DEGRADASI DINDING SEL Phytophthora capsici OLEH ENZIM KARBOSI METIL SELULASE ASAL Trichoderma harzianum - KARDEN MULYA; MELLY HARMEN (Pusat Penelitian dan Pengembangan Perkebunan, 2003)
Phytophthora capsici Leonian adalah patogen penyebab penyakit busuk pangkal batang lada (Piper nigrum L). Trichoderma harzianum Rifai merupakan agen hayati yang cfektif dan menyebabkan lisis miselia P. capsici. Penelitian ini bertujuan unluk mcngc(ahui peran enzim karboksimetilselulase (CMC-ase) yang diproduksi oleh T. harzianum dalam mendegradasi dinding sel P capsici. Penelitian terdiri atas tiga aktivitas yaitu (a) deteksi produksi enzim CMC-ase, (b) hidrolisis dinding sel P. capsici. dan (c) penggunaan siapan kasar dinding sel (SKDS) P. capsici oleh T. harzianum sebagai satu-satunya sumber karbon dalam media tumbuhnya Aktivitas enzim dideleksi secara kualitatif dengan membandingkan zona bening yang terbentuk pada medium karboksi metil selulosa (CMC) yang diperlakukan dengan satu tetcs iltrat kultur 7 harzianum dan diwarnai dengan larulan congo red, sedangkan aktivitas CMC-ase secara kuantitatif diukur sebagai nilai setara glukosa yang terlepas dari substrat setelah diinkubasi dengan ekstrak kasar CMC-ase. Enzim CMC-ase dickstrak dari kultur filtrat T. harzianum F.51 melalui pengendapan protein dengan 85% ammonium sulfat pada suhu 4°C diikuti dengan sentrifusi dan dialisis. Aktivitas spcsifik enzim tersebut dalam mendegradasi CMC (30,29 unif//g protein) lebih rendah dari aktivitas enzim selulase komersial (97.18 unit/^g protein). Enzim selulase komcrsial dan ekstrak enzim dari kultur 7 harzianum juga dapat menghidrolisis SKDS P. capsici N2 dengan aktivitas masing-masing 31.18 unit dan 19.26 unit. Isolat F-51 tumbuh dan menghasilkan aktivitas enzim serupa manakala karboksimclil selulosa pada media tumbuh diganti dengan SKDS sebagai sumber karbon tunggal Hasil ini menunjukkan bahwa CMC-ase berperan penting dalam mckanisme antagonis T. harzianum terhadap /' capsici. Penelitian lebih lanjut dalam mckanisme produksi enzim ini berpeluang untuk meningkatkan potensi agen hayati.Kata kunci : Piper nigrum L., Trichoderma harzianum Rifai, Phytophthora capsici. karbosimctilsclulasc, agen hayati ABSTRACTDegradation of cell wall of Phytophthora capsici N2 by carboxy methyl cellulose <;/ Trichoderma harzianum ES1Phytophthora capsici l-eonian is a causal agent of foot rot disease on black pepper (Piper nigrum L ). Trichoderma harzianum Rifai is an effective biocontrol agent and causes lyscs on P. capsici mycelium This experiment was aimed to study the role of carboxymethylccllulose (CMC- ase) produced by T. harzianum in degrading P. capsici cell wall. The experiment was composed in three activities (a) detection of the CMC-ase enzyme production, (b) degradation of P. capsici cell wall by crude extract of the enzyme, and (c) utilization of crude cell wall preparation (cwp) of P. capsici by T. harzianum as single carbon source in its growth medium CMC-ase activity was detected qualitatively on carboxymethylccllulose (CMC) medium, and quantitatively it was measured as glucose equivalent released from substrate after treated with crude extract of CMC-ase. CMC-ase was extracted from culture iltrate of T. harzianum F-51 by precipitation of protein with 85% ammonium sulphate at 4°C followed by dialysis with distilled water and liophyllizcd. Activity of the extracted enzyme on degradation of CMC (30.29 unil-'/jg protein) was lower than activity of commercial cellulose (97.18 united g protein) Commercial cclullosc and the extracted enzyme also degraded crude cell wall prepared (CWP) from P. capsici N2 as indicated with the presence of glucose equivalent released from CWP after incubation with the enzyme; with specific activity of 31.18 unit and 19.26 unit respectively. Trichoderma harzianum grown in medium suplemented with the crude cell wall of P. capsici as a single carbon source produced CMC-ase. Those results indicated that CMC-ase has important role on parasitism of T. harzianum on P. capsici Further investigation is required to elucidate mechanism of production of CMC-ase in T. harzianum for improvement of biocontrol activity of the fungus.Key words: Piper nigrum L., Trichoderma harzianum Rifai, Phytophthora capsici, carboxymethylcellulosc, biocontrol