Performance of a hybrid anaerobic reactor,combining a sludge blanket and a filter,treating slaughterhouse wastewater

A column reactor, in which the bottom two-thirds were occupied by a sludge blanket and the upper one-third by submerged clay rings, was evaluated using slaughterhouse wastewater as substrate. The reactor was operated at 35°C at loading rates varying from 5 g to 45 g chemical oxygen demand (COD) 1^–1 × day^–1 at an influent concentration of 2450 mg COD 1^–1. A maximum substrate removal rate of 32 g COD 1^–1 × day^–1, coupled with a methane production rate of 6.91 × 1^–1 × day^–1 (STP), was obtained. This removal rate is significantly higher than those previously reported. The rate of substrate utilization by the biomass was 1.22 g COD (g volatile suspended solids)^–1 day^–1. COD removal was over 96% with loading rates up to 25 g COD 1^–1 × day^–1, at higher loading rates performance decreased rapidly. It was found that the filter element of the reactor was highly efficient in retaining biomass, leading to a biomass accumulation yield coefficient of 0.029 g volatile suspended solids g^–1 COD, higher than reported previously for either upflow anaerobic sludge-blanket reactors or anaerobic filters operating independently.     

Influence of a Small Number of Mature T Cells in Donor Bone Marrow Inocula on Reconstitution of Lymphoid Tissues and Negative Selection of a T Cell Repertoire in the Recipient

Allo-chimerism and clonal elimination of self antigen (Ag) (Ia + Mls-1^a) reactive Vβ6+ T cells were analyzed and compared between allogeneic bone marrow (BM) chimeras reconstituted with BM cells which had been treated with anti-Thy-1 monoclonal antibody (mAb) plus complement (C) (T^– chimeras) and BM chimeras which had been reconstituted with BM cells pretreated with anti-Thy-1 mAb alone (T⁺ chimeras). When lethally irradiated AKR (Mls-1^a) mice were reconstituted with BM cells from B10 or B10 H-2 congenic mice, both T⁺ and T^– chimeras were entirely free of signs of graft-versus-host reaction (GVHR). However, complete replacement of the AKR lymphoid tissues by donor BM cells was accomplished at an early stage in T⁺ chimeras but not in T^– chimeras. On the other hand, clonal elimination of Vβ6⁺ T cells reactive to the recipient Ag (Mls-1^a) was abolished in T⁺ chimeras but successfully induced in T^– chimeras. The Vβ6⁺ T cells not eliminated in T⁺ chimeras showed depressed responses against Mls-1^a antigens. The findings herein demonstrate that T cells which contaminate a BM inoculum survive in recipient mice after treatment with anti-Thy-1 mAb without C in vitro followed by BMT. The surviving T cells have been estimated to represent fewer than 0.5% of the BM cells inoculated. These cells appear to accelerate the full replacement of recipient lymphoid tissues by donor cells. Furthermore, the T cells which survive in the marrow inoculum influence eventually the development of a tolerant state in the T cell repertoire of the donor.     

Respirable powder formulation of a shortened vasoactive intestinal peptide analog for treatment of airway inflammatory diseases

The aim of present study was to develop a respirable powder (RP) of a shortened vasoactive intestinal peptide (VIP) analog for inhalation. VIP and C‐terminally truncated VIP analogs were synthesized with a solid‐phase method. A structure‐activity relationship (SAR) study was carried out in terms with binding and relaxant activities of the peptides. Prepared RP formulation of a shortened VIP analog was physicochemically characterized by morphological, in vitro aerodynamic, and pharmacological assessments. The SAR study demonstrated that the N‐terminal 23 amino acid residues were required for biological activity of VIP. Upon chemical modification of VIP(1–23), [R^{15, 20, 21}, L¹⁷]‐VIP(1–23) was newly developed, which had higher binding activity in rat lung and smooth muscle relaxant effect in mouse stomach than VIP(1–23). The [R^{15, 20, 21}, L¹⁷]‐VIP(1–23)‐based RP, [R^{15, 20, 21}, L¹⁷]‐VIP(1–23)/RP, exhibited fine in vitro inhalation performance. Airway inflammation evoked by sensitization of antigen in rats was attenuated by pre‐treatment with the [R^{15, 20, 21}, L¹⁷]‐VIP(1–23)/RP at a dose of 50 μg‐[R^{15, 20, 21}, L¹⁷]‐VIP(1–23)/rat as evidenced by a 70% reduction of recruited inflammatory cells in bronchoalveolar lavage fluid. On the basis of these results, [R^{15, 20, 21}, L¹⁷]‐VIP(1–23)/RP might be a promising agent for treatment of airway inflammatory diseases.     

