Antimicrobial and Antioxidant Activities of Bacterial Extracts from Marine Bacteria Associated with Sponge Stylotella sp.

Abstract

Sponge-associated bacteria have great potential in developing marine pharmaceutical industry since they are capable of synthesizing numerous bioactive metabolite compounds. This study aimed to isolate, characterize and investigate potential antimicrobial, toxicity and antioxidant of bioactive compounds of bacteria associated with sponge Stylotella sp. A total of 138 bacteria were selected. During screening stage, 45 isolates (32%) produced a wide spectrum and species specific bioactive compound against microbial test strains (Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Eschericia coli ATCC 8739, Enteropathogenic Escherichia coli (EPEC) and Candida albicans). Crude extract of five selected potential bacteria were extracted using ethyl acetate solvent. They were identified to have a wide spectrum inhibition capability against microbial test strains. The extracts toxicity were examined using the Brine Shrimp Lethality Test (BSLT) method. All extracts showed toxicity of LC50 in the range of 35.89-484.17 µg mL^-1 against Artemia salina. By using Cupric Reducing Antioxidant Capacity (CUPRAC) radical reduction test revealed all the extracts showed potential antioxidant activites, ranging from 445.33 to 1610.00 µmol trolox/g extract. Based on 16S rRNA sequence analysis revealed that isolates STIL 33, STIL 37, STIL 44, STIL 55 and STIL 9 were closely related with Pseudoalteromonas flavipulchra strain NCIMB 2033, Serratia marcescens strain NBRC 102204, Catenococcus thiocycli strain TG 5-3, Vibrio natriegens strain ATCC 14048 and Bacillus subtilis strain JCM 1465, respectively.