Phytoremediation potential of vetiver grass irrigated with wastewater for treatment of metal contaminated soil

A field experiment was conducted to understand the potential of vetiver grass (Vetiveria zizanioides) in heavy metal uptake from the soil and wastewater. Four main irrigation treatments including T₁ (treated industrial wastewater), T₂ (1:1 ratio of municipal:industrial wastewater), T₃ (treated municipal wastewater) and T₄ (fresh water) were applied. Moreover, the effect of arbuscular mycorrhizal fungus (AMF), Glomus mosseae, on plant growth and heavy metal concentration was evaluated. Three main criteria including bioconcentration factor (BCF), translocation factor (TF) and heavy metal uptake were applied to assess the potential of vetiver grass in accumulation and translocation of heavy metals to aerial parts. The highest concentration of heavy metals was found in plant and soil irrigated with T₁ treatment followed by T₂, T₃ and the lowest concentrations were found in T₄ treatment. Irrigation with treated municipal wastewater led to a significant increase in plant biomass and heavy metal uptake compared to other treatments. In T₁ treatment (industrial wastewater), vetiver grass caused a significant decrease in Zn, Fe, Cu, Cd and Pb concentrations in soil as compared to no-plant treatment (without planting vetiver grass). Therefore, vetiver grass, irrigated with treated industrial wastewater, is a promising method for the development of urban and industrial green space.     

石油污灌土壤污染物的残留与生态毒理

土壤样品采自沈阳东部石油污水灌渠的上、中、下游。进行了污染物 (Cd、矿物油 )含量分析和生态毒性试验。重金属采用原子吸收分光光度仪测定 ,矿物油采用紫外分光光度计测定。生态毒性试验分别参照国际标准组织 (ISO)和OECD指南 ,进行了植物毒性试验和蚯蚓毒性试验。植物试验以小麦种子发芽根伸长抑制率为试验终点 ,试验周期 5 0h ,蚯蚓毒性试验以蚯蚓死亡率和体重增长抑制率为试验终点 ,试验周期 2 8d。结果表明 ,所有土壤均有矿物油积累 ,含量为 6 6 2 2～ 1391 14mg·kg-1,重金属Cd略高于土壤背景值 ,含量为 0 0 6～ 0 37mg·kg-1。然而 ,土壤对高等植物表现有不同程度的生长刺激效应 ,对蚯蚓有急性致死及慢性亚致死效应。种子发芽根伸长抑制率为 - 2 8 6 1%～ - 5 4 6 5 % ,蚯蚓 2 8d死亡率最大值为 10 %。蚯蚓 14d和 2 8d体重增长抑制率分别为 - 5 13%～ - 2 8 0 5 %和 - 31 78%～ 8 0 8%。研究表明 ,长期石油污水灌溉土壤中矿物油的低积累和较明显的生态毒性。     

Impact of incubation period on biodegradation of petroleum hydrocarbons from refinery wastewater in Kuantan,Malaysia by indigenous bacteria

This work studied the biodegradation of petroleum hydrocarbons (PHCs) extracted from refinery wastewater to produce industrially important by-products at different incubation periods. Two out of 13 bacterial isolates, KRD2 and KRA4 were isolated. Dichloromethane was used to extract the PHC, and gas chromatography-mass spectrometry (GC-MS) analysis revealed that the refinery wastewater PHC was successfully biodegraded using the selected bacterial isolates within 15 days of incubation. Both KRD2 and KRA4 isolates degraded all 13 initially extracted PHC compounds within 5 days, except C13BD and C9BD, which produced 6 and 4 compounds as secondary metabolites with peak area percentages of 1.58, 1.38, 0.85, 29.94, 7.59, and 11.16% and 3.55, 2.88, 52.31, and 6.14%, respectively. These metabolites have been reported in industrial and medical applications. After 10 days, only 6 and 8 compounds were degraded by both isolates, respectively, and C11PAD compound was produced, as well as C5PAD, C7PAD, and C13PAD. After 15 days, it was clear that all the initial PHC compounds have been completely degraded by both isolates. Metabolites C5PAD, C6PAD, C8PAD, and C13PAD were produced by KRD2, and metabolites C5PAD, C6PAD, C8PAD, and C9PAD were produced by KRA4 at different peak areas. The alignment revealed that the KRA4 isolate was included in the genus Chryseobacterium gambrini, while KRD2 isolate was successfully identified as Mycobacterium confluentis using the Biolog microbial identification system. The incubation period evidently affected biodegradation process by indigenous degraders. These effective bacteria were shown to be of great potential for further application in biodegradation technology of PHC contaminated refinery wastewater to produce industrially important by-products.     

