Abstract. Yurnaliza. Rambe DI, Sarimunggu L, Purba M, Nurwahyuni I, Lenny S, Lutfia A, Hartanto A. 2020. Screening of Burkholderia spp. from oil palm plantation with antagonistic properties against Ganoderma boninense. Biodiversitas 21: 3431-3437.  Burkholderia spp. are ubiquitous diazotrophic bacteria within β-Proteobacteria group, known for its occurrence in variety of niches from aquatic to terrestrial habitats and as endophytes. Beneficial strains of Burkholderia have been reported as plant growth-promoting rhizobacteria or as antagonistic bacteria against phytopathogenic fungi. This study evaluated the potential of multiple strains of Burkholderia spp. recovered from three ecological niches, such as rhizosphere, humus soil, and root endophytes of oil palm plantations in North Sumatra to suppress the growth of basal stem rot causative agent in oil palm (Elaeis guineensis Jacq.) by Ganoderma boninense Pat. The antagonistic isolates were identified on the basis of molecular identification using 16S rDNA sequence (27F–1462R), revealing twelve isolates (48%) as members of Burkholderia cepacia complex (Bcc), with other minor genera, such as Chitinophaga, Klebsiella, Mycobacterium, Paenibacillus, Rhizobium, Serratia, Stenotrophomonas, and Xanthomonas. The antagonistic activities as expressed in the percentage inhibition of radial growth (PIRG) against G. boninense were considerably potential with the highest percentage of 55%. In comparison, the crude extract (MeOH, EtOAc) was also tested against G. boninense colonies showing PIRG from 0 to 38%. Majority of isolates did not show any visible chitinolytic activity based on plate assay, in exception to B. contaminans RC02 while most of them were producers of glucanase. The collection of indigenous Burkholderia spp. originating from North Sumatran oil palm plantations, i.e. B. cepacia, B. contaminans, B. metallica, and B. stagnalis may then be considered as potential biocontrol agents against G. boninense based on their antagonistic activities, antifungal properties, and hydrolytic enzyme activities.

Essential oils are volatile oils with different compositions according to their source of production and comprise a mixture of substances having different chemical and physical properties. One of the plants containing essential oil is Eucalyptus grandis grown at PT Toba Pulp Lestari (Indonesian company). The purpose of this work is to know the chemical contents and physical properties of essential oil from Eucalyptus grandis as well as to utilize unused leaves at PT. Toba Pulp Lestari to serve as an essential oil. The essential oil of Eucalyptus grandis leaves was extracted using hydrodistillation method, then essential oil is analyzed by GC-MS. The essential oil of Eucalyptus grandis leaves was obtained 0.4 %. The physical properties test with determination of density and refractive index of essential oil respectively were obtained at 0.9143 and 1.4653 nD at 29.4 ºC. The results of GC-MS analysis of essential oil showed 12 components viz. α-pinene (45.21 %), camphene (1.38 %), β-pinene (1.11 %), camphogen (0.74 %), 1,8-cineole (36.55 %), α-campholene aldehyde (0.73 % ), pinocarvone (0.83 %), α-terpineol (8.87 %), β-caryophyllene (1.72 %), spathulenol (0.84 %), elemol (0.85 % ) and 1-nonadecene (1.17 %).

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Penelitian ini bertujuan untuk mendeteksi senyawa fitokimia dan menguji aktivitas antioksidan ekstrak metanol, ekstrak etil asetat, total flavonoida dan flavonoid aglikona daun benalu kakao (Dendrophthoe pentandra (L.) Miq.). Serbuk kering daun D. pentandra (L.) Miq. (10 kg) dimaserasi dengan menggunakan metanol, ekstrak metanol diekstraksi kembali dengan etil asetat, ekstrak etil asetat dipartisi dengan n-heksana. Residu yang tersisa (total flavonoida) dihidrolisis dengan HCl 2 N sehingga diperoleh flavonoid aglikona. Diperoleh ekstrak metanol sebanyak 830 g (8,3%), ekstrak etil asetat 108 g (1,08%), total flavonoida 45 g (0,06%) dan flavonoid aglikona 6,2 g (0,06%) dan semua ekstrak berwarna hitam. Berdasarkan hasil skrining fitokimia yang dilakukan ekstrak metanol D. pentandra (L.) Miq. mengandung senyawa flavonoida, tanin, terpenoid, saponin dan tidak terdeteksi adanya alkaloid. Ekstrak etil asetat mengandung senyawa flavonoida, terpenoid dan saponin dan tidak terdeteksi adanya tanin dan alkaloid. Total flavonoida hanya mengandung flavonoida dan tidak terdeteksi adanya saponin, tanin, alkaloid dan terpenoid. Ekstrak metanol, etil asetat, total flavonoida dan flavonoid aglikona daun D. pentandra (L.) Miq. memiliki aktivitas antioksidan dengan nilai IC 50 berturut-turut sebesar 30,31; 36,23; 24,07 dan 18,22 mg/mL. Sedangkan asam askorbat sebagai kontrol menunjukkan nilai IC 50 12,08 mg/mL. Senyawa flavonoida dari daun benalu kakao (D. pentandra (L.) Miq.) dapat berfungsi sebagai antioksidan namun aktivitasnya lebih rendah dari pada asam askorbat.

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