Reconstitution and Characterization of a Calmodulin-Stimulated Ca-Pumping ATPase Purified from Brassica oleracea L

Purification and functional reconstitution of a calmodulin-stimulated Ca²⁺-ATPase from cauliflower (Brassica oleracea L.) is described. Activity was purified about 120-fold from a microsomal fraction using calmodulin-affinity chromatography. The purified fraction showed a polypeptide at 115 kD, which formed a phosphorylated intermediate in the presence of Ca²⁺, together with a few polypeptides with lower molecular masses that were not phosphorylated. The ATPase was reconstituted into liposomes by 3-([cholamidopropyl]-dimethylammonio-)1-propanesulfonate (CHAPS) dialysis. The proteoliposomes showed ATP-dependent Ca²⁺ uptake and ATPase activity, both of which were stimulated about 4-fold by calmodulin. Specific ATPase activity was about 5 μmol min⁻¹ (mg protein)⁻¹, and the Ca²⁺/ATP ratio was 0.1 to 0.5 when the ATPase was reconstituted with entrapped oxalate. The purified, reconstituted Ca²⁺-ATPase was inhibited by vanadate and erythrosin B, but not by cyclopiazonic acid and thapsigargin. Activity was supported by ATP (100%) and GTP (50%) and had a pH optimum of about 7.0. The effect of monovalent and divalent cations (including Ca²⁺) on activity is described. Assay of membranes purified by two-phase partitioning indicated that approximately 95% of the activity was associated with intracellular membranes, but only about 5% with plasma membranes. Sucrose gradient centrifugation suggests that the endoplasmic reticulum is the major cellular location of calmodulin-stimulated Ca²⁺-pumping ATPase in Brassica oleracea inflorescences.     

Seedling bank dynamics of Fagus grandifolia var. mexicana before and after a mast year in a Mexican cloud forest

Abstract. Fagus grandifolia var. mexicana seedling dynamics were studied in a relict forest inside the crater of a volcano where it is the only canopy tree species. The objectives of the study were (1) to determine changes in seedling density before and after a mast year, as well as to monitor seedling recruitment, mortality and growth rate in relation to the micro‐environment, and (2) to discuss the impact of masting on seedling dynamics of the population. Before masting, seedling density was 8.8 seedlings m^–2, afterwards seedling density peaked at 51.5 seedlings m^–2, then decreased by 50% in 3 months and by 85% after 8 months, down to levels of before the mast year (9.9 seedlings m^–2) after 16 months. Seedlings in the forest floor before the mast‐seeding event showed a low relative growth rate – 0.14 mm mm^–1 mo^–1 against 1.27 mm mm^–1 mo^–1 for seedlings that emerged immediately after masting. Seed germination was high (83%) and rapid (L₅₀= 7 days) following masting. Seedling growth was positively correlated with soil water content but not with temperatures and relative humidity. Data suggested that seed production in mast years is important in maintaining the seedling bank, and thus the viability of relict Fagus populations.     

