Effect of environmental parameters on the biodegradation of oil sludge.

A laboratory study was conducted with the aim of evaluating and optimizing the environmental parameters of "landfarming", i.e., the disposal by biodegradation in soil of oily sludges generated in the refining of crude oil and related operations. Oil sludge biodegradation was monitored by CO2 evolution and by periodic analysis of residual hydrocarbons. The parameters studied were soil moisture, pH, mineral nutrients, micronutrients, organic supplements, treatment rate, teratment frequency, and incubation temperature. Oil sludge biodegradation was optimal at a soil water-holding capacity of 30 to 90%, a pH of 7.5 to 7.8, C:N and C:P ratios of 60:1 and 800:1, respectively, and a temperature of 20 degrees C or above. Addition of micronutrients and organic supplements was not beneficial; sewage sludge interfered with hydrocarbon biodegradation. Breakdown of the saturated hydrocarbon (alkane and cycloalkane) fraction was the highest at low application rates, but higher application rates favored the biodegradation of the aromatic and asphaltic fractions. An application rate of 5% (wt/wt) oil sludge hydrocarbon to the soil (100,000 liters/hectare) achieved a good compromise between high biodegradation rates and efficient land use and resulted in the best overall biodegradation rate of all hydrocarbon classes. Frequent small applications resulted in higher biodegradation than single large applications. Two 100,000-liter/hectare (255 barrels per acre) or four 50,000-liter/hectare oil sludge hydrocarbon applications per growing season seem appropriate for most temperate zone disposal sites.     

Nylon biodegradation by lignin-degrading fungi.

The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively.     

Comparison of pyrene biodegradation by white rot fungi

Six strains of white rot fungi, isolated from soil in Korea, were evaluated as to their ability to biodegrade the 4-ring polycyclic aromatic hydrocarbon pyrene. While growing in a complex fungal medium, Irpex lacteus, Trametes versicolor KR11W, and Phanerochaete chrysosporium mineralized 15.6, 12.7 and 7.0% of the added 0.84 nmol of radioactive pyrene, respectively. In these cultures, 33–46% of the added pyrene was converted to water-soluble polar metabolites, and 22–40% was incorporated into fungal biomass. Pleurotus ostreatus mineralized only 2.5% of the added pyrene, while T. versicolor KR65W and Microporus vernicipes failed to evolve ¹⁴CO₂ from pyrene. The information obtained aids in strain selection for clean-up of polycyclic aromatic hydrocarbon contamination.     

白腐真菌对酸性橙7的脱色降解

偶氮染料广泛应用于纺织、造纸和包装等行业,因其具有三致性、结构稳定且难降解,已成为染料废水处理的研究热点之一。本研究以白腐真菌作为脱色菌株,考察了不同白腐真菌对偶氮类染料酸性橙7(acid orange 7,AO7)的脱色降解,探讨了AO7染料的浓度、pH、温度以及脱色时间对染料脱色率的影响,同时应用紫外-可见光谱吸收法、红外光谱吸收法、高效液相色谱法和气相色谱-质谱法对AO7的降解产物进行分析,并对其产物进行植物毒性实验,以推断AO7可能的降解途径及其降解产物的毒性。结果表明:在pH 4.5、28℃条件下,刺芹侧耳(Pleurotus eryngii)和杂色云芝(Trametes versicolor)的混合菌丝脱色降解100 mg/L AO7,24 h脱色率可达93.46%。推测AO7可能的生物降解途径:AO7偶氮键断裂生成对氨基苯磺酸和1-氨基-2-萘酚;接着对氨基苯磺酸脱去磺酸基,生成对苯二酚;同时1-氨基-2-萘酚开环生成邻苯二甲酸和对羟基苯甲醛,之后进一步降解生成苯甲酸;最后对苯二酚和苯甲酸继续氧化成其他小分子中间体、H2O和CO_(2)。植物毒性实验表明,P.eryngii和T.versicolor混合菌丝对AO7脱毒效果较好。以上研究为探究白腐真菌在工业废水中降解偶氮类染料的应用奠定基础。     

Optimization of environmental parameters for biodegradation of alpha and beta endosulfan in soil slurry by Pseudomonas aeruginosa

