The Study of Streptomyces spp. Effectiveness in Inhibiting Xanthomonas campestris pv. acaciae on Acacia Plant

Abstract

Streptomyces spp. is one of the bacterial antagonists that can be used as biological control of plant microbial pathogens, since they produce antimicrobial compounds. This study was aimed to screen the capability of indigenous isolates of Streptomyces spp. in inhibiting Xanthomonas. campestris pv. acaciae in vitro and in planta assays. Eight isolates used were PS4-16, LSW05, LBR05, LBR02, SSW02, SR01, SR02, and SR03. Four out of the eight tested isolates had various inhibitory capability. The colony of SR02 showed the greatest inhibitory activity which was 20 mm diameter of clear zone followed by LSW05, PS4-16, and LBR02 which have inhibitory zone of 8 mm, 5 mm, and 3.5 mm respectively. Based on their crude extract assay PS416 and SR02 produced inhibitory activity 12,5 cm and 6,5 cm. Furthermore those two isolates were applied on Acacia crassicarpa which was inoculated with pathogenic bacteria Xantomonas campestris pv. Acacia. The result showed SR02 and PS4-16 capable of suppressing disease intensity by 9.14% and 11.71% respectively compared to the control treatment 24.03% and bactericidal agent by 14% at 7 weeks old plant after planting. Application of Streptomyces spp. were also able to increase more plant height, shoot diameter and plant dry weight compared with controls. This indicates that Streptomyces spp. PS4-16 and SR02 have potency to be developed as biological control agents against bacterial blight on acacia leaves.

Streptomyces spp. merupakan salah satu bakteri antagonis yang dapat dimanfaatkan sebagai pengendali hayati mikrob patogen tanaman karena menghasilkan senyawa antimikrob. Penelitian ini bertujuan menapis kemampuan Streptomyces spp. isolat indigenus dalam menghambat Xanthomonas campestris pv. acaciae secara in vitro dan in planta. Delapan isolat yang digunakan yaitu PS4-16, LSW05, LBR05, LBR02, SSW02, SR01, SR02, dan SR03. Hasil uji in vitro menggunakan koloni langsung menunjukkan bahwa empat dari delapan isolat tersebut mempunyai daya hambat cukup baik. Isolat SR02 memiliki daya hambat terbesar yaitu 20 mm disusul oleh isolat LSW05, PS4-16, dan LBR02 yang memiliki zona hambat masing-masing sebesar 8 mm, 5 mm, dan 3,5 mm. Keempat isolat dilakukan uji lanjut menggunakan filtrat kultur. Hasilnya diperoleh dua isolat dengan zona penghambatan cukup baik yaitu isolat PS4-16 dan SR02 dengan diameter zona bening sebesar 12,5 cm dan 6,5 cm pada hari kelimabelas. Uji in planta kedua isolat tersebut pada tanaman akasia (Acacia crassicarpa) yang diinokulasi Xanthomonas campestris pv. acaciae menunjukkan bahwa SR02 dan PS4-16 mampu menekan intensitas penyakit masing-maing sebesar 9,14 % dan 11,71 % dibanding kontrol yaitu sebesar 24,03 % dan bakterisida komersial sebesar 14 % pada 7 minggu setelah tanam. Perlakuan Streptomyces spp. juga terbukti mampu meningkatkan tinggi, diameter batang, dan bobot kering tanaman dibandingkan dengan kontrol. Hal ini mengindikasikan bahwa isolat Streptomyces spp. SR02 dan PS4-16 berpotensi untuk dikembangkan sebagai agens pengendali hayati terhadap bakteri hawar daun pada akasia.

Lestari, Yulin

Meryandini, Anja