Judul: Kajian Paleoklimatologi dan Perubahan Suhu Global
Abstrak: Global climate change is a change of climate patterns and intensity on a global scale as a result of changes in the energy budget components within the earth system and may be caused by both natural and antrophogenic factors. Studies of climate change requires a long data which may be reconstructed by several methods of paleoclimatology including ice cores, tree ring, coral, and pollen methods. Climate reconstruction using Ice core method requires longer data records compared with the tree ring, coral, and pollen method. The complexity of physical and chemical analysis are major constaints in utilizing ice core and coral method. On the other hand, the unven speard of tree on the earth cause limitations to the information obtained from tree ring and pollen method. Among factors consider important to the global climate change include solar constant, properties of earth surface, and atmospheric chemical compositions of greenhouse gases. Radiative forcing is an index defined by the rate of energy change per unit area of the globe as measured at the top of the atmosphere. Global climate change is indicated by increased of global average surface temperature which according to data records has increased by 0.7oC during the last century. A number of literature suggest the temperature rise was due to anthropogenic factors; however, using simplified energy balance model of the earth-atmosphere system reveals that an increase of solar constant by 1% (which may occur during the last century), while holding other factors unchanged, will result in an average global surface temperature increase of 0.6oC which is fairly close to the value obtained from observations. It must be emphasized that climate is an extremely complex system in which various factors interact with each other in some forms of linear and non-linear feedbacks. Analysis of time series data of Jakarta Observatory which cover a period of 1965-2010 shows a slight increase of average temperature and decrease of average rainfall.
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Judul: Analysis of increasing ext reme weather intensity in Jabota (Jakarta, Bogor, Tangerang) Period 1980 - 2008
Abstrak: spaces. This changes causes rising of air temperatures and hence increasing frequent events of extreme weather. Based on research in Taiwan, China and Japan, its have been proven that the existence of rising temper ature and frequent extreme weather were caused by land use changes. Daily observed data from Meteorological Stations around urban area of Jabota during the period 1980-2008 was used to determine the increase of air temperature and the frequency of extreme weather events. Besides the surface air temperature, the upper air temperature data period 1988-2008 was also analysed data to examine the increase of air temperature at particular layer. Further, hourly weather data of 2003-2008 from Meteorological Stasion Curug has been used as an example to analyze the time shifts of maximum air temperature and the time of thunderstorms occurrence. The analysis resulted an increase in average temperature in the latest period; increasing frequency of temperatures above 34° C, the increasing frequency of extreme precipitation at some months, especially in the rainy and transition seasons; the increasing frequency of thunderstorms occurrence, the increase of average upper air temperature, especially at surface layer up to 500 mb layer. The results also showed that the maximum temperature occurrence at certain months in dry and transition season to 02: 00 pm and the mostly hour of thunderstorms occurrence was 03: 00 to 05: 00 and from 07: 00 to 08: 00 pm.
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Judul: Heterologous Expression Of Endo-Β-Xylanase From Bacillus Pumilus Strain Bcrs-01 In Escherichia Coli.
Abstrak: Xylanases are glycoside hydrolase family 11 which depolymerise xylan in the plant cell wall, the most excessive form of hemicellulose. Endo-β-xylanases (EC 3.2.1.8) are most important to breakdown β-1,4-glicoside bond of xylan to produce disaccaride xyloolygosaccaride (XOs) and xylose (monomer). Bovine rumen fluids have potential to obtain endo-β-xylanase produced of bacteria. The objectives of this study were to obtain xylanase producing bacteria and to express xynA gene encoding endo-β-xylanase from bacterium in Escherichia coli. Twenty nine isolate bacteria have been succesfully isolated from bovine rumen fluid in agar medium containing birchwood xylan. Isolate BCRS-01 bacterium was previously screened for the high production of xylanase. Based on 16S rRNA gene sequence analysis, BCRS-01 showed high similarity (99%) to Bacillus pumilus (accession number NR043241). The crude xylanase had optimal activity at 55oC, pH 7.0. Furthermore, the crude xylanase exhibited broad pH stability from 4.0 to 10.0 and remained more than 60% and 40% of its activity after incubation at pH 4.0 until 10.0, respectively for 60 min. It also showed a stability at temperature 25-50oC since it retained 80% and 50% of its activity when incubated at 50oC or 30 and 60 min, respectively. The xylanase activity was strongly inhibited by Ca2+ and Cu2+ at concentration 10 mM, and as little as 1 mM for Mn2+. Therefore, this xylanase has potentially used as additive feeds in animal feed industry. The DNA sequence xynA gene encoded endo-β-xylanase was amplified and cloned into the expression vector pET-15by under the control of T7 promoter. The recombinant protein had succesfully expressed in Escherichia coli BL21 (DE3) pLysS. A protein recombinant of approximately, 26.7 kDa was observed on the SDS-PAGE analysis. Crude extract of recombinant endo-β-xylanase demonstrated activity of enzyme at 56 U mL-1 using birchwood xylan as a substrate at 55oC for 10 min.
Keyword: Bacillus pumilus, bovine rumen fluid, endo-β-xylanase, heterologous expression.