Assessment of the biodegradability of a monosulfonated azo dye and aromatic amines

Biodecolourisation of an azo dye by anaerobic cultures using a liposomal textile levelling agent as primary substrate was assessed. Liposomes seem to facilitate the uptake of the dye (Acid Orange 7) by anaerobic biomass, leading to a fast decolourisation (colour removal of 96% was achieved in the first sample port of the reactor profiles). On the other hand, the presence of dye (60–300 mg l⁻¹) caused a decrease in the chemical oxygen demand (COD) degradation rate (4.1–2.5 g COD removed l⁻¹ d⁻¹ for 60 and 300 mg l⁻¹ of dye, respectively), suggesting inhibitory effects.Aerobic degradation of aromatic amines was investigated in aerobic respirometric assays with different types of inocula. Sulfanilic acid and aniline were mineralised by inocula with a significant microbiological diversity, even with domestic effluent. These results were confirmed by a significant reduction of COD, total organic carbon (TOC) and a high oxygen consumption (biochemical oxygen demand/theoretical oxygen demand), 92±4%. Kinetic analysis showed that a sigmoid function describes quite well the experimental data, even better than the exponential model. Orthanilic and metanilic acids and 1-amino-2-naphtol were persistent under the tested conditions.     

Allocation of carbon in a mature eucalypt forest and some effects of soil phosphorus availability

Pools and annual fluxes of carbon (C) were estimated for a mature Eucalyptus pauciflora (snowgum) forest with and without phosphorus (P) fertilizer addition to determine the effect of soil P availability on allocation of C in the stand. Aboveground biomass was estimated from allometric equations relating stem and branch diameters of individual trees to their biomass. Biomass production was calculated from annual increments in tree diameters and measurements of litterfall. Maintenance and construction respiration were calculated for each component using equations given by Ryan (1991a). Total belowground C flux was estimated from measurements of annual soil CO₂ efflux less the C content of annual litterfall (assuming forest floor and soil C were at approximate steady state for the year that soil CO₂ efflux was measured). The total C content of the standing biomass of the unfertilized stand was 138 t ha^-1, with approximately 80% aboveground and 20% belowground. Forest floor C was 8.5 t ha^-1. Soil C content (0–1 m) was 369 t ha^-1 representing 70% of the total C pool in the ecosystem. Total gross annual C flux aboveground (biomass increment plus litterfall plus respiration) was 11.9 t ha^-1 and gross flux belowground (coarse root increment plus fine root production plus root respiration) was 5.1 t ha^-1. Total annual soil efflux was 7.1 t ha^-1, of which 2.5 t ha^-1 (35%) was contributed by litter decomposition.The short-term effect of changing the availability of P compared with C on allocation to aboveground versus belowground processes was estimated by comparing fertilized and unfertilized stands during the year after treatment. In the P-fertilized stand annual wood biomass increment increased by 30%, there was no evidence of change in canopy biomass, and belowground C allocation decreased by 19% relative to the unfertilized stand. Total annual C flux was 16.97 and 16.75 t ha^-1 yr^-1 and the ratio of below- to aboveground C allocation was 0.43 and 0.35 in the unfertilized and P-fertilized stands, respectively. Therefore, the major response of the forest stand to increased soil P availability appeared to be a shift in C allocation; with little change in total productivity. These results emphasise that both growth rate and allocation need to be estimated to predict changes in fluxes and storage of C in forests that may occur in response to disturbance or climate change.     

Physiological properties of Cellulomonas fermentans,a mesophilic cellulolytic bacterium

