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1.
An enzyme system having phosphotriesterase activity was partially purified from Flavobacterium sp. by means of gel filtration and preparative gel isotachophoresis. Flavobacterium phosphotriesterase showed maximum activity between pH 8–10 and was unaffected by the presence of metal ions. Non-ionic detergents were potent and irreversible inhibitors of activity. Inhibition was also observed with mercurial thiol reagents and cysteine, although in the latter case inhibition could be reversed by oxidation in air or with K3Fe(CN)6. Activity was restricted towards substrates having electron withdrawing aromatic or heterocyclic leaving group such as parathion, paraoxon, diazinon and their analogues. Substrate analogues having the weakly electrophilic 4-aminophenyl group were not hydrolysed and in some cases acted as competitive inhibitors. Product inhibition by 4-nitrophenol (but not by the phosphorus containing moiety) was observed.  相似文献   

2.
Eleven cadmium-tolerant bacterial strains were isolated from the root zone of Indian mustard (Brassica juncea L. Czern.) seedlings grown in Cd-supplemented soils as well as sewage sludge and mining waste highly contaminated with Cd. The bacteria also showed increased tolerance to other metals including Zn, Cu, Ni and Co. The isolated strains included Variovorax paradoxus, Rhodococcus sp. and Flavobacterium sp., and were capable of stimulating root elongation of B. juncea seedlings either in the presence or absence of toxic Cd concentrations. Some of the strains produced indoles or siderophores, but none possessed C2H2-reduction activity. All the strains, except Flavobacterium sp. strain 5P-3, contained the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which hydrolyses ACC (the immediate precursor of plant hormone ethylene) to NH3 and α-ketobutyrate. V. paradoxus utilized ACC as a sole source of N or energy. A positive correlation between the in vitro ACC deaminase activity of the bacteria and their stimulating effect on root elongation suggested that utilization of ACC is an important bacterial trait determining root growth promotion. The isolated bacteria offer promise as inoculants to improve growth of the metal accumulating plant B. juncea in the presence of toxic Cd concentrations and for the development of plant-inoculant systems useful for phytoremediation of polluted soils.  相似文献   

3.
The purpose of this study was to identify microbial strains that have a strong ability to biodegrade lubricating oil. No. 20 lubricating oil was used as the sole carbon source in an isolation medium to screen bacteria from sludge that had been contaminated with crude oil. Through both morphological and biochemical methods, the bacterial strain that had the highest biodegrading capacity was identified as Zoogloea sp. On the basis of these preliminary results, a biological contact oxidation method was employed to further assess the ability of the Zoogloea sp. strain to treat wastewater contaminated by No. 20 lubricating oil using three oxidation cabins and two hydraulic retaining times （HRT）. Results showed that the concentration of No. 20 lubricating oil with a 12 h hydraulic retaining time and 16.5 L h^-1 inflow rate was reduced by 99.3% in 15 d, and with a 6 h hydraulic retaining time and 33 L h%^-1 inflow rate it decreased by 98.6070 in 12 d. The results from this study indicated that Zoogloea sp. had a strong potential to be utilized in biodegradation of lubricating oil.  相似文献   

4.
Several Zn-tolerant bacterial strains were isolated from heavy-metal contaminated sludge, and their effects on root elongation, mobility, and accumulation of Zn in Orychophragmus violaceus were studied. The isolated strains included Bacillus subtilis, B. cereus, Flavobacterium sp. and Pseudomonas aeruginosa which were capable of stimulating root elongation in O. violaceus seedlings either in the presence or absence of Zn. The four bacterial strains significantly increased the concentration of water-extractable Zn compared with axenic soil. In addition, the four Zn-tolerant bacteria significantly increased the shoot biomass and Zn accumulation in O. violaceus compared to non-inoculated plants. The bacterial strains displayed different capacities to enhance plant Zn accumulation. Flavobacterium sp. was identified as the best candidate for enhancing Zn accumulation in plants, increasing Zn accumulation up to 1.21- and 1.19-fold in shoots and roots, respectively, compared to non-inoculated plants. It was indicated that Zn-tolerant bacteria played an important role in influencing the availability of water-soluble Zn in soil and Zn accumulation by plants. This study provides insight into the development of plant–microbe systems for phytoremediation.  相似文献   

