Partial Purification of Bacteriocin from Lactobacillus pentosus Strain 124-2 Isolated from "Dadih".

<b>Background and Objective:</b> Preservation using antimicrobials has been observed to inhibit the growth of pathogenic bacteria in food. Nowadays many people choose food preservatives that are safe for health and natural. Bacteriocins as food preservatives are safe because antimicrobials from the antimicrobial peptide group include GRAS (Generally Recognized As Safe). Bacteriocin-producing LAB can be found in various fermented foods, one of which is "Dadih". Bacteriocins are expected to inhibit the growth of pathogenic bacteria so that they can be developed as an alternative to food preservatives. <b>Materials and Methods:</b> In this study, all experiments were performed with two replicates and the results were expressed as Mean±Standard Deviation (SD). <b>Results:</b> Screening results showed that the DK8 isolate had the highest antimicrobial activity. The DK8 isolate was identified molecularly using 16s RNA sequencing, showing that the DK8 isolate had the highest similarity to <i>Lactobacillus pentosus</i> strain 124-2. Bacteriocins from DK8 isolate and partially purified using ammonium sulfate precipitation at concentrations of 50, 60 and 70%. The addition of ammonium sulfate with a concentration of 50% showed the highest antimicrobial activity against <i>Salmonella</i> sp. (12.63 mm) and <i>Escherichia coli</i> (11.33 mm) while the highest antimicrobial activity against <i>Staphylococcus aureus</i> was the addition of 60% ammonium sulfate (8.13 mm). <b>Conclusion:</b> Lactic acid bacteria isolate was identified to have the highest similarity with <i>Lactobacillus pentosus</i> strain 124-2 and precipitation using 50% ammonium sulfate showed the highest antimicrobial activity.

Purification and Characterization Laccase from Trametes versicolor (L.) Lloyd in Submerged Fermentation.

<b>Background and Objective:</b> Laccase is classified as an oxidoreductase enzyme that catalyzes oxidation reactions of phenolic groups by using oxygen as its electron acceptor. Laccase isolated from <i>Trametes versicolor</i> (L.) Lloyd has a wide range of applications in the industrial sector. The use of enzymes in the industrial sector requires pure enzyme conditions from impurities so that the enzyme can maximize its ability in converting the substrate. This study aims to obtain enzyme activity and the characteristic of purified laccase enzymes isolated from <i>Trametes versicolor</i> (L.) Lloyd. <b>Materials and Methods:</b> This study was conducted with an experimental method followed by descriptive analysis. The steps of this research consist of a qualitative assay of laccase enzyme, crude laccase extract desalting by Sephadex G-25, laccase purification by Sephadex G-100 and laccase optimum pH characterization. <b>Results:</b> The result of this study showed that purification of laccase from <i>Trametes versicolor </i>(L.) Lloyd with Sephadex G-25 increases laccase enzyme-specific activity which is 10.966 U mg¹ and reaches 2.93-fold purity. The highest laccase enzyme activity was achieved at pH 4 with a value of laccase activity 62.39 U L¹. <b>Conclusion:</b> Based on current results, purifying laccase from <i>Trametes versicolor </i>(L.) Lloyd with Sephadex G-25 was recommended which resulting higher enzyme specific activity.

Potential of Lignocellulosic Waste for Laccase Production by Trametes versicolor under Submerged Fermentation.

<b>Background and Objective:</b> Laccase is one of the ligninolytic enzymes classified as a multicopper oxidoreductase group that has the ability in oxidizing phenolic compounds and has widespread use in both food and non-food industries. This enzyme is extracellularly secreted by white-rot fungi, <i>Trametes versicolor</i> (L.) Lloyd in the media containing lignocellulose, for example, kapok banana peels and sawdust. The objective of this study was to evaluate lignocellulosic substrate that able to produce the highest activity of the laccase from the <i>T. versicolor </i>(L.) Lloyd. <b>Materials and Methods:</b> Three substrate variations used in this work included the cultivation media with the addition of either kapok banana peels or sawdust and without using both materials. The inducer (CuSO₄) was added to each substrate variation and the laccase activity was subsequently measured. <b>Results:</b> The qualitative test result for laccase detection showed that <i>T. versicolor </i>(L.) Lloyd<i> </i>was able to produce this enzyme indicated with a reddish-brown surrounding fungal colony. The fungi cultivated in media with the content of sawdust and 1 mM CuSO₄ yielded the highest laccase activity, reaching 573.6 U L¹ with an OD value of 0.5567<i> </i>and a pH of 5.3 after 7 days of incubation. Meanwhile, the addition of kepok banana peels and 1 mM CuSO₄, showed the maximum laccase activity (297.7 U L¹) with the OD value of 0.6932 and a pH of 5 after incubation for 6 days. <b>Conclusion:</b> The white-rot fungi of <i>T. versicolor</i> (L.) Lloyd<i> </i>could produce optimal laccase activity by adding sawdust substrate and 1 mM CuSO₄inducer on submerged fermentation.

