Pathway and rate-limiting step of glyphosate degradation by Aspergillus oryzae A-F02

Aspergillus oryzae A-F02, a glyphosate-degrading fungus, was isolated from an aeration tank in a pesticide factory. The pathway and rate-limiting step of glyphosate (GP) degradation were investigated through metabolite analysis. GP, aminomethylphosphonic acid (AMPA), and methylamine were detected in the fermentation liquid of A. oryzae A-F02, whereas sarcosine and glycine were not. The pathway of GP degradation in A. oryzae A-F02 was revealed: GP was first degraded into AMPA, which was then degraded into methylamine. Finally, methylamine was further degraded into other products. Investigating the effects of the exogenous addition of substrates and metabolites showed that the degradation of GP to AMPA is the rate-limiting step of GP degradation by A. oryzae A-F02. In addition, the accumulation of AMPA and methylamine did not cause feedback inhibition in GP degradation. Results showed that degrading GP to AMPA was a crucial step in the degradation of GP, which determines the degradation rate of GP by A. oryzae A-F02.     

植被退化对温带典型草原根系-土壤系统碳氮分配的影响

以3种不同退化程度的温带典型草原(大针茅轻度退化、中度退化和重度退化)为研究对象,研究植被退化对温带典型草原土壤及根系碳氮含量及储量的影响。结果显示:(1)植被退化对地下根系碳含量影响不显著(P0.05),而对地下根系氮含量的影响显著(P0.05),中度退化样地根系氮含量显著高于轻度退化和重度退化样地(P0.05)。(2)植被退化对根系碳氮储量影响显著(P0.05),根系碳氮储量随着土层深度增加而减少,总根系碳氮储量随退化程度加剧而降低。(3)土壤有机碳、总碳和总氮含量及储量均受退化程度和采样深度的影响显著(P0.05),其含量随着土壤深度的增加而显著减少,随退化程度加剧而显著降低(P0.05)。(4)土壤是根系-土壤系统碳氮储存的最主要场所,储量占比90%以上。虽然土壤碳氮储量均存在表层聚集现象,但表层储量所占比例在各样地间差异显著(P0.05)。     

In vitro Degradation of 2,4,6‐Trinitrotoluene Using Plant Tissue Cultures of Solanum aviculare and Rheum palmatum

The degradation of TNT was tested in suspension cultures (Rheum palmatum and Solanum aviculare) and was followed by the identification of degradation products and the determination of the phytotoxicity of TNT to both cultures. The concentration of TNT inhibited the growth of cell cultures by 50 %, i.e., 37.8 mg/ and 38.1 mg/L for Rheum palmatum and Solanum aviculare, respectively. The TNT uptake was studied by determining the concentration of TNT and its degradation products, such as aminodinitrotoluenes and diaminonitrotoluenes, in the cultivation medium as well as in plant cells. The kinetics of the degradation showed that TNT was mostly taken up within 10 hours and 6 hours for S. aviculare and R. palmatum, respectively. Aminodinitrotoluenes were preferentially produced by cultures of S. aviculare, whereas diaminonitrotoluenes and aminodinitrotoluenes were revealed in cultures of R. palmatum. The final concentrations of identified degradation products did not stoichiometrically correspond to the decreased concentration of TNT in the medium. The different concentrations of degradation products in each culture were an indication that the metabolism of TNT is controlled by different enzymatic systems. Therefore, it was concluded that studying different species for TNT degradation is necessary for the search of most suitable candidates for TNT phytoremediation.     

Biotransformation of dichloro-, trichloro-, and tetrachlorodibenzo-p-dioxin by the white-rot fungus Phlebia lindtneri

The model polychlorinated dibenzo-p-dioxins (PCDDs) 2,7-dichloro-, 2,3,7-trichloro, 1,2,6,7-, 1,2,8,9-, and 1,3,6,8-tetrachlorodibenzo-p-dioxin were used as substrates for a degradation experiment with the white-rot fungus Phlebia lindtneri. 2,7-Dichlorodibenzo-p-dioxin (2,7-diCDD) was biotransformed to hydroxylated diCDD and methoxylated diCDD. With the exception of 1,3,6,8-tetrachlorodibenzo-p-dioxin, the tri- and tetrachlorodibenzo-p-dioxins were biotransformed to hydroxyl and methoxyl compounds by P. lindtneri. The degradation rate of 1,2,6,7-tetrachlorodibenzo-p-dioxin was higher than that of 2,3,7-trichlorodibenzo-p-dioxin and no degradation of 1,3,6,8-tetrachlorodibenzo-p-dioxin was observed. These results indicate that the degradation of these PCDDs depends on the chlorination patterns of the substrates. This is the first report of the hydroxylation and methoxylation of tri- to tetra-CDDs by a fungal strain.     