5.
In conjunction with the start-up of a secondary wastewater treatment facility, population levels ofPrototheca sp. were measured. Wastewater influent levels ofPrototheca sp. were < 1 × 102 mL?1 whilePrototheca sp. trapped in the biological film reached levels > 1 × 105 mL?1. Effluent levels were only slightly less than influent levels because effluent contained the breaking off film. The film along with the primary sediment retained the high levels ofPrototheca sp. throughout the 20 day anaerobic digestion, however growth was not thought to occur. Depending on the method of flocculation, dewatering and disposal, various levels ofPrototheca sp. were returned to the environment in the sludge and effluent. The dynamic change in thePrototheca sp. population levels in the maturing film was thought to reflect the preference for the higher BOD influent. This change was manifest during the fourth month after start-up, as well as when comparing the film at the start with that at the end of the secondary treatment train. Prototheca sp. are ubiquitous inhabitants of all stages of domestic and municipal wastewater from the primary plumbing through all stages of primary and secondary treatment plant processes.Prototheca sp. were isolated from surface water and potable water, but were thought to represent wastewater contamination. SincePrototheca sp. are pathogenic for human beings and animals, wastewater presents a potential threat, but reported infections are rare and risk is minimal.  相似文献   

6.
Substrate samples were artificially infested with Fusarium oxysporum f. sp. conglutinans (FOC) and F. oxysporum f. sp. basilici (FOB) in order to evaluate the shift in fungal population by using culture dependent and culture independent methods. Solarization was carried out with transparent polyethylene film during a summer period on a greenhouse located in Northern Italy, in combination or not with Brassica carinata defatted seed meals and/or compost. Biosolarization treatment was carried out in a growth chamber by heating the substrate for 7 and 14 days at optimal (55–52 °C for 6 h, 50–48 °C for 8 h and 47–45 °C for 10 h/day) and sub-optimal (50–48 °C for 20 h, 45–43 °C for 8 h and 40–38 °C for 10 h/day) temperatures. Plate counts and polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) analyses were performed to evaluate the effect of biosolarization on the microbial population. The abundance of FOC and FOB were reduced as a consequence of biosolarization approach, while bacterial population (total aerobic mesophilic bacteria and Pseudomonas spp.) were higher compared to control samples during the experiment. PCR-DGGE fingerprints of the ascomycete community obtained from DNA directly extracted from infested substrate samples showed that the use of organic amendments increased the similarity of the fungal population.  相似文献   

7.
Environmental pollution with chromium is due to residues of several industrial processes. Bioremediation is an alternative actually considered to remove Cr (VI) from the environment, using adapted organisms that grow in contaminated places. Have been conducted studies with fungi mechanisms of interaction with chromium, most of which have focused on processes biosorption, characterized it by passive binding of metal components of the cell surface, and bioaccumulation, wherein the metal entry to cells occurs with energy expenditure. The paper presents the results of studies carried out on sorption of chromium (VI) ions from aqueous solutions by Fusarium sp. and Myrothecium sp. Both biomasses have the ability to take up hexavalent chromium during the stationary phase of growth and as well inactive conditions. Fusarium sp. showed 26% of biosorption with active biomass and 64% in inactive biomass; meanwhile, Myrothecium sp. obtained 97 and 82%, respectively. Both fungi showed adjust to pseudo-second-order model in active (Fusarium sp. R 2 = 0.99; Myrothecium sp. R 2 = 0.96) and inactive biomass assay (Fusarium sp. R 2 = 0.99; Myrothecium sp. R 2 = 0.99). The data of the active biomass test also confirmed to the intraparticle diffusion model (Fusarium sp. R 2 = 0.98; Myrothecium sp. R 2 = 0.93). The results obtained through this investigation indicate the possibility of treating waste effluents containing hexavalent chromium using Fusarium sp. and Myrothecium sp.  相似文献   