Aim: To determine optimal environmental conditions for achieving biodegradation of α‐ and β‐endosulfan in soil slurries following inoculation with an endosulfan degrading strain of Pseudomonas aeruginosa. Methods and Results: Parameters that were investigated included soil texture, soil slurry: water ratios, initial inoculum size, pH, incubation temperature, aeration, and the use of exogenous sources of organic and amino acids. The results showed that endosulfan degradation was most effectively achieved at an initial inoculum size of 600 μl (OD = 0·86), incubation temperature of 30°C, in aerated slurries at pH 8, in loam soil. Under these conditions, the bacterium removed more than 85% of spiked α‐ and β‐endosulfan (100 mg l^?1) after 16 days. Abiotic degradation in noninoculated control medium within same incubation period was about 16%. Biodegradation of endosulfan varied in different textured soils, being more rapid in course textured soil than in fine textured soil. Increasing the soil contents in the slurry above 15% resulted in less biodegradation of endosulfan. Exogenous application of organic acids (citric acid and acetic acid) and amino acids (l ‐methionine and l ‐cystein) had stimulatory and inhibitory effects, respectively, on biodegradation of endosulfan. Conclusion: The results of this study demonstrated that biodegradation of endosulfan by Ps. aeruginosa in soil sediments enhanced significantly under optimized environmental conditions. Significance and Impact of the Study: Endosulfan is a commonly used pesticide that can contaminate soil, wetlands and groundwater. Our study demonstrates that bioaugmentation of contaminated soils with an endosulfan degrading bacterium under optimized conditions provides an effective bioremediation strategy.     

不同碳源对三种溶磷真菌溶解磷矿粉能力的影响

通过液体培养法 ,对 3种溶磷真菌利用葡萄糖、果糖、蔗糖、麦芽糖、淀粉和纤维素等碳源溶解宜昌产磷矿粉的试验 ,结果表明 ,菌株P2 3在供给葡萄糖时的溶磷能力最高 ,并在一定程度上能够利用长链碳源淀粉和纤维素为营养而溶磷 ;而高效溶磷菌株P6 6和P39溶磷的最佳碳源是果糖和麦芽糖 ,该两菌株利用淀粉和纤维素的溶磷效果很小 ,甚至不溶磷。 3种溶磷真菌培养滤液 pH值、可滴定酸含量与其溶磷量之间的相关性因菌株而异 ,差别很大。菌株P2 3培养滤液pH值、可滴定酸含量与其溶磷量之间相关性很低 ,但菌株P6 6和P39培养滤液pH值、可滴定酸含量与其溶磷量之间相关性却达到极显著水平 (P <0 0 1)。结果表明 ,不同碳源对溶磷菌溶解磷矿粉能力影响很大 ,分析推断 3种菌株产生的有机酸活化磷矿粉能力为P6 6>P39>P2 3。     

Effect of electrode configurations on phytoremediation efficiency and environmental risk

Plant and Soil - Some experiments were designed to evaluate the influences of field directions and voltages on the remediation efficiency and environmental risk during the chelator assisted...     

Effect of operational parameters on Coulombic efficiency in bioelectrochemical systems

To create an efficient bioelectrochemical system, a high Coulombic efficiency is required. This efficiency is a direct measure for the competition between electrogens and methanogens when acetate is used as substrate. In this study the Coulombic efficiency in a microbial electrolysis cell was investigated. As a result of an increase in substrate concentration from 1 to 35 mM, the current density increased to 21.1A/m(2), while the Coulombic efficiency decreased to 52%. As a result of an increase in anode potential from -450 to -0.250 mV, the current density increased to 20.9A/m(2), while the Coulombic efficiency increased 21%. Knowledge about the substrate affinity and growth kinetics is crucial to control the Coulombic efficiency. Further research is required to optimize strategies to find a balance between the Coulombic efficiency, current density and removal rate of organic material.     

Effect of some environmental parameters on fermentative hydrogen production by Enterobacter cloacae DM11

Fermentative hydrogen production was carried out by Enterobacter cloacae DM11, using glucose as the substrate. The effects of initial substrate concentration, initial medium pH, and temperature were investigated. Results showed that at an initial glucose concentration of 1.0% (m/v), the molar yield of hydrogen was 3.31 mol (mol glucose)(-1). However, at higher initial glucose concentration, both the rate and cumulative volume of hydrogen production decreased. The pH of 6.5 +/- 0.2 at a temperature of 37 degrees C was found most suitable with respect to maximum rate of production of hydrogen in batch fermentation. Activation enthalpies of fermentation and that of thermal deactivation of the present process were estimated following a modified Arrhenius equation. The values were 47.34 and 118.67 kJ mol(-1) K(-1), respectively. The effect of the addition of Fe(2+) on hydrogen production was also studied. It revealed that the presence of iron (Fe(2+)) in the media up to a concentration of 20 mg L(-1) had a marginal enhancing effect on total hydrogen production. A simple model developed from the modified Gompertz equation was applied to estimate the hydrogen production potential, production rate, and lag-phase time in a batch process, based on the cumulative hydrogen production curves, using the software program Curve Expert 1.3.     