Biodegradation of cis-1,2-dichloroethylene and vinyl chloride in anaerobic cultures enriched from landfill leachate sediment under Fe(III)-reducing conditions

An anaerobic, Fe(III)-reducing enrichment culture, which originatedfrom a sediment sample collected at a landfill in Nanji-do, Seoul, Korea, was capable ofdegrading cis-1,2-dichloroethylene (cis-DCE) and vinylchloride (VC). Although it exhibited the ability under Fe(III)-reducing conditions, the chlorinated ethenes degradationwas not linked to the Fe(III) reduction. During cis-DCE degradation, no VC, ethene, or ethanewas detected through the experimental period. Also, this culture did not accumulate ethene andethane during the VC degradation. It was unlikely that cis-DCE was reductivelydechlorinated to VC and then the VC formed was dechlorinated fast enough. Because the kinetic datashowed that the rate of cis-DCE degradation was 3.5 times higher than that of VC. Whereasglucose supported the culture growth and the degradation, formate, acetate, butyrate, propionate,lactate, pyruvate, and yeast extract did not. The results appeared consistent with the involvement ofoxidative degradation mechanism rather than reductive dechlorination mechanism. The traits of the culturedescribed here are unusual in the anaerobic degradation of chlorinated ethenes and may be usefulfor searching an effective organism and mechanism regarding anaerobic cis-DCE and VC degradation.     

The effect ofn-alkanes in the degradation of dibenzothiophene and of organic sulfur compounds in heavy oil by aPseudomonas sp.

Summary The microbial degradation of organic sulfur compounds was examined in aerobic conditions employing a pure culture of aPseudomonas sp., isolated from the soil. The effect ofn-alkanes on the degradation of dibenzothiophene (DBT) showed that the assimilation of the sulfur compound by the microorganism is favoured byn-dodecane. Moreover, the saturated fraction was seen to enhance the degradation of the sulfur compounds to be found in a deasphaltenated heavy oil.     

Degradation of indole by enrichment culture and Pseudomonas aeruginosa Gs isolated from mangrove sediment

Microbial degradation of indole was investigated using enrichment culture and Pseudomonas aeruginosa Gs obtained from mangrove sediment of Hong Kong Nature Reserve as inocula. Degradation of indole using this enrichment culture and Ps. aeruginosa Gs was quantified on reversed-phase high-performance liquid chromatography. Initial concentrations of indole affected degradation and the results conformed to the zero-order kinetic model. The optimum pH and salinity were 7.0 and 5‰, respectively, for indole degradation by Ps. aeruginosa Gs. Two major metabolites of indole degradation were detected. This study suggests that indole can be rapidly degraded by indigenous microorganisms of the mangrove environment.     

高寒地区不同退化草地植被特性和土壤固氮菌群特性及其相关性

选取东祁连山不同退化程度的高寒草地为研究对象,调查研究其植物种类、植被盖度、高度、地上生物量等植物指标以及土壤好气性自生固氮菌和嫌气性自生固氮菌数量,在此基础上,采用real-time PCR的方法扩增nifH基因,测定不同退化程度草地土壤中固氮菌相对于土壤总细菌的量,以探讨草地退化过程中植被及土壤固氮菌群的变化规律,结果发现:随着退化程度的加深,草地植物种类逐渐减少,并且优势植物发生变化,毒杂草逐渐增多,植被的高度、盖度、地上生物量都逐渐降低。对土壤固氮菌的研究则表明,土壤好气性自生固氮菌和嫌气性自生固氮菌的数量在不同退化草地随草地退化程度的加重而减少,在同一退化程度草地土壤则是随土层深度加深而下降。对土壤固氮菌nifH基因扩增的结果也表明随着退化加剧,土壤固氮菌相对于土壤总细菌的比例在降低,进一步说明草地退化过程中土壤固氮菌不仅是数量上的下降,更是群落结构层面的变化。对植被特性和土壤固氮菌含量的相关分析表明,植被特性和土壤中固氮菌含量呈显著相关。研究从土壤固氮菌群的角度研究了草地退化的过程,说明了二者具有协同性,研究和治理草地退化必须重视土壤功能菌群尤其是固氮菌群的作用。     

Insulin and glucagon degradation by the kidney II. Characterization of the mechanisms at neutral pH