8.
The main purpose of this work was to conduct a kinetic study on cell growth and hexavalent chromium [Cr(VI)] removal by Candida sp. FGSFEP in a concentric draft-tube airlift bioreactor. The yeast was batch-cultivated in a 5.2-l airlift bioreactor containing culture medium with an initial Cr(VI) concentration of 1.5 mM. The maximum specific growth rate of Candida sp. FGSFEP in the airlift bioreactor was 0.0244 h?1, which was 71.83% higher than that obtained in flasks. The yeast strain was capable of reducing 1.5 mM Cr(VI) completely and exhibited a high volumetric rate [1.64 mg Cr(VI) l?1 h?1], specific rate [0.95 mg Cr(VI) g?1 biomass h?1] and capacity [44.38 mg Cr(VI) g?1 biomass] of Cr(VI) reduction in the airlift bioreactor, with values higher than those obtained in flasks. Therefore, culture of Candida sp. FGSFEP in a concentric draft-tube airlift bioreactor could be a promising technological alternative for the aerobic treatment of Cr(VI)-contaminated industrial effluents.  相似文献   

9.
The main objective of this study was to evaluate the contribution of sorption to the removal of two commonly used antibiotics (amoxicillin and ciprofloxacin) from wastewater. These antibiotics are excreted in large quantities with more than 75% of them being unmetabolized and are therefore likely to end up in domestic wastewater in significant quantities. The specific objectives were to determine the sorption behavior in synthetic wastewater (SWW), the effect of pH and contribution of microbial surfaces, to the sorption of these antibiotics. The SWW, adjusted to various pH levels, was used and sorption kinetics conducted at 100 and 250 ??g L?1 concentrations. Adsorption isotherms were determined at different pH levels. The SWW (pH 6.6) was inoculated with Rhodococcus sp. B30 strain to determine the contribution of microbial surfaces to sorption. Generally, both antibiotics revealed a decrease in sorption with pH increase, suggesting that lowering the solution pH of the wastewater may reduce their amounts in wastewater solution. Comparatively, ciprofloxacin exhibited higher sorption than amoxicillin. The sorption distribution coefficient (K d) values for ciprofloxacin ranged from 0.4356 to 0.8902 L?g?1, with pH?=?5.5 exhibiting the highest K d, while that for amoxicillin ranged from 0.1582 to 0.3858 L?g?1 with the highest K d at pH?=?3.5. There was a significant difference (p?<?0.05) in K d values between various pH levels for both antibiotics except between the pH of 5.5 and 6.6. Both antibiotics were not degraded within 48 h by Rhodococcus sp. B30 strain. These results indicate that degradation may not be the major process of removal of compounds from wastewater treatment plants and hence the importance of sorption as an intervention technique.  相似文献   

10.
Recently, two strains related to Burkholderia terrae, denoted BS001 and BS110, were shown to be strongly interactive with the soil fungus Lyophyllum sp. strain Karsten, forming a biofilm around the L. sp. strain Karsten hyphae and migrating along growing hyphae in soil. Here, we extend the findings obtained with strains BS001 and BS110 and show that the migratory ability with extending fungal hyphae is actually distributed among four Burkholderia phylotypes obtained from a range of soils with different characteristics. The majority of the migrating strains fell into a rather narrow group related to the original strain B. terrae BS001, but others fell in groups related to B. terricola, B. xenovorans and B. phytofirmans. To obtain these novel strains, bacterial inocula were obtained as cell extracts from eight soils and subsequently introduced into four (sandy acidic) pre-sterilized soils in microcosms which were then colonized by L. sp. strain Karsten or kept without this fungus. After 2 weeks of incubation, the soil microcosms were sampled at the migration front and samples were plated on semi-selective PCAT agar medium next to R2A medium. A total of 19 strains that had revealed the capability to comigrate with the fungus were obtained from this set-up, whereas four other strains were found in previous field work. Strains were analysed by BOX-PCR, pulsed-field gel electrophoresis, partial 16S rRNA gene similarity, metabolic profiling using BIOLOG and for the presence of a type three secretion system (TTSS). All strains belonged to the genus Burkholderia. Following this, selected strains were shown to be capable of single-strain comigration with the L. sp. strain Karsten hyphae through different soils. However, their avidity to do so differed across soils. For their ecological competence, the four different comigrating phylotypes may rely on their capacities to migrate as well as consume fungal-released compounds.  相似文献   

