Optimization of surfactin production by Bacillus subtilis ATCC 6633 in a miniaturized bioreactor

In recent years, biosurfactants due to wide applications in chemical, petroleum, food and pharmaceutical industries, have been widely considered by researchers. Biosurfactants are produced by a series of microorganisms, so it is important to screen culture medium and operating conditions in miniaturized bioreactors prior to scaling up to large bioreactors.In this study, using a kind of miniaturized bioreactor called ventilation flask, optimal production conditions, including filling volume and shaking frequency to produce a surfactin-type biosurfactant by Bacillus subtilis ATCC 6633, were examined. Moreover, the effect of oxygen transfer rate [OTR] on the surfactin production was investigated according to Amoabediny and Buchs model. The results indicated that the maximum biomass and biosurfactant yield which obtained under optimal conditions [filling volume of 15 mL and shaking frequency of 300 rpm] were evaluated 0.3 g/L/h and 0.0485 g/L/h, respectively. Also, at the same conditions, the amount of surface tension decreased from 60.5 mN/m to 31.7 mN/m and the maximum oxygen transfer rate [OTR[max]] obtained as 0.01 mol/L/h

Electrochemical behavior and the determination of furan in beverage samples using glassy carbon electrode

Furan is a possible human carcinogen in many types of foods. A new and sensitive electro analytical method for determination of furan has been developed and validated. The best condition for electrochemical response was obtained with 0.1 M britton-rabinson buffer solution [pH=5] a glassy carbon electrode [GCE] was used as the working electrode, a Ag/AgCl/ KCl[sat.] electrode served as the reference electrode, and a platinum wire as the auxiliary electrode under the Differential Pulse Voltammetry [DPV] mode. The peak current obtained from DPV was linearly dependent on the Furan concentration in the range 12-360 Micro M [0.81-24.5 ppm] with correlation coefficients of 0.999 and a limit of detection [LOD] of 3 Micro M [0.2 ppm] and limit of quantification [LOQ] of 10 Micro M [0.68 ppm] were calculated, respectively. The values of the electron-transfer coefficient [Alpha] involved in the rate determining step calculated from the linear plots of Ep against ln [v] in the pH range investigated were 0.8 confirming the irreversible nature of the oxidation peak. The reproducibility of the method was tested by analyzing 10 samples containing 30 Micro M of Furan. The RSD% of the method thus obtained was 3.0% which showed excellent reproducibility for this developed methods

Effect of aeration rate on biosurfactin production in a miniaturized bioreactor

Recently, the production of biosurfactants in bioreactors and their use in various pharmaceutical, chemical and food industries have been developed. Optimum production is directly related to the physicochemical condition of culture medium [such as pH and temperature] and engineering parameters of bioreactors [such as aeration rate, volume of operation and the amount of energy input]. Understanding the gas transfer in shaken bioreactors equipped with a sterile closure is advantageous to avoid oxygen limitation or carbon dioxide inhibition of a microbial culture. In this study, the effect of aeration rates [due to using different design closures] on the amount of biosurfactin production by Bacillus subtilis ATCC 6633 in a ventilation flask as a miniaturized bioreactor was investigated. The highest biosurfactin concentration [0.0485 g/L/h] was obtained in the optimum conditions in which the amount of filling volume and shaking frequency were 15 ml and 300 rpm, respectively. The specific aeration rate [q[in]] and maximum oxygen transfer rate [OTR[max]], were calculated 1.88 vvm and 0.01 mol/L/h, respectively. The results showed the significant biosurfactin productivity increase under non-oxygen limiting condition

[Study on the cytotoxicity level of nanosilver on natural fibroblast [HF2] osteosarcoma [G292] and mesenchymal stem cells]

