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Isolasi dan Kolonisasi Mikoriza Vesikula Arbuskular (MVA) pada Perakaranan Tanaman Jagung (Zea mays L.) di Lahan Kering Kabupaten Timor Tengah Utara
Full text linkNorth Central Timor (TTU) Regency has adry land area for agriculture of 184,421 Ha. Unfortunately, the dry land is known to have low soil fertility. One of alternatives to overcome this problem is to utilize a fungus that has mutualism symbiosis with plant roots, namely vesicular arbuscular mycorrhiza (VAM).This study aims to discover spore character and VAM type, as well as discover the percentage level of VAM colonization on maize roots (Zea mays L.). Samples of soil and maize roots were taken from Fatuneno Village and Bitefa Village using the stratified random sampling method. The isolation of VAM spores was conductedthrough stratified screening method. The microscopic characteristics of the spores were matched with the identification guidelines on the INVAM.com website. Root colonization was seen based on the percentage of root infection by the VAM structure. The results showed that the number of VAM spores per 100 grams of soil from Fatuneno Village was 247 spores and from Bitefa Village was 209 spores. Identification results generated three types of VAM genus, namely Glomus, Acaulospora and Gigaspora. The observations of VAM colonization on the maize roots from Fatuneno Village when the maize was 2 weeks old showed the percentage of 50% with medium category, and when the maize was 4 weeks old the percentage of colonization was 73.3% with high category. In Bitefa Village, the percentage of VAM colonization in maize of 2weeks old was 25% with low category, while when it was 4 weeks old, the percentage of VAM colonization was 33% with medium category.Kabupaten Timor Tengah Utara (TTU) memiliki luas lahan kering untuk pertanian yaitu 184.421 Ha. Masalahnya, lahan kering diketahui memiliki kesuburan tanah rendah. Salah satu alternatif untuk mengatasi permasalahan tersebut adalah memanfaatkan fungi yang bersimbiosis mutualisme dengan akar tanaman yaitu mikoriza vesikular arbuskular (MVA). Penelitian ini bertujuan untuk mengetahui karakter spora dan jenis MVA, serta mengetahui tingkat persentase kolonisasi MVA pada perakaran tanaman jagung (Zea mays L.). Sampel tanah dan akar tanaman jagung diambil dari Desa Fatuneno dan Desa Bitefa dengan metode strata (Stratified random sampling). Isolasi spora MVA dengan metode penyaringan bertingkat. Ciri mikroskopis spora dicocokkan dengan pedoman identifikasi pada website INVAM.com. Kolonisasi perakaran dilihat berdasarkan persentase infeksi perakaran oleh struktur MVA. Hasil penelitian diketahui jumlah spora MVA per 100 gram tanah dari Desa Fatuneno yaitu 247 spora dan Desa Bitefa 209 spora. Hasil identifikasi didapatkan tiga jenis genus MVA yaitu Glomus, Acaulospora dan Gigaspora. Hasil pengamatan kolonisasi MVA pada akar tanaman jagung dari Desa Fatuneno pada saat jagung berumur 2 minggu diketahui persentasenya sebesar 50% dengan kategori sedang, dan saat jagung berumur 4 minggu persentase kolonisasi sebesar 73,3% kategori tinggi. Di Desa Bitefa persentase kolonisasi MVA pada jagung berumur 2 minggu sebesar 25% dengan kategori rendah, sedangkan saat berumur 4 minggu persentase kolonisasi MVA sebesar 33% dengan kategori sedang
