Potensi Bakteri Filosfer pada Daun Kubis untuk Mengendalikan Penyakit Busuk Lunak oleh Pectobacterium carotovorum pada Sawi Putih

The Potentials of Cabbage Phyllospheric Bacteria as Biocontrol Agents of Soft Rot Disease Caused by Pectobacterium carotovorum on Chinese Cabbage Soft rot disease caused by Pectobacterium carotovorum (Syn. Erwinia carotovora subsp. carotovora) is one of the important diseases on chinese cabbage. The bacteria produce pectinase enzyme which decompose pectin on the central lamella of plant cell wall. The infected chinese cabbage become rotted, watery, and slimy. One of the alternatives controls to overcome the disease is the application of biocontrol agent isolated from the phyllosphere of chinese cabbage. This study aimes to evaluate and to select the potential phyllospheric bacteria from cabbage as biocontrol agents of soft rot disease caused by P. carotovorum on Chinese cabbage. The phyllosphere bacteria were isolated from Cianjur, Tegal, and Bogor Districts. Phyllosphere bacteria were tested for their safety by the hypersensitive reaction and hemolysis type on blood agar. They were tested for their inhibition capability to the growth of P. carotovorum in vitro and to control the soft rot disease in vivo. Two isolates with potential control activity to the soft rot disease in chinese cabbage are TG11 and TG20. Based on the sequence of the 16S rRNA gene, isolates TG11 and TG 12 were identified as Chryseobacterium sp.Busuk lunak yang disebabkan oleh Pectobacterium carotovorum (Syn. Erwinia carotovora subsp. carotovora) merupakan salah satu penyakit penting pada tanaman sawi putih. Bakteri ini menghasilkan enzim pektinase yang dapat menguraikan pektin pada dinding sel tanaman bagian lamela tengah. Salah satu alternatif pengendalian penyakit busuk lunak ialah menggunakan agens biokontrol dari filosfer. Penelitian ini bertujuan menyeleksi dan menguji bakteri filosfer dari daun kubis yang berpotensi menghambat penyakit busuk lunak P. carotovorum pada sawi putih. Bakteri filosfer diisolasi dari wilayah Cianjur, Tegal, dan Bogor. Bakteri filosfer diuji keamanan hayati berdasarkan pada reaksi hipersensitivitas dan kemampuan lisis pada agar-agar darah, serta diuji kemampuan penghambatannya terhadap P. carotovorum berdasarkan pada uji antagonis secara in vitro dan uji penghambatan penyakit secara in vivo. Bakteri filosfer dikarakterisasi berdasarkan pada morfologi koloni dan sifat Gram. Dua galur bakteri filosfer paling berpotensi mengendalikan penyakit busuk lunak pada sawi putih diidentifikasi sebagai Chryseobacterium sp