Effect of Medicago sativa L. and compost on organic and inorganic pollutant removal from a mixed contaminated soil and risk assessment using ecotoxicological tests

Several Gentle Remediation Options (GRO), e.g., plant-based options (phytoremediation), singly and combined with soil amendments, can be simultaneously efficient for degrading organic pollutants and either stabilizing or extracting trace elements (TEs). Here, a 5-month greenhouse trial was performed to test the efficiency of Medicago sativa L., singly and combined with a compost addition (30% w/w), to treat soils contaminated by petroleum hydrocarbons (PHC), Co and Pb collected at an auto scrap yard. After 5 months, total soil Pb significantly decreased in the compost-amended soil planted with M. sativa, but not total soil Co. Compost incorporation into the soil promoted PHC degradation, M. sativa growth and survival, and shoot Pb concentrations [3.8 mg kg^?1 dry weight (DW)]. Residual risk assessment after the phytoremediation trial showed a positive effect of compost amendment on plant growth and earthworm development. The O₂ uptake by soil microorganisms was lower in the compost-amended soil, suggesting a decrease in microbial activity. This study underlined the benefits of the phytoremediation option based on M. sativa cultivation and compost amendment for remediating PHC- and Pb-contaminated soils.     

Modulation of phytoremediation and plant growth by the treatment with PGPR,Ag nanoparticle and untreated municipal wastewater

The present attempt was made to determine the effects of untreated municipal wastewater (MW) on growth and physiology of maize and to evaluate the role of Ag nanoparticle and plant-growth-promoting rhizobacteria (PGPR) when interacting with MW used for irrigation. It was used for the isolation of PGPR. The isolates were identified and characterized based on the colony morphology, C/N source utilization pattern using miniaturized identification system (QTS 24), catalase (CAT) and oxidase tests, and 16S rRNA sequence analyses. The three PGPR isolates were Planomicrobium chinense (accession no. NR042259), Bacillus cereus (accession no. CP003187) and Pseudomonas fluorescens (accession no. GU198110). The isolates solubilized phosphate and exhibited antibacterial activities against pathogenic bacteria i.e., Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Klebsiella pneumoniae and Escherichia coli and antifungal activities against Helminthosporium sativum and Fusarium solani. The untreated MW irrigation as well as Ag nanoparticle treatment resulted in significant accumulation of Ni in the rhizosphere soil. PGPR induced accumulation of Ni and Pb in the rhizosphere soil and maize shoot. Ag nanoparticle also caused Ni and Pb accumulation in maize shoot. Combined treatment with PGPR, Ag nanoparticle and MW resulted in decreased accumulation of Pb and Ni both in the rhizosphere soil and maize shoot. Combined treatment of Ag nanoparticle, MW and PGPR decreased Na accumulation and increased K accumulation. Ag nanoparticle increased Fe and Co accumulation but decreased Zn and Cu accumulation in MW treatment; in combined treatment, it reduced PGPR-induced accumulation of Co and Fe in the rhizosphere and Co accumulation in shoot. PGPR significantly increased root weight, shoot weight, root length, shoot length, leaf area, and proline, chlorophyll and carotenoid content of the maize plant. Ag nanoparticle also enhanced the leaf area, fresh weight, root length and antioxidant activities of maize. Treatment with Ag nanoparticle increased the gibberellic acid (GA) and abscisic acid (ABA) content of maize leaves but decreased the accumulation of GA in the presence of PGPR and MW.     

