Aims: To characterize the plantaricin IIA-1A5 crude extract that biosynthesized by Lactobacillus plantarum IIA-1A5 using corn steep liquor (CSL) based medium. Methodology and results: Lactobacillus plantarum IIA-1A5 was grown in several media containing different components including corn steep liquor (CSL), molasses and MRS (de Man Rogosa Sharpe) as control medium for 24 h at 37 °C. Antibacterial activities of the cell-free supernatant were expressed as diameter of inhibition zones observed by paper disc method. The results showed that CSL medium produced cell-free supernatant of L. plantarum IIA-1A5 with significantly higher antibacterial activity againts Staphylococcus aureus ATCC 25923 (9.81 mm), Lactobacillus monocytogenes ATCC 7644 (9.61 mm), Bacillus cereus (8.97 mm) and Escherichia coli ATCC 25922 (9.23 mm) were not significantly different compared to control MRS broth media (9.59 mm). CSL medium added only with 3% yeast extract and Tween 80 produced supernatant which showed similar antibacterial activity either to 10% molasses or control medium (Medium K and B). The CSL medium was considered more efficient and low cost, therefore this medium was selected for production and characterization of plantaricin IIA-1A5 crude extract. Further characterization performed by SDS PAGE analysis showed that crude plantaricin had molecular weight of approximately 9.9 kDa, higher than that produced in control medium (8.0 kDa). However, both plantaricins were categorized under the same class for small bacteriocin (class II). This study also revealed the plantaricin IIA-1A5 produced in CSL medium was stable to heat and pH and not significantly different compared to control MRS broth media. The antibacterial activity of plantaricin IIA-1A5 crude extract against S. aureus ATCC 25923 (10.09 mm) was not significantly different with 1000 ppm sodium benzoate (9.70 mm) and 300 ppm sodium nitrite (9.82 mm). Conclusion, significance and impact of study The CSL medium produced cell-free supernatant of L. plantarum IIA 1A5 had significant antibacterial activity characterization againts S. aureus ATCC 25923, L. monocytogenes ATCC 7644, B. cereus and E. coli ATCC 25922. Comparison of the inhibition activity of plantaricin IIA-1A5 crude extract against pathogen with synthetic preservatives indicated that plantaricin IIA-1A5 crude extract have the potency to replace synthetic preservatives. CSL based medium is potential to be used for low-cost plantaricin IIA-1A5 production.
Anti-Bacterial Agents--metabolism ; Bacteriocins--metabolism ; Lactobacillus plantarum ; Microbial Viability--drug effects ; Staphylococcus aureus

Aims: This study was designed to investigate the antibacterial properties of the sericin protein Bombyx mori and Samia cynthia ricini against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus strains. Methodology and results: Sericin protein was extracted from the cocoons of B. mori races A, B, C, D, F1-1, F1-2 and S. ricini from Indonesia using a degumming process. The extracted sericin protein was evaluated as anti-microbials using Kirby Breuer disc diffusion, spectrometer measurement in decreasing OD value and imaging scanning electron microscope (SEM). The tests revealed that sericin protein from B. mori was more capable of inhibiting bacteria S. aureus than E. coli. Sericin protein from S. ricini was also capable of strongly inhibiting both S. aureus and E. coli bacteria. The sericin proteins of B. mori and S. ricini were found to reduce the number of S. aureus and E. coli bacteria as the OD value decreased at a concentration of 9%. The SEM imaging suggests that sericin B. mori and S. ricini proteins caused changes in cell morphology in S. aureus and E. coli bacteria, resulting in bacterial cell function disruption and death. Conclusion, significance and impact of study Bombyx mori and S. ricini sericin proteins were found to act against S. aureus and E. coli bacteria. Therefore, sericin protein has a greater antibacterial activity against Gram-positive strain S. aureus.
Anti-Bacterial Agents ; Sericins ; Bombyx ; Lepidoptera ; Escherichia coli ; Staphylococcus aureus