11.
Thirty-nine endophytic bacterial strains were isolated from the nodule of Lespedeza sp. grown in two different locations of South Korea. All strains were checked for their plant growth promoting (PGP) abilities under in vitro conditions. Most of the isolates showed multiple PGP activity, i.e., indole acetic acid production, ACC deaminase activity, siderophore production, and phosphate solubilization. The strains were identified by using 16S rRNA gene sequence analysis as belonging to Alphaproteobacteria, Betaproteobacteria, Actinobacteria, and Firmicutes phylum with nine different genera Arthrobacter, Bacillus, Bradyrhizobium, Burkholderia, Dyella, Methylobacterium, Microbacterium, Rhizobium, and Staphylococcus. Gene nodA amplification showed positive results only for strains from Bradyrhizobium and Rhizobium genera. The strains from Bradyrhizobium and Rhizobium genera enhanced plant growth, nodulation, and acetylene reduction activity when inoculated on Vigna unguiculata L. (cowpea), whereas other strains did not induce nodule formation but enhanced plant growth. Herbaceous legume Lespedeza sp. formed root nodules with diverse bacterial group, and probably, these bacteria can be used for stimulating plant growth.  相似文献   

12.
The influence of aluminum on the growth and mineral nutrition oftwo ectomycorrhizal fungi, Cantharellus cibarius and Pisolithus sp. was studied in vitro. The mycelial biomass of both fungi decreased as the concentration ofAl increased in the culture medium but C. cibarius wasmore resistant than Pisolithus sp. This growth inhibition was associated with impaired mineral nutrition. Increasing exogenous Al concentration causes Al accumulation in Pisolithus sp., up to 40 mg g-1 dry weight. Aluminum accumulation was much less with C. cibarius.Exogenous Al concentration only poorly affected Ca, Mg, K and P level in Pisolithus sp. whereas C. cibarius accumulated these elements in response to exogenously supplied Al.The acid phosphatase activity of hyphae increased in the presenceof Al in both fungi suggesting a role of these enzymes in Al detoxification. These results are discussed by reference to the possible use of ectomycorrhizal fungi to improve host plant resistance to Al toxicity.  相似文献   

13.
Mycobiota and chemical composition of bleached and non-bleached portions were studied on leaf litter of beech (Fagus crenata Blume). By surface sterilization method, two xylariaceous species Xylaria sp. and Geniculosporium sp.1 were dominantly isolated in both portions. Frequency of occurrence of Xylaria sp. was significantly higher in the bleached portion than in the non-bleached portion. In the bleached portion, lignin concentration was lower than in the non-bleached portion, indicating that Xylaria sp. and Geniculosporium sp.1 took part in lignocellulose decomposition in the study site. Effects of organic chemical quality of litters and exogenous mineral nitrogen (NH4 and NO3) addition were then investigated on in vitro lignin decomposition by Xylaria sp. Weight loss of lignin was significantly related to lignocellulose index (LCI) for four litter types tested. In NH4 and NO3 addition treatments, lignin decomposition was completely and partially suppressed, respectively. Xylaria sp. produced bleaching spots on beech leaf litter in vitro in which lignin concentration was lower than in the non-bleached portion. These results suggest that heterogeneous distribution of carbon and nitrogen resources may control lignin decomposition on the litter by the fungus.  相似文献   

14.
Streptomyces sp. MC1, previously isolated from sugar cane, has shown ability to reduce Cr(VI) in liquid minimal medium and soil samples. The objective of this work was to demonstrate the intracellular chromium accumulation by Streptomyces sp. MC1 under different culture conditions. This strain was able to accumulate up to 3.54 mg of Cr(III) per gram of wet biomass, reducing the 98% of Cr(VI) and removing 13.9% of chromium from the culture medium supernatants. Streptomyces sp. MC1 chromium bioaccumulation ability was corroborated by using Timm’s reagent technique, a low-cost method, which has been used by first time to detect chromium deposits in bacteria. The results of atomic absorption spectrometry, scanning electron microscopy, and energy dispersive X-ray analysis suggest that the mechanism of Cr(VI) resistance observed in Streptomyces sp. MC1 includes adsorption coupled with reduction to Cr(III), and finally, Cr(III) bioaccumulation. This mechanism have special relevance to remediation of Cr(VI) contaminated environments by Streptomyces sp. MC1.  相似文献   

15.
Four strains of bacteria, Rhizobium leguminosarum biovar trifolii, Pseudomonas fluorescens, Pseudomonas cepacia, and Flavobacterium sp., were introduced into loamy sand and then transported by earthworms of the species Lumbricus rubellus to uninoculated soil. Cell densities recovered from the earthworm gut and casts (both expressed per gram dry material) were significantly lower (up to 3 log units) than cell densities recovered from the inoculated soil. Total bacterial counts in casts were similar to those in the inoculated soil. In casts excreted into a sterile environment numbers of colony-forming units (CFU) increased, suggesting a favourable environment for growth. In casts excreted in a non-sterile environment, cell densities of introduced strains decreased. Casts therefore did not offer the introduced bacteria a protective micro-environment for survival in the bulk soil. Transport by worms of R. leguminosarum biovar trifolii and of P. fluorescens appeared to occur mostly by means of cast production; with the Flavobacterium sp. and P. cepacia a large proportion of the cells was possibly transported on the skin of earthworms.  相似文献   

16.
Hydroponics culture generates large amounts of wastewater that are highly concentrated in nitrate and phosphorus but contains almost no organic carbon. Constructed wetlands (CWs) have been proposed to treat this type of effluent, but little is known about the performance of these systems in treating hydroponic wastewater. In addition, obtaining satisfactory winter performances from CWs operated in cold climates remains a challenge, as biological pathways are often slowed down or inhibited. The main objective of this study was to assess the effect of plant species (Typha sp., Phragmites australis, and Phalaris arundinacea) and the addition of organic carbon on nutrient removal in winter. The experimental setup consisted of 16 subsurface flow CW mesocosms (1 m2, HRT of 3 days) fed with 30 L?d1 of synthetic hydroponics wastewater, with half of the mesocosms fed with an additional source of organic carbon (sucrose). Carbon addition had a significant impact on nitrate and phosphate removal, with removal means of 4.9 g m-2?d-1 of NO3-N and 0.5 g m-2 d-1 of PO4-P. Planted mesocosms were generally more efficient than unplanted controls. Furthermore, we found significant differences among plant treatments for NO3-N (highest removal with P. arundinacea) and COD (highest removal with P. australis/Typha sp.). Overall, planted wetlands with added organic carbon represent the best combination to treat hydroponics wastewater during the winter.  相似文献   

17.
This aim of the study is to investigate a halophilic bacterium Hortaea sp. B15, isolated from petroleum-contaminated soil for biodegradation of phenanthrene. Hortaea sp. B15 has the ability to completely degrade phenanthrene (100 mg/L) under salinity 10% within 1-week incubation. The metabolitic product of phenanthrene was identified and assayed by using ultraviolet-visible spectrophotometer and mass spectral analysis. Result revealed that Hortaea sp. B15 metabolized phenanthrene to form 9,10-phenanthrene quinone, salicylic acid, and gentisic acid. Hortaea sp. B15 has an efficient utilization of phenanthrene in high-saline liquid medium. All the results indicated that the fungus has a promising application for the study of high-molecular-weight PAH biodegradation and contaminated saline-alkali soil bioremediation.  相似文献   