Pertumbuhan Fusarium verticillioides, Aspergillus flavus, dan Eurotium chevalieri pada Berbagai Media
Full text linkFusarium verticillioides, Aspergillus flavus, dan Eurotium chevalieri merupakan cendawan perusak bahan pangan yang ditemukan pada saat bahan pangan belum dipanen atau setelah bahan pangan dipanen. Pertumbuhan ketiga cendawan ini sangat dipengaruhi oleh nutrisi yang terkandung pada media tumbuh. Penelitian ini bertujuan untuk membandingkan pertumbuhan Fusarium verticillioides, Aspergillus flavus, dan Eurotium chevalieri pada beberapa media untuk isolasi dan identifikasi. Ketiga cendawan tersebut ditumbuhkan pada media yang berbeda yaitu Chloramphenicol Peptone Agar (DCPA), Dichloran 18% Glycerol Agar (DG18), Czapek Yeast Extract Agar (CYA), Czapek Yeast Extract Agar 20% Sucrose (CY20S), Malt Extract Agar (MEA), dan 25% Glycerol Nitrate Agar (G25N) dan diinkubasi pada suhu + 280C. Pengamatan koloni dilakukan setiap 2 x 24 jam, 4 x 24 jam, dan 6 x 24 jam selanjutnya diameter isolat diukur. Hasil isolasi pertumbuhan dan panjang diameter koloni dari A. Flavus (61 mm) dan E. Chevalieri (45mm) diketahui dapat tumbuh baik pada media DG18, sedangkan F. verticillioides (46 mm) tumbuh baik di media DCPA. Sementara pada media identifikasi A. Flavus (80 mm) dapat tumbuh baik pada media CY20S, sedangkan E. Chevalieri (40 mm) dapat tumbuh baik pada media G25N dan CY20S. Koloni F. verticillioides (62 mm) dapat tumbuh baik di media CYA dan CY20S. Fusarium verticillioides, Aspergillus flavus, dan Eurotium chevalieri merupakan cendawan perusak bahan pangan yang ditemukan pada saat bahan pangan belum dipanen atau setelah bahan pangan dipanen. Pertumbuhan ketiga cendawan ini sangat dipengaruhi oleh nutrisi yang terkandung pada media tumbuh. Penelitian ini bertujuan untuk membandingkan pertumbuhan Fusarium verticillioides, Aspergillus flavus, dan Eurotium chevalieri pada beberapa media untuk isolasi dan identifikasi. Ketiga cendawan tersebut ditumbuhkan pada media yang berbeda yaitu Chloramphenicol Peptone Agar (DCPA), Dichloran 18% Glycerol Agar (DG18), Czapek Yeast Extract Agar (CYA), Czapek Yeast Extract Agar 20% Sucrose (CY20S), Malt Extract Agar (MEA), dan 25% Glycerol Nitrate Agar (G25N) dan diinkubasi pada suhu + 280C. Pengamatan koloni dilakukan setiap 2 x 24 jam, 4 x 24 jam, dan 6 x 24 jam selanjutnya diameter isolat diukur. Hasil isolasi pertumbuhan dan panjang diameter koloni dari A. Flavus (61 mm) dan E. Chevalieri (45mm) diketahui dapat tumbuh baik pada media DG18, sedangkan F. verticillioides (46 mm) tumbuh baik di media DCPA. Sementara pada media identifikasi A. Flavus (80 mm) dapat tumbuh baik pada media CY20S, sedangkan E. Chevalieri (40 mm) dapat tumbuh baik pada media G25N dan CY20S. Koloni F. verticillioides (62 mm) dapat tumbuh baik di media CYA dan CY20S. 
