Aini, Afifah Nur (2019) Potensi Jamur Rhizosfer Antagonis dalam Menghambat Pertumbuhan Bakteri Pembusuk Umbi Porang (Amorphophallus muelleri Blume) Pascapanen. Magister thesis, Universitas Brawijaya.
Abstract
Umbi porang bernilai ekonomi tinggi karena tepung hasil olahannya dapat digunakan sebagai bahan tambahan pangan dan bahan baku industri. Produksi umbi seringkali terkendala oleh pembusukan umbi pascapanen akibat bakteri busuk lunak. Salah satu upaya penanganan busuk umbi adalah pengendalian hayati dengan jamur rhizosfer antagonis. Penelitian ini bertujuan untuk menentukan potensi jamur rhizosfer dari perkebunan porang dalam menghambat pertumbuhan bakteri pembusuk umbi porang. Bakteri pembusuk umbi porang sebanyak tujuh isolat yaitu L9, R4, R11, T4, T9A, T9B dan T14 diperoleh dari koleksi kultur Laboratorium Mikrobiologi, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Brawijaya. Ketujuh isolat tersebut dimurnikan kembali dengan teknik spread plate. Ketujuh isolat bakteri diskrining patogenitasnya dengan uji Postulat Koch untuk menentukan isolat dengan potensi tertinggi dalam membusukkan umbi berdasarkan perubahan parameter fisikokimia umbi. Selanjutnya, jamur rhizosfer diisolasi dari perkebunan porang di Desa Rejosari, Kecamatan Bantur, Kabupaten Malang. Jamur dari sampel tanah yang diambil dari tiga titik secara komposit diisolasi dengan teknik pour plate. Tiap koloni dengan morfologi yang berbeda dimurnikan dengan teknik monospora. Isolat-isolat jamur rhizosfer diuji kemampuannya dalam menghambat pertumbuhan isolat bakteri pembusuk utama dengan cakram miselia dan filtrat steril. Isolat bakteri dengan potensi pembusuk tertinggi dan isolat jamur dengan potensi penghambatan tertinggi diidentifikasi berdasarkan sekuen 16S rDNA untuk bakteri dan ITS rDNA untuk jamur. Isolat bakteri T4 dan T9A menunjukkan potensi pembusukan tertinggi berdasarkan tingkat keparahan gejala pembusukan umbi. Keduanya menimbulkan perubahan warna umbi menjadi cokelat dan tekstur menjadi sangat lunak. Perubahan warna disebabkan oleh nekrosis jaringan umbi, sedangkan pelunakan disebabkan oleh maserasi jaringan umbi akibat degradasi dinding sel oleh enzim pektinolitik bakteri. Kadar gula pereduksi hasil pembusukan umbi dari kedua isolat berturut-turut mencapai 14,38 dan 15,32 mg/mL. Kadar gula yang tinggi mengindikasi adanya pemecahan pati menjadi gula sederhana yang digunakan oleh bakteri sebagai sumber nutrisi. Kadar etanol hasil pembusukan umbi dari kedua isolat berturut-turut mencapai 32,17 dan 35,05 %. Kadar etanol yang tinggi mengindikasi adanya fermentasi yang menghasilkan etanol. Isolat T4 dan T9A tersebut berturut-turut memiliki similaritas 16S rDNA dengan Bacillus altitudinis sebesar 99,8 % dan Pseudomonas stutzeri sebesar 99,1 %. Isolat jamur A3 dan A6 menunjukkan daya hambat tertinggi terhadap kedua bakteri pembusuk dengan diameter zona hambat masing-masing sebesar 9,67 dan 4,67 mm terhadap B. altitudinis, serta 15,79 dan 5,04 mm terhadap P. stutzeri. Adanya zona hambat membuktikan bahwa kedua isolat jamur menghasilkan metabolit sekunder yang bersifat antibakteri. Filtrat steril yang diperoleh dari kultur yang diinkubasi selama 16 hari memiliki daya hambat tertinggi. Masa inkubasi berpengaruh terhadap daya hambat karena semakin lama masa inkubasi, maka semakin banyak metabolit sekunder dan asam-asam organik yang terakumulasi dalam filtrat jamur. Isolat A3 dan A6 tersebut berturut-turut memiliki similaritas ITS rDNA dengan Trichoderma spirale sebesar 99,2 % dan Penicillium javanicum sebesar 99,8 %. Dari penelitian ini dapat disimpulkan bahwa jamur rhizosfer perkebunan porang memiliki potensi sebagai antagonis bakteri pembusuk umbi porang pascapanen.
