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Abstrak :
Penelitian bertujuan mengetahui keanekaragaman bakteri Ktedonobacteria dari sampel tanah hutan di sekitar Geiser Cisolok, Jawa Barat dengan metode culture-dependent dan metode culture-independent. Isolasi bakteri menggunakan medium Reasoner's 2A (10%) dengan penambahan 2% gellan gum, cycloheximide, dan sodium azide. Inkubasi dilakukan pada suhu 30 oC selama 3 minggu. Amplifikasi gen 16S rRNA isolat bakteri menggunakan primer spesifik Ktedonobacteria (primer 161F dan 941R), dan primer universal bakteri (9F dan 1510R). Identitas isolat bakteri diperoleh berdasarkan data full sequence gen 16S rRNA melalui pencarian homologi pada EZBioCloud (www.ezbiocloud.net). Analisis filogenetik menggunakan metode Neighbour Joining, Maximum Evolution, dan Maximum Likelihood. Analisis keanekaragaman bakteri Ktedonobacteria menggunakan Next Generation Sequencing berdasarkan data partial sequence (daerah variabel V1--V3) dari gen 16S rRNA. Analisis data komposisi taksonomi bakteri dan indeks keanekaragaman menggunakan software QIIME2. Empat isolat Ktedonobacteria dengan kode K17-1, K17-2, K42, dan K44 berhasil diperoleh. Analisis filogenetik menunjukkan bahwa keseluruhan isolat merupakan anggota kelas Ktedonobacteria dan berada dalam satu grup dengan type strain Dictyobacter aurantiacus S-27T. Namun demikian, persentase homologi sequence gen 16S rRNA keempat isolat menunjukkan nilai yang rendah terhadap type strain Dictyobacter aurantiacus S-27T, yaitu 97.16 -- 98.02%. Berdasarkan nilai tersebut, keempat isolat yang diperoleh diduga merupakan spesies baru. Hasil analisis dengan software QIIME2 menunjukkan bahwa sampel tanah yang digunakan memiliki nilai indeks keanekaragaman bakteri yang tinggi, dengan nilai sebagai berikut: 6,49 (Shannon-Winner); 0,98 (Simpson); 177 (Chao1); dan 117 (Ace). Filum Acidobacteria, Proteobacteria dan Bacteriodetes, merupakan tiga filum dengan persentase paling besar pada sampel tanah, dengan nilai persentase masing-masing 44%, 25%, dan 9%. Kelas Ktedonobacteria pada filum Chloroflexi memiliki persentase yang sangat rendah, yaitu 1,89%. Namun demikian, analisis filogenetik data amplikon (culture-independent) menunjukkan bahwa Ktedonobacteria yang terdapat pada sampel tanah tersebar dalam 5 grup, yang seluruhnya mengindikasikan taksa baru. Penelitian ini menunjukkan bahwa metode culture-dependent hanya berhasil menemukan satu dari lima grup Ktedonobacteria yang berhasil dideteksi menggunakan metode culture-independent. ......The study aims to determine the diversity of Ktedonobacteria from forest soil samples around the Cisolok Geiser, West Java with culture-dependent and culture-independent methods. Bacterial isolation using Reasoner's 2A (10%) medium with 2% gellan gum, cycloheximide, and sodium azide. Incubation was carried out at 30 oC for three weeks. Amplification of 16S rRNA gene of bacterial isolates performed using Ktedonobacteria specific primers (primers 161F and 941R), and universal bacterial primers (9F and 1510R). The identity of bacterial isolates was obtained based on full 16S rRNA gene sequence data through a homology search on EZBioCloud (www.ezbiocloud.net). The phylogenetic analysis was performed by Neighbor-Joining, Maximum Evolution, and Maximum Likelihood methods. Analysis of Ktedonobacteria diversity using Next-Generation Sequencing based on partial sequence data (variable regions V1 -- V3) of the 16S rRNA gene. Analysis of bacterial taxonomy composition data and diversity index was conducted using QIIME2 software. Four isolates of Ktedonobacteria, namely K17-1, K17-2, K42, and K44, were successfully obtained. Phylogenetic analysis showed that all isolates were members of the class Ktedonobacteria and were in the same group as Dictyobacter aurantiacus S-27T. However, the percentage of homology of the 16S rRNA gene sequence of the four isolates showed a low value on the type strain of Dictyobacter aurantiacus S-27T, which accounted for 97.16 -- 98.02%. Based on these values, the four isolates obtained probably belonged to the new species. The results of the analysis with QIIME2 software showed that the soil samples had high bacterial diversity index values, with the following values: 6,49 (Shannon-Winner); 0,98 (Simpson); 177 (Chao1); and 117 (Ace). Phylum Acidobacteria, Proteobacteria, and Bacteriodetes are the three phyla with the largest percentage in soil samples, with percentage values of 44%, 25%, and 9%, respectively. Whereas the class Ktedonobacteria in the phylum Chloroflexi has a very low percentage, which is 1.89%. However, phylogenetic analysis of the amplicon data (culture-independent) showed that Ktedonobacteria found in soil samples distributed into five groups, indicating new taxa. In this study, culture-dependent methods found only one of the five groups of Ktedonobacteria that detected using the culture-independent method.