Effects of organic amendments on Cd, Zn and Cu bioavailability in soil with repeated phytoremediation by Sedum plumbizincicola

Organic materials with different functional groups can be used to enhance metal bioavailability. Traditional organic materials (rice straw and clover) and ethylenediamine disuccinic acid (EDDS) were applied to enhance metal uptake from polluted soil by Sedum plumbizincicola after repeated phytoextraction. Changes in pH, dissolved organic carbon (DOC) and metal concentrations were determined in the soil solution after EDDS application. Amendment of the soil with ground rice straw or ground clove resulted in higher concentrations of Cd only (by factors of 1.92 and 1.71 respectively) in S. plumbizincicola compared to control soil. Treatment with 3 mmol kg(-1) EDDS increased all the metals studied by factors of 60.4, 1.67, and 0.27 for Cu, Cd, and Zn, respectively. EDDS significantly increased soil solution DOC and pH and increased soil plant-available metals above the amounts that the plants could take up, resulting in high soil concentrations of soluble metals and high risk of ground water contamination. After repeated phytoremediation of metal contaminated soils the efficiency of metal removal declines as the concentrations of bioavailable metal fractions decline. Traditional organic materials can therefore be much more effective and environmentally friendly amendments than EDDS in enhancing phytoremediation efficiency of Cd contaminated soil     

Phytoremediation of lead (Pb) and Arsenic (As) by Melastoma malabathricum L. from Contaminated Soil in Separate Exposure

This study was conducted to investigate the uptake of lead (Pb) and arsenic (As) from contaminated soil using Melastoma malabathricum L. species. The cultivated plants were exposed to As and Pb in separate soils for an observation period of 70 days. From the results of the analysis, M. malabathricum accumulated relatively high range of As concentration in its roots, up to a maximum of 2800 mg/kg. The highest accumulation of As in stems and leaves was 570 mg/kg of plant. For Pb treatment, the highest concentration (13,800 mg/kg) was accumulated in the roots of plants. The maximum accumulation in stems was 880 mg/kg while maximum accumulation in leaves was 2,200 mg/kg. Only small amounts of Pb were translocated from roots to above ground plant parts (TF < 1). However, a wider range of TF values (0.01–23) for As treated plants proved that the translocation of As from root to above ground parts was greater. However, the high capacity of roots to take up Pb and As (BF > 1) is indicative this plants is a good bioaccumulator for these metals. Therefore, phytostabilisation is the mechanism at work in M. malabathricum's uptake of Pb, while phytoextraction is the dominant mechanism with As.     

Biosorption of nickel and cadmium by metal resistant bacterial isolates from agricultural soil irrigated with industrial wastewater

Agricultural soil irrigated with industrial wastewater (more than two decades) analysed for heavy metals revealed high levels of Fe, Cr, Cu, Zn, Ni and Cd. Out of a total of 40 bacterial isolates obtained from these soils, 17 belonged to the family enterobacteriaceae and 10 were Pseudomonas spp. A maximum MIC of 200 for Cd, 400 for Zn and Cu, 800 for Ni, and 1600 microg/ml for Pb was observed. Biosorption of Ni and Cd studies over a range of metal ion concentrations with Escherichia coli WS11 both in single and bi-metal systems showed that the adsorption of Cd and Ni was dependent on the concentrations and followed the Freundlich adsorption isotherm. The biosorption of Ni increased from 6.96 to 55.31 mg/g of cells, and Cd from 4.96 to 45.37 mg/g of cells at a concentration ranging from 50 to 400 microg/ml after 2h of incubation in a single metal solution. A further increase in incubation time had no significant effect on the biosorption of metals.     

Phytoextraction of cadmium and zinc by Salix from soil historically amended with sewage sludge

Short rotation coppice (SRC) such as Salix spp. can be grown as an energy crop and offers some potential for economic and practical phytoextraction of marginally contaminated arable soil. This study tested various soil amendments intended to increase soil metal availability to Salix, investigated the distribution of metal between different tree fractions and assessed the viability of phytoextraction using SRC on arable soils. Several Salix genotypes were grown in field trials over 4 years. Cd and Zn concentrations were generally ranked in the order leaves > bark > wood. Metal concentrations in wood increased towards the top of the willow stems, whereas concentrations in leaves showed the opposite trend. None of the amendments significantly increased uptake of Zn by willow. However, in response to a range of soil HCl treatments, mean Cd concentrations in stems and leaves were 112% and 130% of control values. Data from the current experiment, and previous studies, were combined to develop a predictive model of Cd and Zn stem uptake by Salix. The minimum biological concentration factor (BCF) required to achieve a prescribed soil metal target was also calculated based on typical proportions of bioavailable Cd in sludge-amended soils for a 25-year Salix rotation. The best Salix genotypes investigated achieved less than 20% of the uptake rate required to remove one third of the soil Cd content (equivalent to the average isotopically exchangeable Cd fraction in soils at the study site).     

