Anak Agung Sri Agung Aryastuti's scientific contributions

Seaweed-associated bacteria have a pivotal role to synthesize arrays of secondary metabolites. This study described a bacterial isolate encoded as ISP1RL3 that was isolated from seaweed Eucheuma cottonii. Ethyl acetate extracts of ISP1RL3 was screened against non-multidrug bacteria (Staphylococcus aureus ATCC 25923, Streptococcus mutans FNCC 0405, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603) and multi-drug resistance bacteria (Methicilin-resistance S. aureus (MRSA), E. coli ESBL, K. pneumoniae ESBL, dan A.baumanii ESBL). Our result showed that ISP1RL3 displayed rod structure, Gram negative and identified as Pseudomonas aeruginosa. The crude extract displayed strong antibacterial activity against all bacterial test with the range zone of inhibition of 10 mm – 18 mm. The GC-MS analysis detected the presence of 13 antibacterial compounds with four dominant moleculer were o-Xylene, Ethylbenzene, p-Xylene and Benzene, 1,3-dimethyl. Overall, this finding highlights the potency of seaweed-associated bacteria to synthesize active compounds against multidrug resistance bacteria.

Seaweeds have a strong relationship with prokaryotic community especially bacteria. Bacteria-associated with seaweeds generally produce active compounds which could be potential for pharmaceutical purposes. This research was focused to study antibacterial, antifungal and antioxidant activities from a bacteria encoded as SMPRL-2, isolated from Eucheuma cottonii . Molecular identification of the isolate was performed based on 16S rRNA sequencing and its morphology was assessed using scanning electronic microscope (SEM). The isolate SMPRL-2 was fermented in 100 mL ISP-2 liquid media for 14 days and extracted using ethyl acetate (1:1 ratio, v/v). The obtained crude extract was screened against bacterial and fungal isolates based on Kirby-Bauer method. The extract was screened for its antioxidant activities using DPPH method. The isolate was identified as Bacillus cereus , with short rod morphology under SEM observation. Zone of inhibition (ZOI) of the extract was 14.7±0.8 mm and 9.1±0.8 mm against Streptococcus mutans FNCC 0405 and Escherichia coli ATCC 25922, respectively. Furthermore, ZOI of the extract against Candida albicans and Aspergillus flavus were 9.6±0.9 mm and 8.8±2.3 mm respectively. A very weak antioxidant activity with IC 50 value of 33000 ppm was observed. Overall, this result provides a preliminary finding of marine bacteria as naturally active compounds producer.