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1.
Industrial wastes are of great interest as a substrate in production of value-added products to reduce cost, while managing the waste economically and environmentally. Bio-ethanol production from industrial wastes has gained attention because of its abundance, availability, and rich carbon and nitrogen content. In this study, industrial potato waste was used as a carbon source and a medium was optimized for ethanol production by using statistical designs. The effect of various medium components on ethanol production was evaluated. Yeast extract, malt extract, and MgSO4·7H2O showed significantly positive effects, whereas KH2PO4 and CaCl2·2H2O had a significantly negative effect (p-value < 0.05). Using response surface methodology, a medium consisting of 40.4 g/L (dry basis) industrial waste potato, 50 g/L malt extract, and 4.84 g/L MgSO4·7H2O was found optimal and yielded 24.6 g/L ethanol at 30 °C, 150 rpm, and 48 h of fermentation. In conclusion, this study demonstrated that industrial potato waste can be used effectively to enhance bioethanol production.  相似文献   

2.
Anabaena sp. was used to examine the toxicity of exposure to a nano-TiO2 suspension, Zn2+ solution, and mixtures of nano-TiO2 and Zn2+ suspensions. Typical chlorophyll fluorescence parameters, including effective quantum yield, photosynthetic efficiency and maximal electron transport rate, were measured by a pulse-amplitude modulated fluorometer. Nano-TiO2 particles exhibited no significant toxicity at concentrations lower than 10.0 mg/L. The 96 h concentration for the 50% maximal effect (EC50) of Zn2+ alone to Anabaena sp. was 0.38 ± 0.004 mg/L. The presence of nano-TiO2 at low concentrations (<1.0 mg/L) significantly enhanced the toxicity of Zn2+ and consequently reduced the EC50 value to 0.29 ± 0.003 mg/L. However, the toxicity of the Zn2+/TiO2 system decreased with increasing nano-TiO2 concentration because of the substantial adsorption of Zn2+ by nano-TiO2. The toxicity curve of the Zn2+/TiO2 system as a function of incremental nano-TiO2 concentrations was parabolic. The toxicity significantly increased at the initial stage, reached its maximum, and then decreased with increasing nano-TiO2 concentration. Hydrodynamic sizes, concentration of nano-TiO2 and Zn2+ loaded nano-TiO2 were the main parameters for synergistic toxicity.  相似文献   

3.
The objective of the present study was to determine the antimicrobial resistance profile of planktonic and biofilm cells of Staphylococcus aureus and coagulase-negative staphylococci (CoNS). Two hundred Staphylococcus spp. strains were studied, including 50 S. aureus and 150 CoNS strains (50 S. epidermidis, 20 S. haemolyticus, 20 S. warneri, 20 S. hominis, 20 S. lugdunensis, and 20 S. saprophyticus). Biofilm formation was investigated by adherence to polystyrene plates. Positive strains were submitted to the broth microdilution method to determine the minimum inhibitory concentration (MIC) for planktonic and biofilm cells and the minimal bactericidal concentration for biofilm cells (MBCB). Forty-nine Staphylococcus spp. strains (14 S. aureus, 13 S. epidermidis, 13 S. saprophyticus, 3 S. haemolyticus, 1 S. hominis, 3 S. warneri, and 2 S. lugdunensis) were biofilm producers. These isolates were evaluated regarding their resistance profile. Determination of planktonic cell MIC identified three (21.4%) S. aureus strains that were resistant to oxacillin and six (42.8%) that were resistant to erythromycin. Among the CoNS, 31 (88.6%) strains were resistant to oxacillin, 14 (40%) to erythromycin, 18 (51.4%) to gentamicin, and 8 (22.8%) to sulfamethoxazole/trimethoprim. None of the planktonic isolates were resistant to vancomycin or linezolid. MICs were 2-, 4-, 8-, and up to 16-fold higher for biofilm cells than for planktonic cells. This observation was more common for vancomycin and erythromycin. The MBCB ranged from 8 to >256 µg/mL for oxacillin, 128 to >128 µg/mL for vancomycin, 256 to >256 µg/mL for erythromycin and gentamicin, >64 µg/mL for linezolid, and 32/608 to >32/608 µg/mL for sulfamethoxazole/trimethoprim. The results showed considerably higher MICs for S. aureus and CoNS biofilm cells compared to planktonic cells. Analysis of MBCM confirmed that even high concentrations of vancomycin were unable to eliminate the biofilms of S. aureus and CoNS species. Linezolid was the most effective drug in inhibiting staphylococci in the biofilm, without an increase in the MIC, when compared to planktonic cells. None of the isolates were resistant to this drug.  相似文献   