Insulin and glucagon degradation by rat kidney homogenates and subcellular fractions was examined under a variety of conditions including high and low substrate concentrations, at pH 4 and pH 7, with and without glutathione. At high insulin concentration (4.1 · 10⁻⁵ M) insulin degradation by the homogenate was greatest at pH 4 but at low insulin concentration (1 · 10⁻¹⁰ M) insulin degradation was greatest at pH 7. At either high or low glucagon concentration glucagon degradation by the homogenate was greatest at pH 7. Glutathione at pH 7 stimulated insulin degradation at high insulin concentrations and inhibited insulin degradation at low concentrations. Glucagon degradation at pH 7 was inhibited at both high and low concentrations of glucagon by glutathione.Separation of kidney into cortex and medulla prior to homogenation produced a pattern of insulin and glucagon degradation identical to the whole homogenate but glucagon degradation by the medulla was greater than by the cortex.Examination of degradation by subcellular fractions revealed that at high concentration at neutral pH most insulin was degraded by the 100 000 × g pellet but at low insulin concentrations over 90% of the activity was in the 100 000 × g supernatant. At pH 7, at both high and low concentrations, most glucagon-degrading activity was in the 100 000 × g pellet, although the cytosol also had activity. At pH 4 most degradation occurred in the lysosomal fractions.Separation into cortex and medulla again showed similar distribution of activity as the whole gland with the medulla having more glucagon-degrading activity than the cortex. With low insulin concentrations the cortex 100 000 × g supernatant had higher relative specific activities than the medulla supernatant.Examination of recoveries of enzyme activity revealed that the subcellular fractions consistently had markedly less insulin-degrading activity than the original homogenate. This loss of activity was only discernible when insulin degradation was performed at pH 7 at low substrate concentrations. Comparable losses of glucagon-degrading activity were not seen.     

Separating the effects of water quality and urbanization on temperate insectivorous bats at the landscape scale

Many local scale studies have shown that bats respond to water quality degradation or urbanization in a species‐specific manner. However, few have separated the effects of urbanization versus water quality degradation on bats, in single city or single watershed case studies. Across North Carolina, USA, we used the standardized North American Bat Monitoring Program mobile transect protocol to survey bat activity in 2015 and 2016 at 41 sites. We collected statewide water quality and urban land cover data to disentangle the effects of urbanization and water quality degradation on bats at the landscape scale. We found that statewide, water quality degradation and urbanization were not correlated. We found that bats responded to water quality degradation and urbanization independently at the landscape scale. Eptesicus fuscus and Lasiurus cinereus negatively responded to water quality degradation. Lasiurus borealis and Perimyotis subflavus positively responded to water quality degradation. Lasionycteris noctivagans did not respond to water quality degradation but was more active in more urbanized areas. Tadarida brasiliensis positively responded to urbanization and was less active in areas with degraded water quality. We show that bat–water quality relationships found at the local scale are evident at a landscape scale. We confirm that bats are useful bioindicators for both urbanization and water quality degradation. We suggest that water quality can be used to predict the presence of bat species of conservation concern, such as P. subflavus, in areas where it has not been studied locally.     

Fungal degradation of pine and straw alkali lignins

Summary Kraft pine and straw lignins were fractionated into aqueous soluble and organic soluble-ether insoluble parts. Chemical analysis, UV characteristics, and gel permeation chromatograms of crude and fractionated lignins were studied. Using pure and mixed, N-limited and non N-limited standing cultures of several fungal species, the biodegradability of curde and fractionated lignins was compared. Straw lignins, especially the aqueous fraction were degraded by most of the fungi studied. Except for Sporotrichum pulverulentum, nitrogen limitation did not seem to favour degradation. The best fungi for degradation under conditions of N-limitation were S. pulverulentum, Humicola fuscoatra, and Aspergillus wentii, under sufficient nitrogen: A. wentii, Chaetomium cellulolyticum and H. fuscoatra. The greatest percentage degradation, 55%, was obtained with S. pulverulentum under nitrogen limited conditions from 1 gl^–1 organic soluble-ether insoluble kraft lignin. Gel chromatography showed that the degradation was over the complete molecular size range.     

