| In previous study, 141 isolates of marine bacteria were successfully isolated from Indonesian coastal sediment. This study was aimed to investigate whether crude extracts of these selected isolates exerted potential antimicrobial and antioxidant activities in vitro. Crude extract was prepared by solvent extraction using 1-butanol. Antimicrobial assay of crude extracts (1-500 µg/mL) against Bacillus cereus and Staphylococcus aureus was determined by using Minimum Inhibitory Concentration (MIC). Antioxidant assay of crude extracts (5-500 µg/mL) was done by employing 3 assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferrous chelating activity (FCA), and anti-lipid peroxidation. Our results demonstrated that crude extracts of isolates exerted moderate antimicrobial activities against growth of B. cereus and S. aureus with MIC values > 500 µg/mL. Some isolates showed potential antioxidant activity in a independent-dose manner. Among 3 antioxidant systems, crude extracts of isolates at 500 µg/mL exerted antioxidant activity < 45% using DPPH assay, < 35% using FCA assay, and < 75% using anti-lipid peroxidation assay. Based on molecular identification using 16S rRNA gene sequence, these isolates with antimicrobial and antioxidant properties were identified as Psychrobacter alimentarius, Bacillus sp. and B. niabensis. These results suggest that crude extracts of P. alimentarius may potentially be an alternative antimicrobial and antioxidant agents. |