Judul: Prevalence of Toxigenic Bacillus cereus in Chili and White Pepper from Bogor Area, Indonesia
Abstrak: Chili and white pepper are widely used as spices and/or condiments in many Indonesian cuisines, especially Ready-to-eat (RTE) foods. These spices are often associated with pathogenic microorganisms such as Bacillus (B.) cereus, and have the potential to contaminate foods to which they are added. Bacillus cereus is a spore-forming bacterium widely found in the environment and is responsible for causing diarrheal and emetic syndromes. The organism has been implicated in various food borne outbreaks in different parts of the world. This study aimed to determine the prevalence and concentration of B. cereus in chili and white pepper from markets around Bogor, and to determine the potential toxicity of these isolates based on ces and nheA genes. The study consisted of several stages including sample collection and preparation, isolation and enumeration of Bacillus cereus on Mannitol-egg yolk- polymyxin agar (MYP), presumptive confirmation of the isolates based microscopic observations and biochemical tests, molecular confirmation by detection of 16S rRNA gene, 16S rRNA gene sequencing, phylogenetic analysis and analysis for the possession of nheA and ces toxigenic genes. Out of the forty (20 chili and 20 white pepper) samples analyzed, 33 (82.5%) contained presumptive Bacillus cereus. Ninety percent of white pepper samples (18/20) and 75% of chili samples (15/20) contained presumptive B. cereus. The highest B. cereus concentration in white pepper was 5.77 log10 CFU/g and the lowest was 1.70 log10 CFU/g while the highest in chili was 3.93 log 10 CFU/g and the lowest was 0.70 log10 CFU/g. Ninety five percent (19/20) of samples from the traditional markets and 70% (14/20) from supermarkets contained presumptive B. cereus. Samples from the traditional market had a higher mean log10 CFU/g of 3.25 compared to 2.55 log10 CFU/g from the supermarkets. However, the difference was not statistically significant (P > 0.05). Samples containing B. cereus of >5 log10 CFU/g were found in both market types. Twelve of 13 isolates tested were confirmed as B. cereus based on 16S rRNA gene and BLAST identification. The isolates shared similarity (>98%) with B. cereus strains from GenBank and were phylogenetically related to B cereus. All twelve isolates (100%) possessed the nheA gene but none of them owned the ces gene. Absence of ces gene suggests a reduced risk for emesis from chili and white pepper but the 100% prevalence of nheA gene presents a potential food safety concern and risk for B. cereus diarrheal food borne disease.
Keyword: chili, Indonesia, spices, toxigenic Bacillus cereus, white pepper

Judul: Literature Review of Isolation, Confirmation, Occurrence of Toxigenic Genes, and The Prevalence of Bacillus cereus in Rice
Abstrak: Bacillus cereus merupakan salah satu bakteri patogen penyebab keracunan pangan yang dihubungkan dengan nasi. Keracunan pangan akibat Bacillus cereus dapat disebabkan oleh enterotoksin dan cereulida. Kajian ini bertujuan untuk mereview metode isolasi dan konfirmasi Bacillus cereus, mengetahui gen penyandi enteretoksin dan cereulida pada Bacillus cereus, dan mengetahui prevalensi Bacillus cereus pada produk nasi berdasarkan sumber pustaka ilmiah. Metode pengumpulan sumber pustaka dilakukan dengan mengunduh beberapa pustaka dari google scholar dengan mengetik kata kunci, yaitu “Bacillus cereus, cooked rice, polymerase chain reaction, biochemical test, prevalence, toxigenic, enterotoxin, cereulide”. Berdasarkan metode tersebut, ditemukan 75 pustaka metode uji, prevalensi, dan keanekaragaman gen penyandi toksin Bacillus cereus. Sebanyak 9 sumber pustaka dari jurnal internasional bereputasi yang dipublikasi dalam rentang tahun 2006-2021 digunakan sebagai data sekunder utama, sedangkan 66 pustaka lainnya digunakan sebagai data pendukung. Metode deteksi biokimia melibatkan beragam jenis uji seperti, pewarnaan Gram, reaksi terhadap kuning telur, katalase, reduksi nitrat, Voges Proskauer, motilitas, β-Hemolisis, indol, pertumbuhan anaerobik, penggunaan sitrat, koagulase, pertumbuhan rhizoid, fermentasi laktosa, fermentasi glukosa, dan hidrolisis berbagai substrat seperti pati kasein, tributirin, dan urea. Metode PCR dilakukan untuk mendeteksi gen penyandi 16S rRNA, enterotoksin maupun cerulida. Keberadaan gen penyandi enterotoksin pada B. cereusyang diisolasi dari nasi meliputi hblA, hblC, dan hblD dengan prevalensi 2.9-100%, nheA, nheB, nheC dengan prevalensi 38.2-100%, cytK dengan prevalensi 50.0-89.8%, entFM dengan prevalensi 76.5-100%, dan bceT memiliki prevalensi sebesar 51.0-55.5%. Sementara itu prevalensi ges ces penyandi toksin emetic adalah 0-14.7%. Berdasarkan kajian Pustaka yang digunakan prevalensi B. cereus pada nasi dari beberapa negara berada pada kisaran 20-82.5%., Bacillus cereus is one of the pathogenic bacteria that causes food poisoning associated with rice. Food poisoning due to Bacillus cereus can be caused by enterotoxins and cereulida. This study aims to review the isolation and confirmation method of Bacillus cereus, determine the genes encoding enteretoxin and cereulida in Bacillus cereus, and determine the prevalence of Bacillus cereus in rice products based on scientific literature sources. The method of collecting library resources is done by downloading several libraries from Google Scholar by typing keywords, namely "Bacillus cereus, cooked rice, polymerase chain reaction, biochemical test, prevalence, toxigenic, enterotoxin, cereulide". Based on this method, there were 75 libraries of test methods, prevalence, and diversity of genes encoding the toxin Bacillus cereus. A total of 9 sources of literature from reputable international journals published in the period 2006-2021 were used as primary secondary data, while the other 66 libraries were used as supporting data. The biochemical detection method involves various types of tests such as, Gram stain, reaction to egg yolk, catalase, nitrate reduction, Voges Proskauer, motility, -Hemolysis, indole, anaerobic growth, use of citrate, coagulase, rhizoid growth, lactose fermentation, glucose fermentation, and hydrolysis of various substrates such as casein starch, tributyrin, and urea. The PCR method was used to detect genes encoding 16S rRNA, enterotoxins and cerulides. The presence of enterotoxin-coding genes in B. cereus isolated from rice included hblA, hblC, and hblD with a prevalence of 2.9-100%, nheA, nheB, nheC with a prevalence of 38.2-100%, cytK with a prevalence of 50.0-89.8%, entFM with a prevalence of 76.5-100%. 100%, and bceT has a prevalence of
Keyword: Bacillus cereus, Biochemical, Prevalence, Polymerase chain reaction (PCR), Rice

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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