Irfan Dwidya Prijambada

Solubility of artificial proteins with random sequences

A library of artificial random proteins of 141 amino acid residues of which 95 are random and which includes the 20 kinds of amino acids was prepared. Out of the 25 identified random proteins, 5 were soluble in the cell lysate, indicating that about 20% of the random proteins expressed in Escherichia coli are expected to be soluble. The soluble random proteins RP3–42 and RP3–45 and insoluble RP3–70 were purified. The solubility of the purified form is the same as that in the cell lysate.

Characterization of soluble artificial proteins with random sequences

The structural and catalytic properties of two soluble random proteins, RP3‐42 and RP3‐45, of 141 amino acid residues were investigated. Although no marked secondary structure was detected by CD spectrum, sedimentation equilibrium and small‐angle X‐ray scattering studies showed that they form an oligomeric structure and are as compact as the molten globule. The random proteins have low but distinct esterase activity; the values of the second‐order rate constant for the hydrolysis of p‐nitrophenol were 0.78 and 1.39 M−1 s−1 for RP3‐42 and RP3‐45, respectively. The differences in the properties of the random and the native proteins are discussed from the evolutionary point of view.

Properties of Artificial Proteins with Random Sequencesa

Abstract: A library of artificial proteins of 141 amino acid residues, of which 95 are random and which include 20 kinds of amino acids, was prepared. As the properties of the artificial random proteins are free from the evolutionary constraint, they can be used as a standard to discriminate the specialized properties of natural proteins. Out of the 25 identified random proteins, 5 are soluble in the cell lysate, indicating that about 20% of the random proteins expressed in Escherichia coli are expected to be soluble. Therefore, as natural soluble or insoluble proteins can arise from the line of soluble or insoluble ancestry, respectively, solubility does not seem a specialized property of natural proteins. The soluble random proteins RP3‐42 and RP3–45 were purified and their properties were investigated.

Isolation and Identification of Plant Growth Promoting and Chromium Uptake Enhancing Bacteria from Soil Contaminated by Leather Tanning Industrial Waste

Abstract: Hexavalent chromium is considered as a priority pollutant. Phytoremediation has been widely pursued for the cleanup of heavy metal from contaminated area. The success of phytoremediation is depending on two factors: metal accumulating capability and biomass production of the plants. This paper reports on the isolation and characterization of rhizobacteria having ability to promote plant growth and increase its chromium uptake. Thirty nine of bacterial isolates were obtained from the rhizosphere of wild plants ( Sida sp., Sida acuta , Sida rhombifolia , Eupatorium sp., Acelypha sp, Acelypha indica , Amaranthus caudatus , Borreria sp., Leucas lavandulifolia , Eleusine indica , Pennisetum purpurium , Imperata cylindrical , and Vigna sinensis ) grow well on soil contaminated by leather tanning industrial waste. Three isolates, namely I26, I30, and I37, have an ability to enhance biomass production of maize ( Zea mays ) by 2.3, 2.6, and 4.0 times higher compare to the uninoculated one, respectively. The isolates also have an ability to increase chromium uptake by the maize from 7 to 14 times. All of the isolates increase the accumulation of Cr in the maize root. The 16S rDNA gene sequence of the isolates relates them to Agrobacterium tumefaciens .