4.
The phenol-degrading efficiency of Pseudochrobactrum sp. was enhanced by ultraviolet (UV) irradiation. First, a bacterial strain, Pseudochrobactrum sp. XF1, was isolated from the activated sludge in a coking plant. It was subjected to mutation by UV radiation for 120 s and a mutant strain with higher phenol-degrading efficiency, Pseudochrobactrum sp. XF1-UV, was selected. The mutant strain XF1-UV was capable of degrading 1800 mg/L phenol completely within 48 h and had higher tolerance to hydrogen ion concentration and temperature variation than the wild type. Haldane’s kinetic model was used to fit the exponential growth data and the following kinetic parameters were obtained: μmax = 0.092 h−1, Ks = 22.517 mg/L, and Ki = 1126.725 mg/L for XF1, whereas μmax = 0.110 h−1, Ks = 23.934 mg/L, and Ki = 1579.134 mg/L for XF1-UV. Both XF1 and XF1-UV degraded phenol through the ortho-pathway; but the phenol hydroxylase activity of XF1-UV1 was higher than that of XF1, therefore, the mutant strain biodegraded phenol faster. Taken together, our results suggest that Pseudochrobactrum sp. XF1-UV could be a promising candidate for bioremediation of phenol-containing wastewaters.  相似文献   

5.
The potential of two zygomycetes fungi, Mucor indicus and Rhizopus oryzae, in assimilating citrus waste free sugars (CWFS) and producing fungal chitosan, oil, and protein as well as ethanol was investigated. Extraction of free sugars from citrus waste can reduce its environmental impact by decreasing the possibility of wild microorganisms growth and formation of bad odors, a typical problem facing the citrus industries. A total sugar concentration of 25.1 g/L was obtained by water extraction of citrus waste at room temperature, used for fungal cultivation in shake flasks and airlift bioreactor with no additional nutrients. In shake flasks cultivations, the fungi were only able to assimilate glucose, while fructose remained almost intact. In contrast, the cultivation of M. indicus and R. oryzae in the four-liter airlift bioreactor resulted in the consumption of almost all sugars and production of 250 and 280 g fungal biomass per kg of consumed sugar, respectively. These biomasses correspondingly contained 40% and 51% protein and 9.8% and 4.4% oil. Furthermore, the fungal cell walls, obtained after removing the alkali soluble fraction of the fungi, contained 0.61 and 0.69 g chitin and chitosan per g of cell wall for M. indicus and R. oryzae, respectively. Moreover, the maximum ethanol yield of 36% and 18% was obtained from M. indicus and R. oryzae, respectively. Furthermore, that M. indicus grew as clump mycelia in the airlift bioreactor, while R. oryzae formed spherical suspended pellets, is a promising feature towards industrialization of the process.  相似文献   

6.
Urena lobata has been used as a traditional medicinal plant in India and China. In this study, we investigated the antimicrobial activity and isolated the active compound from the leaves of U. lobata. The 80% ethanol extract from U. lobata leaves showed an effective anti-yeast activity against Saccharomyces cerevisiae (S. cerevisiae) strains. Using a combination of chromatographic methods, (−)-trachelogenin (1) and clematoside-S (2) were isolated from this plant for the first time, and their chemical structure was identified by mass spectrometry (MS) and extensive nuclear magnetic resonance (NMR) data analysis. In addition, 1 was found to be inactive against all of the test microorganisms in the antimicrobial assay, whereas 2 exhibits a specific anti-yeast activity against S. cerevisiae strains with diameter of inhibition zones in the range from 11 to 20 mm. Furthermore, the MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) values of 2 against S. cerevisiae strains were detected to be in the ranges of 0.61 to 9.8 μg/mL and 2.42 to 9.8 μg/mL, respectively. This is the first report of 2 with a specific anti-yeast activity. The above result suggests the potential application of U. lobata to be used as a natural anti-yeast agent in food preservation.  相似文献   

7.
Poplar is a model system for the regeneration and genetic transformation of woody plants. To shorten the time required for studies of transgenic poplar, efforts have been made to optimize transformation methods that use Agrobacterium tumefaciens. In this study, an Agrobacterium infective suspension was treated at 4 °C for at least 10 h before infecting explants. By transforming the Populus hybrid clone “Nanlin895” (Populus deltoides × P. euramericana) with Agrobacterium harboring the PBI121:CarNAC6 binary vector, we showed that the transformation efficiency was improved significantly by multiple independent factors, including an Agrobacterium infective suspension with an OD600 of 0.7, an Agrobacterium infection for 120 min, an Agrobacterium infective suspension at a pH of 5.0, an acetosyringone concentration of 200 µM, a cocultivation at 28 °C, a cocultivation for 72 h and a sucrose concentration of 30 g/L in the cocultivation medium. We also showed that preculture of wounded leaf explants for two days increased the regeneration rate. The integration of the desired gene into transgenic poplars was detected using selective medium containing kanamycin, followed by southern blot analysis. The expression of the transgene in the transgenic lines was confirmed by northern blot analysis.  相似文献   

