I Made Samudra - Academia.edu (original) (raw)

Papers by I Made Samudra

Kitinase merupakan enzim yang menghidrolisis polimer kitin menjadi oligomer kitin atau monomer Na... more Kitinase merupakan enzim yang menghidrolisis polimer kitin menjadi oligomer kitin atau monomer Nasetilglukosamin. Penelitian ini bertujuan melakukan isolasi dan karakterisasi kitinase untuk memperoleh informasi aktivitas optimum kitinase asal B. cereus 11 UJ. Isolasi enzim kasar kitinase dan purifikasi parsial dilakukan dengan pengendapan amonium sulfat jenuh 70% dan dialisis menggunakan membran selofan, selanjutnya dikarakterisasi untuk memperoleh aktivitas optimum pada berbagai kondisi pH, suhu, waktu inkubasi, ion logam serta penentuan nilai Km dan Vmaks. Hasil penelitian menunjukkan pemurnian kitinase dengan amonium sulfat 70% dan dialisis menunjukkan tingkat kemurnian masing-masing 2.40 kali dan 5.23 kali dibandingkan dengan ekstrak kasar enzim. Hasil karakterisasi menunjukkan bahwa kitinase asal B. cereus isolat 11 UJ mempunyai pH optimum 8, suhu optimum 37oC, dan waktu inkubasi optimum selama 120 menit. Kation Mn2+, Fe2+, dan Cu2+ dengan konsentrasi 10 mM diketahui dapat berf...

JRST (Jurnal Riset Sains dan Teknologi), Sep 18, 2022

Phosporus (P) deficiency is one of limiting factor for rice growth. In Indonesia P deficiency muc... more Phosporus (P) deficiency is one of limiting factor for rice growth. In Indonesia P deficiency much occurs in acid soils. The use of P deficiency tolerant varieties is the best solution compared to the application of P fertilizer due to more efficient in cost. The purpose of this study was to evaluate the local rice germplasm collected from several regions in Indonesia to P deficiency in acid soil. The study was conducted in Jasinga West Java during wet season of 2006- 2007 with the soil condition lack of P. The experiments were conducted with the two treatments: first, without P fertilizer and second with P fertilizer equivalent of 25 kg P/ha. The total 100 accessions of rice germplasm were screened in this field based on a randomized block design with three replications. Fertilizing were given on experiments I and II with the composition: urea 300 kg/ha and 100 kg KCl. The field design was done by plotting size is 1 x 5 m2, spacing plant of 25 cm x 25 cm, and planting two seeds per...

Applied Entomology and Zoology, 1989

Applied Entomology and Zoology, 1991

Jurnal Penelitian Sains

Anthracnose disease caused by the fungus Colletotrichum gloeosporioides is one of the most import... more Anthracnose disease caused by the fungus Colletotrichum gloeosporioides is one of the most important diseases on fruit trees. Chitosan material have been applied to many different application fields including disease biocontrol because of its biocompatible and biodegradable effect. This research was aimed to synthesize low molecular weight chitosan (LMWC) which prepared via enzymatic process using a bacterium Burkholderia cepacia E76 and ionic gelation method, using sodium tripolyphosphate (NaTPP), and to test their activity against C. gloeosporioides on mangoes fruits. In this study the effect of concentration and volume ratio of LMWC : NaTPP was determined based on particle characteristics, i.e particle size, polydispersity index, zeta potential and FTIR structure. The results showed that LMWC could be synthesized by means of enzymatic hydrolysis using chitinase originated from B. cepacia E76. The optimal nanoparticle conditions was obtained by concentration of 0.3% LMWC, 0.1% TPP with volume ratio 5 : 1, stirring for 30-60 min incubation with the particle size of 126.2 nm and ZP value of 25.5 + 6.1 mV. LMWC and nano chitosan product could be evidenced by FTIR analysis. Nano chitosan could inhibit the growth of C. gloeosporioides ranging from 61.28-96% under in vitro test. The result of in vivo test on manggoes fruit cv Manalagi, showed that chitosan nano particle could effectively inhibit the growth of anthracnose (74.5%