Abstrak :
ABSTRAK
Indonesia terletak di antara pertemuan tiga lempeng tektonik yang saling berinteraksi. Kondisi ini menyebabkan Indonesia menjadi salah satu daerah yang rawan bencana geologi, salah satunya adalah gerakan tanah. Daerah yang paling rawan mengalami gerakan tanah adalah dataran tinggi dengan kemiringan lereng yang terjal, salah satunya berada di kabupaten Cianjur, Jawa Barat. Melihat potensi rawannya bencana geologi yang dapat terjadi, terutama gerakan tanah, maka perlu dilakukan penelitian untuk mengetahui posisi bidang gelincir dari longsoran, serta bagaimana kondisi kestabilan lereng di daerah penelitian tersebut. Metode geofisika digunakan untuk memperoleh informasi akurat mengenai posisi bidang gelincir tersebut, yang didukung oleh data mekanika tanah hasil pengujian sampel tanah dan batuan. Sampel tanah dan batuan diambil menggunakan bor tangan (hand auger), yang kemudian diuji di laboratorium mekanika tanah. Hasil pengujian berupa data mekanika tanah kemudian digunakan dalam analisis kestabilan lereng. Data yang diperoleh menunjukan terdapat lapisan dengan nilai resistivitas tinggi, dengan lapisan di bawahnya memiliki resistivitas yang lebih rendah sekitar 2 ? 20 Ω m. Berdasarkan hasil uji laboratorium, nilai resistivitas rendah mengindikasikan dominasi dari material pasir. Lapisan dengan nilai resistivitas lebih tinggi mengindikasikan dominasi dari lempung dan lanau. Bidang gelincir longsor dapat terlihat, yang merupakan batas antara lapisan permeable dengan lapisan impermeable. Peningkatan curah hujan yang terjadi di daerah penelitian dapat menyebabkan lapisan permeable menjadi jenuh, sehingga menurunkan tingkat stabilitas lereng. Penurunan tingkat stabilitas lereng akan menurunkan nilai faktor keamanan lereng, sehingga kondisi lereng yang kritis akan menyebabkan lapisan jenuh mengalir, dan terjadinya longsoran.

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ABSTRAK
Indonesia is located between three tectonic plates which were actively interacting with each other. This condition has caused Indonesia to become vulnerable to the geological disaster, one of which is land movement. The most critical area for land movement occurrence is the highland with steep hillside; one of which is at Cianjur region, West Java. Looking at the critical potential of the geological disaster that could happen, especially the land movement, it?s important to study the position of the slip surface of the landslide, and how the slope stability conditions in the study area. Geophysics methods are used to collect accurate information about the position of the slip surface, and is supported by the soil mechanics data - results of sample testing of soil and rock. Soil and rock samples were taken using hand auger, which is then tested in a soil mechanics laboratory. Results of the test are in the form of data of soil mechanics, which then used in the slope stability analysis. In addition, resistivity geophysical method is used to determine the geometry and the depth of slip surface. Data from 2-D electrical resistivity tomography (ERT) shows a layer of resistivity clayey/silty materials with high resistivity value dominate the shallow subsurface of the area; while a low resistivity sandy materials with resistivity less than 20 Ω m dominate the deep subsurface of the area. According to the laboratory testing, low resistivity indicates a sandy material domination, while a high resistivity indicates a clay and silt domination. We can determine if there is a slip surface, which is the threshold between the permeable layer and the impermeable layer. With increased rainfall level, the ground becomes over-saturated - decrease the slope instability in the area, caused this over-saturated materials to flow, leading to the landslide.