8.
The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102–138 g·water/g·dry bacterial cellulose, viscosities of 4.7–9.3 dL/g, degree of polymerization of 1889.1–2672.8, stress at break of 72.3–139.5 MPa and Young’s modulus of 0.97–1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.  相似文献   

9.
Background: The incidence of fungal infections, especially those caused by Candida yeasts, has increased over the last two decades. However, the indicated therapy for fungal control has limitations. Hence, medicinal plants have emerged as an alternative in the search for new antifungal agents as they present compounds, such as essential oils, with important biological effects. Published data demonstrate important pharmacological properties of the essential oil of Cymbopogon nardus (L.) Rendle; these include anti-tumor, anti-nociceptive, and antibacterial activities, and so an investigation of this compound against pathogenic fungi is interesting. Objective: The aim of this study was to evaluate the chemical composition and biological potential of essential oil (EO) obtained from the leaves of C. nardus focusing on its antifungal profile against Candida species. Methods: The EO was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Testing of the antifungal potential against standard and clinical strains was performed by determining the minimal inhibitory concentration (MIC), time-kill, inhibition of Candida albicans hyphae growth, and inhibition of mature biofilms. Additionally, the cytotoxicity was investigated by the IC50 against HepG-2 (hepatic) and MRC-5 (fibroblast) cell lines. Results: According to the chemical analysis, the main compounds of the EO were the oxygen-containing monoterpenes: citronellal, geranial, geraniol, citronellol, and neral. The results showed important antifungal potential for all strains tested with MIC values ranging from 250 to 1000 μg/mL, except for two clinical isolates of C. tropicalis (MIC > 1000 μg/mL). The time-kill assay showed that the EO inhibited the growth of the yeast and inhibited hyphal formation of C. albicans strains at concentrations ranging from 15.8 to 1000 μg/mL. Inhibition of mature biofilms of strains of C. albicans, C. krusei and C. parapsilosis occurred at a concentration of 10× MIC. The values of the IC50 for the EO were 96.6 μg/mL (HepG-2) and 33.1 μg/mL (MRC-5). Conclusion: As a major virulence mechanism is attributed to these types of infections, the EO is a promising compound to inhibit Candida species, especially considering its action against biofilm.  相似文献   

10.
Microbial fuel cells (MFCs) represent a novel platform for treating wastewater and at the same time generating electricity. Using Pseudomonas putida (BCRC 1059), a wild-type bacterium, we demonstrated that the refinery wastewater could be treated and also generate electric current in an air-cathode chamber over four-batch cycles for 63 cumulative days. Our study indicated that the oil refinery wastewater containing 2213 mg/L (ppm) chemical oxygen demand (COD) could be used as a substrate for electricity generation in the reactor of the MFC. A maximum voltage of 355 mV was obtained with the highest power density of 0.005 mW/cm2 in the third cycle with a maximum current density of 0.015 mA/cm2 in regard to the external resistor of 1000 Ω. A maximum coulombic efficiency of 6 × 10−2% was obtained in the fourth cycle. The removal efficiency of the COD reached 30% as a function of time. Electron transfer mechanism was studied using cyclic voltammetry, which indicated the presence of a soluble electron shuttle in the reactor. Our study demonstrated that oil refinery wastewater could be used as a substrate for electricity generation.  相似文献   

11.
Diacylglycerol (DAG)-like lipases are found to play an important role in the life sciences and industrial fields. A putative DAG-like lipase (MgMDL2) from Malassezia globosa was cloned and expressed in recombinant Pichia pastoris. The recombinant MgMDL2 was expressed as a glycosylated protein and purified into homogeneity by anion exchange chromatography. The activity of recombinant MgMDL2 was optimal at 15 °C and pH 6.0, and it keeps over 50% of relative activity at 5 °C, suggesting that MgMDL2 was a cold active lipase. MgMDL2 retained over 80% of initial activity after incubation at 30 and 40 °C for 2.5 h, but it was not stable at 50 °C. Incubation of methanol and ethanol at a concentration of 30% for 2 h did not affect the recombinant enzyme activity, while metal ions, including Ca2+, Mn2+ and Ni2+, sharply inhibited the MgMDL2 activity at 5 mM by 42%, 35% and 36%, respectively. MgMDL2 exhibited a preference for medium chain-length esters with highest activity toward p-nitrophenyl caprylate, while it was active on mono- and diacylglycerol but not on triacylglycerol, indicating that it was a typical DAG-like lipase. By homology modeling, Phe278 was predicted to be involved in the preference of MgMDL2 for monoacyl- and diacyl-glyceride substrates, but not triglycerides.  相似文献   

12.
In this study the effects of phosphate, potassium, yeast extract, and trace metals on the growth of Mucor indicus and chitosan, chitin, and metabolite production by the fungus were investigated. Maximum yield of chitosan (0.32 g/g cell wall) was obtained in a phosphate-free medium. Reversely, cell growth and ethanol formation by the fungus were positively affected in the presence of phosphate. In a phosphate-free medium, the highest chitosan content (0.42 g/g cell wall) and cell growth (0.66 g/g sugar) were obtained at 2.5 g/L of KOH. Potassium concentration had no significant effect on ethanol and glycerol yields. The presence of trace metals significantly increased the chitosan yield at an optimal phosphate and potassium concentration (0.50 g/g cell wall). By contrast, production of ethanol by the fungus was negatively affected (0.33 g/g sugars). A remarkable increase in chitin and decrease in chitosan were observed in the absence of yeast extract and concentrations lower than 2 g/L. The maximum chitosan yield of 51% cell wall was obtained at 5 g/L of yeast extract when the medium contained no phosphate, 2.5 g/L KOH, and 1 mL/L trace metal solution.  相似文献   

13.
Laccase production by Pycnoporus sanguineus RP15 grown in wheat bran and corncob under solid-state fermentation was optimized by response surface methodology using a Central Composite Rotational Design. A laccase (Lacps1) was purified and characterized and the potential of the pure Lacps1 and the crude culture extract for synthetic dye decolorization was evaluated. At optimal conditions (eight days, 26 °C, 18% (w/w) milled corncob, 0.8% (w/w) NH4Cl and 50 mmol·L−1 CuSO4, initial moisture 4.1 mL·g−1), the laccase activity reached 138.6 ± 13.2 U·g−1. Lacps1 was a monomeric glycoprotein (67 kDa, 24% carbohydrate). Optimum pH and temperature for the oxidation of 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) were 4.4 and 74.4 °C, respectively. Lacps1 was stable at pH 3.0–8.0, and after two hours at 55–60 °C, presenting high redox potential (0.747 V vs. NHE). ABTS was oxidized with an apparent affinity constant of 147.0 ± 6.4 μmol·L−1, maximum velocity of 413.4 ± 21.2 U·mg−1 and catalytic efficiency of 3140.1 ± 149.6 L·mmol−1·s−1. The maximum decolorization percentages of bromophenol blue (BPB), remazol brilliant blue R and reactive blue 4 (RB4), at 25 or 40 °C without redox mediators, reached 90%, 80% and 60%, respectively, using either pure Lacps1 or the crude extract. This is the first study of the decolorization of BPB and RB4 by a P. sanguineus laccase. The data suggested good potential for treatment of industrial dye-containing effluents.  相似文献   

14.
A series of novel oxyalkylchalcones substituted with alkyl groups were designed and synthesized, and the antioomycete activity of the series was evaluated in vitro against Saprolegnia strains. All tested O-alkylchalcones were synthesized by means of nucleophilic substitution from the natural compound 2′,4′-dihydroxychalcone (1) and the respective alkyl bromide. The natural chalcone (1) and 10 synthetic oxyalkylchalcones (2–11) were tested against Saprolegnia parasitica and Saprolegnia australis. Among synthetic analogs, 2-hydroxy,4-farnesyloxychalcone (11) showed the most potent activity against Saprolegnia sp., with MIC and MOC values of 125 µg/mL (similar to bronopol at 150 µg/mL) and 175 µg/mL, respectively; however, 2′,4′-dihydroxychalcone (1) was the strongest and most active molecule, with MIC and MOC values of 6.25 µg/mL and 12.5 µg/mL.  相似文献   