Summary The fermentation of cellobiose, glucose and cellulose MN 300 by Cellulomonas fermentans was studied. The molar growth yields (i.e. grams of cells per mole of hexose equivalent) were similar on cellobiose and cellulose at low sugar consumption levels (47.8 and 46.5 respectively), but was lower on glucose (38.0). The occurrence of cellobiose phosphorylase activity, detected in cellobiose- and cellulose-grown cells, might explain this result. The specific growth rates measured in cultures on cellobiose, glucose and cellulose were 0.055 h^-1, 0.040 h^-1 and 0.013 h^-1 respectively. Growth inhibition was observed, and a drop in Y_H occurred after relatively low but different quantities of hexose were consumed (2.2 mM, 5 mM and 8 mM hexose equivalent with cellulose, glucose and cellobiose respectively), which coincided with a change in the fermentative metabolism from a typical mixed acid metabolism (1 ethanol, 1 acetate and 2 formate synthesized by consumed hexose) to a more ethanolic fermentation. When growth ceased in cellulose cultures, consumption of cellulose continued, as did production of ethanol.Molar growth yields of C. fermentans were similar in anaerobic and aerobic cellobiose cultures (47.8 g/mol and 42.2 g/mol respectively). Specific growth rates were also quite similar under both culture conditions (0.055±0.013 h^-1 and 0.070±0.007 h^-1 respectively). Aerobic metabolism was studied using ¹⁴C glucose. During the exponential growth phase, acetate, succinate and nonidentified compound(s) accumulated in the supernatant, but no ¹⁴CO₂ was produced. During the stationary phase, acetate was oxidized and ¹⁴CO₂ produced, but without any further biomass synthesis. It seems that a blocking of metabolite oxidation may have occurred in C. fermentans except in the case of acetate, but acetate oxidation was apparently not coupled with production of energy utilizable in biosynthesis.     

Performance of a thermophilic sulfate and sulfite reducing high rate anaerobic reactor fed with methanol

Thermophilic sulfate and sulfite reduction was studied in lab-scale Expanded Granular Sludge Bed (EGSB) reactors operated at 65°C and pH 7.5 with methanol as the sole carbon and energy source for the sulfate- and sulfite-reducing bacteria. At a hydraulic retention time (HRT) of 10 h, maximum sulfite and sulfate elimination rates of 5.5 gSO₃ ^2- L^-1 day^-1 (100 % elimination) and 5.7 gSO₄ ^{2- -1} day^-1 (55% elimination) were achieved, resulting in an effluent sulfide concentration of approximately 1800 mgS L^-1. Sulfate elimination was limited by the sulfide concentration, as stripping of H₂S from the reactor with nitrogen gas was found to increase the sulfate elimination rate to 9.9 gSO₄ ^2- L^-1 day^-1 (100 % elimination). At a HRT of 3 h, maximum achievable sulfite and sulfate elimination rates were even 18 gSO₃ ^2- L^-1 day^-1 (100% elimination) and 11 gSO₄ ^2- L^-1 day^-1(50% elimination). At a HRT of 3 h, the elimination rate was limited by the biomass retention of the system. 5.5 ± 1.8% of the consumed methanol was converted to acetate, which was not further degraded by sulfate reducing bacteria present in the sludge. The acetotrophic activity of the sludge could not be stimulated by cultivating the sludge for 30 days under methanol-limiting conditions. Omitting cobalt as trace element from the influent resulted in a lower acetate production rate, but it also led to a lower sulfate reduction rate. Sulfate degradation in the reactor could be described by zeroth order kinetics down to a threshold concentration of 0.05 g L^-1, while methanol degradation followed Michaelis-Menten kinetics with a K_m of 0.037 gCOD L^-1.     

Biofiltration of waste gases containing a mixture of formaldehyde and methanol

Several biofilters and biotrickling filters were used for the treatment of a mixture of formaldehyde and methanol; and their efficiencies were compared. Results obtained with three different inert filter bed materials (lava rock, perlite, activated carbon) suggested that the packing material had only little influence on the performance. The best results were obtained in a biotrickling filter packed with lava rock and fed a nutrient solution that was renewed weekly. A maximum formaldehyde elimination capacity of 180 g m^–3 h^–1 was reached, while the methanol elimination capacity rose occasionally to more than 600 g m^–3 h^–1. Formaldehyde degradation was affected by the inlet methanol concentration. Several combinations of load vs empty bed residence time (EBRTs of 71.9, 46.5, 30.0, 20.7 s) were studied, reaching a formaldehyde elimination capacity of 112 g m^–3 h^–1 with about 80% removal efficiency at the lowest EBRT (20.7 s).     

