Performance Analysis of Helical Ribbon Impeller in Production of Red Pigment By Monascus Purpureus Ftc 5391

Agitation in stirred tank bioreactors require a great deal of attention as damage to microorganisms limit the extent of impeller speed or power input, which in effect will disturb the actual mass transfer capability and productivity of a bioreactor. A new variant of low shear impeller under helical ribbon class (Paravisc) was investigated for its potential to replace the Rushton turbine which was found to exert excessive shearing in mixing processes and proved less efficient in handling non- Newtonian fluids. Performance analysis on Paravisc impeller covered the aspect of physical mixing as well as the integration model fungal system. Under nonbiological environment, the impeller torque measurement gave Newtonian powerflow relationship with a power constant (Kp) of 424.7 for mixing under laminar condition. Reynolds number (Re) at 60 marked the critical point, Recrit, where flow shifted to transitional regime. In case of non-Newtonian fluids, impeller power draw decreases as shear thinning behavior increases. The vessel shear rate was calculated from the superposition of both Newtonian and non-Newtonian power data. The vessel shear rate constant (Ks) was then derived as a function of Kp(n) of the given power law fluids. The mixing time analysis produced a mixing time constant (Km) of 53.8 throughout laminar regime but decreases when approaching Recrit before stabilized again at 11.8 in turbulent flow regime. The volumetric oxygen transfer coefficient (kLa) was more affected by the agitation of Paravisc than it had with superficial gas velocity for non-viscous fluids when mixing was above a certain critical impeller speed (NC). However, gassing rate became more influential on oxygen transfer for tests using 0.2 % to 0.8 % w/v carboxymethylcellulose sodium (CMCNa) solutions. Predictive kLa correlations in the form power law equations derived via multiple linear regressions resulted in separate correlations for water, electrolytes and viscous simulant fluids. Application of Paravisc in red pigment production by Monascus purpureus FTC5391 was based on the theoretical kLa attainable in media using calculations from the developed model. The highest yield and productivity by Paravisc mixing was achieved at 250 rpm and 1.5 VVM with YP/S and P equaled to 0.47 UA500/g.glucose and 0.15 UA500/h, respectively. These were 58% and 14% more than what was obtained by Rushton impeller. Operationwise, mixing with a single Paravisc was more efficient since it require 42% less energy than a typical double Rushtons operation. Consequently, this led to two-fold red pigment yield per energy consumed (YP/E) for helical ribbon impeller, of which 152.1 UA500/kW.h was measured from stirred tank bioreactor retrofitted with the novel agitator compared to 69.2 UA500/kW.h produced by Rushtons at 600 rpm

Heterotrophic cultivation of microalgae for production of biodiesel

High cell density cultivation of microalgae via heterotrophic growth mechanism could effectively address the issues of low productivity and operational constraints presently affecting the solar driven biodiesel production. This paper reviews the progress made so far in the development of commercial-scale heterotrophic microalgae cultivation processes. The review also discusses on patentable concepts and innovations disclosed in the past four years with regards to new approaches to microalgal cultivation technique, improvisation on the process flow design to economically produced biodiesel and genetic manipulation to confer desirable traits leading to high valued lipid-bearing microalgae strains

Gas-liquid mass transfer performance of dual impeller system employing rushtons, concave-bladed disc (CD-6) turbines and their combination in stirred tank bioreactor

The degree of oxygenation in stirred tank bioreactor is normally described and characterized L by the volumetric gas-liquid mass transfer coefficient (kL a). Throughout this study, the gas liquid mass transfer performance of dual impeller stirring system employing either two Rushton turbines (RT), two Concave-bladed disc (CD-6) turbines or the combination of both was comparatively investigated in Newtonian and non-Newtonian fluid systems. Static gassing-out technique was applied in all experimental kLa determinations and subsequent modeling of mass transfer correlations for all configurations were developed by incorporating the effects of power number (N3D2) and superficial velocity (Vg) on kLa. Ultimately, the use of dual CD-6 stirrers on a mixing shaft improved the oxygen transfer rate (OTR) by about 5-50 % and 18-65 % higher than the conventional RT-RT system in Newtonian and non-Newtonian systems, respectively

Enhanced production of thermophilic xylanase by recombinant Escherichia coli DH5a through optimization of medium and dissolved oxygen level.

