Biotropika: Journal of Tropical Biology

Isolation and Identification of Endophytic Bacteria from Kumis Kucing Leaves (Orthosiphon aristatus Benth.)

Nur Asni Setiani — 2024-04-02

Endophytic bacteria are in symbiosis with plants and have the potential to produce secondary metabolites similar to their host. Kumis kucing (Orthosiphon aristatus) is a traditional medicinal plant that has been proven to have many pharmacological activities, including antiviral and antibacterial. This study aims to isolate and characterize endophytic bacteria from kumis kucing leaves. Endophytic bacteria were isolated from kumis kucing leaf by spreading method on Trypticase Soy Agar (TSA) media and incubated for 24 hours at room temperature. Colonies that grew with bacterial morphology were inoculated on TSA media to obtain pure cultures. Pure cultures of isolates were identified through Gram staining, 16S rRNA gene sequencing, and bacterial growth curves. There were eight isolates with bacterial morphology, which were identified by Gram staining. The staining results showed that all were classified as Gram-negative with rod and coccus shapes. The 16S rRNA gene sequencing identified three bacterial isolates: Acinetobacter schindleri, Pantoea agglomerans, and Pseudomonas lurida. The three bacteria have different time to reach stationary phases in order to produce their secondary metabolites.

Secondary Metabolite Profile in Stem and Root of Keji Plant (Staurogyne elongata [Blume] Kuntze)

Hana Safitri — 2024-04-02

Keji (Staurogyne elongata [Blume] Kuntze) is an herbal medicinal plant that is often found on the Java to Sumatra islands. The leaves and roots of keji (S. elongata) have been used by the community as diuretic drugs, increasing blood pressure and trusted to treat bladder stones, kidney stones, and joint problems. However, research on secondary metabolites in the stems and roots of keji has never been done. The study aimed to identify the secondary metabolite content and marker compounds in the stems and roots of S. elongata. The research stages were drying and sample grinding, extraction, and metabolite compound analysis using Gas Chromatography-Mass Spectrometry (GC-MS). The results showed nine secondary metabolite compounds found in S. elongata stem, such as phenol, terpenoid, and alcohol. Meanwhile, secondary metabolite compounds of S. elongata root were ten compounds from the coumaran, phenols, and ester group. The 2,2’-methylenebis[6-(1,1-dimethylethyl)-4-methyl-phenol is proposed as a marker compound in S. elongata stem. Meanwhile, no secondary metabolites can be used as marker compounds in S. elongata roots because octadecanoic acid, 2-hydroxy-1-(hydroxymethyl)ethyl ester is the primary metabolite.

Diversity and Potential Analysis of Liquid Biopesticide Bacteria for Fusarium sp. Control of Shallot -Basal Rot

Nur Aini — 2024-04-19

Shallot basal rot disease (Allium cepa L.) caused by the fungus Fusarium causes many crop losses thus control efforts are required. Microbial biopesticides are used as an alternative to control pests and plant pathogens that are environmentally friendly and target-specific. This study aims to evaluate the diversity of liquid biopesticide bacteria and their potential to control the Fusarium sp. pathogen of shallots. This study includes shallot sampling, isolation, and purification of liquid biopesticide bacteria, liquid biopesticide antifungal test, double culture antagonistic test of bacterial isolates against Fusarium sp., and identification of potential bacterial isolates based on 16S rDNA sequence similarity. The results showed that two bacterial isolates, B7 and B2, had the highest importance value index of 94.21% and 90.59%, respectively, with a bacterial diversity index of 1.44. Liquid biopesticide microbial biomass has a high inhibition zone in the antifungal test against Fusarium sp. with an average inhibition zone of 6.45 mm. Bacterial isolate B2 has the highest potential inhibition of 71.3% against Fusarium sp. and was identified as Genus Serratia with a similarity value of 96.79%.