Identification of a cadmium-binding protein from a cadmium-resistant variant of human lymphoblastoid cells (WI-L2)

Cadmium-binding protein synthesis and induction by cadmium chloride were studied in the human lymphoblastoid cell line WI-L2. Lymphoblasts were adapted to growth in 5 μM cadmium chloride (Cd^r) and these cells were 2.5-fold more resistant to cadmium than the parental line. There was no difference in the cellular protein profile between the parental line and lymphoblasts grown for a short period, less than 10 days, in cadmium chloride as measured by [³⁵S]cysteine labelling and SDS-polyacrylamide gel electrophoresis. A basal level of cadmium binding protein was apparent, however, by gel filtration. The Cd^r lymphoblasts were found to synthesize a substantial amount of cadmium-binding protein, approximately 25-fold more than the parental line. The cadmium-binding protein has the following properties which are consistent with its being a metallothionein: (1) [³⁵S]Cysteine-labelled protein eluted at a on a Sephadex G-75 column; (2) the molecular weight was estimated as 11 kDa on 7–17% SDS polyacrylamide gels; (3) the protein was heat-stable; (4) the unlabelled protein bound ¹⁰⁹Cd²⁺.     

Prodigiosin formation by Serratia marcescens in a chemostat

In a study of the control of metabolite formation, prodigiosin production by Serratia marcescens was used as a model. Specific production rates of prodigiosin formation were determined using batch culture technique. Sucrose as carbon source and NH₄NO₃ as nitrogen source resulted in a specific production rate of 0.476 mg prodigiosin (g cell dry weight)⁻¹ h⁻¹. Prodigiosin formation and productivity was inversely correlated to growth rate when the bacterium was grown under carbon limitation on a defined medium in a chemostat culture. The maximum specific growth rate (μ_max) was 0.54 h⁻¹ and prodigiosin was formed in amounts over 1 mg l⁻¹ up to a growth rate (μ) of 0.3 h⁻¹ at steady state conditions. At a dilution rate of 0.1 h⁻¹ growth at steady state with carbon and phosphate limitation supported prodigiosin formation giving a similar specific yield [1.17 mg prodigiosin (g cell dry weight)⁻¹ and 0.94 mg g⁻¹, respectively], however, cells grown with nitrogen limitation [(NH₄)₂SO₄] did not form prodigiosin. Productivity in batch culture was 1.33 mg l⁻¹ h⁻¹ as compared to 0.57 mg l⁻¹ h⁻¹ in the chemostat.     

Structure of a Double Transmembrane Fragment of a G-Protein-Coupled Receptor in Micelles

The structure and dynamic properties of an 80-residue fragment of Ste2p, the G-protein-coupled receptor for α-factor of Saccharomyces cerevisiae, was studied in LPPG micelles with the use of solution NMR spectroscopy. The fragment Ste2p(G31-T110) (TM1-TM2) consisted of 19 residues from the N-terminal domain, the first TM helix (TM1), the first cytoplasmic loop, the second TM helix (TM2), and seven residues from the first extracellular loop. Multidimensional NMR experiments on [¹⁵N], [¹⁵N, ¹³C], [¹⁵N, ¹³C, ²H]-labeled TM1-TM2 and on protein fragments selectively labeled at specific amino acid residues or protonated at selected methyl groups resulted in >95% assignment of backbone and side-chain nuclei. The NMR investigation revealed the secondary structure of specific residues of TM1-TM2. TALOS constraints and NOE connectivities were used to calculate a structure for TM1-TM2 that was highlighted by the presence of three α-helices encompassing residues 39-47, 49-72, and 80-103, with higher flexibility around the internal Arg⁵⁸ site of TM1. RMSD values of individually superimposed helical segments 39-47, 49-72, and 80-103 were 0.25 ± 0.10 Å, 0.40 ± 0.13 Å, and 0.57 ± 0.19 Å, respectively. Several long-range interhelical connectivities supported the folding of TM1-TM2 into a tertiary structure typified by a crossed helix that splays apart toward the extracellular regions and contains considerable flexibility in the G⁵⁶VRSG⁶⁰ region. ¹⁵N-relaxation and hydrogen-deuterium exchange data support a stable fold for the TM parts of TM1-TM2, whereas the solvent-exposed segments are more flexible. The NMR structure is consistent with the results of biochemical experiments that identified the ligand-binding site within this region of the receptor.     

