Judul: Observation on Bioplastic Degradation by  River Microbial Communities
Abstrak: Plastik merupakan polimer polietilen yang rekalsitran karena ikatan kimianya tidak mudah diuraikan oleh kebanyakan mikrob pengurai. Produksi sampah plastik yang tinggi menyebabkan penumpukan hingga pencemaran air atau tanah oleh sampah plastik. Hal ini dapat diminimalkan dengan metode penguraian sampah berbasis biologi menggunakan bakteri pendegradasi plastik yang ramah lingkungan dan ekonomis. Penelitian ini bertujuan memperoleh bakteri untuk mempercepat proses degradasi plastik oleh komunitas mikrob asal air sungai. Metode yang digunakan dalam penelitian ini meliputi pengambilan sampel air dan lumpur dari Sungai Ciliwung, Sungai Cisadane, dan Sungai Ciapus, pengamatan degradasi bioplastik, pengayaan bakteri pendegradasi plastik, isolasi bakteri pendegradasi plastik dan uji degradasi plastik. Hasil penelitian menunjukkan degradasi terdapat pada seluruh sampel bioplastik. Penambahan pupuk NPK menghasilkan proses degradasi pada bioplastik lebih cepat. Sebanyak 15 isolat bakteri diperoleh dari seluruh sampel dan dapat mendegradasi plastik. Proses biodegradasi dilakukan oleh sekolompok bakteri, bukan koloni tunggal., Plastics are recalcitrant polyethylene polymers because their chemicals are not easily broken down by most decomposers. The high production of plastic waste causes the accumulation of air or soil pollution by plastic waste. This can be minimized by a biological-based waste decomposition method using plastic degrading bacteria that is environmentally friendly and economical. This study aims to obtain bacteria to support the plastic degradation process by microbes from river water. The methods used in this study include taking samples of water and mud from the Ciliwung River, Cisadane River, and Ciapus River, observing bioplastic degradation, enriching plastic-degrading bacteria, isolating plastic degrading bacteria and testing plastic degradation. The results showed some degree of degradation in all bioplastic samples. The addition of NPK fertilizer made the degradation process of bioplastics run faster. 15 different bacterial isolates were obtained from all samples and could degrade plastics. The biodegradation process is carried out by groups of bacteria, not single colonies.
Keyword: Bacteria, Biodegradation, Bioplastic, River

Judul: Bioplastic Degradation by Microbes from Ancol
Beach Sea Waters
Abstrak: Sampah yang banyak dan belum dikelola dengan baik adalah sampah plastik. Penanganan sampah plastik yaitu mencari kandidat mikrob pendegradasi polimer. Penelitian ini bertujuan mengisolasi dan mengobservasi degradasi bioplastik oleh mikrob dari perairan laut Pantai Ancol. Metode penelitian meliputi penentuan lokasi sampling, pengambilan sampel, persiapan isolasi sampel, pengayaan kultur dalam sampel dan perhitungan degradasi bobot bioplastik, isolasi dan pemurnian bakteri pendegradasi bioplastik, serta uji kualitatif dalam tabung reaksi sebagai bakteri pendegradasi bioplastik. Sampel berupa air laut, air laut yang mengandung pasir, dan air laut yang sudah dipanaskan hingga mendidih (kontrol). Hasil pengayaan kultur dalam sampel air laut yang mengandung pasir mendapatkan nilai persentase degradasi 57,5% dan 46,5% pada sampel yang hanya berupa air laut. Sebanyak 10 isolat yang diperoleh dari tiga sampel tersebut. isolat BB7 dan BB10 menampakan zona bening sebagai indikator degradasi bioplastik. Hasil uji kualitatif pada kontrol negatif menunjukkan tidak ada perubahan, isolat BB7 dan BB10 berubah sedikit keruh, dan isolat campuran (BB7 dan BB10) berubah keruh. Uji pendegradasi bioplastik pada isolat campuran memberikan hasil kekeruhan yang lebih baik daripada sampel lainnya, tetapi belum bisa mendegradasi kepingan bioplastik. Hasil ini mengindikasikan bahwa komunitas mikrob pada suatu lingkungan dapat memiliki fungsi yang saling melengkapi., Most of the waste that needs to be managed better is plastic waste. Handling plastic waste is to look for candidate polymer-degrading microbes. This research aimed to isolate and observe the degradation of bioplastics by microbes from the marine waters of Ancol Beach. The research methods include determining the sampling locations, sampling, sample isolation preparation, enrichment of cultures in samples and calculation of bioplastic degradation weight, as well as isolation and purification of bioplastic degrading. Samples were only seawater, seawater containing sand, and seawater that had been heated to boiling (control). The results of culture enrichment obtained a degradation percentage value of 57,5% in seawater samples containing sand and 46,5% in samples that were only seawater. A total of 10 isolates were obtained from these three samples. The BB7 and BB10 isolates showed a clear zone as an indicator of bioplastic degradation. Qualitative test results on the negative control showed no change, BB7 and BB10 turned slightly cloudy, and mixed isolates (BB7 and BB10) turned cloudy. The bioplastic degradation test on mixed isolates gave better turbidity results than other samples but could not degrade bioplastic pieces. These results indicate that microbial communities in an environment can have complementary functions.
Keyword: bakteri, Air laut, biodegradasi, bioplastik, pasir

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology