Enhanced phenanthrene biodegradation in river sediments by harnessing calcium peroxide nanoparticles and minerals in Sphingomonas sp. DSM 7526 cultivation.

Coupling chemical oxidation and biodegradation to remediate polycyclic aromatic hydrocarbon (PAH)-contaminated sediment has recently gained significant attention. In this study, calcium peroxide nanoparticles (nCaO2) were utilized as an innovative oxygen-releasing compound for in-situ chemical oxidation. The study investigates the bioremediation of phenanthrene (PHE)-contaminated sediment inoculated with Sphingomonas sp. DSM 7526 bacteria and treated with either aeration or nCaO2. Using three different culture media, the biodegradation efficiencies of PHE-contaminated anoxic sediment, aerobic sediment, and sediment treated with 0.2% w/w nCaO2 ranged from 57.45% to 63.52%, 69.87% to 71.00%, and 92.80% to 94.67%, respectively. These values were significantly higher compared to those observed in non-inoculated sediments. Additionally, the type of culture medium had a prominent effect on the amount of PHE removal. The presence of minerals in the culture medium increased the percentage of PHE removal compared to distilled water by about 2-10%. On the other hand, although the application of CaO2 nanoparticles negatively impacted the abundance of sediment bacteria, resulting in a 30-42% decrease in colony-forming units after 30 days of treatment, the highest PHE removal was obtained when coupling biodegradation and chemical oxidation. These findings demonstrate the successful application of bioaugmentation and chemical oxidation processes for treating PAH-contaminated sediment.

Facile Capture of Recombinant Human Erythropoietin on Mesoporous Affinity Hydrogel Matrix Functionalized with Azoboronate.

Boronate affinity ligands (BALs) have gained attention for glycoproteins capture and recognition due to their unique affinity interaction with glycans. In this paper, the effect of azo immobilization of phenylboronic acid on the reduction of adsorption pH of a recombinant glycoprotein (i.e., rhEPO) on hydrogel microparticles was investigated. To evaluate the influence of intraparticle porosity on protein adsorption, microporous (MicroBead) and mesoporous (MesoBead) agarose beads carrying two levels of amine densities were functionalized with azoboronate ligand. Affinity adsorption of the glycoprotein during static and dynamic adsorptions at relatively low pHs of 8 and 7 was studied. Results revealed successful adsorption of rhEPO at pH = 8 through affinity capture of glycans by azoboronate ligands. Increased amine density provided 1.1 and 1.5 times higher static adsorption capacities and dynamic performance efficiencies, respectively. In addition, adsorption capacities and initial adsorption rates of rhEPO on MesoBeads were respectively 1.4 and 2.5-2.8 times of MicroBeads. Also, at pH = 8, MesoBeads recorded higher dynamic recoveries (59 and 91%) compared with microporous ones (46 and 69%) since mesoporosity facilitates intraparticle mass transfer. Reduction of binding pH from 8 to 7 resulted in a sharp decrease in dynamic recovery (14%), indicating the appropriate binding pH of azoPBA to be above 7. The azoboronate affinity ligand is a leading candidate for capturing glycoproteins at relatively low pH. Also, mesoporous microparticles are appropriate tools in more efficient medium-sized protein binding applications.

Influence of alumina nanoparticles on the performance of polyacrylonitrile membranes in MBR.

This study aims to investigate the effect of using Al2O3 nanoparticles (NPs) in membrane structure on the operation condition of the membrane bioreactor. To this end, alumina NPs as the high hydrophilic agents with an approximate size of 40 nm and a concentration of 0-3 wt.% were placed within the PAN polymeric membrane matrix structure with high hydrophilicity and high mechanical resistance over the others via the phase inversion method. Characterization of synthesized nanocomposite membranes was carried out by SEM analysis. In the presence of the alumina NPs, the porosity of the membranes improved. The water contact angle measurement confirmed the superior hydrophilicity of mixed PAN membranes compared to the pure polymeric membranes. The best nanocomposite membrane with better antifouling properties was selected to evaluate the MBR's performance in wastewater treatment and assessed in terms of the resistance, flux recovery, and COD removal rates. The result of a comparison with pure membrane showed that by increasing the Al2O3 amount up to 2wt.%, irreversible fouling resistance mitigated as much as 50%. Moreover, the flux recovery ratio was increased by 15%, and the COD removal rate was also raised as large as 16%. Our investigation illustrated that the presence of alumina NPs has improved the MBR performance and decreased the irreversible fouling resistance of the membrane.

Hybrid powdered activated carbon-activated sludge biofilm formation to mitigate biofouling in dynamic membrane bioreactor for wastewater treatment.

Membrane costs and biofouling limit applications of membrane bioreactors (MBRs) for wastewater treatment. Here, powdered activated carbon (PAC) utilization in the formation and performance of a self-forming dynamic membrane consisting of activated sludge and PAC during hybrid wastewater treatment process was studied. Short-term agitation helped (non)biological particles to quickly uniformly settle on mesh filter, forming more uniform PAC-containing dynamic membranes (PAC-DMs). PAC adsorbed adhesive materials, resulting in an increase in average floc size and DM permeability while decreasing biofouling. The most efficient PAC concentration was 4 g L-1 considering techno-economics, i.e. the highest effluent quality (turbidity of 19.89 NTU) and the lowest biofouling (transmembrane pressure rise of 2.89 mbar). Short-term performance of hybrid PAC-DM bioreactor (PAC-DMBR) showed stability in effluent quality improvement including 92%, 95%, 83%, 84% and 98% reductions in turbidity, chemical oxygen demand, total dissolved solids, total nitrogen, and total phosphorous, respectively. Accordingly, adopting hybrid PAC-DMBR has potential to alleviate biofouling and capital cost.

Magnetic MBR technology: from the fabrication of membrane to application in wastewater treatment.

The aim of this study is to synthesize a magnetic nanocomposite membrane using iron oxide and alumina nanoparticles and employing it in magnetic membrane bioreactors (MBRs) for oily wastewater treatment. Al2O3 and Fe3O4 nanoparticles with approximate sizes of 20 and 30 nm respectively, were settled into a polysulfone (PSf) membrane matrix via magnetic casting method. The concentration of alumina and iron oxide nanoparticles were 0-0.25 wt% and 0.03 wt%, respectively. Compared with the blank membrane, an increase in the concentration of Fe3O4 up to 0.2 wt%, led to the flux as much as 70% and mitigated total resistance by 70%. The presence of the magnetic field around the bioreactor increased the flux significantly and reduced the cake resistance by 93%. Moreover, by applying the static magnetic field to MBR, the Chemical Oxygen Demand (COD) removal rate was increased to 93%, while in the MBR without the magnetic field the COD removal rate was 80%. Our investigation illustrated that the magnetic casting is an effective method to improve the flux and mitigate the fouling of the magnetic nanocomposite membrane. The output of this research indicates that the magnetic casting method enhance the magnetic MBRs performance for wastewater treatment.

Heterologous production of porcine derived antimicrobial peptide PR-39 in Escherichia coli using SUMO and intein fusion systems.

About half a century after antibiotics discovery, multi-antibiotic-resistant bacteria posed a new challenge to medicine. Attempts to discover new antibiotics have drawn the attention to Antimicrobial Peptides (AMPs). The rapid growth, besides its known genetic and manipulation systems, makes E. coli the preferred host system for production of recombinant proteins on an industrial scale. To produce AMPs in E. coli, the application of fusion-tags with the aim of stability, solubility, and prevention of antimicrobial activity is one of the best practices in this regard. In this study, we presented two different expression systems for the production of PR-39 in E. coli; one in fusion with intein-Chitin binding domain (CBD) and another in fusion with SUMO accompanied by polyhistidine affinity tag. Both were cloned in the NdeI-XhoI sites of pET-17b and transformed to E. coli BL21 (DE3) pLysS. Recombinant bacteria were cultured and induced with 0.4 mM IPTG at 30 °C. Expression and purification of target proteins were confirmed by Tricine- SDS-PAGE and dot blot analysis. Recovery of 250 µg PR-39/L from SUMO fusion system and 280 µg PR-39/L from the intein fusion system was achieved. Both purified peptides showed antibacterial activity using MIC/MBC demonstrating their functionality after SUMO and intein mediated purification.

Employing magnetism of Fe3O4 and hydrophilicity of ZrO2 to mitigate biofouling in magnetic MBR by Fe3O4-coated ZrO2/PAN nanocomposite membrane.

