Rachmawati, Sholikah Widyanitta and Dr. Ir. Mintarto Martosudiro,, M.S. and Luqman Qurata Aini,, S.P., M.Si., Ph.D. (2024) Eksplorasi Bakteri Endofit Jeruk Purut Sebagai Agens Pengendali Hayati untuk Mengendalikan Penyakit Kanker Jeruk Xanthomonas axonopodis pv. citri Secara In Vitro. Magister thesis, Universitas Brawijaya.
Abstract
Produksi buah, daun dan ranting tanaman jeruk terhambat oleh serangan penyakit kanker jeruk (Xanthomonas axonopodis pv. citri (Xac) dari genus Xanthomonas. Infeksi Xanthomonas sp. Patogen memasuki tanaman melalui stomata, lentisel, hidatoda, dan luka, terutama pada jaringan muda yang sedang tumbuh. Infeksi parah menyebabkan penggundulan hutan, kematian, deformasi buah, dan jatuhnya buah secara prematur pada tanaman jeruk yang terkena kanker jeruk. Infeksi kanker jeruk pada buah menurunkan kualitas dan kuantitas buah jeruk. Pengendalian penyakit dengan menggunakan campuran bahan kimia dan pestisida dapat menyebabkan resistensi patogen, berbahaya bagi kesehatan manusia dan hewan, serta merusak ekosistem. Cara pengendalian yang ramah lingkungan adalah dengan mengembangkan varietas tahan penyakit, namun pengendalian ini memerlukan waktu yang lama dan belum tersedia secara luas. Pengendalian yang ramah lingkungan dan ekonomis dapat dilakukan dengan menggunakan mikroorganisme antagonis yaitu bakteri endofit. Bakteri endofit berkembang di jaringan tanaman inang untuk menghambat pertumbuhan patogen. Bakteri endofit mampu menghasilkan zat antagonis yang dapat menghambat pertumbuhan bakteri patogen pada tanaman inang. Jeruk purut dipilih karena mengandung senyawa bioaktif seperti flavonoid, steroid, tanin, fenolik dan saponin. Senyawa dari bakteri endofit mampu menghasilkan metabolit sekunder yang salah satunya bersifat antibakteri. Upaya pengembangan dan pemanfaatan potensi mikroorganisme endofit dalam menghasilkan metabolit sekunder dari tanaman inang mempunyai peluang besar di masa depan sebagai alternatif mengatasi dan mengendalikan infeksi kanker jeruk oleh Xanthomonas sp. patogen. Berdasarkan uraian di atas, maka penelitian ini bertujuan untuk melakukan eksplorasi isolat bakteri endofit dari tanaman jeruk purut yang diduga mampu menghasilkan antibakteri untuk menghambat pertumbuhan patogen Xanthomonas sp. Hasil eksplorasi bakteri endofit dari tanaman jeruk purut yang berasal dari daun, batang, dan akar menghasilkan 33 isolat bakteri. Isolat bakteri tersebut berasal dari daun sebanyak 16 isolat, batang sebanyak 1 isolat, dan akar sebanyak 16 isolat. Daun jeruk purut bergejala Xanthmonas sp. dari lapang menunjukkan adanya halo kuning dan menonjol di bagian permukaan daun. Hasil penelitian isolasi patogen bakteri Xanthomonas sp. secara in vitro dari jeruk purut bergejala menghasolkan isolat tunggal bakteri berwarna kuning, tidak menghasilkan fluorescent, berwarna kuning pada media selektif YDC dan memiliki gram negatif (berwarna merah). Hasil pengujian hipersensitif didapatkan isolat yang berpotensi menjadi antagonis yaitu isolat asal daun JPD2, JPD3, JPD6, JPD15, isolat asal batang JPB1, isolat asal akar JPA15, dan JPA13. Hasil pengujian antagonisme bakteri endofit hasil eksplorasi dengan bakteri patogen Xac diketahui isolat bakteri JPD2, JPA13, dan JPA15 mampu menghasilkan zona bening dengan diameter hambat berbeda. Pewarnaan isolat bakteri menunjukkan pada isolat bakteri JPA15, JPA13, JPD2, JPB1, JPD6, JPD15 memiliki gram positif ditunjukkan dengan warna ungu hingga biru, sedangkan pada isolat bakteri JPD3 memiliki gram negatif ditunjukkan dengan warna merah pada bakteri. Hasil identifikasi BLAST diketahui kode isolat JPD2 merupakan Bacillus cereus dengan persent identity 100,00%, JPA13 Enterobacter cloaceae mempunyai persent identity 99,19%, dan JPA15 Pantoea agllomerans dengan persent identity 99,58%. Hasil penelitian perbandingan isolat baktri endofit dengan antibakteri dan bakterisida didapatkan bahwa hari kedua bakteri endofit B. cereus berbeda nyata dengan kontrol positif (bakterisida, antibiotik) dan kontrol negatif (air). Isolat bakteri B. cereus yang telah dilakukan pengujian perbandingan dengan antibakteri murni dan bakterisida, diuji kembali dengan menggunakan GC-MS. Isolat bakteri B. cereus diketahui memiliki senyawa antibakteri yaitu sulfamethoxazole dan lupulon.
