Current Biochemical Engineering (Discontinued) - Volume 1, Issue 2, 2014

In this study, the preconditioning of anaerobic culture by aging was carried out followed by testing various pretreatments (heat shock and alkali) to improve H2 production. It has turned out that aging could enhance the hydrogen generation meanwhile heat- and alkali curing led to comparable H2 formation activity with a slight advantage of the former one. Subsequently, the heat treated microflora was applied under different pHs and Gas to Liquid phase ratios and according to the statistical analysis both were significant factors since they affected not only the hydrogen productivity but also the developing H2 partial pressures in the system. Furthermore, an indirect relationship between hydrogen productivity and hydrogen partial pressure was found, which means that higher H2 turnouts were associated with lower H2 partial pressure conditions. The PCR-DGGE analysis of the microbial community after heat- and alkali pretreatments showed the dominancy of Clostridium species.

In this study an attempt was made to enhance anaerobic hydrogen production from beverage wastewater (BWW) by augmenting anaerobic enriched mixed cultures (EMC) with facultative Enterobacteriaceae strains (E. Coli XL1-BLUE, Enterobacter cloacae) under mesophilic temperature 37°C, pH 5.5 and substrate concentration of 10 gglucose equivalent /L. Among the bioaugmented cultures, E. cloacae+EMC led to the peak hydrogen production rate (HPR) of 2250 mL/L-d. Furthermore, the variables substrate concentration and pH was statistically optimized using response surface methodology (RSM). Results show that the predicted maximum HPR of 3096 mL/L-d was achieved under optimal operation conditions: substrate concentration 25.6 g glucose equivalent /L and pH 5.7. Verification experimental results showed HPR of 3044 mL/L-d, reveals that predicted results were closure with the experimental data and proved experimental design optimization processes are more feasible techniques for biohydrogen production. PCR-DGGE analysis indicates that Clostridium sp. and Enterobacter sp. were appeared under optimal conditions.

Artificial separation membranes, as selective mass transport barriers allow different gases to permeate at different rates. Many polymers exhibit great differences in the permeation rates and polymers, often in the form of non-porous films, constitute the group of the most important materials for gas separation membranes. Feasibility and efficiency of membrane technology – besides material selection – significantly depend on the separation circumstances such as feed composition, pressures and flows. All these aspects are discussed in this study. Polymeric membranes are very suitable for hydrogen recovery from biohydrogen. They can be employed under similar conditions of biohydrogen formation. Commercial membranes and apparatus can be utilized. Some biohydrogen components – such as nitrogen – can be removed easily, while others – e.g. carbon dioxide, moisture and hydrogen sulfide – likely require multi-stage or cascade processes to be separated. In the recent decade, a range of new polymers, new membrane materials, novel membrane processes were developed and have been proven in the laboratory scale. They brought higher separation efficiency with better economy. Process utilizing polymer foams with closed pores combine membrane based separation and hydrogen absorption capacity. Ionic liquid supported membranes utilize ionic liquids filled in the pores of polymer membranes and take advantage of ionic liquids separation abilities. Integrated solutions seem most feasible for biohydrogen purification and storage.

Fossil fuels are becoming depleted and their excessive utilization is bringing about destructive climate changes on a global scale. Hydrogen is the cleanest energy carrier known today. This article reviews the biochemistry and enzymology of various biological hydrogen production technologies. Direct biophotolysis is the most elegant and most promising approach, but it is currently also the most expensive one. Photofermentation and dark fermentation technologies are closer to large-scale application. The benefits and drawbacks of the various approaches are discussed, and important directions for future research and development are highlighted.

Over the past few decades, the upcoming scientific scenario of the ever growing area of biotechnology finds a successful application of some eco-diversified microorganisms which are employed for the recovery of metals from ores and other industrial wastes. A lot of mineral oxidizers and reducers are found in natural environments which involve a different mode of action for mineral oxidation and reduction. Mineral oxidizers are found in natural leaching environments such as acid mine drainage, dump disposal sites, tailing ponds and are mostly aerobic in nature while the reducers are found in environments under facultative anerobic or strictly anerobic conditions. Mineral Biotechnology is primarily aimed at the application of such mineral metal oxidizers and reducers for the development and advancement of a sustainable biotechnological industry in the mineral processing sector. Analyzing several aspects, the leaching microbes have a number of features in common that make them especially suitable for their role in mineral solubilization. This particular review focuses on such mineral oxidizing and reducing microorganisms, their mode of action and area of application towards development and growth of mineral biotechnological industry.