Indigenous Bacteriocin of Lactic Acid Bacteria from "Dadih" a Fermented Buffalo Milk from West Sumatra, Indonesia as Chicken Meat Preservative.

BACKGROUND AND OBJECTIVE: The bacteriocin isolated from fermented buffalo milk from West Sumatra-Indonesia, called Dadih, can be considered as a natural and safe antimicrobial compound for food products. The objective of this research was to evaluate the antimicrobial activity of bacteriocin from Dadih and its effectiveness as a preservative in chicken meat. MATERIALS AND METHODS: This study used experimental method followed by statistical analysis using 3 experiments with duplication including experiment of meat samples (0 and 10% bacteriocin), storage temperatures (7 and 26°C) and storage duration (0, 1, 2, 3, 4, 5, 6 days and 0, 6, 12 hrs). Each experiment consists of a bacteriocin test, antimicrobial activity assay, physicochemical measurement and storability. RESULTS: From 10 LAB isolates successfully obtained from Dadih, two isolates with D7 code and D10 code had the highest antimicrobial activity, reaching 11.75 mm and 12 mm, respectively. The meat treated by 10% of bacteriocin gave the lower total microbial (3rd and 5th day) and total E. coli (5th day) at 7 and 26°C. The pH and water activity (aw) values of chicken meat with 10% of bacteriocin showed lower values at 7 and 26°C. The application of bacteriocin to chicken meat was able to inhibit the microbial growth that was still below standard for 3 days at 7°C and 6 hrs at 26°C. CONCLUSION: Based on research, lactic acid bacteria isolated from buffalo milk curd produced bacteriocin compound which has antimicrobial properties. This bacteriocin showed potential as a natural preservative for chicken meat by inhibiting the growth of pathogen microorganisms.

Study of Ganoderma lucidum in Laccase Production using Corncob and Paddies Straw Substrates on Submerged Fermentation System.

BACKGROUND AND OBJECTIVE: Ganoderma lucidum a white rot fungi, produce laccase which capable to degrade lignin due to its activity as ligninolytic enzymes. The production of laccase by G. lucidum using various agroindustrial wastes, including corncob and paddies straw, as substrates have been studied. The purpose of this study was to determine substrate that able to produce the highest activity of the laccase from the G. lucidum. MATERIALS AND METHODS: The method used an experimental design followed by descriptive analysis using 4 treatments with duplication including treatment G. lucidum growth into A (control, Potato Dextrose Broth (PDB)), B (PDB+corncob), C (PDB+rice straw) and D (PDB+corncob+rice straw). This study includes; (1) Qualitative assay determination of laccase, (2) Extraction and laccase activity, (3) Cell concentration of G. lucidum measurement and (4) pH measurement. RESULTS: Laccase qualitative assay showed brownish red ring on PDA media that indicated a positive of the laccase enzyme secreted by G. lucidum. Enzyme activity under submerged fermentation condition was achieved by the treatment of adding corncobs with the highest activity accounting 68.75 U mL-1. The fermentation process causes a decrease in pH during the incubation time to pH 4.83. The results of pH measurements showed that the laccase enzyme from G. lucidum worked optimally at pH 4-5 achieved after 5 day of incubation. CONCLUSION: Our results suggest that G. lucidum has potential to produce laccase enzyme by using substrate comprising corncob and rice straw on submerged fermentation.