Optimization of gold ore Sumbawa separation using gravity method: Shaking table

Most of artisanal small gold mining in Indonesia has been using amalgamation method, which caused negative impact to the environment around ore processing area due to the usage of mercury. One of the more environmental-friendly method for gold processing is gravity method. Shaking table is one of separation equipment of gravity method used to increase concentrate based on difference of specific gravity. The optimum concentration result is influenced by several variables, such as rotational speed shaking, particle size and deck slope. In this research, the range of rotational speed shaking was between 100 rpm and 200 rpm, the particle size was between -100 + 200 mesh and -200 + 300 mesh and deck slope was between 3° and 7°. Gold concentration in concentrate was measured by EDX. The result shows that the optimum condition is obtained at a shaking speed of 200 rpm, with a slope of 7° and particle size of -100 + 200 mesh.Most of artisanal small gold mining in Indonesia has been using amalgamation method, which caused negative impact to the environment around ore processing area due to the usage of mercury. One of the more environmental-friendly method for gold processing is gravity method. Shaking table is one of separation equipment of gravity method used to increase concentrate based on difference of specific gravity. The optimum concentration result is influenced by several variables, such as rotational speed shaking, particle size and deck slope. In this research, the range of rotational speed shaking was between 100 rpm and 200 rpm, the particle size was between -100 + 200 mesh and -200 + 300 mesh and deck slope was between 3° and 7°. Gold concentration in concentrate was measured by EDX. The result shows that the optimum condition is obtained at a shaking speed of 200 rpm, with a slope of 7° and particle size of -100 + 200 mesh.

Simultaneous Hydrolysis and Fermentation of Sweet Sorghum Varieties (FS501 and KCS105) into Bioethanol Using Saccharomyces steineri – A Kinetics Study

In this study, kinetics of bioethanol production by fermentation of three different substrates, which were artificial substrate and the juice of two sweet sorghum varieties (FS501 and KCS105) using Saccharomyces steineri, were examined using two proposed models by assuming that simultaneous hydrolysis and fermentation occurred. Fermentation of the substrate of FS501 and KCS105 juices showed better data fitting by using the modified version of the kinetics model while the fermentation of artificial substrate which was free of any other components followed Philippidis’s kinetics model. This difference was caused by the change of the yeast behavior in the form of the reduction of both the rate of fructose and/or glucose consumption by the yeast and the rate of fructose and or glucose conversion into ethanol during lag phase. As the consequence, sucrose hydrolysis seems very dominant in the FS501 and KCS105 juices fermentation during the lag phase. The change of behavior of the yeast was estimated being caused by the existence of “impurities” such as acetic acid, glycerol, nitrogen, phosphor, and potassium in the FS501 and KCS105 juices. From statistical analysis using correlation coefficient (between kinetics parameters and “impurities”), acetic acid was the most influential component to change the behavior.

Effect of Biofertilizer Addition on Nitrous Oxide Emission

Application of nitrogen fixing biofertilizer, such as Azotobacter, has a potential for reducing nitrous oxide (N2O) emission. The aim of this study was to examine the effect of nitrogen fixing biofertilizer addition to common practices of urea and fresh cattle manure usages for maize (Zea mays L.) growing on N2O emission. The field experiment was conducted at Gunung Kidul, Yogyakarta, Indonesia. The treatments were addition of fresh cattle manure (M), fresh cattle manure added with nitrogen fixing biofertilizer (MB), urea (U), urea added with nitrogen fixing biofertilizer (UB), and control (no N fertilizer added). Nitrogen contents of the added urea and fresh cattle manure were adjusted to be equal. Urea and fresh cattle manure were given three times throughout the experiment period, i.e. 12, 30, and 48 days after planting (DAP). Urea was given at a rate of 44, 29, and 15 kg.ha -1 , respectively while fresh cattle manure was given at a rate of 6000, 4000, and 2000 kg.ha -1 , respectively. The emitted N2O was collected using a closed-chamber method at 24, 42, 60, and 72 DAP and were determined using Gas Chromatograph. Soil properties including available N (NH4 + -N and NO3 - -N) and organic C contents were also analyzed. On the harvesting time, the harvest index and the grain yield were determined. Biofertilizer addition influence decomposition process of cattle manure and urea that led to mineralization and nitrification of residual organic matter and hence to cause soil NH4 + N in the order concentration of M treatment > MB > U > UB > C, and soil NO3 - -N of MB treatment > M > U > UB > C. Reduction of NO3 - N was resulted in the highest N2O emission of M > U > MB > UB > C (P UB > U > M> C treatments. Available mineral N and soil organic C contents strongly affected N2O emission (P < 0.01). The results suggested that biofertilizer addition to common agricultural practices reduce N2O emission and simultaneusly increased grain yield, and harvest index of maize.