Enhancement of thermophilic xylanase production by recombinant Escherichia coli DH5α through suitable medium formulation was initially investigated using shake flask cultures. Thereafter the effect of dissolved oxygen tension (DOT) level on the performance of xylanase fermentation by E. coli DH5α was investigated in 2 L stirred tank bioreactor using the optimal medium. Among the two basal medium tested (complex medium of Luria Bertani & defined mineral medium), defined mineral medium gave the highest growth and xylanase production. The optimal glucose and (NH4)2504 for xylanase production was obtained at 10 g L -1 and 2 g L-1, respectively. Growth of E. coli DH5α and xylanase production was inhibited in oxygen limited fermentation, where dissolved oxygen tension level was controlled at 0% saturation. On the other hand,xylanase production was enhanced at DOT level controlled at 20% saturation, though growth was not significantly improved. Substantially high xylanase production (1784.57 U mL -1) was obtained in fermentation using optimal medium composition and DOT level. These results indicate that efficient process control strategy is important for the mass production of xylanase enzyme by E. coli DH5α

Kojic acid: applications and development of fermentation process for production

Kojic acid, 5-hydroxy-2-hydroxymethyl-g-pyrone, has many potential industrial applications. In this review, the properties and diverse applications of kojic acid in industries are described. The review also discusses the advance in kojic acid fermentation, focusing on the process development in microorganisms and strain selection, medium and culture optimization, as well as fermentation modes for commercially viable industrial scale production. The performances of various fermentation techniques that have been applied for the production of kojic acid are compared, while the advantages and disadvantages of each technique are discussed in this paper

Optimization of osmotic shock process variables for enhancement of the release of periplasmic interferon-α2b from Escherichia coli using response surface method

The osmotic shock process for the release of periplasmic recombinant human interferon-α2b from Escherichia coli was optimized using response surface method (RSM). The process parameters such as pH, buffer concentration and sucrose concentration in hypertonic solution, cell concentration to hypertonic solution, contact time of cells with hypertonic solution, temperature of hypertonic solution, cell concentration to hypotonic solution, contact time of cells with hypotonic solution and temperature of hypotonic solution were initially screened using Plackett Burman design. Further optimization was carried out using central composite design (one of the design in RSM) for sucrose concentration in hypertonic solution as well as cell concentration to hypertonic and hypotonic solutions. The optimal cell concentration was 0.05 g/mL in hypertonic solution and 0.2 g/mL in hypotonic solution. The use of hypertonic solution containing 18% sucrose with a combination of 100 mM Tris and 2.5 mM EDTA buffer (pH 8.0 and 25 °C) and cold water (4 °C) as a hypotonic solution gave the optimum release of interferon-α2b. Increased product concentration in the final solution resulted from the optimized process would reduce the downstream steps during purification. The concept of reuse of hypertonic solution was also demonstrated

Improvement of medium composition for heterotrophic cultivation of green microalgae, Tetraselmis suecica, using response surface methodology

Optimization of medium composition for the improvement of heterotrophic cultivation of green microalgae, Tetraselmis suecica, was performed using response surface methodology (RSM). Heterotrophic cultivation of T. suecica was conducted in total darkness using Walne medium formulated with natural sea water. Initially, the effect of two types of carbon source (glucose and sodium acetate) and various types of nitrogen source (peptone, yeast extract, meat extract, malt extract, urea, sodium nitrate and ammonium nitrate) on growth of T. suecica was studied. The concentration of medium component that was found to significantly influence the heterotrophic growth of T. suecica (glucose, peptone, yeast extract and meat extract) was further optimized using RSM. The medium that consists of 5.78 g/L glucose, 9 g/L peptone, 4.48 g/L yeast extract and 3.01 g/L meat extract was found optimal for heterotrophic cultivation of T. suecica. The final cell concentration (28.88 g/L) obtained in heterotrophic cultivation using this optimized medium was about 3 and 2 times higher than obtained in photoautotrophic culture (8.40 g/L) and non-optimized medium for heterotrophic cultivation (13.81 g/L), respectively. In addition, the cell yield based on glucose consumed (9.31 g cell/g glucose) was increased by about 3 times as compared to non-optimized medium (3.61 g cell/g glucose)

