Nitrification in fixed-bed reactors treating saline wastewater

Halophilic nitrifiers belonging to the genus Nitrosomonas and Nitrospira were enriched from seawater and marine sediment samples of the North Sea. The maximal ammonia oxidation rate (AOR) in batch enrichments with seawater was 15.1 mg N L⁻¹ day⁻¹. An intermediate nitrite accumulation was observed. Two fixed-bed reactors for continuous nitrification with either polyethylene/clay sinter lamellas (FBR A) or porous ceramic rings (FBR B) were run at two different ammonia concentrations, three different ammonia loading rates (ALRs), ± pH adjustment, and at an increased upflow velocity. A better overall nitrification without nitrite accumulation was observed in FBR B. However, FBR A revealed a higher AOR and nitrite oxidation rate of 6 and 7 mg N L⁻¹ h⁻¹, compared to FBR B with 5 and 5.9 mg N L⁻¹ h⁻¹, respectively. AORs in the FBRs were at least ten times higher than in suspended enrichment cultures. Whereas a shift within the ammonia-oxidizing population in the genus Nitrosomonas at the subspecies level occurred in FBR B with synthetic seawater at an increasing ALR and a decreasing pH, the nitrite oxidizing Nitrospira population apparently did not change.     

Identifications small molecules inhibitor of p53-mortalin complex for cancer drug using virtual screening

Mortalin was over expressed in tumor cells and bind to p53 protein. This interaction was suggested to promote sequestration of p53 in the cytoplasm, thereby inhibiting its nuclear activity. The p53 is a tumor suppressor that is essential for the prevention of cancer development and loss of p53 function is one of the early events in immortalization of human cells. Therefore, abrogation p53-mortalin interaction using small molecule is guaranteed stop cancer cell grow. However study interaction of p53-mortalin, and its inhibition using small molecule is still challenging because specific site of mortalin that bind to p53, vice versa, is still debatable. This study has aims to analyze the p53-binding site of mortalin using molecular docking and to screen drug-like compounds that have potential as inhibitors of p53-mortalin interaction using virtual screening. The result showed that the lowest energy binding of p53-mortalin complex is -31.89 kcal/mol, and p53 protein bind to substrate binding domain of mortalin (THR433; VAL435; LEU436; LEU437; PRO442; ILE558; LYS555). Furthermore, the p53-binding domain of mortalin was used as receptor to screen 9000 drug-like compounds from ZINC database using molecular docking program Auto Dock Vina in PyRx 0.8 (Virtual Screening Tools). Here, we have identified three drug-like compounds that are ZINC01019934, ZINC00624418 and ZINC00664532 adequate to interrupt stability of p53-mortalin complex that warrant for anticancer agent.     

Epitope mapping of gp350/220 conserved domain of epstein barr virus to develop nasopharyngeal carcinoma (npc) vaccine

Nasopharyngeal carcinoma (NPC) is a malignant tumor in the nasopharyngeal epithelial cells that caused by many factors, one of which is the viral infection of EBV (Epstein Barr Virus). The standard treatments to cure NPC still have not been encouraging. The prevention through vaccination is an effective way to stop the disease. However, EBV vaccine being able to cover all variants of virus is still not available yet. Therefore, we identified the conserved region of glycoprotein 350/220 of EBV which has immunogenic and antigenic properties. The glycoprotein 350/220 is viral surface protein responsible to bind CR2 receptor, mediated EBV to enter the host cell. The conserved domain is crucial for EBV in infecting host cells. Further, by blocking CR2 binding domain of gp350/220 using antibody will inhibit EBV's spreading, and provoke an immune system to eliminate the virus in a patient. Glycoprotein 350/220 from all variants of Epstein-Barr virus was retrieved from NCBI. The conserved domain of gp350/220 was identified by aligning the protein sequences and structures. The polymorphic structure was used as a template for docking analysis to identify the resemblance of amino acid from polymorphic variants of gp350/220 that binds CR2. The epitope mapping of gp350/220 was done by Discotope BepiPred method. The result revealed that the conserved region of gp350/220 was predicted to have an epitope, QNPVYLIPETVPYIKWDNC residue, and it does not have any similarities to the human's cell surface protein. Therefore, it can be used as a reference to develop vaccine to prevent NPC.     

Screening of commercial cyclic peptide as inhibitor NS5 methyltransferase of Dengue virus through Molecular Docking and Molecular Dynamics Simulation

Dengue has become a major global health threat, especially in tropical and subtropical regions. The development of antiviral agent targeting viral replication is really needed at this time. NS5 methyltransferase presents as a novel antiviral target. This enzyme plays an important role in the methylation of 5''-cap mRNA. Inhibition of the NS5 methyltransferase could inhibit dengue virus replication. In this research, two sites of NS5 methyltransferase (S-Adenosyl methionine/SAM binding site and RNA-cap site) were used as targets for inhibition. As much as 300 commercial cyclic peptides were screened to these target sites by means of molecular docking. Analysis of ligand-enzyme binding free energy and pharmacological prediction revealed two best ligands, namely [Tyr123] Prepro Endothelin (110-130), amide, human and Urotensin II, human. According to molecular dynamic simulation, both ligands maintain a stable complex conformation between enzyme and ligand at temperature 310 K and 312 K. Hence, Urotensin II, human is more reactive at 312 K than at 310 K. However, both ligands can be used as potential inhibitor candidates against NS5 methyltransferase of dengue virus with Urotensin II, human exposes more promising activity at 312 K.     