The aim of this research is benefiting from the synergistic effect of the simultaneous presence of Fe3O4 and ZrO2 in the form of Fe3O4-coated ZrO2 (Fe3O4@ZrO2) nanoparticles within the structure of PAN membrane to reduce membrane fouling. The role of Fe3O4 nanoparticles in increasing the pore size and magnetic saturation as well as the role of ZrO2 in decreasing surface roughness and hydrophobicity can mitigate membrane fouling in magnetic-assisted membrane bioreactors. For this purpose, Fe3O4, ZrO2, and Fe3O4@ZrO2 nanoparticles were embedded into PAN membrane structure and magnetic (M nM), hydrophilic (H nM), and magnetic-hydrophilic (HM nM) membranes were synthesized. H 1M (1ZrO2/PAN) membrane with a contact angle of 31 degrees, M 1N (1Fe3O4/PAN) with a pore size of 90 nm, and H 3M (3ZrO2/PAN) membrane with an RMS roughness of 13.5 nm were the most hydrophilic, porous, and smoothest membranes, respectively. High sensitivity to magnetic field along with high porosity, high hydrophilicity and low surface roughness simultaneously exist within the structure of MHMs membranes, such that MH 1M (1Fe3O4@ZrO2/PAN) indicated 116% greater flux, 121% greater flux recovery, and 85% less total filtration resistance in comparison with the blank membrane in magnetic membrane bioreactor, at a magnetic field intensity of 120 mT and MLSS = 10,000 mg/l. As an overall conclusion, the output of this research was compared with other research in term of normalized flux. Results reveal that at MLSS = 10,000 mg/l, HRT = 8 h and TMP = 0.3 bar, MH 1M membrane has normalized flux equal to 1.56 g/m2 h bar which is an acceptable value compared to normalized flux reported by other researchers.

Biodegradation of long chain alkanes in halophilic conditions by Alcanivorax sp. strain Est-02 isolated from saline soil.

In this study, through a multistep enrichment and isolation procedure, a halophilic bacterial strain was isolated from unpolluted saline soil, which was able to effectively and preferentially degrade long chain alkanes (especially tetracosane and octacosane). The strain was identified by 16S rRNA gene sequence as an Alcanivorax sp. The growth of strain Est-02 was optimized at the presence of tetracosane in different NaCl concentrations, temperatures, and pH. The consumption of different heavy alkanes was also investigated. Optimal culture conditions of the strain were determined to be as follows: 10% NaCl, temperature 25-35 °C and pH 7. Alcanivorax sp. strain Est-02 was able to use a wide range of aliphatic substrates ranging from C14 to C28 with clear tendency to utilize heavy chain hydrocarbons of C24 and C28. During growth on a mixture of alkanes (C14-C28), the strain consumed 60% and 65% of tetracosane and octacosane, respectively, while only about 40% of the lower chain alkanes were degraded. This unique ability of the strain Est-02 in efficient and selective biodegradation of long chain hydrocarbons could be further exploited for remediation of wax and heavy oil contaminated soils or upgrading of heavy crude oils. Comparison of the sequence of alkane hydroxylase gene (alkB) of strain Est-02 with previously reported sequences for Alcanivorax spp. and other hydrocarbon degraders, showed a remarkable phylogenetic distance between the sequence alkB of Est-02 and other alkane-degrading bacteria.

Towards rational design of porous nanostructured biopolymeric microparticles for biomacromolecules separation: A case study of intraparticle diffusion facilitation and BSA adsorption on agarose microspheres.

Synthesis and employing advanced materials for emerging applications is of great challenge for the scientific community. Recombinant proteins production and purification is one of the fastest growing fields in the global economy. In this regard, it is essential to fabricate biocompatible low-cost materials with high specificity to enhance purification efficiency. This requires the regulation of mass transfer based on the protein molecular size and interactions with the matrix interface; thus, needs synthesizing novel materials with tuned porosity. In this study, we proposed rational alteration in porous structure of biopolymeric microspheres using appropriate-sized porogen to facilitate intraparticle molecular diffusion. The tailored porous nanostructures, which were generated by phase separation in the polymer blend of agarose and polyethylene glycol, were analyzed with optical and scanning electron microscopy, Fourier transform infrared spectroscopy, water diffusion, and albumin adsorption. The well-tuned beads possessed highly porous structures with dominant mesopores owing to PEG phase migration out of the network. The high speed homogenizer caused an uncommon dense morphology with interwoven two-type porosity. Optimally tuned mesoporous beads with considerably high specific surface area exhibited dramatically fast and enhanced intraparticle diffusion of both water and protein molecules. Thus, the introduced porosity modification is a promising design for enhancing mass transfer in the bio-separation process. Finally, useful insights for developing future smart hydrogel microparticles with tuned porous network for biomolecules purification are provided by the conducted experiments.

Functional synergy of anti-mir221 and nanohydroxyapatite scaffold in bone tissue engineering of rat skull.