15.
The Nitrate Directive of the European Union (EU) forces agriculture to reduce nitrate emission. The current study addressed nitrate emission and nitrate-N concentrations in leachate from cropping systems with and without the cultivation of catch crops (winter rye: Secale cereale L. and forage rape: Brassica napus ssp. oleifera (Metzg.) Sinksk). For this purpose, ceramic suction cups were used, installed at 80 cm below the soil surface. Soil water samples were extracted at intervals of ca 14 days over the course of three leaching seasons (September – February) in 1992–1995 on sandy soil in a crop rotation comprising potato (Solanum tuberosum L.), spring wheat (Triticum aestivum L.), sugar beet (Beta vulgaris L.) and oats (Avena sativa L.). Nitrate-N concentration was determined in the soil water samples. In a selection of samples several cations and anions were determined in order to analyze which cations primarily leach in combination with nitrate. The water flux at 80 cm depth was calculated with the SWAP model. Nitrate-N loss per interval was obtained by multiplying the measured nitrate-N concentration and the calculated flux. Accumulation over the season yielded the total nitrate-N leaching and the seasonal flux-weighted nitrate-N concentration in leachate. Among the cases studied, the total leaching of nitrate-N ranged between 30 and 140 kg ha–1. Over the leaching season, the flux-weighted nitrate-N concentration ranged between 5 and 25 mg L–1. Without catch crop cultivation, that concentration exceeded the EU nitrate-N standard (11.3 mg L–1) in all cases. Averaged for the current rotation, cultivation of catch crops would result in average nitrate-N concentrations in leachate near or below the EU nitrate standard. Nitrate-N concentrations correlated with calcium concentration and to a lesser extent with magnesium and potassium, indicating that these three ion species primarily leach in combination with nitrate. It is concluded that systematic inclusion of catch crops helps to decrease the nitrate-N concentration in leachate to values near or below the EU standard in arable rotations on sandy soils.  相似文献   

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18.
Mercury (Hg) is a highly hazardous pollutant widely used in industrial, pharmaceutical and agricultural fields. Mercury is found in the environment in several forms, elemental, inorganic (iHg) and organic, all of which are toxic. Considering that the liver is the organ primarily involved in the regulation of metabolic pathways, homeostasis and detoxification we investigated the morphological and ultrastructural effects in Danio rerio liver after 96 h exposure to two low HgCl2 concentrations (7.7 and 38.5 μg/L). We showed that a short-term exposure to very low concentrations of iHg severely affects liver morphology and ultrastructure. The main effects recorded in this work were: cytoplasm vacuolization, decrease in both lipid droplets and glycogen granules, increase in number of mitochondria, increase of rough endoplasmic reticulum and pyknotic nuclei. Pathological alterations observed were dose dependent. Trough immunohistochemistry, in situ hybridization and real-time PCR analysis, the induction of metallothionein (MT) under stressor conditions was also evaluated. Some of observed alterations could be considered as a general response of tissue to heavy metals, whereas others (such as increased number of mitochondria and increase of RER) may be considered as an adaptive response to mercury.  相似文献   

19.
The antioxidant activity of different Satureja montana L. subsp. kitaibelii extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using ESR spectroscopy. Also, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (I) sunflower oil (37 ºC, 3h) induced by 4,4′-azobis(4-cyanovaleric acid) (ACVA) and (II) liposomes induced by 2,2′-azobis(2- amidino-propane)dihydrochloride (AAPH) was studied. n-Butanol extract had the best antioxidant activity (100% at 0.5 mg/mL in Fenton reaction system; 89.21% at 5 mg/mL in system I; 83.38% at 5 mg/mL in system II). The antioxidant activities of the extracts significantly correlated with total phenolic content. The antimicrobial activity of Satureja montana L. subsp. kitaibelii extracts was investigated. Petroleum ether, chloroform and ethyl acetate extracts expressed a wide range of inhibiting activity against both grampositive and gram-negative bacteria.  相似文献   

20.
A gene encoding Rhizopus oryzae lipase containing prosequence (ProROL) was cloned into the pPICZαA and electrotransformed into the Pichia pastoris X-33 strain. The lipase was functionally expressed and secreted in Pichia pastoris with a molecular weight of 35 kDa. The maximum lipase activity of recombinant lipase (rProROL) was 21,000 U/mL, which was obtained in a fed-batch cultivation after 168 h induction with methanol in a 50-L bioreactor. After fermentation, the supernatant was concentrated by ultrafiltration with a 10 kDa cut off membrane and purified with ion exchange chromatography using SP Sepharose Fast Flow chromatography. The optimum pH and temperature of the rProROL were pH 9.0 and 40 °C, respectively. The lipase was stable from pH 4.0 to 9.0 and from 25 to 55 °C. The enzyme activity was enhanced by Ca2+ and inhibited by Hg2+ and Ag+. The lipase showed high activity toward triglyceride-Tripalmitin (C16:0) and triglyceride-Trilaurin (C12:0).  相似文献   

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