Preliminary detection of antimicrobial activities of exiguobacterium indicum

Abstract

Nowadays, drug resistance is increasing. Hence, finding out the new compound to overcome is essential in pharmaceutical fields. This study focused on the antimicrobial activities of the pigment producing bacteria, Exiguobacterium indicum cultured in Luria broth in different incubation time (24h, 48h, 72h) at different incubation temperature (25 oC, 37oC, 45oC). The antimicrobial activity test was carried out, basing on the agar diffusion method. The 25 oC cultured supernatant of the bacteria showed the maximal ability against the pathogens such as Salmonella typhi (1.4 ± 0.1 mm), Pseudomonas aeruginosa (1.27 ± 0.06 mm), and Serratia marcescens (1.13 ± 0.15 mm). By calculating the equivalent concentration of ceftriaxone for the potency determination of the supernatants, the highest potency on Salmonella typhi, Pseudomonas aeruginosa, and Serratia marcescens was 15.14 μg/ml, 3.98 μg/ml, 3.98 μg/ml, respectively. The antimicrobial activity was stable at pH6, 7, 8. The extraction step was conducted for the preliminary identification of the pigment compounds. The study also suggested the extraction process to isolate two different kinds of yellow pigments with different solubiity in distilled water and chloroform, which showed a weak antimicrobial activity on Micrococcus luteus. This was a first reports on antimicrobial activity of Exiguobacterium indicum isolated in Vietnam. Keywords: Exiguobacterium indicum Antimicrobial activities Agar diffusion method Preliminary identification