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"Isolat-isolat actinomycetes laut dari ekosistem bakau Pulau Pramuka, Kepulauan Seribu, DKI Jakarta dilaporkan dapat menghasilkan senyawa bioaktif dengan aktivitas sebagai antibakteri dan antifungi. Penelitian ini bertujuan untuk menyeleksi isolat-isolat actinomycetes laut yang berpotensi sebagai agen biokontrol berdasarkan aktivitas antagonistik terhadap fungi patogen tanaman Colletotrichum siamense KA, mengevaluasi aktivitas senyawa antifungi, dan menelaah profil isolat actinomycetes laut terpilih. Penapisan isolat dilakukan dengan metode plug dengan penundaan uji hingga 9 hari pada medium Potato Dextrose Agar (PDA) modifikasi. Hasil penapisan diperoleh 12 isolat actinomyctes laut mampu menghambat pertumbuhan C. siamense KA, dengan persentase hambatan berkisar antara 47,96% hingga 84,94%. Enam dari 12 isolat diuji aktivitas antagonistik menggunakan metode plug dan gores dengan variasi penundaan uji (6, 9, dan 12 hari). Hasil uji aktivitas antagonistik menunjukkan penundaan uji hingga 12 hari memiliki persentase hambatan pertumbuhan tertinggi hingga 84,16% (metode plug) dan 85,91% (metode gores). Uji antagonistik dengan penundaan (3 dan 5 hari) serta tanpa penundaan menggunakan metode plug menunjukkan dua isolat (SM11 dan SM15) memiliki peningkatan persentase hambatan pertumbuhan hingga 57,99% (SM11) dan 59,88% (SM15). Aktivitas antifungi tiga isolat actinomycetes laut terpilih (SM11, SM14, dan SM15) diuji menggunakan uji antibiosis pada medium Potato Dextrose Broth (PDB) modifikasi. Fermentasi untuk memproduksi senyawa antifungi dilakukan selama 6, 9, dan 12 hari. Hasil uji antibiosis menunjukkan isolat SM14 memiliki aktivitas antifungi tertinggi pada hari ke-12 dengan persentase hambatan 64,90%. Tiga isolat actinomycetes laut terpilih memiliki karakter morfologi dan biokimia yang serupa. Identifikasi molekular ketiga isolat tersebut menunjukkan hubungan dekat dengan Streptomyces sanyensis dengan persentase kemiripan hingga 99,66%.

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Marine actinomycetes isolates from mangrove ecosystem Pramuka Island, Kepulauan Seribu, DKI Jakarta have been reported produce bioactive compound with antibacterial and antifungal activity. The aims of this research were to select potential marine actinomycetes isolates as biocontrol agent based on antagonistic activity against fungal phytopathogen Colletotrichum siamense KA, evaluate antifungal activity, and analyze profile of selected marine actinomycetes isolates. Screening of isolates was performed using plug method with delayed antagonist assay for 9 days on modified Potato Dextrose Agar (PDA) medium. The result of screening displayed that 12 marine actinomycetes isolates can inhibit the growth of C. siamense KA, with percentage inhibition from 47.96% to 84.94%. Among 12 isolates, six isolates have been subjected for antagonistic assay using plug and streak method with various delayed assay (6, 9, and 12 days). The result presented delayed antagonist assay until 12 days has higher percentage inhibition up to 84.16% (plug method) and 85.91% (streak method). The antagonistic assay using delayed assay (3 and 5 days) and non-delayed assay using plug method presented two isolates (SM11 and SM15) showed increasing percentage inhibition up to 57.99% (SM11) and 59.88% (SM15). Antifungal activity of selected isolates (SM11, SM14, and SM15) was assayed using antibiosis assay in modified Potato Dextrose Broth (PDB) medium. Fermentation for producing antifungal compound was performed for 6, 9, and 12 days. The result of antibiosis assay showed SM14 isolate has higher antifungal activity at 12 days incubation with percentage inhibition was 64.90%. The three marine actinomycetes isolates have similar morphological and biochemical characters. Molecular identification of three isolates showed that the isolates were closely related to Streptomyces sanyensis with 99.66% percent similarity."