English Abstract
Porang tuber has high economic value because the flour processed from it can be used as food additives and materials for industry. Tuber production is often hindered by postharvest tuber rot caused by soft rot bacteria. One of the methods to solve tuber rot problem is through biological control using antagonistic rhizosphere fungi. This research was aimed to isolate rhizospheric fungi from porang field which has the highest potency in inhibiting the growth of bacteria causing tuber rot in porang. Seven isolates of porang tuber rot bacteria, namely L9, R4, R11, T4, T9A, T9B and T14, were obtained from culture collection of Laboratory of Microbiology, Faculty of Mathematics and Natural Sciences, Brawijaya University. The seven isolates were repurified using spread plate technique. Koch’s Postulates test of the seven isolates was done to determine the isolate with the highest potency in causing tuber rot based on the physicochemical changes in tuber. Afterwards, rhizospheric fungi were isolated from porang field in Rejosari Village, Bantur, Malang. Fungal isolation from soil obtained by composite sampling from three locations was done using pour plate technique. Every colony with different morphology was purified using monospore technique. Fungal isolates were tested for their abilities to inhibit the growth of selected tuber rot bacteria using mycelial discs and sterile filtrates. Bacterial isolate with the highest potency in causing tuber rot and fungal isolate with the highest potency in inhibiting tuber rot bacteria were identified based on the similarity of 16S rDNA for bacteria and ITS rDNA for fungi. Two bacterial isolates, namely T4 and T9A, showed the highest potency in causing tuber rot based on the severity of tuber rot symptoms. Both isolates caused the tuber to change color into brown and become very soft in texture. The color change is caused by the necrosis of tuber tissue, while the softening is caused by the maceration of tuber tissue due to cell wall degradation caused by the bacterial pectinolytic enzymes. The reducing sugar content in the rotting tuber of both isolates reached 14.38 and 15.32 mg/mL, respectively. The high sugar content indicated the occurance of starch degradation into simple sugars utilized by the bacteria as nutrition source. The ethanol content in the rotting tuber of both isolates reached 32.17 and 35.05 %, respectively. The high ethanol content indicated the occurance of ethanol-yielding fermentation. Isolate T4 and T9A shared 16S rDNA similarities of 99.8 % with Bacillus altitudinis and 99.1 % with Pseudomonas stutzeri, respectively. Two fungal isolates, namely A3 and A6, had the highest inhibition potency against both tuber rot bacteria. The inhibition zone diameter of both isolates were, respectively, 9.67 and 4.67 mm against B. altitudinis, 15.79 and 5.04 mm against P. stutzeri. The formation of inhibition zone proved that both fungal isolates produce secondary metabolites with antibacterial activity. Sterile filtrates obtained from fungal cultures that was incubated for 16 days had the highest inhibition potency. The duration of incubation period affected the inhibition potency because as the incubation period increases, the secondary metabolites and organic acids will accumulate in the fungal filtrate. Isolate A3 and A6 shared ITS rDNA similarities of 99.2 % with Trichoderma spirale and 99.8 % with Penicillium javanicum, respectively. From this research, it can be concluded that rhizospheric fungi from porang field had the potency to be the antagonists of bacteria causing postharvest tuber rot in porang.
Other obstract
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| Item Type: | Thesis (Magister) |
|---|---|
| Identification Number: | TES/571.7/AIN/p/2019/041911452 |
| Uncontrolled Keywords: | BIOLOGICAL CONTROL SYSTEMS, MUSHROOMS, BACTERIA, AMORPHOPHALLUS |
| Subjects: | 500 Natural sciences and mathematics > 571 Physiology and related subjects > 571.7 Biological control and secretions |
| Divisions: | S2/S3 > Magister Biologi, Fakultas MIPA |
| Depositing User: | Budi Wahyono Wahyono |
| Date Deposited: | 08 Jan 2020 03:20 |
| Last Modified: | 25 Oct 2021 04:39 |
| URI: | http://repository.ub.ac.id/id/eprint/177631 |
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