Heavy metal uptake by arbuscular mycorrhizas of Elsholtzia splendens and the potential for phytoremediation of contaminated soil

A pot culture experiment and a field experiment were carried out separately to study heavy metal (HM) uptake from soil contaminated with Cu, Zn, Pb and Cd by Elsholtzia splendens Nakai ex F. Maekawa inoculated with arbuscular mycorrhizal (AM) fungi and the potential for phytoremediation. The HM-contaminated soil in the pot experiment was collected from the field experiment site. Two AM fungal inocula, MI containing only one AM fungal strain, Glomus caledonium 90036, and M II consisting of Gigaspora margarita ZJ37, Gigaspora decipens ZJ38, Scutellospora gilmori ZJ39, Acaulospora spp. andGlomus spp., were applied to the soil under unsterilized conditions. In the pot experiment, the plants were harvested after 24 weeks of growth. Mycorrhizal colonization rate, plant dry weight (DW) and P, Cu, Zn, Pb, Cd concentrations were determined. MI-treated plants had higher mycorrhizal colonization rates than MII-treated plants. Both MI and MII increased shoot and root DW, and MII was more effective than MI. In shoots, the highest P, Cu, Zn and Pb concentrations were all observed in the plants treated with MII, while MI decreased Zn and Pb concentrations and increased P but did not alter Cu, and Cd concentrations were not affected by either of two inocula. In roots, MII increased P, Zn, Pb concentrations but did not alter Cu and Cd, and MI did not affect P, Cu, Zn, Pb, Cd concentrations. Cu, Zn, Pb, Cd uptake into shoots and roots all increased in MII-treated plants, while in MI-treated plants, Cu and Zn uptake into shoots and Cu, Zn, Pb, Cd into roots increased but Pb and Cd uptake into shoots decreased. In general, MII was more effective than MI in promoting plant growth and HM uptake. The field experiment following the pot experiment was carried out to investigate the effects of MII under field conditions. The 45-day-old nonmycorrhizal and MII-colonized seedlings of E. splendens were transplanted to HM-contaminated plots and harvested after 5 months. MII-inoculation increased shoot DW and shoot P, Cu, Zn, Pb concentrations significantly but did not alter shoot Cd concentrations, which led to higher uptake of Cu, Zn, Pb, Cd by E. splendens shoots. These results indicate that the AM fungal consortium represented by MII can benefit phytoextraction of HMs and therefore play a role in phytoremediation of HM-contaminated soils.     

Chromium and cadmium removal from wastewater using duckweed - Lemna gibba L. and ultrastructural deformation due to metal toxicity

Phytoremediation potential of Lemna gibba was evaluated for chromium (Cr) and cadmium (Cd) under laboratory conditions for variable metal load of 1?mg/l, 3?mg/l, 5mgl, 7?mg/l and 9?mg/l, respectively, for 7 and 15?days of treatment period. Effects of both metals on structural attributes of L. gibba were also analyzed by Scanning Electron Microscopic (SEM) study. The metal removal percentage by L. gibba for Cr metal was found in the range of 37.3% to 98.6% and for cadmium it was found within the range of 81.6% to 94.6%. Bio concentration factor (BCF) of L .gibba was observed within the range of 37 to 295 for Cr metal and for Cd metal it ranged from 237 to 1144, which shows that the plant is a hyper accumulator for Cd metal and moderate accumulator for Cr metal. Statistical analysis (Two-way ANOVA) was performed on experimental results to confirm the individual effect of metal concentration and treatment period as well as cumulative effect of both factors together on percentage metal removal and on BCF. Research studies indicated that with the progress of treatment period metal removal percentage increases but increasing metal load during experiment negatively co-relates the metal removal percentage and BCF.     