ISOLASI DAN PENAPISAN AKTINOMISET PENGHASIL SENYAWA ANTIMOKROB ISOLATION AND SCREENING AKTINOMISETES TO PRODUCE ANTIMICROBIAL COMPOUNDS
No full textTelah dilakukan isolasi dan penapisan aktinomiset yang mampu menghasilkan senyawa antimikroba. Isolasi dan penapisan dilakukan di laboratorium Mikrobiologi Institut Pertanian Bogor (IPB). Isolasi dilakukan dengan metode pengenceran berseri dan disebar pada media HV agar. Dari hasil isolasi diperoleh total isolat sebanyak 6 isolat. Setelah dilakukan penapisan diperoleh 3 isolat yang mampu menghambat bakteri patogen E. coli, S. aureus, dan cendawan patogen Aspergillus sp, Penicillium sp, dan Fusarium sp. Hasil uji antagonis isolat AK1 mampu menghambat E. coli dengan indek zona hambat tertinggi yaitu 1.3 cm. Sedangkan uji antagonis terhadap cendawan patogen isolat AK2 mampu menghambat Penicillium sp dengan indek zona hambat tertinggi yaitu 1.7 cm. Isolat AK1 dan AK2 merupakan isolat yang potensial sebagai penghasil senyawa antimikrob. Hasil identifikasi koloni, isolat AK1 warna koloninya kuning putih dengan karakteristi koloni rata dan tidak berlendir. Sedangkan isolat AK2 warna koloninya putih gelap dengan karakteristik koloninya rata dan tidak berlendir.
Kata kunci: Aktinomiset, penapisan, antibiotik, mikroba patoge
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Eksplorasi Bakteri Endofit Dari Jahe Merah (Zingiber officinalevar. Rubrum) Asal Pulau Timor
Full text linkGinger (Zingiber officinale) is one of the plants of the zingiberaceae family that grows evenly on the island of Timor. The condition of the island of Timor with a long dry season (± 8 months) resulted in the condition of the plants being in a state of drought stress. The purpose of this study was to obtain endophytic bacteria from ginger plants and to identify macroscopically, and test the endophytic bacterial antagonists as producing antibiotics. Samples were obtained from North Central Timor District (TTU), especially from Naibenu District, Kefamenanu City District, and West Miomaffo District. Bacterial isolation method used is the method of spreading and planting on petri dishes using Nutrient Agar (NA) media. While the test of antibiotic-producing activity is seen from the formation of inhibitory zones around the colony. The results of isolation of endophytic bacteria in ginger plants obtained 14 isolates that have the potential to produce antibiotics. Antagonist test results showed that endophytic bacterial isolates were able to inhibit the growth of Staphylococus aureus bacteria with the highest inhibitory zone diameter, namely from JMKBD3 isolates of 2.66 mm. Morphological identification of JMKBD3 isolate colonies is known that irregular colony shape, undulate edge, flat elevation, and white colony color.Jahe (Zingiber officinale) merupakan salah satu tanaman dari famili zingiberaceae yang tumbuh tersebar secara merata di Pulau Timor. Kondisi pulau Timor dengan musim kering yang panjang (± 8 bulan) mengakibatkan kondisi tanaman berada dalam keadaan cekaman kekeringan. Tujuan penelitian ini untuk mendapatkan bakteri endofit asal tanaman jahe dan mengidentifikasi secara makroskopis, dan uji antagonis bakteri endofit sebagai penghasil antibiotik. Sampel diperoleh dari Kabupaten Timor Tengah Utara (TTU) kususnya dari Kecamatan Naibenu, Kecamatan Kota Kefamenanu, dan Kecamatan Miomaffo Barat. Metode isolasi bakteri yang digunakan yaitu metode penyebaran dan penanaman pada cawan petri menggunakan media Nutrient Agar (NA). Sedangkan uji aktivitas penghasil antibiotik dilihat dari pembentukan zona hambat disekitar koloni. Hasil isolasi bakteri endofit pada tanaman jahe diperoleh 14 isolat yang berpotensi sebagai penghasil antibiotik. Hasil uji antagonis menunjukkan bahwa isolat bakteri endofit mampu menghambat pertumbuhan bakteri Staphylococus aureus dengan diameter zona hambat tertinggi yaitu dari isolat JMKBD3 sebesar 2.66 mm. Identifikasi morfologi koloni isolat JMKBD3 diketahui bahwa bentuk koloni irregular, tepi undulate, elevasi flat, dan warna koloni putih
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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