Judul: Isolasi dan karakterisasi bakteri penghasil ahl-laktonase asal lahan pertanian luar Pulau Jawa
Abstrak: Quorum sensing (QS) is communication between bacterial cells mediated by autoinducer (AI) to regulate the expression of specific genes in certain bacterial population quorum. AI of Gram negative bacteria is N-acyl homoserine lactone (AHL). QS system controls behaviors of bacterial population on biofilm formation, virulence, bioluminescence, and formation of antibiotics. QS process can be inhibited by anti-QS compound. AHL-lactonase is one of anti-QS compound encoded by aiiA gene. The aims of this study were to isolate and characterize bacteria producing AHL-lactonase from agricultural land outside Java. Soil samples were taken from 16 locations of agricultural lands. Bioassay was performed by AHL degradation of Chromobacterium violaceum. Detection of aiiA gene was conducted using specific primer aiiAF and aiiAR, while molecular identification was conducted based on 16S rRNA gene sequence. It was found that from 58 isolates, six isolates had AHL degradation activity i.e. PAD1a, BAL2a, NTT3a, NTT3e, NTT6B6, dan NTT6B7 isolates. Two isolates (i.e. NTT3a and NTT3e isolates) had aiiA gene. And indicated by 800 bp product. They were 99% closely related to AHL-lactonase gene from Bacillus sp 91.
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Judul: Isolation and Characterization of Acyl Homoserine Lactonase (AHL-lactonase) Producing Bacteria from Agricultural Field in Java
Abstrak: Quorum sensing (QS) is a bacterial communication mechanism correlating with the number of bacterial population and accumulation of autoinducer (AI). Quorum sensing in Gram-negative bacteria involves a AI group of acyl homoserine lactone (AHL) to regulate the expression of several genes, including virulence genes. Anti-quorum sensing compounds can degrade AHL so that virulence genes can not be expressed. Acyl homoserine lactonase (AHL-lactonase) encoded by the aiiA gene is one enzyme that can act as an anti-quorum sensing. This study aimed to isolate and characterize the AHL-lactonase producing bacteria isolated from agricultural field in Java. Activity of AHL degradation bioassay using Chromobacterium violaceum as a bacterial indicator. Verification the presence of AHL-laktonase was performed by gene aiiA amplification. As many as 12 bacterial isolates showed AHL degradation activity and two isolates had the aiiA gene i.e. INT1c and SGT3g isolates. These isolates had bacil cells with chain arrangement and endospores. They were grouped in Gram-positive bacteria. AiiA gene sequence analysis showed that aiiA gene of INT1c had homology with aiiA gene of Bacillus cereus ATTCC 14579 while the SGT3g isolate had homology with aiiA gene of Bacillus thuringiensis BMB171. Molecular identification based on 16S rRNA gene showed that INT1c isolate had the closest similarity with the Bacillus cereus strain GM3 (98%) while SGT3g isolate had the closest similarity with the Bacillus thuringiensis strains A1-1 (99%).
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Judul: Monotonicity Properties of Trapezoid Sum Sequence on Class of Nonconvex and Nonconcave Function
Abstrak: Bernhard Riemann mendefinisikan integral tentu sebagai luas daerah di bawah kurva dari suatu fungsi real taknegatif pada sebuah interval yang tertutup dan terbatas. Beberapa alternatif yang dapat digunakan untuk menghampiri luas tersebut adalah Darboux sums melalui penjumlahan beberapa luas persegi panjang dan trapezoid sum melalui penjumlahan luas trapesium. Trapezoid sum lebih baik dalam menghampiri nilai integral untuk fungsi-fungsi yang well-behaved daripada Darboux sums. Untuk fungsi f yang bernilai real dan kontinu pada interval [a,b], f terintegral Riemann jika dan hanya jika f terintegral Darboux. Pada tesis ini ditunjukkan bahwa f terintegral Riemann jika dan hanya jika f terintegral secara trapesium. Misalkan f adalah suatu fungsi bernilai real yang kontinu pada interval [a,b]. Untuk setiap partisi P_n yang membagi [a,b] menjadi n subinterval dengan jarak yang sama, dibentuk trapezoid sum T_n (f) yang merupakan jumlah luas n trapesium sebagai pendekatan dari nilai integral f pada [a,b]. Jika f adalah fungsi konveks maka barisan trapezoid sum {T_n (f)} bersifat monoton turun dan akan bersifat monoton naik jika f fungsi konkaf. Fokus tesis ini adalah sifat kemonotonan barisan {T_n (f)} untuk fungsi f yang nonkonkaf dan fungsi f yang nonkonveks. Pada tesis ini dibuktikan sifat monoton turun dari {T_n (f)} secara generik tidak terjadi pada kelas fungsi nonkonkaf f, serta secara generik, barisan itu juga tidak monoton naik pada kelas fungsi nonkonveks. Meskipun demikian, sifat generik mengakibatkan bahwa untuk sebarang fungsi f baik di kelas fungsi nonkonkaf maupun nonkonveks, terdapat fungsi g yang menghampiri f sedemikian sehingga ekor barisan {T_n (g)} bersifat monoton. Ditunjukkan pula bahwa himpunan fungsi naik nonkonkaf dengan {T_n (f)} yang tidak monoton turun dense terhadap kelas fungsi naik nonkonkaf f. Hal tersebut juga ditunjukkan untuk himpunan fungsi turun nonkonkaf terhadap kelas fungsi turun nonkonkaf. Lalu, dibuktikan bahwa himpunan fungsi naik nonkonveks dan himpunan fungsi turun nonkonveks dengan {T_n (f)} yang tidak monoton naik, berturut-turut dense terhadap kelas fungsi naik nonkonveks dan turun nonkonveks. Himpunan-himpunan yang dense tersebut mengartikan bahwa setiap fungsi f pada kelas-kelas tersebut, dapat dihampiri oleh suatu fungsi g yang bersesuaian dengan kelas-kelas tersebut sedemikiam sehingga barisan {T_n (g)} tidak monoton., Bernhard Riemann defined definite integral as an area under the curve of a real nonnegative function on a closed bounded interval. The alternatives that can be used to estimate the area are Darboux sum which is sum of rectangular areas and trapezoid sum which is sum of trapezium areas. Trapezoid sum is better than Darboux sum as approximations toward the integral of well-behaved functions. Let f be a real valued continuous function on interval [a,b], f is Riemann integrable if and only if it is Darboux integrable. In this master’s thesis, it showed that f is Riemann integrable if and only if it is trapezium integrable. Let f be a real valued continuous function on interval [a,b]. For each partition P_n that divides the interval [a,b] into n equal length subintervals, defined trapezoid sum T_n (f) which is the total of n trapezium areas as an approach of integral value f on [a,b]. If f is a convex function then the trapezoid sum sequence {T_n (f)} is decreasing
Keyword: monotonicity, nonconcave, nonconvex, trapezoid sum