Nanotechnology offers numerous opportunities for invention of new and reformed applicable products for the benefit of human society. In spite of a vast application of nanomaterials there is little information about their impact on human health. This study examines the biological activity of nanosilver on mesenchymal, natural fibroblast [HF2], and osteoblast [G292] cells. The effects of nanosilver on the cells were observed by a light microscope and the amplification of the cells was assayed by using a standard cell toxicity test. The results show that the cytotoxicity depends on nanosilver concentration. The amount of IC50 on mesenchymal stem was 6.33; and on HF2 was 6.68; and on G292 cells was 3.42 micro g/L. The results show that nanosilver has two times more of an inhibition effect on cancerous cells' growth as compared to the normal cells. This phenomenon is due to the direct effect of nanosilver on the cell oxidation system. Due to the extraordinary activation of the mitochondorial respiration system in cancer cells, when compared to the normal cells, it can provide suitable opportunity for nanosilver to cause cell disruption

Cleaning oil-contaminated vessel by emulsan producers [autochthonous bacteria]

In a process for cleaning hydrocarbonaceous residues, including residual petroleum from laboratory made oil-contaminated vessels, several previously isolated bacteria from Ilam and Paydar oil reservoirs, were used. The isolated strains were compared with the standard sample of Acinetobacter calcoaceticus PTCC 1318 from Persian Type Culture Collection [PTCC]. This gram-negative bacterium grows on a variety of different substrates as sole carbon and energy sources, including crude oil, soy oil and ethanol. It is oxidase-negative, non-motile and strictly aerobic. Among the isolated strains, two autochthonous strains were found to produce an extracellular emulsifying agent when grown in Mineral Salt Medium containing soy oil, ethanol or local crude oil. The crude emulsifier of PTCC1318, Paydar-4 and Ilam-1 were concentrated from the cell-free culture fluid by ammonium sulfate precipitation to yield 1.89 g, 1.78 g and 1.69 g of bioemulsan, respectively. Although measuring the surface tension [ST] is not very applicable procedure in case of bioemulsan, but in order to prove this theory, ST was conducted.Further analysis of purified emulsion was performed to prove the molecular structure by Carbon13 Nuclear Magnetic Resonance, Proton1Nuclear Magnetic Resonance and Fourier Transform Infrared Radiation methods. These investigations showed that the molecular weight of emulsion produced by species isolated from Ilam and Paydar crude oil reservoirs are comparable with Acinetobacter calcoaceticus PTCC 1318

Antidermatophyte activity of the essential oil of Hypericum perforatum of north of Iran

Dermatophytes are the main cause of human superficial mycosis that is still a public health problem especially in tropical countries such as Iran. The aim of this study was determining the antifungal effect of Hypercom perforatum essential oil. The minimum inhibitory concentration [MIC] and minimum fungicidal concentration [MFC] for the essential oil of the plant Hypericum perforatum against various dermatophytes were determined. The essential oil of Hypericum perforatum was obtained by hydro distillation of the dried plant. Clinical isolates of dermatophytes [Epidermophyton floccosum, Microsporum canis, Microsporum gypseum, T. mentagrophytes var. interdigital, T. mentagrophytes var. mentagrophytes., T. rubrum and Trichophyton tonsurans] were used for determining antifungal activity of this essential oil by in vitro tube dilution technique. MIC90 and MFC90 values were remarkable. T. mentagrophytes var. interdigital showed a>1 log10 difference in viable count between treatment and control within the first hour, whereas E. floccosum did not. The essential oil of H. perforatum sufficiently inhibited and killed all tested dermatophytes in all different dilutions. The changes in growth curve of the treated dermatophytes were significant compared with the untreated dermatophytes. Terpinen-4-ol is the main component of the essential oil of H. perforatum, and perhaps could play the important role in antidermatophyte activity among the other components. It is suggested trying the in-vivo effects of Hypericum perforatum ointment or its other medicinal forms in the treatment and controlling of dermatophytes infections