Effect of some operational parameters on textile dye biodegradation in a sequential batch reactor

The combination of anaerobic and aerobic periods in the operation cycle of a Sequencing Batch Reactor (SBR) was chosen to study biological color removal from simulated textile effluents containing reactive, sulfonated, monoazo and diazo dyes, respectively, Remazol Brilliant Violet 5R and Remazol Black B. 90% color removal was obtained for the violet dye in a 24-h cycle with a Sludge Retention Time (SRT) of 15 days and an aerated reaction phase of 10 h. For the black dye only 75% color removal was achieved with the same operational conditions and no improvement was observed with the increase of the SRT to 20 days. For the violet dye a reduction of the color removal values from 90 to 75% was observed with the increase of the aerated reaction phase from 10 to 12 h. However, this increase did not promote the aerobic biodegradation of the produced aromatic amines. Abiotic tests were performed with sterilized SBR samples and no color removal was observed in cell-free supernatants. However color removal values of 30 and 12% were observed in the presence of sterilized cells and supernatants with violet and black dye, respectively and could be attributed to the presence of active reducing principles in the sterilized samples.     

Effect of several environmental parameters on carbon metabolism in histosols

High specific activity¹⁴C-labeled glucose, succinate, acetate, salicylate, and amino acids were used to examine carbon metabolism by the microbial community of Pahokee muck (aLithic medisaprist), a drained, cultivated soil of the Florida Everglades. Variations in carbon oxidation were observed from the end of the wet season through the dry season in a fallow (bare) field. Evolution of¹⁴CO₂ varied with the substrate added and time. Calculation of¹⁴CO₂ evolution for each substrate as a proportion of total respiration of the microbial community which was measured by succinate oxidation (relative oxidation) allowed for determination of the proportion of metabolic activity contributed by the oxidation of each carbon source. Except for the May sample when an approximate 30% decline in relative salicylate oxidation activity was observed, the proportion of total catabolic activity contributed by salicylate oxidation and acetate degradation was constant with time. Relative oxidation of glucose and amino acids ranged from 0.12 to 0.52 and 0.10 to 0.23, respectively. At two times during the dry season, the effect of depth of soil and crop on the carbon oxidation was examined. Relative acetate and amino acid oxidation were constant with depth whereas statistically significant variation was observed in glucose and salicylate oxidation. Generally, with the latter substrates, the activity declined with increased soil depth. Greatest effect of crop on these metabolic activities was noted with oxidation of salicylate in soils from a St. Augustinegrass [Stenatophrum secundatum (Walt.) Kuntz] pasture. In these soils, oxidation of salicylate was nearly double that of the fallow field or of soil planted with sugarcane (Saccharum sp.).     

A viscometric study of the biodegradation of photographic gelatin by fungi isolated from cinematographic films

The biodegradation of photographic gelatin grade (Bloom 225) material was studied by viscometry in aqueous solution (at 37 °C, 6.67% w/w) using filamentous fungi isolated and identified from cinematographic film stored in different Spanish archives. From viscosity data, different variables such as molecular weight and chain scission were calculated. To ensure initial spore suspension concentration was standardized for all the biodegradation experiments, a correlation between transmittance at 530 nm of fungal spore suspensions and the corresponding cytometric determination of populations was established for all the fungal strains studied in this work. The bioassay experiments were carried out at 25 and 4 °C using an initial concentration of fungi of 4.5×10⁵ conidia/mL except in the case of the genus Alternaria, where the concentration was 10 times lower. The fungal strains were three species of Aspergillus, i.e., A .ustus, A. nidulans var. nidulans, A. versicolor, seven Penicillium chrysogenum strains, and Cladosporium cladosporioides, Alternaria alternata, Mucor racemosus, Phoma glomerata, and Trichoderma longibrachiatum. All were gelatinase positive. Through the viscosity decay profiles with bioassay-time and the corresponding calculated chain scission, the relative quantitative gelatinase efficiency of these fungi has been evaluated.     

A viscometric study of the biodegradation of photographic gelatin by fungi isolated from cinematographic films

The biodegradation of photographic gelatin grade (Bloom 225) material was studied by viscometry in aqueous solution (at 37 °C, 6.67% w/w) using filamentous fungi isolated and identified from cinematographic film stored in different Spanish archives. From viscosity data, different variables such as molecular weight and chain scission were calculated. To ensure initial spore suspension concentration was standardized for all the biodegradation experiments, a correlation between transmittance at 530 nm of fungal spore suspensions and the corresponding cytometric determination of populations was established for all the fungal strains studied in this work. The bioassay experiments were carried out at 25 and 4 °C using an initial concentration of fungi of 4.5×10⁵ conidia/mL except in the case of the genus Alternaria, where the concentration was 10 times lower. The fungal strains were three species of Aspergillus, i.e., A .ustus, A. nidulans var. nidulans, A. versicolor, seven Penicillium chrysogenum strains, and Cladosporium cladosporioides, Alternaria alternata, Mucor racemosus, Phoma glomerata, and Trichoderma longibrachiatum. All were gelatinase positive. Through the viscosity decay profiles with bioassay-time and the corresponding calculated chain scission, the relative quantitative gelatinase efficiency of these fungi has been evaluated.     