An appropriate cell source, effective cell modification, and proper supportive matrices are the main bases of tissue engineering. The effectiveness of anti-mir221 or hydroxyapatite (HA) in improving the osteogenic differentiation of mesenchymal stem cells (MSCs) has been reported previously. Herein, simultaneous application of these osteogenic inducers was investigated in vivo. The Poly-caprolactone (PCL)/HA nanofibers were characterized using contact angle measurement, tensile test, Fourier transform infrared spectroscopy, and electron microscopy. Rat MSCs were isolated, characterized and transfected with anti-mir221. The rats were divided into 4 groups and an 8 mm defect were created in the mid-calvaria of each rat by trephine bur. Group 1 received (PCL)/HA nanofibers, group 2 received (PCL)/HA nanofibers plus autologous MSCs, group 3 received (PCL)/HA nanofibers plus MSCs transfected with anti-mir221, and group 4 rats were left empty as an additional control group. Histomorphometric and radiomorphometric evaluation after 4 and 8 weeks revealed more new bone formation in the cell-treated groups compared to the scaffold alone group. There was evidence for a combination of increased osteoclasts and osteoblast vascular lake containing red blood cells in the anti-mir221 transfected group. New bone penetration into the scaffolds empirically demonstrated the capability of this combination for efficient osteointegration. Altogether, the co-application of HA and anti-mir221 transfected cells can enhance bone healing of the rat skull.

Dynamic membrane behaviours during constant flux filtration in membrane bioreactor coupled with mesh filter.

This study investigated the long-term filtration of mesh filter with the formed dynamic membrane in bioreactor. The trend of transmembrane pressure (TMP) variations highly corresponded to the thickness and compactness index of dynamic membrane. The dynamic membrane was fractionated by applying two cleaning protocols, that is, rinsing and chemical cleaning. The desorbed fraction, consisting of soluble microbial products (>70%), provided a stickiness surface for formation of consecutive biomass layer which featured a high concentration of extracellular polymeric substances (>75%). The chemical oxygen demand (COD) removal was 70%, 89%, and 92% for period of 0-26, 26-49, and 49-67 day, respectively, which indicated that further development of dynamic membrane increased the TMP without improvement in the effluent quality (TMP: 50-200 mbar, COD removal: 89%; TMP: 200-600 mbar, COD removal: 92%). The average NH4+-N and TN removal was about 76% and 21%, respectively. The effluent turbidity fell less than 2 NTU after 26 days of filtration.

Reduction of membrane fouling by innovative method (injection of air jet).

BACKGROUND: One of the most important challenges about the Membrane Bio Reactors is membrane fouling. Fouling has been at the centre of a globe debate for more recent years. It leads to high operational and maintenance costs such as membrane damage and replacement of membrane. Membrane fouling is attributed to the physicochemical interactions between the bio fluid and membrane. In order to decrease the fouling in bioreactors there are common anti fouling strategies such as operation at low flux, Optimization of aeration flow-rate and Physical and chemical cleanings. However, often they are not effective. METHODOLOGY: This work deal with fouling crisis by a new and innovative method in order to reduce of fouling on membrane surface by injection of parallel air jet on membrane bio reactor. This is a new idea and fundamental study about the influence of wall jet on fouling of membrane surface. This study is included both experimental and numerical investigations. In order to polarize the stream path on the surface of the membrane, four symmetric nozzles were implemented at the bottom of the membrane surface upon the sparger. The changes in the fouling resistance were experimentally measured at five various jet velocities and all of them recorded by a computer system. In addition the effect of air jet velocity and shear stress on fouling resistances was also investigated by computational fluid dynamics at the similar conditions. RESULTS: It was revealed that the permeate flux and resistance of fouling can be related to shear stress of air flow at the membrane surface. When the velocity of air jets increase, the permeate flux increase too. Also, results illustrate that jet injection can partially remove the cake which was formed on the surface of the membrane. CONCLUSIONS: Correlations were developed for estimating each resistance of the membrane surface via the shear stress. The resistances of the cake are removed by the jet velocity changes, from 20% in lower jet velocity up to 40% in higher jet velocity.

Dielectric monitoring and respirometric activity of a high cell density activated sludge.