Amino acids (AAs) combine to form a three-dimensional protein structure and are of very much importance in understanding the biophysical properties of biomolecules. Basically, the nature and the arrangement of the AAs in a protein backbone is only responsible for the individual characteristics of the macromolecule. The AAs in a protein backbone are influenced by the solvent molecules hence, it is very important to have a clear idea on the solubility, stability, and thermodynamic properties of these AAs in various solvents and co-solvents. A basic level of quantifying protein-solvent interactions involve the use of transfer free energies, ΔGtr from water to solvents. The values of ΔGtr for side chains and peptide backbone quantify the thermodynamic consequences of solvating a protein species in a co-solvent solution relative to pure water. Based on the transfer model and experimental ΔGtr for these AAs, it has been proposed that these cosolvents exert their effect on protein stability primarily via the protein backbone. The ΔGtr of AAs from water to another solvent system will be either favorable or unfavorable. By definition, an unfavorable transfer free energy, ΔGtr > 0, means that the protein becomes solvophobic on transfer to a solvent, whereas a favorable transfer free energy, ΔGtr < 0, represents that the protein becomes solvophilic on transfer to a solvent. The sign and magnitude of the measured ΔGtr quantifies the protein response to changes in solvent quality. Therefore, this review will provide the basis of a universal mechanism for co-solvent-mediated (that includes the new novel biocompatible ionic liquids (ILs)) protein stabilization and destabilization as the protein backbone is shared by all proteins, regardless of side chain sequence.

Production of bio-based chemicals nowadays is more crucial than ever. The fact that 3-Hydroxypropionic acid can serve as a building block chemical for the production of other high added value chemicals, has made it as one of the most valuable chemicals according to US DOE. Recently, researchers have turned their interest to the construction of a microbial cell factory that will be capable of producing 3-hydroxypropionic acid from renewable raw materials. Most of the work is dedicated to the utilization of glycerol as raw material by employing either Escherichia coli or Klebsiella pneumoniae strains. Several genes were tested and evaluated and different cultivation techniques were applied. During the last few years, promising levels of 3- hydroxypropionic acid were obtained, however more efforts have to be dedicated in this direction of the commercialization of the process that seems to be closer than even before.

Partitioning studies of invertase are carried out by incorporating different nanoparticles at varied concentrations (0-2 %, w/w) employing polymer/polymer (PEG-3350/dextran-T70) and polymer/salt (PEG-3350/magnesium sulphate) phase systems. The partition coefficient of total protein (KTP) is found to decrease in case of PEG-3350/dextran-T70 system with an increase in concentration of nanoparticles. However, the extent of decrease varied depending on the nanoparticle. Significant changes are not observed in partition coefficient of invertase (KINV). In case of PEG- 3350/magnesium sulphate systems, gradual increase in KTP and KINV values is observed with an increase in concentration of nanoparticles. The partition coefficient varied (KTP from 0.06 to 0.25 and KINV from 0.01 to 0.04) depending on the nanoparticles. Highest enrichment of enzyme is observed in case of PEG-3350/magnesium sulphate system with gold nanoparticles (32.64 U/mg specific activity with 9 fold enrichment and enzyme activity recovery of 92%) among all the systems studied.

The aim of this work was to evaluate the kinetics of colour change for bananas and pears dried in hot air at different temperatures, and also to test different kinetic models to verify which describe best the experimental data. Banana fruits from Madeira island and Costa Rica were and pears from cultivar D. Joaquina were peeled, cut and dried with hot air at 0.5 m/s and temperatures ranging from 50 to 70 ºC, until reaching a final moisture content lower than 10% (wet basis). Along drying colour measurements were done using a tristimulus colorimeter measuring the CIELab coordinates, L*, a* and b*. The experimental data was then fit to different kinetic models found in literature (first order, second order and exponential rise functional). The results obtained showed that bananas undergo a more intense color change than pears. It was further observed that the increase in drying temperature lead in general to an increase in the colour degradation, being this effect more pronounced in the pears. As to the kinetics of color change, the exponential rise function showed the best fitting, and the values of the kinetic constant found with this model varied from 5.7023x10-5 to 1.0086 h-1.