Neorhizobium petrolearium OS53联合紫花苜蓿协同修复石油污染土壤研究

【目的】探究Neorhizobium petrolearium OS53与紫花苜蓿协同修复石油污染土壤的机制。【方法】使用Illumina和Nanopore平台对菌株OS53进行全基因组测序,构建菌株基因组完成图,并进行基因预测及功能注释,分析其中与结瘤促生及石油降解相关基因,并通过实验测定菌株OS53产吲哚乙酸(indole acetic acid, IAA)、铁载体、溶磷和解钾等与促生相关的能力。使用试剂盒对联合修复前后土壤中土壤脲酶、脱氢酶、多酚氧化酶和脂肪酶活性及紫花苜蓿的叶绿素、丙二醛、脯氨酸、可溶性蛋白、可溶性糖和超氧化物歧化酶等生理指标进行测定。【结果】菌株OS53的基因组由一个5.56 Mb的环形染色体和2个大小分别为0.92 Mb和0.38 Mb的质粒组成,基因组G+C含量为60.2%,共编码6 968个基因。菌株OS53与N. petrolearium DSM 26482^T的16S rRNA基因序列相似性最高,为99.86%,且在系统发育树上形成稳定分支,表明菌株OS53与N. petrolearium为同一种,因此将OS53命名为N. petrolearium OS53。试验结果表明,菌株OS53具有产IAA能力,并在其基因组中也发现相关基因。在初始石油含量为(4 403.30±222.10) mg/kg时,经过120 d修复,OS53与紫花苜蓿协同修复效率能够达到57.53%,比不接种OS53、仅接种OS53和仅种植苜蓿分别提高了44.26%、41.69%和8.84%。在联合修复体系中,紫花苜蓿叶绿素、可溶性蛋白和可溶性糖的含量有所提高,丙二醛和脯氨酸的含量以及超氧化物歧化酶的活性有所降低,同时土壤中多酚氧化酶、脱氢酶、脂肪酶和脲酶的活性都有所提高。【结论】菌株OS53具有产IAA的能力,并且能够促进紫花苜蓿在石油污染土壤中的生长,进而提高土壤中与石油降解相关部分酶活,最终提高联合修复体系对石油污染土壤的修复效果。     

Effects of the mycorrhizal fungus Glomus intraradices on uranium uptake and accumulation by Medicago truncatula L. from uranium-contaminated soil

Phytostabilization strategies may be suitable to reduce the dispersion of uranium (U) and the overall environmental risks of U-contaminated soils. The role of Glomus intraradices, an arbuscular mycorrhizal (AM) fungus, in such phytostabilization of U was investigated with a compartmented plant cultivation system facilitating the specific measurement of U uptake by roots, AM roots and extraradical hyphae of AM fungi and the measurement of U partitioning between root and shoot. A soil-filled plastic pot constituted the main root compartment (C_A) which contained a plastic vial filled with U-contaminated soil amended with 0, 50 or 200 mg KH₂PO₄−P kg^–1soil (C_B). The vial was sealed by coarse or fine nylon mesh, permitting the penetration of both roots and hyphae or of just hyphae. Medicago truncatula plants grown in C_A were inoculated with G. intraradices or remained uninoculated. Dry weight of shoots and roots in C_A was significantly increased by G. intraradices, but was unaffected by mesh size or by P application in C_B. The P amendments decreased root colonization in C_B, and increased P content and dry weight of those roots. Glomus intraradices increased root U concentration and content in C_A, but decreased shoot U concentrations. Root U concentrations and contents were significantly higher when only hyphae could access U inside C_B than when roots could also directly access this U pool. The proportion of plant U content partitioned to shoots was decreased by root exclusion from C_B and by mycorrhizas (M) in the order: no M, roots in C_B > no M, no roots in C_B > M, roots in C_B > M, no roots in C_B. Such mycorrhiza-induced retention of U in plant roots may contribute to the phytostabilization of U contaminated environments.     

Cadmium tolerance and its phytoremediation by two oil yielding plants Ricinus communis (L.) and Brassica juncea (L.) from the contaminated soil

The effect of increasing level of cadmium in soil was investigated on biomass production, antioxidants, Cd bioaccumulation and translocation in Ricinus communis vis-à-vis a commonly studied oil crop Brassica juncea. The plants were exposed to 25, 50, 75, 100, and 150 mg Cd/Kg soil for up to 60 days. It was found that R. communis produced higher biomass at all the contamination levels than that of B. juncea. Proline and malondialdehyde in the leaves increased with increase in Cd level in both the species, whereas soluble protein decreased. The bioaccumulation of Cd was higher in B. juncea on the basis of the per unit biomass, total metal accumulation per plant was higher in R. communis. The translocation of Cdfrom roots to shoot was also higher in B. juncea at all Cd concentrations. R. communis appeared more tolerant and capable to clean Cd contaminated soil for longer period in one sowing than B. juncea and the former can grow in wasteland soil also in which later cannot be cultivated.     

Treatment of coal gasification wastewater by a two-continuous UASB system with step-feed for COD and phenols removal

A two-continuous mesophilic (37 ± 2 °C) UASB system with step-feed was investigated as an attractive optimization strategy for enhancing COD and total phenols removal of the system and improving aerobic biodegradability of real coal gasification wastewater. Through the step-feed period, the maximum removal efficiencies of COD and total phenols reached 55-60% and 58-63% respectively in the system, at an influent flow distribution ratio of 0.2 and influent COD concentration of 2500 mg/L; the corresponding efficiencies were at low levels of 45-50% and 43-50% respectively at total HRT of 48 h during the single-feed period. The maximum specific methanogenic activity and substrate utilization rate were 592 ± 16 mg COD-CH₄/(gVSS d) and 89 ± 12 mg phenol/(gVSS d) during the step-feed operation. After the anaerobic digestion with step-feed, the aerobic effluent COD concentration decreased from 270 ± 9 to 215 ± 10 mg/L. The results suggested that step-feed enhanced the degradation of refractory organics in the second reactor.     

UV-B辐射增强对小麦秸秆化学成分及其施用后土壤N2O排放的影响

在室外试验的基础上,研究了地表UV-B辐射增强条件下小麦秸秆成分的变化,及在室内不同培养条件下施用UV-B辐射处理后小麦秸秆对土壤N₂O排放的影响.室外试验结果表明：地表UV-B辐射增强减少了小麦地上部分生物量,显著增加了小麦秸秆木质素和全氮含量,增幅分别达94.2%和12.3%,降低了其C/N.室内培养试验结果表明：与常规小麦秸秆相比,UV-B辐射处理后的小麦秸秆显著提高了旱地和淹水条件下N₂O的排放量;施用秸秆同时伴施硝态氮条件下,经过UV-B辐射处理的小麦秸秆显著促进了旱地条件下N₂O的排放,其排放量为常规秸秆处理的3.2倍,但在淹水条件下对N₂O排放无显著影响;无论何种培养条件下,经过UV-B辐射处理的小麦秸秆对土壤呼吸都未产生显著影响.     

Functional characterization and expression analysis of a glutathione transporter, BjGT1, from Brassica juncea: evidence for regulation by heavy metal exposure

Glutathione and its derivatives play an important role in the tolerance of plants against heavy metals. A glutathione transporter, BjGT1 (AJ561120), was cloned and functionally characterized from Brassica juncea, a plant which may be used for phytoremediation. The full‐length BjGT1 cDNA showed homology with the high affinity glutathione transporter HGT1 from Saccharomyces cerevisiae and shares 92% identity with a putative glutathione transporter from A. thaliana (At4g16370). When expressed in the S. cerevisiae hgt1Δ strain, BjGT1 complemented the mutant on medium with glutathione as the only sulphur source and mediated the uptake of [³H]GSH. Immunoblot analysis with a peptide‐specific antiserum directed against a C‐terminal sequence revealed high BjGT1 expression in leaf tissue and relatively low expression in stem tissue, whereas BjGT1 protein was not detectable in root tissue. The amounts of BjGT1 mRNA and protein were analysed during a 6 d exposure of B. juncea to 25 µm Cd(NO₃)₂. BjGT1 mRNA was strongly induced by cadmium in stems and leaves. Unexpectedly, the amount of BjGT1 protein in leaves showed a pronounced decrease with a minimum after 96 h of Cd exposure, followed by partial recovery. The strong regulation of BjGT1 by cadmium suggests a role of this glutathione transporter during heavy metal exposure.     