Identification of a rabbit B cell alloantigen with an antiserum produced by alloimmunization with thymus cells.

Alloimmunization with rabbit thymus cells resulted in an antiserum (anti-Rly) which was shown to react with rabbit lymphocytes by an indirect rosette technique. The titration curve obtained with dilutions of anti-Rly antiserum on lymph node cells revealed two plateaus indicating that the antiserum was multispecific; at low dilutions of antiserum, within the first plateau, both B and T cells were rosetted whereas at high dilutions, within the second plateau, only B cells were rosetted. The antigen detected at high dilution was designated LB-1 (lymphocyte B cell alloantigen 1). The evidence that the cells identified within the second plateau are B cells is as follows: 1) simultaneous enumeration of LB-1⁺ and Ig⁺ (B) cells by use of distinguishable erythrocytes (sheep and human) as indicator cells revealed that of the 53% rosettes observed, essentially all (51%) were mixed rosettes containing both erythrocytes whereas simultaneous enumeration of LB-1⁺ and T⁺ cells (identified by anti-T cell antiserum) showed essentially no mixed rosettes (less than 2%); 2) approximately 80% of purified Ig⁺ (B) cells were identified as LB-1⁺ cells whereas essentially no (< 1%) purified T cells could be detected as LB-1⁺; 3) the percentages of LB-1⁺ cells and Ig⁺ cells were both reciprocal to the precentages of T⁺ cells identified in various lymphoid organs except for bone marrow; 4) the removal of LB-1⁺ cells from spleen cells of rabbits immunized with sheep red blood cells resulted in a depletion (42–71%) of direct plaque forming cells (PFC). Since the percentages of bone marrow cells rosetted using anti-LB-1 antiserum (approximately 70%) was much greater than the percentage rosetted using anti-Ig (approximately 10%), it appears that the anti-LB-1 antiserum is not directed against an Ig allotype. The titration curves of the anti-Rly antiserum on peripheral blood lymphocytes of a large rabbit family suggested that the LB-1 antigen on B cells is an alloantigen probably inherited in simple Mendelian fashion. Adsorption studies indicated that the LB-1 antigen on B cells is not detectable on brain, liver, kidney or erythrocytes.     

Climate impact assessment of willow energy from a landscape perspective: a Swedish case study

Locally produced bioenergy can decrease the dependency on imported fossil fuels in a region, while also being valuable for climate change mitigation. Short‐rotation coppice willow is a potentially high‐yielding energy crop that can be grown to supply a local energy facility. This study assessed the energy performance and climate impacts when establishing willow on current fallow land in a Swedish region with the purpose of supplying a bio‐based combined heat and power plant. Time‐dependent life cycle assessment (LCA) was combined with geographic information system (GIS) mapping to include spatial variation in terms of transport distance, initial soil organic carbon content, soil texture and yield. Two climate metrics were used [global warming potential (GWP) and absolute global temperature change potential (AGTP)], and the energy performance was determined by calculating the energy ratio (energy produced per unit of energy used). The results showed that when current fallow land in a Swedish region was used for willow energy, an average energy ratio of 30 MJ MJ^?1 (including heat, power and flue gas condensation) was obtained and on average 84.3 Mg carbon per ha was sequestered in the soil during a 100‐year time frame (compared with the reference land use). The processes contributing most to the energy use during one willow rotation were the production and application of fertilizers (~40%), followed by harvest (~35%) and transport (~20%). The temperature response after 100 years of willow cultivation was ?6·10^?16 K MJ^?1 heat, which is much lower compared with fossil coal and natural gas (70·10^?16 K MJ^?1 heat and 35·10^?16 K MJ^?1 heat, respectively). The combined GIS and time‐dependent LCA approach developed here can be a useful tool in systematic analysis of bioenergy production systems and related land use effects.     

Identification of a gene for alpha-tubulin in Aspergillus nidulans.

