Judul: Kajian Produksi Aflatoksin dari Isolat Kapang Aspergillus flavus
Abstrak: Aflatoxin is known as toxigenic compound as the secondary metabolite produced by Aspergillus flavus and Aspergillus parasiticus. Aflatoxin is found both in food and feed in Indonesia. Aflatoxin standard is needed in every analysis of aflatoxin contamination. But it is rather difficult to get. It is imported, high costs, and take times. The aim of the research is to assess the potential local isolate of producing aflatoxin that can be used to be the alternative aflatoxin standard. The comparison with foreign isolate is done to observe the productivity of aflatoxin by local isolate. The result is shown that local isolate F0219 is potential to be the candidate of standard aflatoxin even the productivity is lower that the foreign isolate. The most suitable pH condition of incubation is in the value of 4.0, below that the production of aflatoxin is decent as well as in the alkaline medium. Temperature of 25oC is considered to be the most favorable condition by molds to grow and produce secondary metabolites. YES medium was proved to be the recommended medium for growing molds than modified GAN. Although aflatoxin production does not only depend on medium but also other external factors
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Judul: Uji potensi isolat lokal Aspergillus flavus sebagai penghasil aflatoksin
Abstrak: Aflatoxin is found in food and livestock feed in Indonesia. Aflatoxin is toxigenic, mutagenic, teratogenic, carcinogenic, and immunosuppresive compound. Hazardous potential of aflatoxin demands the avaibility of aflatoxin standard for analysis. Pure 55 strains of Aspergillus flavus were screened with ELISA to evaluate the potential yield of aflatoxin. Result of screening suggested that isolate S.26 contained the highest AFB1 (1212,3 ppb). This isolate was chosen for aflatoxin production on PDB (Potato Dextrose Broth) media and GAN (glucose ammonium nitrate) media with five replications. A. flavus from JCM was also grown in the same media under the same condition as the reference isolate to produce aflatoxins. TLC analysis results suggested that both A. flavus cultures from S.26 and JCM isolates grown on GAN showed no ability to produce aflatoxin while those grown on PDB could produce aflatoxin. Aflatoxin analysis of the A. flavus culture of S.26 isolate grown on PDB by TLC suggested that the highest aflatoxin production was reached at the ninth until twelfth day with a range of aflatoxin concentrations 200-500 ppb and the average of 310 ppb (n=5). Analysis of A. flavus culture of JCM isolate on PDB by TLC suggested that the highest aflatoxin production was reached at the twelfth day with a range of aflatoxin concentrations 150-400 ppb and the average of 240 ppb. HPLC analysis of A. flavus culture of S.26 isolate had the highest amount of aflatoxin of 935,8 ppb at the ninth day while A. flavus culture of JCM isolate had the highest aflatoxin production of 847,7 ppb at the twelfth day. A. flavus of local isolate (S.26) has higher potential in producing aflatoxins on PDB media compared to A. flavus of reference isolate (JCM). Production of alfatoxin might be affected by variations in nitrate source, initial pH, medium composition, and chain of serial transfers during preparation and analysis. The aflatoxin produced by A. flavus of local isolate in PDB media could be the candidate of aflatoxin standards which are essential for the analysis of aflatoxins by means of purification on column chromatography.
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Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology