<p>Ekspresi gen-gen virulensi pada Dickeya dadantii diatur oleh proses quorum sensing menggunakan asil-homoserin lakton (AHL) sebagai molekul sinyal. Patogenisitas bakteri tersebut dapat dihambat oleh aktivitas quorum quenching (QQ) bakteribakteri penghasil AHL-laktonase. Tujuan penelitian ini adalah mengisolasi dan mengarakterisasi bakteri penghasil AHLlaktonase asal rizosfer dan filosfer yang berpotensi untuk dikembangkan sebagai quorum quencher untuk D. dadantii. Isolasi bakteri dilakukan dari sampel daun dan sampel tanah rizosfer beberapa komoditas tanaman asal Sukabumi, Tegal, Kupang, dan Wonosobo. Sebanyak 8 dari 79 isolat bakteri yang diperoleh menunjukkan aktivitas QQ terhadap bioindikator Chromobacterium violaceum. Bioasai respons hipersensitif (hypersensitive response) yang dilakukan pada tanaman tembakau<br />menunjukkan enam (KT2, KT9, KT10, KUT1, TKF2, and WKF3) dari delapan isolat tersebut tidak menimbulkan respons hipersensitif. Keenam isolat tersebut mampu menekan virulensi D. dadantii pada umbi kentang. Sekuen 16S rRNA enam isolat tersebut memiliki kemiripan tertinggi dengan Bacillus cereus, B. aryabhattai, B. acidiceler, dan Micrococcus aloeverae. B. cereus KT9 and B. aryabhattai TKF2 terdeteksi memiliki gen penyandi AHL-laktonase (aiiA). Ini merupakan laporan yang pertama tentang aktivitas QQ pada spesies M. aloeverae, B. aryabhattai, and B. acidiceler. Keberadaan gen aiiA pada B.<br />aryabhattai juga belum pernah dilaporkan sebelumnya. Penelitian ini memberikan informasi baru tentang aktivitas QQ ketiga isolat tersebut dan potensinya sebagai quorum quencher untuk D. dadantii.</p>
Drainase lahan gambut diperkirakan akan mempengaruhi populasi dan keanekaragaman hayati di tanah gambut. Tujuan dari penelitian ini adalah untuk mengevaluasi pengaruh drainase dan tutupan lahan gambut di Tanjung Jabung Timur, Provinsi Jambi terhadap populasi dan keanekaragaman mikroba tanah gambut. Sampel tanah gambut diambil dari tiga lokasi yang berbeda yaitu: (A) perkebunan sawit dengan kedalaman saluran drainase 50-70 cm, (B) perkebunan sawit dengan kedalaman saluran drainase 20-50 cm, dan (C) hutan gambut. Total populasi mikroba dihitung menggunakan metode Total Plate Count dan media selektif pertumbuhan bakteri, fungi, dan aktinomicetes. Mikroba yang memperlihatkan tampilan morfologis yang berbeda masing-masing dihitung populasinya, lalu dilakukan identifikasi menggunakan Biolog Identification Kit. Hasil penelitian menunjukkan bahwa total populasi dengan keragaman mikroba tertinggi terdapat pada contoh tanah gambut yang telah didrainase pada kedalaman tanah 0-20 cm. Bakteri penambat nitrogen Azotobacter hanya terdeteksi pada tanah gambut lapisan tanah 0-20 cm di lokasi A. Mikroba pelarut P dengan total populasi 2,00 x 10 4-4,00 x 10 4 cfu g-1 terdapat di tiga lokasi, tetapi hanya ditemukan pada kedalaman 0-20 cm. Pada tanah gambut di lokasi A di kedalaman 0-20 cm dijumpai delapan jenis mikroba, yaitu: Azotobacter sp., Bacillus luciferensis, B. salarius, B. soli, Cupriavidus paucalus, Mycobacterium cubhense, Paenibacillus illinoisensis, dan P. wynnii. Sedangkan pada kedalaman 20-50 cm diperoleh spesies bakteri yang lebih sedikit, yakni Bacillus kribbensis, Bacillus panaciterrae, Chryseobacterium balustinum, dan Paenibacillus peoriae. Pada lokasi B, jenis mikroba yang dijumpai lebih sedikit dan didominasi oleh enam spesies bakteri (Bacillus salarius, B. soli, Cupriavidus paucalus, Nocardia jiangxiensis, Paenibacillus wynnii, dan Pseudomonas aeruginosa), sedangkan di lokasi C didominasi oleh hanya lima spesies mikroba (Bacillus vallismortis, Nocardia jiangxiensi, Paenibacillus glycaniliticus, P. peoriae, dan Rhodococcus equi). Tampaknya drainase dan pemupukan pada lahan gambut di perkebunan sawit mendorong pertumbuhan mikroba.
Jambi Province has around 617,000 hectares of peatlands spread across six districts, including Tanjung Jabung Timur. Reports on microbial diversity under different land cover, especially those using molecular techniques, were very limited. The study aimed to evaluate the impact of peatlands conversion on soil bacterial biodiversity, through the analysis of 16S-rDNA gene employing polymerase chain reaction combined with denaturing gradient gel electrophoresis (PCR-DGGE). Peat soil samples were taken from the topsoil (rhizosphere) of 3 sites, i.e. (A) conventional drained (50 to 70 cm) oil palm plantation, (B) shallow drained (30 to 50 cm) oil palm plantation, and (C) logged-over peat forest. Sequential analysis based on the 16S rRNA gene showed that 15 operational taxonomic units (OTUs) could be grouped into 3 phyla, namely Proteobacteria, Acidobacteria, and Actinobacteria. The alignment result of nucleotide shows that 4 of 15 bands of DGGE were identified as the uncultured bacterium (Sulfurospirillum, Acidobacteria, Rhodoplane, and Magnetospirillum). Overall, the Shannon-Weaver biodiversity index showed that the conversion of peatlands to oil palm plantation increased bacterial biodiversity. This could be attributed to drainage, ferlilization, and biomass inputs under the oil palm plantations. The higher biodiversity under oil palm plantations also implies a higher rate of peat decomposition under this land use, relative to the forest.
Composting is an alternative for recycling organic waste. Microorganisms that can degrade the components of organic waste are an essential part of composting. Isolation and selection of bacteria with the ability to degrade the elements of organic waste are the first steps to obtain an organic waste degrading agent. This study aimed to determine the characteristics and the enzymatic potential (cellulolytic, amylolytic, and proteolytic) of bacteria isolated from soil, cow dung and kitchen waste as candidates for organic waste degradation agents. The research begins with sampling and isolation of bacteria. The isolates obtained were tested qualitatively for their amylolytic, cellulolytic and proteolytic activities. Furthermore, bacterial isolates were characterized morphologically and biochemically. A total of 30 bacterial isolates were isolated from soil samples, cow dung and kitchen waste. The screening result showed that 6 isolates had amylolytic activity, 7 isolates had cellulolytic activity and 3 isolates had proteolytic activity. These bacterial isolates showed various morphological and biochemical characteristics. In general, soil samples, kitchen waste and cow dung contain potential bacteria as organic waste degrading agents
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