Agrointek : Jurnal Teknologi Industri Pertanian

Silver (Ag) in ionic form is toxic to microbial cells, but is environmentally friendly and safe f... more Silver (Ag) in ionic form is toxic to microbial cells, but is environmentally friendly and safe for humans. This study aims to synthesize silver nanoparticles (AgNP) using Gram-positive bacterial isolate (B. firmus E65) as a bioreductor and to test its activity as an antimicrobial against Eschericia coli, Xanthomonas oryzae pv. oryzae (Xoo) and the fungus Colletotrichum gloeosporioides under in-vitro assays. AgNP was obtained by adding bacterial culture supernatant B. firmus E-65 to 5mM AgNO3 solution. The formation of AgNP was observed by changing the color of the solution after incubation at 37 °C for 72 hours. The UV-Vis spectrophotometer measurement to AgNP solution showed a maximum wavelength of 425 nm. The particle size of AgNP was 252.1 nm with intensity of 98.90 %. The result of bioassay against E. coli showed the greatest inhibition at 50 % AgNP (degree of inhibition (DI) =96.15 %), followed by 25 % AgNP (DI=76.92 %), and 12.5 % AgNP (DI=53.84 %). The bioassay against Xoo showed the greatest degree of inhibition was at AgNP 50 % (DI=92.85 %), followed by 25 % AgNP and 12.5 % AgNP (DI=85.71 %). Meanwhile bioassay against C.gloeosporioides, the greatest inhibition was observed at 25 % AgNP (DI=94.35 %), followed by 50 % AgNP (DI=91.9 %).

Biota : Jurnal Ilmiah Ilmu-Ilmu Hayati, 2010

Sel ataupun supernatan bebas sel dari kultur cair isolat bakteri entomopatogen PRU8 memiliki toks... more Sel ataupun supernatan bebas sel dari kultur cair isolat bakteri entomopatogen PRU8 memiliki toksisitas tinggi terhadap larva Tenebrio molitor. Bioesei protein ekstrasel kasar hasil pengendapan amonium sulfat menunjukkan bahwa toksisitas tertinggi terdapat pada protein yang diendapkan pada kejenuhan amonium sulfat 70%. Pemurnian protein menggunakan kolom Hi Prep 16/60 Sephacryl S-200 HR menghasilkan satu fraksi protein toksin. Mortalitas larva uji yang disuntik dengan 19,2 nanogram toksin murni mencapai 71%. Uji toksisitas menggunakan toksin murni menunjukkan bahwa toksin tersebut termasuk kelompok toksin tipe injeksi. Berdasarkan analisa SDS-PAGE toksin tersebut tersusun atas dua protein dengan berat molekul 116,25 dan 66,24 kDa

Jurnal AgroBiogen, 2018

Bioremediation is an inexpensive, easy, and safe technology to rehabilitate agricultural land whi... more Bioremediation is an inexpensive, easy, and safe technology to rehabilitate agricultural land which is highly polluted with pesticides. The aims of this study were to isolate and characterize profenofos degrading bacteria isolated from Pangalengan soils. The isolation step was carried out by using spread plate method on Nitrate Mineral Salts (NMS) medium containing 100 ppm profenofos. The isolates were selected based on hypersensitive response (HR) and hemolytic test, and ability of the isolates to use and degrade profenofos. The selected isolates were characterized based on the sequence of 16 rRNA and detection of the α and β subunits of terminal deoxygenase and naphtalene dioxygenase encoded genes. Three isolates (CN26, CN44, and CN86), which could use profenofos as the exclusive C source, could degrade more than 86.75% profenofos containing growth medium. Based on the 16S rRNA sequences, the three isolates were closely related to Stenotrophomonas maltophilia (99%), Comamonas terr...

Buletin Plasma Nutfah, 2020

Wilt disease caused by Fusarium spp. is a major disease in shallot-producing areas particularly i... more Wilt disease caused by Fusarium spp. is a major disease in shallot-producing areas particularly in the North Coast of West Java. The research was aimed to select rhizosphere bacteria and develop an antagonistic bacterial-based formulation for its effectiveness to suppress wilt disease caused by Fusarium spp. on shallot plant under greenhouse and field trials. The field trials were carried out using randomized complete block design with four replications at the shallot farmer condition in Subang and Indramayu during the 2019 planting season. Antagonistic test of bacterial isolates from the rhizosphere showed that most of the bacterial isolates can be used as a biocontrol to Fusarium spp. pathogen. The result revealed that bacterial suspension formulation (E-76 + DBS-2 isolates) in combination with phytohormone (1:1 [v/v]) at Subang and Indramayu tended to suppress Fusarium wilt disease intensity with the disease inhibition ranging from 73.54–93.39% and 66.3–95.65%, respectively. The ...

Jurnal AgroBiogen, 2016

is one of the entomopathogenic fungus that produces chitinase when infecting its host. This study... more is one of the entomopathogenic fungus that produces chitinase when infecting its host. This study was aimed to purify, isolate and characterize chitinase of B. bassiana isolate BB200109. Pathogen identity was determined both morphologically and molecularly using ITS primer, whilst characterization was done at various conditions i.e. temperature, pH, metal ion and incubation time. Results showed that the BB200109 isolate belonged to B. bassiana. The isolate produced extracellular chitinase with chitinolytic index of 1.035. Partial purification of three saturated ammonium sulphate precipitation (10, 30, and 70%) showed maximum purity of 1.2 times, while dialysis could increase the purity of 1.9 times compared to that of crude enzyme extract. Characterization results showed that the chitinase isolated from B. bassiana isolate BB200109 had an optimum activity at pH 4, temperature 50 o C, and optimum incubation time of 90 minutes. The effect of metal ions (60 mM) Mn 2+ served as activator, while EDTA, K + , Mg 2+ , Cu 2+ , Fe 2+ , Zn 2+ , and Na + acted as inhibitors. The chitinase demonstrated lower affinity to chitin substrate as indicated by high K m value of 0.266 mg/l and a V max of 0.067 mg/l sec. Based on SDS-PAGE, chitinase from B. bassiana isolate BB200109 had molecular weight of 60.25 kDa. The study implied the potency of B. bassiana isolate BB200109 as extracellular chitinase producer with its enzyme charateristics seems to be developed as an insect biocontrol agent.

Bioeksperimen: Jurnal Penelitian Biologi

日本環境感染学会誌, 2009

Dispersal evolves as an adaptive mechanism to optimize individual fitness across the landscape. S... more Dispersal evolves as an adaptive mechanism to optimize individual fitness across the landscape. Specifically, dispersal represents a mechanism to escape fitness costs resulting from changes in environmental conditions. Decades of empirical work suggest that individuals use local habitat cues to make movement decisions, but theory predicts that dispersal can also evolve as a fixed trait, independent of local conditions, in environments characterized by a history of stochastic spatiotemporal variation. Until now, however, both conditional and fixed models of dispersal evolution have primarily been evaluated using emigration data (stay vs. leave), and not dispersal distances: a more comprehensive measure of dispersal. Our goal was to test whether conditional or fixed models of dispersal evolution predict variation in dispersal distance in the stream salamander Gyrinophilus porphyriticus. We quantified variation in habitat conditions using measures of salamander performance from 4 yr of spatially explicit, capture-mark-recapture (CMR) data across three headwater streams in the Hubbard Brook Experimental Forest in central New Hampshire, USA. We used body condition as an index of local habitat quality that individuals may use to make dispersal decisions, and survival probability estimated from multistate CMR models as an index of mortality risk resulting from the long-term history of environmental variation. We found that dispersal distances increased with declining survival probability, indicating that salamanders disperse further in risky environments. Dispersal distances were unrelated to spatial variation in body condition, suggesting that salamanders do not base dispersal distance decisions on local habitat quality. Our study provides the first empirical support for fixed models of dispersal evolution, which predict that dispersal evolves in response to a history of spatiotemporal environmental variation, rather than as a conditional response to current habitat conditions. More broadly, this study underscores the value of assessing alternative scales of environmental variation to gain a more complete and balanced understanding of dispersal evolution.