A novel method was developed to assess the viability of activated sludge present in a biological wastewater treatment process and signify its distinction from respirometric activity. The respirometric activity and viability of activated sludge at high cell density, such as typically encountered in membrane bioreactors, were investigated in batch and fed-batch systems. The method for measuring the viability of activated sludge was based on the sludge permittivity monitored online by a capacitive sensor. Results from permittivity measurement were compared with usual biological activity measurement through oxygen uptake rate determination. The similar downward trend was observed for both measurements. The respirometric activity and permittivity, respectively, reduced to 50% and 68% of initial value in the fed-batch system and 18% and 27% of initial value for the batch system which was due to quantitative and qualitative changes in the microbial culture in the activated sludge. The novel method allows to made distinction between viable versus dead and inactive versus active microbial cells in the activated sludge system and can be used for better and more efficient control of the biological processes.

Effect of microalgae/activated sludge ratio on cooperative treatment of anaerobic effluent of municipal wastewater.

In this work, capability of the green microalga (MA), Chlorella vulgaris, in treating synthetic anaerobic effluent of municipal wastewater was investigated. While pure C. vulgaris (100 % MA) provided maximum soluble chemical oxygen demand (sCOD) and N-NH4(+) removal efficiencies of 27 and 72 % respectively, addition of activated sludge (AS) to MA in different mass ratios (91, 80, 66.7, 9 % MA) improved wastewater treatment efficiency. Thus giving maximum sCOD and N-NH4(+) removal efficiencies 85 and 86.3 % (for MA/AS = 10/1), respectively. Utilizing AS without C. vulgaris, for treating the synthetic wastewater resulted in 87 % maximum sCOD and 42 % maximum N-NH4(+) removal efficiencies. Furthermore, algal growth and specific growth rates were measured in the systems with microalga as the dominant cellular population. As a result, faster algal growth was observed in mixed systems. Specific growth rate of C. vulgaris was 0.14 (day(-1)) in 100 % MA and 0.39 (day(-1)) in 80 % MA. Finally, data gathered by online measurement of dissolved oxygen indicate that algae-activated sludge mixture improves photosynthetic activity of examined microalga strain during anaerobic effluent treatment.

Biomass characterization by dielectric monitoring of viability and oxygen uptake rate measurements in a novel membrane bioreactor.

The application of permittivity and oxygen uptake rate (OUR) as biological process control parameters in a wastewater treatment system was evaluated. Experiments were carried out in a novel airlift oxidation ditch membrane bioreactor under different organic loading rates (OLR). Permittivity as representative of activated sludge viability was measured by a capacitive on-line sensor. OUR was also measured as a representative for respirometric activity. Results showed that the biomass concentration increases with OLR and all biomass related measurements and simulators such as MLSS, permittivity, OUR, ASM1 and ASM3 almost follow the same increasing trends. The viability of biomass decreased when the OLR was reduced from 5 to 4 kg COD m(-3)d(-1). During decreasing of OLR, biomass related parameters generally decreased but not in a similar manner. Also, protein concentration in the system during OLR decreasing changed inversely with the activated sludge viability.

Fouling mitigation in membrane bioreactors using multivalent cations.

Several cations have been used to study the effect of mineral coagulants on activated sludge properties and membrane fouling in submerged membrane bioreactors (MBRs). The flocculability and settling properties of activated sludge were studied in various concentrations of sodium, potassium, magnesium, calcium, ferrum (in Fe(3+) form), and aluminum. Significant effect of cations and their concentrations on different parameters have been analyzed by 2-way ANOVA. Results showed that multivalent cations induce flocculation in bioreactors while monovalent cations have a detrimental effect on flocculability of activated sludge. The ratio of tight bound extracellular polymeric substances (TB-EPSs) to loosely bound (LB-EPSs) increased with concentration of multivalent cations that was in accordance with enhancement of biosorption in high concentration of multivalent cations. Moreover, these cations improved the settleability and dewatering properties of activated sludge. They also mitigated membrane fouling in the MBRs so that calcium and aluminum reduced membrane fouling to nearly 30%. Simple but useful correlations were developed for description of activated sludge properties based on easy measurable parameters that could be used also for estimation of membrane fouling. It was found that the ratio of TB-EPS to LB-EPS and also flocs size distribution are the main parameters affecting membrane fouling.

Amoxicillin separation from pharmaceutical wastewater by high permeability polysulfone nanofiltration membrane.

