash/message digest/digital signature value fro, the message. A secure hash function is the one which has pre-image resistance, 2nd pre-image resistance and collision resistance. Hash function has been classified into hash keyed function (Message Authentication Codes/MAC) and unkeyed (Modification Detection Codes/MDC)
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