English Abstract
The production of fruit, leaves and twigs of citrus plants is hampered by the attack of citrus canker disease (Xanthomonas axonopodis pv. citri (Xac) from the genus Xanthomonas. Xanthomonas sp. infection pathogens enter plants through stomata, lenticels, hydathodes, and wounds, especially in young growing tissue. Severe infections cause deforestation, death, fruit deformation, and premature fruit drop in citrus plants affected by citrus canker. Citrus canker infection on fruit reduces the quality and quantity of citrus fruit. Disease control using a mixture of chemicals and pesticides can cause pathogen resistance, be dangerous for human and animal health, and damage the ecosystem. An environmentally friendly way to control is to develop disease-resistant varieties, but this control takes a long time and is not yet widely available. Environmentally friendly and economical control can be carried out using antagonistic microorganisms, namely endophytic bacteria. Endophytic bacteria develop in host plant tissue to inhibit the growth of pathogens. Endophytic bacteria are able to produce antagonistic substances that can inhibit the growth of pathogenic bacteria on host plants. Kaffir lime was chosen because it contains bioactive compounds such as flavonoids, steroids, tannins, phenolics and saponins. Compounds from endophytic bacteria are capable of producing secondary metabolites, one of which is antibacterial. Efforts to develop and utilize the potential of endophytic microorganisms in producing secondary metabolites from host plants have great opportunities in the future as an alternative to overcome and control citrus canker infection by Xanthomonas sp. pathogen. Based on the description above, this research aims to explore endophytic bacterial isolates from kaffir lime plants which are thought to be capable of producing antibacterials to inhibit the growth of the pathogen Xanthomonas sp. The results of exploration of endophytic bacteria from kaffir lime plants from leaves, stems and roots produced 33 bacterial isolates. The bacterial isolates came from 16 isolates from leaves, 1 isolate from stems, and 16 isolates from roots. Kaffir lime leaves have symptoms of Xanthmonas sp. from the field shows a yellow halo and stands out on the surface of the leaves. The results of research on the isolation of the bacterial pathogen Xanthomonas sp. in vitro, symptomatic kaffir limes produced a single isolate of yellow bacteria, did not produce fluorescent, were yellow on YDC selective media and were gram negative (red). The results of hypersensitive testing showed isolates that had the potential to be antagonists, namely isolates from leaves JPD2, JPD3, JPD6, JPD15, isolates from stems JPB1, isolates from roots JPA15, and JPA13. The results of the endophytic bacterial antagonism test results from exploration with the pathogenic bacteria Xac showed that the bacterial isolates JPD2, JPA13, and JPA15 were able to produce clear zones with different inhibitory diameters. Bacterial isolate staining showed that the bacterial isolates JPA15, JPA13, JPD2, JPB1, JPD6, JPD15 were gram positive, shown in purple to blue, while the bacterial isolate JPD3 was gram negative, shown in red in the bacteria. The results of BLAST identification showed that the isolate code JPD2 was Bacillus cereus with a percent identity of 100.00%, JPA13 Enterobacter cloaceae had a percent identity of 99.19%, and JPA15 Pantoea agllomerans had a percent identity of 99.58%. The results of research comparing endophytic bacterial isolates with antibacterials and bactericides showed that on the second day the endophytic B. cereus bacteria were significantly different from the positive control (bactericide, antibiotic) and negative control (water). The B. cereus bacterial isolate, which had been tested comparatively with pure antibacterials and bactericides, was tested again using GC-MS. The bacterial isolate B. cereus is known to contain antibacterial compounds, namely sulfamethoxazole and lupulon.
| Item Type: | Thesis (Magister) |
|---|---|
| Identification Number: | 0424040022 |
| Divisions: | S2/S3 > Magister Ilmu Tanaman, Fakultas Pertanian |
| Depositing User: | Unnamed user with username nova |
| Date Deposited: | 25 Mar 2024 04:33 |
| Last Modified: | 25 Mar 2024 04:33 |
| URI: | http://repository.ub.ac.id/id/eprint/217550 |
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