Sharif Digital Repository

Biosurfactants are microbial substances which influence interfacial tension. The kinetic study was carried out for Pseudomonas aeruginosa MR01 during biosurfactant production in a two-phase liquid-liquid batch fermentation system. The maximum rhamnolipid concentration (Pmax) and the yield of biosurfactant per 1 biomass (YP/X) in a 5-L bioreactor containing soybean oil medium were found to be approximately 20.9 g.L and 3.1 g.g-1, respectively. Previously reported kinetic models in aqueous systems, three-parameter Gompertz, 2 Luedeking-Piret and Mercier equations, demonstrated adequate goodness-of-fit (r >0.9) to kinetic data recorded for biomass growth, nitrate consumption and rhamnolipid... 

This study deals with the large-scale production of biosurfactant from soybean oil soapstock by Pseudomonas aeruginosa MR01. The production of biosurfactant was carried out in a newly designed bioreactor equipped with recycling flow under three operational conditions. Kinetic studies were conducted at both shake flask and 5-L bioreactor scales during fermentation in a soapstock medium. Mathematical equations were developed to model the kinetic patterns at both scales. RESULT: Statistical analyses demonstrated the goodness of fit, with regression r-squared, R2, between 0.97and 0.99 for different models. Furthermore, biosurfactant concentration in the bioreactor including the recycling flow,... 

Drawing on prior reports highlighting the redox mediator properties of powdered activated carbon (PAC), this study was designed to evaluate these properties to enhance the decolorization of azo dye by Klebsiella quasipneumoniae GT7. It was found that the presence of 0.5 % PAC in the medium increased the biodecolorization rate early in incubation. Chemical analysis revealed that dye conversion into aromatic amines occurred in microbial systems both with and without PAC. However, at initial dye concentrations (Cid) of 2 mM or higher, some dye remained on the PAC surface and in the medium. In contrast, the PAC-free system achieved nearly 100 % biodecolorization at all initial dye... 

The effect of an efficient biosurfactant produced from Pseudomonas aeroginosa MR01, a bacterial strain isolated from oil excavation areas in southern Iran, on the recovery of residual oil trapped within carbonate rocks, was investigated. In a core holder set-up, bearing a number of limestone-and dolomite-containing core samples, biosurfactant flooding resulted in oil recoveries as large as 20% to 28% Residual Oil (R.O). Biosurfactant injection in less permeable rocks in a range of 0.5 to 32 md was more successful, in terms of oil production. In the case of the least oil recovery via biosurfactant flooding, incubation of the core with a biosurfactant solution at reservoir conditions,... 

Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover,... 

Background: Recently, concerns have been raised regarding the environmental and public health safety of azo dyes, the most widely used synthetic dyes. The membrane technique has been introduced as one of the efficient methods for dye removal treatments. Polyvinylidene fluoride (PVDF) membrane manipulated by surfactants was studied for removal of the azo dye, carmoisine. Methods: PVDF membrane was prepared via non-solvent-induced phase separation (NIPS) and used to remove the azo dye, carmoisine. Three nonionic surfactants including Tween 20, Tween 60, and Tween 80 were used individually as additives in casting solutions to improve PVDF membrane properties. Results: Fourier-transform infrared... 

Livestock blood is a protein-rich waste byproduct produced during meat production processes in slaughterhouses. Its utilization through conversion into value-added products is an intriguing management strategy. In this study, bovine blood was used to obtain the protein hydrolysate for use as a peptone for microbial growth medium. Lyophilized bovine blood was heat treated to make it susceptible to enzymic hydrolysis, and then enzymatically treated with trypsin (bovine pancreas protease) to produce protein hydrolysate. Physico-chemical features were determined for protein hydrolysate and compared to commercial Merck peptone from meat. Amino acid compositions of bovine blood and commercial... 

A bacterial strain was isolated and cultured from the oil excavation areas in tropical zone in southern Iran. It was affiliated with Pseudomonas. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, MR01, was identical to those of cultured representatives of the species Pseudomonas aeruginosa. This bacterium was able to produce a type of biosurfactant with excessive foam-forming properties. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages lipid (∼65%, w/w) and carbohydrate (∼30%, w/w) in addition to a minor fraction of protein (∼4%, w/w). The best production of 2.1 g/l was obtained when the cells were grown on... 

Azo dyes are common dye groups widely used in different industries. Industrial effluents which contain these dyes pervade water resources and have various known and unknown physiological effects on living organisms. In this study, methyl red (MR) was proposed as a model azo dye to examine the capability of Saccharomyces cerevisiae ATCC 9763 for cleavage of the azo bond leading to decolourization. The spectrophotometry method showed that complete decolourization occurred statically during ≃12 h and this time reduced to several minutes less than 10 min where cell mass increased. Thin layer chromatography (TLC), mass spectroscopy and Fourier transform infrared (FTIR) confirmed degradation of... 

In the present study, an aqueous root-extract of Acanthophyllum laxiusculum (AREAL) was evaluated for phenanthrene removal from two samples of contaminated soil. AREAL showed a linear solubilization enhancement for phenanthrene with a weight solubilization ratio of 0.05. Batch soil washing experiments caused the removal of phenanthrene with efficiencies of 96.7% and 78% from soils with 0.78% and 2.73% organic carbon, respectively. Desorption kinetics of phenanthrene exhibited a twophase pattern, namely, a rapid release as the initial phase and a slower removal as a subsequent phase. A two-compartment exponential model could adequately represent the two phases of the kinetic pattern of...