Screening and Production of Antibacterial from Lactobacillus plantarum NS(9) Isolated from Nile Tilapia Bekasam
Lactic acid bacteria has been used as biopreservatif becouse produce a number of antibacterial<br />substances are safety and has inhibitory activity against enteropatogenic bacteria. The aims of this study<br />were to screen of antibacterial compounds produced by Lactobacillus plantarum NS (9) and to produce<br />their antibacterial compounds. The research was devided into two stages. In the first stage was L. plantarum<br />NS (9) inoculated at 37°C, for 24 hours in semi-anaerobic conditions. The cell-free supertnatant was given<br />three treatment, ie not neutralized (A), neutralized (pH 7) (N), and precipitated with ammonium sulfate<br />50% (P). This three supernatant was assayed their antibacterial activity against E. coli, S. typhimurium<br />ATCC 14028, S. aureus, B. cereus and L. monocytogenes using the agar well diffusion method. In the second<br />stage, production of antibacterial compound was L. plantarum NS (9) inoculated at 37°C, for 24 hours<br />in semi-anaerobic conditions. The Dencity Optical, value pH, acid total and antibacterial activity were<br />measured every three hours during growth of bacteria. The results of the antibacterial screening showed<br />that L. plantarum NS (9) produced inhibitory zone againts the five indicator bacteria from a supernatant,<br />whereas N and P supernatant were not produced inhibitory zone. This result indicated that inhibition activity of L. plantarum (NS 9) was caused by the lower pH of supernatant. The antibacterial compouds were<br />produced at 6 hours of incubation and were increased to simultaneously with increasing of bacteria growth.<br />The highest antibacterial activity against E. coli, B. cereus and L.monocytogenes were produced at the end<br />of the exponential growth phase (12 -15 hours incubation) while against S. aureus and S. typhimurium<br />ATCC 14028 at 21 and 24 hour of incubation, respectively. The antibacterial activity also was increased to<br />simultaniously with increasing of acid total (1.350 to 4.050%) and decreasing of pH value (6-4) during<br />growth of bacteria.