18.
A phenanthrene-degrading bacterial strain Pseudomonas sp. GF3 was examined for plant-growth promoting effects and phenanthrene removal in soil artificially contaminated with low and high levels of phenanthrene (0, 100 and 200 mg kg−1) in pot experiments. Low and high phenanthrene treatments significantly decreased the growth of wheat. Inoculation with bacterial strain Pseudomonas sp. GF3 was found to increase root and shoot growth of wheat. Strain GF3 was able to degrade phenanthrene effectively in the unplanted and planted soils. Over a period of 80 days the concentration of phenanthrene in soil in which wheat was grown was significantly lower than in unplanted soil (p<0.05). At the end of the 80-d experiments, 62.2% and 42.3% of phenanthrene had disappeared from planted soils without Pseudomonas sp. GF3 when the phenanthrene was added at 100 and 200 mg kg−1 soil, respectively, but 84.8% and 70.2% of phenanthrene had disappeared from planted soils with the bacterial inoculation. The presence of vegetation significantly enhances the dissipation of phenanthrene in the soil. There was no significant difference in soil polyphenol oxidase activities among the applications of 0, 100 and 200 mg kg−1 of phenanthrene. However, the enzyme activities in planted and unplanted soils inoculated with the strain Pseudomonas sp. GF3 were significantly higher than those of non-inoculation controls. The bacterial isolate was also able to colonize and develop in the rhizosphere soil of wheat after inoculation.  相似文献   

19.
Arthrobacter sp. Sphe3 and Bacillus sphaericus cells were used for Cu(II) biosorption. The effect of contact time, biosorbent dose, equilibrium pH, temperature and the presence of other ions on the efficiency of the process were extensively studied. Optimum pH value and biomass concentration were determined at 5.0 and 1.0?g/l, whereas contact time was found to be 5 and 10?min for Arthrobacter sp. Sphe3 and Bacillus sphaericus biomass, respectively. Equilibrium data fitted very well to Freundlich model (R 2?=?0.996, n?=?2.325, K f?=?8.141) using Arthrobacter sp. Sphe3. In the case of B. sphaericus, a Langmuir adsorption model [R 2?=?0.996, Q max?=?51.54?mg-Cu(II)/g] showed to better describe the results. Potentiometric titration and Fourier transform infrared (FTIR) spectroscopy showed that amine, carboxyl and phosphate groups participate in Cu(II)-binding. The calculated thermodynamic parameters indicated the spontaneous and feasible nature of Cu(II) biosorption on both biosorbents. Selectivity of Cu(II) biosorption was examined in binary and multi-ions systems with various anions and cations which are commonly found in municipal and industrial wastewater. A specificity towards Cu(II) was observed in binary mixtures with Cl-, CO 3 -2 , NO 3 - , SO 4 -2 , PO 4 -3 , Mg+2 and Ca+2, and As(V) with the maximum uptake capacity remaining constant even at high competitive ion??s concentrations of 200?mg/l. Desorption studies showed that Cu(II) could be completely desorbed from Cu(II)-loaded Arthrobacter strain Sphe3 and B. sphaericus biomass using 1.0 and 0.8?M HCl, respectively, and both bacterial species could be effectively reused up to five cycles, making their application in wastewater detoxification more attractive.  相似文献   

20.
Plant growth promoting rhizobacteria (PGPR) has been a focus of research for its potential as an eco-friendly alternative to chemical fertilizers in the agriculture industry. In current study, the effect of culture suspension (CS) of a novel gibberellins (GAs) producing bacterial strain Burkholderia sp. KCTC 11096BP, was observed on shoot length, shoot fresh and dry biomass, root fresh and dry biomass, chlorophyll contents, endogenous bioactive GAs (GA1 and GA4) and their immediate precursors, abscisic acid (ABA), soluble sugar contents and crude protein contents of cucumber (Cucumis sativus L.). We found that growth attributes of cucumber were significantly promoted by the application of CS of Burkholderia sp. KCTC 11096BP. The quantity of GA1 and GA4 and their immediate precursors GA20 and GA9 respectively, were also significantly promoted as compared to their respective controls. Contrary to GAs, the quantity of endogenous free ABA in cucumber leaves was much lower in bacterial CS treated plants. Soluble sugar contents and crude protein contents of cucumber leaves were also significantly higher in bacterial CS treatments as compared to control. It was concluded that Burkholderia sp. KCTC 11096BP can be used as an eco-friendly bio-fertilizer in our farming systems.  相似文献   

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