Bioprospecting Ascidian-Associated Aspergillus sp. from Sigillina sp. in Bunaken as a Source of Bioactive Metabolites: Phytochemical Profiling, Antioxidant–Antimicrobial Activities, and ITS-Based Identification
DOI:
https://doi.org/10.35800/jip.v14i2.68654Keywords:
ascidian, Aspergillus sp, antimicrobial, antioxidant, Bunaken, DPPH, marine-derived fungi, Sigillina sp.Abstract
This study aimed to isolate a symbiotic fungus from the ascidian Sigillina sp. collected from Bunaken waters, evaluate the phytochemical profile of its ethyl acetate extract, determine antioxidant and antimicrobial activities, and identify the isolate using internal transcribed spacer (ITS) sequences. The ascidian sample was collected purposively by SCUBA at 5-13 m depth. Fungal isolation was performed on Potato Dextrose Agar, followed by purification, rice-medium cultivation, ethyl acetate extraction, phytochemical screening, DPPH assay, disc diffusion antimicrobial assay, and ITS-based molecular identification through PCR, sequencing, BLAST, and phylogenetic interpretation. The isolate AFBK 5c produced 0.719 g of dry extract. The extract was positive for phenolics, flavonoids, triterpenoids, tannins, and alkaloids, while steroids and saponins were not detected. DPPH inhibition increased from 51.68% at 25 ppm to 71.19% at 125 ppm, with a linear regression of y = 0.20112x + 48.002 (R² = 0.9590), indicating strong in vitro radical-scavenging capacity. The extract showed selective antimicrobial activity, particularly against Candida albicans and Aeromonas hydrophila, with inhibition zones up to 15 mm. ITS analysis produced a 779 bp sequence showing 100% similarity to Aspergillus sp. These findings indicate that Aspergillus sp. AFBK 5c associated with Sigillina sp. from Bunaken is a promising preliminary source of bioactive metabolites, although claims should remain limited to crude-extract-based in vitro screening.
Keywords: ascidian; Aspergillus sp.; antimicrobial; antioxidant; Bunaken; DPPH; marine-derived fungi; Sigillina sp.
Abstrak. Penelitian ini bertujuan mengisolasi jamur simbion dari ascidia Sigillina sp. asal perairan Bunaken, mengevaluasi profil fitokimia ekstrak etil asetat, menentukan aktivitas antioksidan dan antimikroba, serta mengidentifikasi isolat secara molekuler menggunakan sekuens internal transcribed spacer (ITS). Sampel ascidia dikoleksi secara purposive menggunakan SCUBA pada kedalaman 5-13 m. Isolasi jamur dilakukan pada media Potato Dextrose Agar, dilanjutkan pemurnian isolat, kultur pada media nasi, ekstraksi etil asetat, penapisan fitokimia, uji antioksidan DPPH, uji antimikroba difusi cakram, serta identifikasi molekuler melalui PCR, sekuensing ITS, BLAST, dan interpretasi filogenetik. Isolat AFBK 5c menghasilkan ekstrak kering sebesar 0,719 g. Ekstrak menunjukkan hasil positif terhadap fenolik, flavonoid, triterpenoid, tanin, dan alkaloid, sedangkan steroid dan saponin tidak terdeteksi. Inhibisi DPPH meningkat dari 51,68% pada 25 ppm menjadi 71,19% pada 125 ppm, dengan persamaan regresi y = 0,20112x + 48,002 (R² = 0,9590), sehingga menunjukkan kapasitas peredaman radikal bebas in vitro yang kuat. Aktivitas antimikroba bersifat selektif, terutama terhadap Candida albicans dan Aeromonas hydrophila dengan zona hambat hingga 15 mm. Identifikasi ITS menghasilkan sekuens 779 bp dengan kemiripan 100% terhadap Aspergillus sp. Temuan ini menunjukkan bahwa Aspergillus sp. AFBK 5c simbion Sigillina sp. dari Bunaken berpotensi sebagai sumber awal metabolit bioaktif, dengan klaim yang tetap dibatasi pada skrining in vitro berbasis ekstrak kasar.
Kata kunci: antimikroba; antioksidan; ascidia; Aspergillus sp.; Bunaken; DPPH; jamur simbion; Sigillina sp.
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