Effects of dual impeller system of Rushton turbine, concave disk turbine and their combinations on the performance of kojic acid fermentation by Aspergillus flavus Link 44-1

In the present work, the effects of dual impeller configurations comprising of Rushton turbine (RT) and Concave-bladed disk turbine (CD-6) on the oxygen transfer profile and fermentation performance of kojic acid production by Aspergillus flavus Link 44-1 was investigated. Batch cultivations of A. flavus Link 44-1 were performed in 2 L stirred tank bioreactor. The fermentations were conducted using different dual impeller systems; (1) RT-RT, (2) CD6-CD6, (3) RT-CD6, and (4) CD6-RT (bottom-top impeller). It was perceived that dual CD-6 system was able to improve oxygen transfer rate by about 25–45% over the hybrids of RT and CD-6 and the typically configured dual RT system. While no substantial disparity could be seen on the fungal growth rate by the manipulation of the impeller, high concentration of kojic acid (44.93 g L−1) was attained with the use of dual CD-6 as the mixer. Efficient agitating system that can facilitate good gas dispersion capability is crucially required in order to counteract the problem of oxygen solubility limitation faced in such viscous fungal fermentation broth. The results from this work suggested the promising capability of dual CD-6 configuration in enhancing productivity of kojic acid fermentation in stirred tank bioreactor

Influence of culture trophic conditions on growth performance and microanatomy changes of microalgae, Tetraselmis suecica

This study aimed to evaluate the influence of photo- and hetero-trophic culture conditions on growth performance and microanatomy changes of microalga, Tetraselmis suecica shake flask and stirred tank bioreactor. The changes in cell composition such as lipid, protein and carbohydrate content were determined and the kinetic parameters and microanatomy of T. suecica under heterotro- and photo-autotrophic conditions were studied. Results revealed that lipid content in the heterotrophic cells was about two times higher when compared to that of photoautotrophic cells. The final cell concentration obtained at the end of exponential phase in heterotrophic cultivation (74 g.L¯¹) was higher than that obtained in photoautotrophic cultivation (13.7 g.L¯¹), in photobioreactor. The shape of photoautotrophic T. suecica cells was oval (12.5 μm long and 7.5 μm wide) with a volume of about 552 μm3. In heterotrophic cultivation, the cell was changed to a spherical shape with a diameter of approximately 3.41 μm, giving a cell volume of about 20.6 μm3

Kinetics and optimization of lipophilic kojic acid derivative synthesis in polar aprotic solvent using lipozyme RMIM and its rheological study

The synthesis of kojic acid derivative (KAD) from kojic and palmitic acid (C16:0) in the presence of immobilized lipase from Rhizomucor miehei (commercially known as Lipozyme RMIM), was studied using a shake flask system. Kojic acid is a polyfunctional heterocycles that acts as a source of nucleophile in this reaction allowing the formation of a lipophilic KAD. In this study, the source of biocatalyst, Lipozyme RMIM, was derived from the lipase of Rhizomucor miehei immobilized on weak anion exchange macro-porous Duolite ES 562 by the adsorption technique. The effects of solvents, enzyme loading, reaction temperature, and substrate molar ratio on the reaction rate were investigated. In one-factor-at-a-time (OFAT) experiments, a high reaction rate (30.6 × 10−3 M·min−1) of KAD synthesis was recorded using acetone, enzyme loading of 1.25% (w/v), reaction time of 12 h, temperature of 50 °C and substrate molar ratio of 5:1. Thereafter, a yield of KAD synthesis was optimized via the response surface methodology (RSM) whereby the optimized molar ratio (fatty acid: kojic acid), enzyme loading, reaction temperature and reaction time were 6.74, 1.97% (w/v), 45.9 °C, and 20 h respectively, giving a high yield of KAD (64.47%). This condition was reevaluated in a 0.5 L stirred tank reactor (STR) where the agitation effects of two impellers; Rushton turbine (RT) and pitch-blade turbine (PBT), were investigated. In the STR, a very high yield of KAD synthesis (84.12%) was achieved using RT at 250 rpm, which was higher than the shake flask, thus indicating better mixing quality in STR. In a rheological study, a pseudoplastic behavior of KAD mixture was proposed for potential application in lotion formulation