Nucleation and Atmospheric Aerosols, 2022

Penyakit hawar daun bakteri (HDB) yang disebabkan oleh Xanthomonas oryzae pv oryzae (Xoo) telah d... more Penyakit hawar daun bakteri (HDB) yang disebabkan oleh Xanthomonas oryzae pv oryzae (Xoo) telah diketahui sejak lama merupakan penyakit bakteri utama terjadi di banyak negara-negara penghasil padi. Penelitian ini dilakukan untuk mengetahui pengaruh bakteri endofit yang diformulasikan berbahan dasar talek terhadap pengendalian hayati Xoo di agroekosistem padi berbasis sistem intensifikasi padi (SRI)-organik di Cianjur-Jawa Barat. Formulasi berbahan dasar talek disiapkan mengandung bakteri endofit Bacillus firmus (isolat E65) yang sebelumnya diisolasi dari padi sawah. Penekanan penyakit HDB berkisar 2,14% sampai 97,15%. Di antara kultivar yang diuji, rata-rata tingkat keparahan HDB di antara enam kultivar adalah 9,79%. Kultivar Inpari 10 (Sedang) menunjukkan tingkat keparahan penyakit yang paling rendah dibandingkan dengan yang tahan (cv. Sintanur, Mekongga dan Code). Hal ini menunjukkan bahwa efikasi biokontrol B. firmus E65 berbasis talek tidak dipengaruhi oleh kerentanan kultivar. Formulasi bakteri antagonis meningkatkan hasil hingga 9%. Hasil tertinggi untuk masing-masing perlakuan dengan formulasi bakteri berbasis talek diperoleh pada cv. Inpari 10 dan Cisantana. Untuk skala produksi yang dapat memperpanjang aktivitas biokontrol, kendala yang mungkin terjadi adalah umur simpan formulasi. Kajian ini menunjukkan keuntungan dari kultur tunggal bakteri antagonis yang

Kitinase mampu menghidrolisis kitin dan berpotensi sebagai agen biokontrol. Tujuan penelitian ada... more Kitinase mampu menghidrolisis kitin dan berpotensi sebagai agen biokontrol. Tujuan penelitian adalah memurnikan dan mengkarakterisasi kitinase dari isolat terpilih, serta menentukan kemampuan kitinolitiknya dalam penghambatan jamur Colletotrichum sp. Aktivitas kitinase ditentukan dengan metode Spindler, sementara kadar protein ditentukan dengan metode Bradford. Produksi kitinase isolat rizobakteri (isolat C5C) menunjukkan aktivitas enzim spesifik tertinggi sebesar 0.0489 U/mg melalui pemurnian parsial NH 4 SO 4 70%, serta dapat meningkatkan kemurnian 13.97 kali dibandingkan ekstrak kasar. Karakterisasi kitinase isolat C5C menunjukkan bahwa enzim aktif optimal pada suhu 55°C, pH 7, waktu inkubasi 120 menit, serta memiliki nilai K m sebesar 1.300 x 10 3 mg/L dan V maks sebesar 0.0294 mgL -1 detik -1 . Aktivitas antifungi pada uji in vitro menunjukkan bahwa isolat C5C dapat menghambat pertumbuhan Colletotrichum sp. Kata kunci: biokontrol, Colletotrichum sp., kitinase, rizobakteri