In this study, high permeability flat sheet polysulfone nanofiltration membranes were prepared for amoxicillin (AMX) recovery from pharmaceutical wastewater. Membrane fabrication includes two steps: raw ultrafiltration membrane synthesis by phase inversion method and nanaofiltration membrane synthesis by surface photopolymerization. Raw ultrafiltration membranes were synthesized using different molecular weights of polyethylene glycol (PEG) as pore former and different coagulation bath temperatures (CBTs). The synthesized ultrafiltration membranes were modified using UV-assisted polymerization technique and their performance in the separation of AMX at different pHs, were studied. The results showed that the more irradiation time, the smaller surface pore size. Moreover, the membranes made with higher molecular weight of PEG and coagulation bath temperatures were more susceptible for UV-modification at these conditions; fabricated membranes had higher flux as well as relatively high AMX separation. Moreover, pH enhancement increased AMX rejection by 85%. The effect of irradiation on membrane surface morphology was studied by SEM surface images and the morphological effects of pore former and coagulation bath temperatures on membrane structure were confirmed by SEM cross section images. A fairly comprehensive discussion about the effects of PEG, coagulation bath temperature and irradiation time on membrane structure and AMX recovery performance was represented in this study.

Soluble microbial products (SMPs) release in activated sludge systems: a review.

This review discusses the characterization, production and implications of soluble microbial products (SMPs) in biological wastewater treatment. The precise definition of SMPs is open to talk about, but is currently regarded as "the pool of organic compounds that are released into solution from substrate metabolism and biomass decay"'. Some of the SMPs have been identified as humic acids, polysaccharides, proteins, amino acids, antibiotics, extracellular enzymes and structural components of cells and products of energy metabolism. They adversely affect the kinetic activity, flocculating and settling properties of sludge. This review outlines some important findings with regard to biodegradability and treatability of SMPs and also the effect of process parameters on their production. As SMPs are produced during biological treatment process, their trace amounts normally remain in the effluent that defines the highest COD removal efficiency. Their presence in effluent represents a high potential risk of toxic by-product formation during chlorine disinfection. Studies have indicated that among all wastewater post-treatment processes, the adsorption by granular activated carbon combined with biologically induced degradation is the most effective method for removal of SMPs. However, it may be concludes that the knowledge regarding SMPs is still under progress and more work is required to fully understand their contribution to the treatment process.

Analysis of petroleum biodesulfurization in an airlift bioreactor using response surface methodology.

For the first time, growing cells of Gordonia alkanivorans RIPI90A were used for biodesulfurization (BDS) of diesel. This process was carried out in an internal airlift bioreactor. BDS parameters (oil/water phase ratio and initial sulfur concentration) were optimized in flasks using response surface methodology. Predicted results were found to be in good agreement with experimental results. Initial sulfur concentration had a remarkable effect on BDS process. Maximum removal of sulfur (21 mg/l) can be achieved at oil/water phase ratio of 25% (v/v) and initial sulfur concentration of 28 mg/l. Moreover, effect of superficial gas velocity (Ug) and working volume (v) on volumetric gas liquid mass transfer coefficient was studied in an airlift bioreactor for BDS of diesel. The best results were achieved at Ug and v of 2.5l/min and 6.6l, respectively. Subsequently, BDS of diesel was investigated in an airlift bioreactor under optimized conditions. Sulfur reduction after 30 h was 14 mg/l.

Scale up and application of biosurfactant from Bacillus subtilis in Enhanced Oil recovery.

There is a lack of fundamental knowledge about the scale up of biosurfactant production. In order to develop suitable technology of commercialization, carrying out tests in shake flasks and bioreactors was essential. A reactor with integrated foam collector was designed for biosurfactant production using Bacillus subtilis isolated from agricultural soil. The yield of biosurfactant on biomass (Y(p/x)), biosurfactant on sucrose (Y(p/s)), and the volumetric production rate (Y) for shake flask were obtained about 0.45 g g(-1), 0.18 g g(-1), and 0.03 g l(-1) h(-1), respectively. The best condition for bioreactor was 300 rpm and 1.5 vvm, giving Y(x/s), Y(p/x), Y(p/s), and Y of 0.42 g g(-1), 0.595 g g(-1), 0.25 g g(-1), and 0.057 g l(-1) h(-1), respectively. The biosurfactant maximum production, 2.5 g l(-1), was reached in 44 h of growth, which was 28% better than the shake flask. The obtained volumetric oxygen transfer coefficient (K(L)a) values at optimum conditions in the shake flask and the bioreactor were found to be around 0.01 and 0.0117 s(-1), respectively. Comparison of K(L)a values at optimum conditions shows that biosurfactant production scaling up from shake flask to bioreactor can be done with K(L) a as scale up criterion very accurately. Nearly 8% of original oil in place was recovered using this biosurfactant after water flooding in the sand pack.