Dahrul Syah

Purification and Characterization of a Fibrinolytic Enzyme from Bacillus pumilus 2.g Isolated from Gembus, an Indonesian Fermented Food

Bacillus pumilus 2.g isolated from gembus, an Indonesian fermented soybean cake, secretes several proteases that have strong fibrinolytic activities. A fibrinolytic enzyme with an apparent molecular weight of 20 kDa was purified from the culture supernatant of B. pumilus 2.g by sequential application of ammonium sulfate precipitation, ion-exchange chromatography, and hydrophobic chromatography. The partially purified enzyme was stable between pH 5 and pH 9 and temperature of less than 60°C. Fibrinolytic activity was increased by 5 mM MgCl2 and 5 mM CaCl2 but inhibited by 1 mM phenylmethylsulfonyl fluoride (PMSF), 1 mM sodium dodecyl sulfate (SDS), and 1 mM ethylenediaminetetraacetic acid (EDTA). The partially purified enzyme quickly degraded the α and β chains of fibrinogen but was unable to degrade the γ chain.

The influences of coagulation conditions and storage proteins on the textural properties of soy-curd (tofu)

The contribution of storage proteins (e.g., 7S, 11S) in soybean (variety Raja Basa) on the textural properties of tofu was investigated. Applying glucono-δ-lactone (GDL) as coagulant, the protein recovery was varied, dependent on coagulant concentration (p ≤ 0.05). Different coagulants yielded different proportions of 11S/7S storage protein ratios (p ≤ 0.05). Curd coagulated with CaSO4·2H2O lacked 7S subunits. The amount of 7S was up to 8.35% of the total storage proteins. This led to increased 11S/7S storage protein ratio and consequently increased curd hardness and gumminess (23.34 and 9.10 N, respectively). An upsurge of 11S/7S storage protein ratio resulted in a higher number of covalent bonds from disulfide bonding as 11S protein contains more total cysteine groups than 7S. Conclusively, this study shows 11S/7S storage protein ratio apparently has a contribution on the textural properties of curd especially on the characteristics of hardness and gumminess.

Differences in Protease Expression of Mutants Bacillus licheniformis F11

The objective of the study was to investigate the differences in protease productions of mutans Bacillus licheniformis F11. In this study B. licheniformis F11.1 (DchiA; Dpga) and B. licheniformis F11.4 (DchiAB; Dpga) was used. Two types (LB and MLB + collagen) of media were used for bacterial growth, protease production and zymogram analysis : Luria Broth (LB) and Modified Luria Broth plus collagen (MLB + collagen) media. The LB media contained tryptone 1%, NaCl 1% dan yeast extract 0.5%. The Modified LB + collagen media contained tryptone 0.5%; NaCl 1%, yeast extract 0.25% and collagen 5%. Two protease producing B. licheniformis F11 mutans were screened from Palembang Indonesia, Bacillus licheniformis F11.1 (DchiA; Dpga) and Bacillus licheniformis F11.4 (Dchi AB; Dpga). Both mutants showed different growth pattern and protease production in media containing collagen. F11.1 displays a higher protease activity than F11.4 in Luria Bertani media with an optimum after 15 hours for F11.1 and 15-25 hours for F11.4. Upon addition of collagen to LB medium F11.4 overmatched F11.1 with respect to collagenolytic activity. The presence of collagen led to a shift in the substrate preference of the two strains towards collagen compared to other protein substrates (gelatin, fibrin and casein). Zymogram analysis on gel embedded substrates suggests a higher molecular variation for strain F11.4.The different genetic mutation of the same species (Bacillus licheniformis F11.1 and F11.4) displayed different protease production patterns and substrate specificities especially on collagen.

Extraction of Squid (Photololigo Duvaucelii) Myofibrillar and Sarcoplasmic Proteins to Create A Skin Prick Test Reagent In The Diagnosis of Food Allergy

The major and minor allergens in fish and shellfish that have been identified are broadly spread in the myofibrillar and sarcoplasmic proteins. This study aimed to create the SPT reagents of squid myofibrillar and sarcoplasmic proteins to improve sensitivity and specificity diagnosis. Myofibrillar protein fraction was composed of 11 protein bands with the molecular weights of 18.2-108.4 kDa and sarcoplasmic protein fraction was composed of 13 protein bands with the molecular weights of 9.5-119.3 kDa. The allergenic myofibrillar protein has the molecular weights of 8.9-122.7 kDa while the allergenic sarcoplasmic protein has the molecular weights of 11.8-143.9 kDa. Each allergen extract was formulated into a SPT reagent met the requirements of the European Pharmacopoeia Monograph on Allergen Products 7 (2010:1063) for the parameters of moisture content, protein content, sterility and microbiology. A SPT to the respondents indicated that the sensitivity value of squid myofibrillar reagent was 86% and squid sarcoplasmic reagent was 64% with a negative error rate for each myofibrillar and sarcoplasmic reagents was 14% and 36%, respectively. The result diagnosis of squid myofibrillar and sarcoplasmic would generate sensitivity value at 100%. The separation of squid proteins into myofibrils and sarcoplasm for SPT could improve its sensitivity value and lowered the negative misdiagnosis. The specificity of each myofibrillar and sarcoplasmic proteins was 100% with an error rate of positive diagnosis occurrence at 0%.