Journal des bioprocédés et des biotechniques

Hydrodynamics studies in Semi-fluidized bed relating to bed pressure drop, height of top packed bed, minimum and maximum semi-fluidization velocities with regular (spherical glass beads) homogeneous ternary mixtures, have been made in 0.01, 0.025, 0.037, 0.05, and 0.065 m internal diameter Perspex columns, with water as the fluidizing medium. Ternary mixtures of glass beads of different sizes (-8+10, -10+12 and -12+14 BSS) have been used as the semi-fluidized solids. Experimental studies relate to establish the effect of system parameters viz. column diameter, average particle size of semi-fluidized solid and initial static bed height and operating parameters viz. superficial liquid velocity and bed expansion ratio on the above mentioned system variables. Empirical and semi-empirical models have been developed using dimensional as well as statistical analyses. The calculated values from the predicted models have been compared with their experimental counterparts and fairly good agreement has been obtained. The results have also been compared with those available in the literature for irregular homogenous ternary mixtures.

Microbial cellulose has proven to be a remarkably versatile biomaterial and can be used in wide variety of applied scientific endeavors, such as paper product, electronics and biomedical devices. In fact, biomedical devices recently have gained a significant attention owing to increase in tissue-engineering products for both wound care and the regeneration of demand or diseased organs. So, microbial cellulose production, characterization and influence of additives during its production are important to understand the microbial pathway and create new application.

The aim of this work was to determine the solubility as well as the acidicconstants of trans-4-hydroxy-L-proline in 0.16 and 3.5 Mol.kg-1 NaClO₄ and in 0.16 and 3.18 Mol.kg^-1 NaCl at two different temperature, i.e. 298.15 and 310.15 K. trans-4-Hydroxy-L-proline, HL, is one of the most abundant amino acids present in collagen. As a major part of this protein, the measurement of hydroxyproline levels can be used as an indicator of collagen content. The protonation constants of ligand, K₁ and K₂, combined with the salting effects on the ligand in the ionic media were treated by the specific ion interaction theory, SIT, to give equilibrium constants at the infinite dilution reference state at 298.15 K and at 310.15 K, as well as specific interaction coefficients of the cation and anion of trans-4-hydroxy-L-proline with the media ions at the standard temperature, i.e. 298.15 K.

The aim of this study is to evaluate the biological activity of a crude chitinase extracted from fish offal (scorpion) on the chickpea weevil Callosobruchus maculatus (Coleoptera: Bruchidae) at various concentrations: 3%, 6%, 9%, 12%, 15%, 18%, 21% and 24% (V/V). The biological tests were performed under the typical experimental conditions: temperature and relative humidity at 28°C and 75%, respectively. The results have shown that the concentration of 24% of crude chitinase extracted has 100% of insecticide activity after a contact time of 1 h. The lethal dose (LD50) is estimated for every sample and for a range time from 1 to 72 h. The lower percentage of mortality (10%) is obtained for low values of concentrations and contact time (dose of 3% of crude chitinase and 1 h of contact time). The maximum mortality rate is observed for the high values of two parameters (dose of 24% of crude chitinase and 72 h contact time). However, it is observed that for a higher dose (24%) and for a lower contact time (1 h), the mortality rate increased rapidly. The novelty of this work consists in the use of a new bioinsecticide obtained from offal scorpion fish.

The purpose of this study is to investigate a new bio-electrochemical technique based on the utilisation of electric potential to enhance the enzymatic reaction. The efficiency of bio-electrochemical reactor has been achieved by studying the production of reducing sugar by enzymatic hydrolysis of olive mill. The results indicate that the application of a continuous electric potential of about 50 mV allowed a significant increase of the saccharification efficiency by about 25% (compared to an enzymatic process without electric potential). For an electric potential higher than 60 mV, the saccharification efficiency decreased, suggesting that the enzyme, a biological substance, could be damaged at high electric potential. It has been shown that the kinetics of the bio-catalyzed reactions could be controlled by an applied electric potential.