Isolation of the PCB-degrading bacteria Mesorhizobium sp. ZY1 and its combined remediation with Astragalus sinicus L. for contaminated soil

A bacterial strain ZY1 capable of utilizing PCBs as its carbon source was isolated from the root nodules of Chinese milk vetch (Astragalus sinicus L.). The strain was identified as Mesorhizobium sp. according to its physiological-biochemical properties and the analysis of its 16S rRNA gene sequence. When the initial OD600 was 0.15, 62.7% of 15 mg L^?1 3,3′,4,4′-TCB in a liquid culture was degraded by Mesorhizobium sp. ZY1 within 10 days. Mesorhizobium sp. ZY1 also greatly increased the biotransformation of soil PCBs. Pot experiments indicated that the soil PCB concentrations of a single incubation of strain ZY1 (R) and a single planting of A. sinicus (P) decreased by 20.5% and 23.0%, respectively, and the concentration of PCBs in soil treated with A. sinicus and strain ZY1 decreased by 53.1%. We also observed that A. sinicus-Mesorhizobium sp. ZY1 treatment (PR) improved plant biomass and the concentration of PCBs in plants compared with a single A. sinicus planting treatment (P). The results suggest that the synergistic association between A. sinicus and PCBs-degrading Mesorhizobium sp. ZY1 can stimulate the phytoextraction of PCBs and the rhizosphere microflora to degrade PCBs, and might be a promising bioremediation strategy for PCB-contaminated soil.     

Effects of intermittent addition of cellulase for production of L-lactic acid from wastewater sludge by simultaneous saccharification and fermentation

An attempt was made to create L-lactic acid, a precursor of poly-lactic acid, which is a biodegradable plastic, from wastewater sludge from the paper-manufacturing industry. The sludge contained a high percentage of cellulose and needed to be hydrolyzed to glucose by the action of the cellulase before being treating with lactic acid bacteria. Therefore, a method involving simultaneous saccharification and fermentation (SSF) was carried out. The optimum pH of the SSF for production of the lactic acid by the newly isolated lactic acid bacterium with a high selectively of L-lactic acid was found out to be around pH = 5.0, and the optimum temperature to be approximately 40 degrees C. On the basis of the measurement of the cell density changes in the lactic acid bacteria, it was ascertained that the bacterial activity could continue at a high level for a relatively long period of time, and that the L-lactic acid productivity was diminished by the rapid deactivation of the cellulase. With the intermittent addition of cellulase once daily for the sake of compensating for the cellulase deactivation, the L-lactic acid attained a maximum concentration of 16.9 g/L, i.e., a 72.2% yield based on the potential glucose contained in the sludge under optimum pH and temperature conditions.     

不同病因肝硬化患者L3骨骼肌指数特征及其对患者营养状况的预测价值分析

摘要 目的：探讨不同病因肝硬化患者L3骨骼肌指数特征及其对患者营养状况的预测价值分析。方法：选取2019年6月-2022年6月在我院收治的120例肝硬化患者作为研究对象,其中乙肝肝硬化40例,酒精性肝硬化40例,自身免疫性肝炎肝硬化40例。比较乙肝肝硬化组,酒精性肝硬化组,自身免疫性肝炎肝硬化L3 SMI的特征。采用Pearson相关检验分析L3 SMI与肝硬化患者营养状况的相关性。采用Logistics回归模型构建影响肝硬化营养状况的独立危险因素。采用受试者工作曲线（ROC）评估L3 SMI对肝硬化营养状况的预测价值。结果：自身免疫性肝炎肝硬化组L3 SMI、25（OH）D、ALB、PA、TRF的表达水平均显著低于酒精性肝硬化组和乙肝肝硬化组（P<0.05）,且酒精性肝硬化组显著低于乙肝肝硬化组（P<0.05）。肝硬化患者LSM与25（OH）D、ALB、PA、TRF均显著正相关（P<0.05）。以肝硬化患者营养状况作为因变量（营养正常=0,营养不良=1）纳入logistics回归模型,结果显示,25（OH）DALB、PA、TRF、L3 SMI是危险因素（P<0.05）。多因素分析结果显示,25（OH）DALB、PA、TRF、L3 SMI是影响肝硬化患者营养状况的独立危险因素（P<0.05）。L3 SMI预测评估肝硬化患者营养状况的Youden指数0.765,敏感度85.00（%）,特异度82.00（%）,AUC值0.810,95%CI：0.685~0.912。结论：不同病因肝硬化患者L3 SMI存在明显差异,临床可采用L3 SMI对肝硬化患者营养状况做出预测评估。