Production of rhamnolipids by pseudomonas aeruginosa growing on carbon sources

Arhamnolipid producing bacterium, Pseudomonas aeruginosa was previously isolated from Iranian oil over years. Isolated strain was identified by morphological, biochemical, physiological and 16 sr RNA [1]. Glycolipid production by isolated bacterium using sugar beet molasses as a carbon and energy source was investigated. Biosurfactant production was quantified by surface tension reduction, Critical Micelle Dilution [CMD], Emulsification Capacity [EC], and Thin Layer Chromatogeraphy. biosurfactants during growth on waste Dates as the primary carbon and nitrogen sources, respectively. After 48 h of growth the culture supernatant fluid had a rhamnose concentration of 0.18 g/L and surface tension was reduced to 20 mN/m [%].[reduced the interfacial tension against crude oil from 21 mN/m to 0,47 mN/m] Result from the study showed that the growth of the bacteria using molasses as carbon sources is growth-associated. The specific production rate of rhamnolipid with 2%, 4%, 6%, 8% and 10% of molasses are 0.00065; 4.556; 8.94; 8.85; and 9.09. respectively The yield of rhamnolipid per biomass with 2%,4%,6%,8% and 10% molasses are 0.003;0.009;0.053;0.041 and 0.213 respectively. The production of rhamnolipid [0.0531 g rhamnolipid/g biomass] is higher compare to the culture grown in aerobic condition [0.04 g rhamnolipid/g biomass].The rhamnolipids were able to form stable emulsions with n-alkanes, aromatics, crude oil and olive oil. These studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes

Environmental importance of rhamnolipid production from molasses as a carbon source

Rhamnolipid has been known as biosurfactant which is produced by Pseudomonas aeruginosa in fermentation process. Several carbon sources such as ethanol, glucose, vegetable oil and hydrocarbon have been used to produce rhamnolipid. In this study, we are trying to use molasses which is a waste product from sugar industry as carbon source to produce rhamnolipid. The bacterium which was previously isolated from Iranian oil over years Glycolipid production by isolated bacterium using sugar beet molasses as a carbon and energy source was investigated. Result from the study showed that the growth of the bacteria using molasses as carbon sources is growth-associated. The specific production rate of rhamnolipid with 2%, 4%, 6%, 8% and 10% of molasses are 0.00065, 4.556, 8.94, 8.85, and 9.09 respectively. The yield of rhamnolipid per biomass with 2%, 4%, 6%, 8% and 10% molasses are 0.003, 0.009, 0.053, 0.041 and 0.213 respectively. The production of rhamnolipid [0.0531 g. rhamnolipid/g biomass] is higher compare to the culture grown in aerobic condition [0.04 g. rhamnolipid/g biomass]. These studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes

Isolation and production of biosurfactant from pseudomonas aeruginosa isolated from Iranian southern wells oil

In this study one hundred and fifty two bacterial strains were isolated from oil contaminated. Hemolysis was used as a criterion for the primary isolation of biosurfactant producing-bacteria. Fifty five strains had haemolytic activity, among them twelve strains were good biosurfactant producers by measuring surface tension and emulsification activity. Two microorganisms showed the highest biosurfactant production when grown on paraffin and glycerol as sole carbon source. As a result of biosurfactant synthesis the surface tension of the medium were reduced from 73 mN/m to values below 32 mN/m. A rhamnolipid producing bacterium, P.aeruginosa isolate from oil wells in the southern of Iran. Isolated strain was identified by morphological, biochemical, physiological. The identified Pseudomonas aeruginosa confirmed by Persian type culture collection. Glycolipid production by isolated bacterium using different carbon [gasolin, paraffin oil, glycerol, whey] and nitrogen sources [NaNO[3], [NH[4]][2]SO[4] and CH[4]N[2]O] was studied. Biosurfactant production was quantified by surface tension reduction, critical micelle dilution [CMD], emulsification capacity [EC], and ThinLayerChromatogeraphy. The best result were obtained when using glycerol as a C/N ratio of 55/1 and use of sodium nitrate as nitrogen source resulted in higher production of the rhamnolipid, expressed by rhamnose [4.2 g/l] and by the yield in relation to biomass [Yp/x = 0.65 g/g]. Additionally, physical-chemical characteristics of the spent broth with and without cells were studied, providing a low critical micelle concentration of 19 mg/l and surface tension was reduced to 20 mN/m [%]