"Sektor kelapa sawit (Elaeis guineensis Jacq.) berperan penting dalam perekonomian nasional, tetapi terancam oleh infeksi Ganoderma boninense yang menyebabkan penyakit Busuk Pangkal Batang (BPB). Salah satu upaya pengendalian penyebaran fungi fitopatogen yaitu menggunakan bakteri antagonis. Penelitian ini bertujuan untuk menguji potensi antagonis ko-kultur Bacillus siamensis LDR dan Stenotrophomonas maltophilia G17 terhadap Ganoderma boninense melalui uji antagonis dan antibiosis. Uji antagonis dilakukan menggunakan metode dual culture berupa pour plate dan disc delayed culture pada medium. Filtrat ko-kultur yang difermentasi selama 5 dan 7 hari pada Nutrient Broth (NB) dan NB dengan tambahan glukosa digunakan untuk uji antibiosis menggunakan metode agar well diffusion dan pour plate. Uji antagonis maupun uji antibiosis dilakukan pada medium Plate Count Agar (PCA) dan Potato Dextrose Agar (PDA). Potensi antagonis dan antibiosis ko-kultur bakteri terhadap fungi diukur berdasarkan diameter pertumbuhan fungi yang menunjukkan hambatan menggunakan rumus Growth Inhibition Rate (GIR). Hasil uji antagonis menunjukkan hambatan pertumbuhan fungi mencapai 69.63% ± 2,46% pada metode disc delayed culture sedangkan pada metode pour plate mencapai 100%. Sementara, filtrat hasil fermentasi ko-kultur bakteri berusia 5 hari dan 7 hari menghasilkan senyawa antifungi yang menghambat pertumbuhan fungi uji dengan GIR mencapai 100% pada metode pour plate dan 48,20% ± 2,23% pada metode agar well diffusion. Filtrat hasil fermentasi selama 5 hari menunjukkan performa antibiosis yang lebih baik. Sementara, penambahan glukosa pada proses fermentasi tidak meningkatkan performa antibiosis. Selanjutnya, perlu dilakukan identifikasi senyawa antifungi yang dihasilkan oleh ko-kultur B. siamensis LDR dan S. maltophilia G17.

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The oil palm sector (Elaeis guineensis Jacq.) plays a crucial role in the national economy but is threatened by Ganoderma boninense, causing Basal Stem Rot (BSR). One strategy to control the spread of this phytopathogenic fungus is to employ antagonistic bacteria. This research aims to assess the antagonistic potential of co-cultured Bacillus siamensis LDR and Stenotrophomonas maltophilia G17 against G. boninense through antagonism and antibiosis assays. Antagonism assays were conducted using pour plate and disc delayed culture methods. Fermented co-culture filtrates (5 and 7-day) in Nutrient Broth (NB) and NB supplemented with glucose were utilized for antibiosis assays, using agar well diffusion and pour plate methods. Both assays were conducted on Plate Count Agar (PCA) and Potato Dextrose Agar (PDA) media. Potency of bacterial co-culture against G. boninense were evaluated based on the inhibition diameter of fungal growth, calculated using the Growth Inhibition Rate (GIR) formula. The antagonism assay results showed fungal growth inhibition of 69.63% ± 2.46% with the disc delayed culture, while the pour plate achieved 100% inhibition. Meanwhile, the filtrate from the 5 and 7-day fermented bacterial co-culture produced antifungal compounds that inhibited fungal growth by 100% using the pour plate and 48.20% ± 2.23% using the agar well diffusion. The 5-day fermented filtrate showed better antibiosis performance. The addition of glucose during the fermentation process did not enhance antibiosis performance. Further identification of antifungal compounds produced by the B. siamensis LDR and S. maltophilia G17 co-culture is needed."