Judul: Validasi dan verifikasi metode analisis bakteri asam laktat pada produk susu
Abstrak: Lactic acid bacteria (LAB) is a group of bacteria that capable converting carbohydrates (glucose) into lactic acid and mostly grow at facultatif anaerobic condition. At present, the most widely method used to enumerate LAB in some laboratory in Indonesia is incubation in aerob condition. In order to ensure that the method has a good performance, there is a need of method validation. Validation is the confirmation by examination and provision of objective evidence that particular requirements for specified intended use are fulfilled. The purpose of this study is to validate the quantitative method for enumeration of lactic acid bacteria. Two methods of enumeration of LAB in yoghurt were studied, i.e. ISO 7889-2003(E) as a reference method and SNI 2981-2009 as an alternative method. The principle of this method is to grow the facultative anaerobic bacteria in aerobic and anaerobic condition incubated for 3 days at 37 oC on MRSA media. The anaerobic condition was made using Anaxomat jar whose enrich with 10% CO2. The result obtained by these two method were compared. Therefore several parameters such as precision (RSD), relative accuracy, linearity, limit of detection, and limit of quantification were evaluated. The results showed that RSD of these methods between 0.44% and 3.03%, percent recovery of these methods between 97% and 101%, and limit of detection are 3 cfu/mL. It can be concluded that these two methods have good performance characteristics.
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Judul: Identifikasi Dan Karakterisasi Substrat Antimikroba Dari Bakteri Asam Laktat Kandidat Probiotik Yang Diisolasi Dari Dadiah Dan Yogurt
Abstrak: Probiotic has been defined as living microorganism that, when administered in adequate of amounts, confered a health benefit on the host. One of criterias that must be fulfilled by lactic acid bacteria as a probiotic is its ability to produce antimicrobial compounds that were capable inhibit toward pathogenic bacterias. Lactic acid bacteria (LAB) can be isolated from fermented milk. Maheswari (2008) isolated Lactobacillus plantarum D-01 and Lactococcus lactis D-01 from buffalo milk fermented called ‘dadiah’ traditionally produced by people from West and North Sumatra, and also isolated Bifidobacterium longum Y-01 and Lactobacillus acidophilus Y-01 from yogurt. Their potential as probiotic culture was interested to determine especially for their ability to produce antimicrobial substrate that inhibit pathogenic bacterias. Identification of nature and characterization of antimicrobial substrate produce by LABs tested for its stability at different pH and storage’s temperature, and proteolitic’s enzyme by agar well diffusion method. The culture supernatants inhibited toward Salmonella Ser. Typhimurium ATCC 14028, Escherichia coli ATCC 25922, and Staphylococcus aureus ATCC 25923. The supernatants showed an antimicrobial activity against phatogenic bacteria and identified as organic acid and hydrogen peroxide. The existance of proteinaceous antibacterial compound, which referred as bacteriosin, was proved through proteolityc activity on supernatants that resulted in decrease of zone inhibition diameters. Characterization determined that proteinaceous antibacterial compound was stable at room storage temperature within five days and at cold storage temperature within two weeks. Meanwhile, proteinaceous antibacterial compounds were not heat stable and not stable when adjusted in different pH, especially when adjusted in pH above 5. Four LABs tested could be considered as probiotic bacterias because all of LABs produced antimicrobial compounds consist of organic acid, hydrogen peroxide and bacteriosin that inhibited pathogenic indicator bacterias.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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