Antibacterial, antifungal and antioxidant activities of Bacillus cereus SMPRL-2 isolated from seaweeds Eucheuma cottonii

Abstract

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 IC50 value of 33000 ppm was observed. Overall, this result provides a preliminary finding of marine bacteria as naturally active compounds producer.