This paper demonstrates that revertants of temperature-sensitive benA (β-tubulin) mutations in Aspergillus nidulans can be used to identify proteins which interact with β-tubulin. Three benomyl-resistant benA (β-tubulin) mutants of Aspergillus nidulans, BEN 9, BEN 15 and BEN 19, were found to be temperature-sensitive (ts^?) for growth. Temperature sensitivity co-segregated with benomyl resistance among the progeny of outcrosses of BEN 9, 15 and 19 to a wild-type strain, FGSC#99, indicating that temperature sensitivity was caused by mutations in the benA gene in these strains. Eighteen revertants to ts⁺ were isolated by selection at the restrictive temperature. Four had back-mutations in the benA gene and fourteen carried extragenic suppressor mutations. Two of the back-mutated strains had β-tubulins which differed from the β-tubulins of their parental strains by one (1^?) or two (2^?) negative charges on two-dimensional gel electrophoresis. Although the β-tubulins of the extragenic suppressor strains were all electrophoretically identical to those of the parental strains, one of the suppressor strains, BEN 9R7, had an electrophoretic abnormality in α1-tubulin (1⁺). A heterozygous diploid between this strain and a strain with wild-type α1-tubulin was found to have both wild-type and mutant (1⁺) α1-tubulins. This experiment rules out post-translational modification as a possible cause of the α1-tubulin abnormality. Thus the suppressor mutation in BEN 9R7 must be in a structural gene for α1-tubulin. We propose that this gene be designated tubA to denote that it is a gene for α1-tubulin in A. nidulans.     

Isolation and identification of a yeast strain capable of degrading four and five ring aromatic hydrocarbons

A yeast strain AEH was isolated from oil contaminated soil and identified by analysis of 18S and 26S ribosomal DNA sequences asPichia anomala. Strain AEH was capable of degrading naphthalene, phenanthrene and chrysene, singly, and benzo(a)pyrene in combination. The yeast degraded 5.36 mg naphthalene l^?1 within 2 days, and 5.04 mg phenanthrene l^?1 and 1.54 mg chrysene 1^?1 within 10 days. When a mixture of the four polycyclic aromatic hydrocarbons (PAHs) was treated at a concentration between 2.98 mg l^?1 and 6.89 mg l^?1, degradation rates were delayed for naphthalene and phenanthrene (3.79 mg l^?1 and, 4.20 mg l^?1 within 10 days, respectively), but enhanced for chrysene and benzo(a)pyrene (3.37 mg l^?1 and, 1.91 mg l^?1 within 10 days, respectively). In a binary system, all of the other 3 PAHs could be utilized as the carbon source for the cometabolic degradation of benzo(a)pyrene with naphthale ne as the best one.     

增加降水对干旱河谷区云南松人工林土壤呼吸的影响

2013年5月至2014年6月,对干旱河谷区云南松(Pinus yunnanensis)人工林进行增加降水试验,试验设置对照(CK,0 mm m~(-2)a~(-1))、增水10%(A1,80 mm m~(-2)a~(-1))、增水20%(A2,160 mm m~(-2)a~(-1))和增水30%(A3,240 mm m~(-2)a~(-1))4个处理水平。采用LI-8100开路式土壤碳通量测量系统测定每月土壤呼吸速率。结果表明,4个处理云南松人工林土壤呼吸速率均呈明显的季节变化,7月最高,2月最低。与CK相比,A1年均土壤呼吸速率无显著性差异(P0.05),A2显著增加了12.88%(P0.05),而A3明显减少了17.71%(P0.05)。3个增水处理均提高了土壤呼吸的温度敏感性,减弱了土壤呼吸与土壤湿度的关系。与土壤温度相比,土壤湿度对土壤呼吸的影响相对较小。增水增加了湿季土壤微生物碳、氮含量,干季对微生物碳含量无影响,但明显降低了微生物氮含量。这说明,降水增加对干旱河谷区云南松人工林土壤呼吸的影响是不尽相同的,适当的增水会促进土壤呼吸,而过量的增水会抑制土壤呼吸。