Effect of catabolic plasmids on physiological parameters and efficiency of oil destruction by Pseudomonas bacteria

The ability of microbial degraders of polycyclic aromatic hydrocarbons to grow at 24°C in liquid mineral medium supplemented with oil as the sole source of carbon and energy was studied. Growth characteristics (CFU) and the level of oil destruction by plasmid-bearing and plasmid-free strains were determined after seven days of cultivation. The presence of catabolic plasmids in the degrader strains, including rhizosphere pseudomonads, was shown to increase cell growth and enhance the level of oil degradation. Strain Pseudomonas chlororaphis BS1391 bearing plasmid pBS216 was found to be the most effective oil degrader.     

Effect of beta-carotene accumulation on spectral parameters of microscopic fungi Blakeslea trispora biomass

Parameters of reflectance spectra in visible region and colorimetry for Blakeslea trispora biomass with different content of beta-carotene were determined. Correlation level of pigment accumulation and spectral characteristics were revealed. It is established, that objective control of color characteristics for biomass is possible using measurement of colorimetric parameters.     

Effect of catabolic plasmids on physiological parameters and efficiency of oil destruction by bacteria of the genus Pseudomonas

The ability of microbial degraders of polycyclic aromatic hydrocarbons to grow at 24 degrees C in liquid mineral medium supplemented with oil as the sole source of carbon and energy was studied. Growth characteristics (CFU) and the level of oil destruction by plasmid-bearing and plasmid-free strains were determined after seven days of cultivation. The presence of catabolic plasmids in the degrader strains, including rhizosphere pseudomonads, was shown to increase cell growth and enhance the level of oil degradation. Strain Pseudomonas chlororaphis BS 1391 bearing plasmid pBS216 was found to be the most effective oil degrader.     

Effect of phosphate-solubilizing bacteria and vesicular-arbuscular mycorrhizal fungi on the utilization of Bayovar rock phosphate by alfalfa plants using a sand-vermiculite medium

Phosphate-solubilizing bacteria (PSB) exhibited a high efficiency to improve plant growth and nutrition in the presence of Bayovar rock phosphate when sand-vermiculive was used as a culture medium. Treatments with dual inoculum (PSB plus mycorrhiza) significantly (P≤0.05) increased alfalfa growth. Bacteria-microbial fungi interactions resulted in a greater utilization of the rock phosphate added to the rooting medium. Although Bayovar rock phosphateper se can be considered an inert substrate because it did not stimulate plant growth, metabolites released by PSB were able to transform the rock into available forms which could be utilized by alfalfa plants.Glomus fasciculatum was the most efficient mycorrhizal endophyte under the experimental conditions employed.     

The effect of rock composition on cyanobacterial weathering of crystalline basalt and rhyolite

The weathering of volcanic rocks contributes significantly to the global silicate weathering budget, effecting carbon dioxide drawdown and long‐term climate control. The rate of chemical weathering is influenced by the composition of the rock. Rock‐dwelling micro‐organisms are known to play a role in changing the rate of weathering reactions; however, the influence of rock composition on bio‐weathering is unknown. Cyanobacteria are known to be a ubiquitous surface taxon in volcanic rocks. In this study, we used a selection of fast and slow growing cyanobacterial species to compare microbial‐mediated weathering of bulk crystalline rocks of basaltic and rhyolitic composition, under batch conditions. Cyanobacterial growth caused an increase in the pH of the medium and an acceleration of rock dissolution compared to the abiotic controls. For example, Anabaena cylindrica increased the linear release rate () of Ca, Mg, Si and K from the basalt by more than fivefold (5.21–12.48) and increased the pH of the medium by 1.9 units. Although A. cylindrica enhanced rhyolite weathering, the increase in was less than threefold (2.04–2.97) and the pH increase was only 0.83 units. The values obtained with A. cylindrica were at least ninefold greater with the basalt than the rhyolite, whereas in the abiotic controls, the difference was less than fivefold. Factors accounting for the slower rate of rhyolite weathering and lower biomass achieved are likely to include the higher content of quartz, which has a low rate of weathering and lower concentrations of bio‐essential elements, such as, Ca, Fe and Mg, which are known to be important in controlling cyanobacterial growth. We show that at conditions where weathering is favoured, biota can enhance the difference between low and high Si‐rock weathering. Our data show that cyanobacteria can play a significant role in enhancing rock weathering and likely have done since they evolved on the early Earth.