Judul: Endophytic Microbiota Profile of Freshly-Consumed Vegetables of Pohpohan Leaf (Pilea melastomoides (Poir.) Wedd.) Based on Metagenomic Analysis
Abstrak: Penelitian terbaru menunjukkan bahwa sayuran segar merupakan habitat utama komunitas bakteri endofit. Di Indonesia, beberapa tanaman tropis dikonsumsi segar tanpa melalui proses memasak, sehingga dapat menimbulkan kekhawatiran terhadap kesehatan manusia dan kesadaran keamanan pangan. Pilea melastomoides merupakan makanan etnik tradisional yang dikenal dengan Traditional and Etnic Food (TEF) dan dimanfaatkan oleh masyarakat Sunda di Indonesia sebagai sayuran untuk dikonsumsi segar. Tanaman ini dapat tumbuh secara liar dan dibudidayakan dengan standar pertanian, sehingga menimbulkan pertanyaan mengenai komunitas bakteri endofit diantara kedua jenis sistem tanam tersebut. Oleh karena itu, penelitian ini bertujuan untuk menyelidiki profil komunitas bakteri pada P. melastomoides liar dan budidaya berdasarkan pendekatan metagenomik dengan menargetkan gen 16S rRNA. Sampel daun P. melastomoides diperoleh dari kawasan hutan Taman Nasional Gunung Halimun Salak, Kabupaten Bogor, Jawa Barat. Teknik pengambilan sampel dilakukan secara cluster random sampling yang terbagi menjadi tiga petak. Metode pengumpulan sampel dilakukan menggunakan sample pooling pada masing-masing petak, yaitu dengan menggabungkan atau mencampur 10 sampel daun hasil ekstraksi P. melastomoides budidaya dan liar, masing-masing kedalam satu tabung (pool) untuk dilakukan pengujian sebagai sampel tunggal. Selanjutnya, sampel hasil ekstraksi DNA diamplifikasi melalui teknik PCR dengan target daerah amplifikasi V3-V4 menggunakan dua primer universal bakteri yaitu primer 341F dan primer 806R. Konstruksi library (perpustakaan) dilakukan untuk mempersiapkan sampel metagenom sebelum dilakukan sekuensing meliputi proses fragmentasi DNA, end conversion, adapter ligation, cleanup of adapter-ligated, library amplification, dan library quantitation. Kemudian perpustakaan metagenom diurutkan pada platform pair-end sequencing Illumina NovaSeq 6000 (2×250 bp). Data mentah hasil sekuensing (RawPE) dilakukan analisis bioinformatika. Analisis data mengungkapkan sampel daun pohpohan budidaya mempunyai keanekaragaman bakteri endofit tertinggi, ditunjukkan melalui indeks keanekaragaman dengan kekayaan jenis berdasarkan indeks Chao1 (0,0244), indeks Shannon (0,0291), dan kemerataan jenis berdasarkan indeks Pielou (0,0282). Filum yang paling melimpah adalah filum Firmicutes dan Proteobacteria. Beberapa bakteri endofit spesifik pada tanaman budidaya teridentifikasi sebagai Limosilactobacillus (5,38%), Escherichia/Shigella (4,96%), Bacillus (4,76%), Salmonella (3,57%), Staphylococcus (3,57%). Sebaliknya, Escherichia/Shigella (15,59%), Bacillus (10,48%), Limosilactobacillus (9,00%), Salmonela (7,78%), Listeria (5,94%), merupakan genus dominan pada tanaman liar. Analisis lebih lanjut perlu dilakukan konfirmasi untuk memastikan virulensi patogen potensial pada tanaman P. melastomoides liar maupun budidaya. Kata kunci: mikrobioma, endofit, 16S rRNA, next-generation sequencing, Firmicutes, Recent studies exhibited that fresh vegetables are the major habitat for endophytic bacterial communities. In Indonesia, some of the tropical plants are consumed fresh without a cooking process, which may concern human health and food security awareness. Pilea melastomoides is a Traditional and Ethnic Food plant used by the Sundanese people in Indonesia as a vegetable for fresh consumption. This plant can be grown wild and cultivated in a standard plantation, thus raising the question of the endophytic bacterial communities between these two types of planting systems. Therefore, our research aimed to investigate the bacterial community profile of wild and cultivated P. melastomoides based on a metagenomic approach targeting the 16S rRNA gene. Samples of P. melastomoides leaves were obtained from the forest area of Mount Halimun Salak National Park, Bogor Regency, West Java. The sampling technique was carried out using cluster random sampling, divided into three plots. The sample collection method was carried out using sample pooling in
Keyword: next-generation sequencing, Firmicutes, mikrobioma, endofit, 16S rRNA

Judul: The Ability of Endophytic Fungi from Pilea microphylla (L.) Leibm In Indole Acetic Acid Production
Abstrak: Pilea microphylla (L.) Liebm. merupakan herba sukulen yang memiliki kemampuan toleran cekaman kekeringan. Kemampuan tersebut mungkin terkait dengan keberadaan cendawan endofit dalam jaringan P. microphylla dan dapat menghasilkan metabolit sekunder di antaranya asam indol asetat (IAA) atau auksin. Namun, kemampuan dan waktu optimum cendawan endofit asal P. microphylla dalam menghasilkan IAA belum diteliti. Penelitian ini bertujuan mengukur konsentrasi auksin yang dihasilkan oleh isolat cendawan endofit PM 2A2.3 dan PM 2A2.4 asal P. microphylla pada berbagai waktu inkubasi. Hasil penelitian menunjukkan bahwa morfologi koloni dua kultur pada medium PDA berwarna putih dengan tekstur miselium berupa cottony. Namun dua kultur memiliki tipe pertumbuhan miselium berbeda yaitu miselium PM 2A2.3 tumbuh ke atas substrat (aerial), sedangkan miselium PM 2A2.4 merata (non aerial). Dua kultur menghasilkan konsentrasi IAA paling banyak pada masa inkubasi 2 minggu, yaitu 27,61 ppm oleh PM 2A2.4 dan 19,68 ppm oleh PM 2A2., Pilea microphylla (L.) Liebm is a succulent herb which tolerates drought stress. This fitness may be related to endophytic fungi in P. microphylla tissue and could produce secondary metabolites, including indole acetic acid (IAA). However, the ability and optimum time of endophytic fungi from P. microphylla to produce IAA have not yet been studied. This study aimed to measure the concentration of IAA produced by isolates of endophytic fungi PM 2A2.3 and PM 2A2.4 from P. microphylla at various incubation times. The colony morphology on the PDA medium from both isolates was white with a cottony mycelium texture. Both cultures had different types of mycelium growth, that was PM 2A2.3 had aerial mycelium, while PM 2A2.4 was evenly distributed (non-aerial). The isolates of PM 2A2.4 and PM 2A2.3 produced the highest concentrations of IAA at two weeks of incubation, that is 27.61 and 19.68 ppm, respectively.
Keyword: drought stress, IAA, potato dextrose broth, succulent herb

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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