Kajian isolat jamur kitinolitik sebagai agens pengendalian hayati rhizoctonia solasi

KHIKMAH, Nur, Prof. Dr. Ir. Sebastian Margino

2009 | Tesis | S2 Biologi

Rhizoctonia solani adalah salah satu jamur patogen tanaman yang menyebabkan penyakit rebah semai (damping-off) pada tanaman Solanaceae dan kerusakan ekonomi yang ditimbulkan dapat mencapai 40%. Pengendalian hayati terhadap R. solani dapat dilakukan dengan menggunakan jamur kitinolitik, melalui aktivitas enzim kitinase yang dihasilkan akan melisiskan dinding jamur patogen dan menyebabkan kematian. Tujuan penelitian ini adalah untuk mendapatkan isolat jamur kitinolitik dari lingkungan alam sebagai agens pengendalian hayati R. solani. Kajian dilakukan secara in vitro meliputi isolasi, seleksi, optimalisasi produksi kitinase, identifikasi isolat dan mekanisme perusakan kitinase terhadap R. solani. Sebanyak 70 isolat jamur kitinolitik berhasil diisolasi dari tanah yang mengandung kitin, limbah berkitin dan tanah rizosfer. Berdasarkan uji aktivitas enzim maka dipilih isolat jamur KUP2 sebagai isolat yang mempunyai aktivitas spesifik kitinase tertinggi yaitu 744,2040 U/mg. Kondisi optimal untuk produksi kitinase isolat jamur KUP2 yaitu pada konsentrasi inokulum 5% (v/v), pH medium 5,5; konsentrasi kitin 0,2% (b/v), temperatur 30°C, agitasi 150 rpm dan waktu inkubasi 4 hari. Isolat jamur KUP2 diidentifikasi sebagai Trichoderma harzianum. Uji antifungal kitinase secara in vitro menunjukkan bahwa tidak terjadi penghambatan pertumbuhan R. solani. Pengamatan mikroskopis aplikasi kitinase mampu menyebabkan struktur abnormal pada hifa dan melisiskan dinding sel hifa. Mekanisme antagonis T. harzianum KUP2 dengan R. solani berbentuk mikoparasitisme dan hasil pengamatan secara mikroskopis mampu membelit dan tumbuh di dalam hifa R. solani.

Rhizoctonia solani is one of the phytopathogenic fungi causing dampingoff and causes 40% economic loses. Chitinolytic fungi has been effectively used in biological control of R. solani. The chitinase activity causes lysis of the fungi cell wall pathogen. The aim of the research was to find chitinolytic fungi from soil environmental containing of chitin and used as biological control agents of R. solani. The research was conducted in vitro in five steps, those were isolation, selection of chitinolytic fungi, optimalization of chitinase production, identification of selected isolate and destruction mechanism of R. solani. There are 70 isolates of chitinolytic fungi that had been isolated from chitinous soil, chitinous waste and rhizosphere soil. Based on chitinase specific activity it was found KUP2 fungi isolate that had higher chitinase activity 744,2040 U/mg. Optimal growth chitinase production for KUP2 fungi isolate were inoculum concentration 5% (v/v), pH 5,5; concentration of chitin 0,2% (w/v), temperature 300C, agitation 150 rpm and incubation time at 4 days. KUP2 fungi isolate was identified as Trichoderma harzianum. Result of antifungal test of chitinase activity in vitro showed that there was no growth inhibitation against the mycelia of R. solani. Microscopic observation showed that chitinase caused abnormal structure the hyphae and lysis of cell wall of R. solani. The antagonistic mechanism of T. harzianum KUP2 with R. solani was mycoparasitism and microscopic observation showed that the hyphae was coiled and could grow inside hyphae of R. solani.

Kata Kunci : jamur kitinolitik,pengendalian hayati,Rhizoctonia solani, chitinolytic fungi, biological control, Rhizoctonia solani