Lactic acid bacteria (LAB) produce bacteriocin, which is potentially administered as biopreservative. It is important to study bacteriocin continuously from an applied perspective. However, isolate LAB strain Pr 4.3L obtained from peda fish are known to produce antimicrobial compounds such as bacteriocin. Therefore, it is important to optimize the production of bacteriocin from these strains by examining the effect of incubation temperatures and pH on the activity of LAB strain Pr 4.3L. The biomass of lactic acid bacteria strain Pr 4.3L was grown in MRS broth medium with pH conditions of 4-8 which was adjusted using 1 N HCl and NaOH. Furthermore, the culture was incubated at 30 and 37°C for 36 hours, and the bacteriocin activity was tested for its inhibition against pathogenic bacteria (S.aureus ATCC 25923, S.typhi BPE 122.4 CCA and S.typhi NCTC 786) using agar well diffusion method. The treatment at 30°C on MRS broth medium with a pH of 7 is the best growth condition for bacteriocin production. Under these conditions, antimicrobial and bacteriocin activities are more inhibited than other treatments. This inhibition showed a broad-spectrum against indicator bacteria (S.aureus ATCC 25923, S.typhi BPE 122.4 CCA and S.typhi NCTC 786). Therefore, the results provided useful information on the potential of bacteriosinogenic LAB as a natural preservative.