Efficient harvesting of <Emphasis Type="Italic">Synechocystis</Emphasis> sp. PCC 6803 with filamentous fungal pellets

Cyanobacteria play a major role as direct producers of biofuels, such as ethanol and butanol, with the aid of genetic engineering. However, development of a new harvesting-technology is essential to achieve economic viability of biofuel production from cyanobacteria. In this study, we demonstrated the feasibility of harvesting the unicellular cyanobacterium Synechocystis sp. PCC 6803 using pre-made filamentous fungal pellets and investigated key factors affecting efficiency of harvest, including fungal strain, pellet quantity (number of pellets), initial pH, and organic carbon source. Synechocystis sp. PCC 6803 cells attached to Aspergillus oryzae pellets, indicating that this fungal pellet had a desirable harvesting effect, while Rhizopus oryzae pellets had no effect on harvesting. Increasing pellet quantity and adding organic carbon sources, such as glucose and xylose, improved the harvesting efficiency of Aspergillus oryzae pellet; efficiency was not affected by the initial pH.     

Effect of varying salinity, temperature, ammonia and nitrous acid concentrations on nitrification of saline wastewater in fixed-bed reactors

Nitrification under changing salinities (0-9%), temperatures (6-50 °C), ammonia (0-5 g N L⁻¹) and nitrite concentrations (0-0.4 g N L⁻¹) was investigated in fixed-bed reactors. For all conditions ammonia oxidation rates (AOR) were lower than nitrite oxidation rates (NOR). AORs and NORs increased from 12.5 to 40 °C and were very low at 6 °C and almost zero at 50 °C. No recovery of nitrification was obtained after incubation at 50 °C, whereas nitrification was restorable after incubation at 6 °C. Ammonia concentrations of 5 g N L⁻¹ or nitrite concentrations up to 0.125 g N L⁻¹ decreased AOR to almost zero. AORs and NORs recovered if ammonia or nitrite was removed. At concentrations of 1 and 5 g N L⁻¹ ammonia AOR and NOR were inhibited by 50%, whereas 27 mg N/L nitrite inhibited AOR by 50%.     

A comparison of penetrometer pressures and the pressures exerted by roots

Summary Previous work is reviewed in which the ratio of the pressures required for soil penetration by roots and penetrometers are compared. It appears that this ratio can vary from about 2 to 8 depending on conditions. However, there is very little experimental evidence and most of the work has been inferential.Direct measurements are reported for the stresses exerted by a 1 mm diameter penetrometer probe and by the roots of pea seedlings when penetrating Urrbrae fine sandy loam. Six soil conditions were used: (non-weathered remoulded soil cores + artificially weathered remoulded soil cores + undisturbed field clods) × (confined + unconfined cores or clods). The confinement treatment was to test for any effects of additional restraint to cylindrical root expansion. The weathering and field clod treatments were to test the hypothesis that root elongation is facilitated by tensile failure ahead of the root tip.The principal conclusions are as follows. The laboratory weathering treatment reduced the soil tensile strength by 25%. This resulted in a small but significant reduction in the pressure for root penetration into confined cores. Compared with remoulded non-weathered cores, field clods had a 2 to 3 fold greater penetrometer resistance and a 50% lower tensile strength. The force required for root penetration into unconfined field clods was only 10% greater than for unconfined non-weathered cores. For the former (which is closest to field conditions) the penetrometer had to exert a pressure 5.1 times greater than a root tip in order to penetrate the soil. Penetrometer penetration pressure was independent of probe diameter in the 1–2 mm range in the soil used. Core confinement restricts root radial expansion and modifies the penetration force of metal probes and plant roots.On the basis of the new results it is tentatively concluded that soil tensile failure can facilitate penetration by roots.     

Growth and regenerability of long-term suspension cultures of the U.S. rice cultivar Mercury

Suspension cultures of the U.S. rice cultivar Mercury have been maintained in modified General Medium for more than 3 years. These suspensions have continued to have high and relatively stable regeneration rates. Two different explants, immature panicles and seeds, were compared during the development of these embryogenic suspensions. Initial formation of secondary embryogenic callus from immature panicles on induction medium was greater than that from seeds. Suspensions of these two cell lines, however, did not differ morphologically and maintained similar regeneration rates. After 5 months in culture the rates of regeneration began to decline. The suspensions were plated onto regeneration medium without growth regulators for 2 weeks and then embryogenic cells were manually selected and used to develop secondary suspensions. Through this simple rejuvenation procedure, the suspensions retained high and stable regeneration rates. Variability in suspension growth, however, was observed during the culture period. Slower growth occurred at weeks 13, 15, 27, and 29 and was associated with a decrease in regeneration rates. Reproductive fertility of regenerated plants remained high for 3.5 years but then declined.Abbreviations CH casein (acid hydrolysate) - 2,4-d 2,4-dichlorophenoxyacetic acid - MS Murashige & Skoog basal medium - SE standard error