Solid-state fermentation of sugarcane bagasse with Flammulina velutipes and Trametes versicolor

The mushroom Flammulina velutipes and the white-rot fungus Trametes versicolor were cultivated separately on sugarcane bagasse for 40 days. Trametes versicolor produced laccase and manganese-peroxidase activities, showing a simultaneous degradation of lignin and holocellulose. However, only phenoloxidase activity was found with Flammulina velutipes. A preferential degradation of lignin was detected in F. velutipes, which exhibited a greater reduction in the ratio of weight loss to lignin loss than T. versicolor. A decrease in the syringyl/guaiacyl ratio observed with both fungi indicated the preferential degradation of non-condensed (syringyl-type) lignin units. An increase in the relative abundance of aromatic carboxylic acids suggested that the oxidative transformation of lignin unit side-chains was occurring. This was more noticeable with Flammulina velutipes than with T. versicolor.     

Biotransformation of chlorpyrifos and bioremediation of contaminated soil

Five aerobic consortia capable of degrading chlorpyrifos as a sole carbon source in aqueous medium showed degradation in the range of 46–72% after 20 days. Pseudomonas fluorescence, Brucella melitensis, Bacillus subtilis, Bacillus cereus, Klebsiella species, Serratia marcescens and Pseudomonas aeroginosa, isolated from these consortium, showed 75–87% degradation of chlorpyrifos as compared to 18% in control after 20 days of incubation. Bioremediation of chlorpyrifos-contaminated soil with P. fluorescence, B. melitensis, B. subtilis and P. aeroginosa individually showed 89%, 87%, 85% and 92% degradation, respectively, as compared to 34% in control after 30 days. Population dynamics of the introduced isolates based on antibiotic resistance survival and REP-PCR indicated 60–70% survival based on antibiotic resistance, but only 35–45% of the inoculated population based on REP-PCR. During bioremediation studies, 3,5,6-trichloro-2-pyridinol (TCP) was detected as metabolite of chlorpyrifos degradation by P. aeroginosa after 20 days, which was utilized and disappeared after 30 days. Whole-cell studies also showed that P. aeroginosa gave TCP as the product of chlorpyrifos degradation, which was further metabolized to unknown polar metabolites.

Scientific relevance

Potential application in sites for effective in situ bioremediation of chlorpyrifos, a neurotoxic insecticide widely used in India.     

微生物菌剂对秸秆降解及秸秆中微生物变化规律的影响

为明确不同微生物菌剂对秸秆降解率及秸秆降解过程中秸秆周围微生物变化规律的影响，在温室大棚内进行不同微生物菌剂降解秸秆试验。以玉米秸秆为基质，设玉米秸秆（对照组）、玉米秸秆+哈茨木霉（Trichoderma harzianum）（处理1）、玉米秸秆+哈茨木霉+地衣芽胞杆菌(Bacillus licheniformis)（处理2）三个处理。研究结果显示，单独用哈茨木霉处理可显著提高秸秆降解率，前期作用尤其明显；在秸秆降解的前30 d，秸秆降解率与秸秆中可培养真菌、细菌、放线菌呈显著正相关。不同微生物菌剂对秸秆中可培养微生物数量变化有显著影响，单独接种哈茨木霉后，秸秆中可培养真菌、细菌、放线菌数在前30 d显著高于对照组和混合菌剂处理，不同处理可培养活菌数均在90～120 d达到峰值，然后开始下降。研究结果表明，不同微生物菌剂对秸秆降解有显著影响，单独用哈茨木霉处理可显著提高秸秆降解率；不同处理对秸秆中可培养真菌、细菌、放线菌的影响有显著差异。可为秸秆降解与微生物相关性研究提供参考。     

1株四环素降解菌的分离鉴定及降解特性研究

应用微生物降解四环素具有经济有效和环境友好特点,已成为当前研究的热点。采用选择性培养基,从鸡粪中分离出1株能以四环素作为唯一碳源生长的菌株TC-1,培养7 d降解率为56.2%,初步鉴定为蜡状芽胞杆菌(Bacillus cereus)。从碳氮源组合、培养基初始pH、Na Cl浓度和装液量四方面研究了TC-1降解四环素的特性。结果表明,TC-1在以葡萄糖和酵母粉为碳、氮源生长时效果最优,培养7 d时OD600达2.17;但最优降解率出现在蔗糖和大豆蛋白胨的碳氮源组合中,为46.8%。当培养基初始pH为7时,菌株TC-1生长最好,OD600为0.44,四环素降解率为92.3%。当培养基中Na Cl浓度达15 g/L时,TC-1生长受到抑制,降解率仅为28.6%;培养基装液量为40%时降解率最高,为56.2%。     

Photo-oxidative Degradation of Chlorophyll-a and Unsaturated Lipids in Liposomal Dispersions at Low-Temperature

Liposomal dispersions in water were used as a tool to study photo-oxidation of chlorophyll-a and photo-oxidation of unsaturated lipids at 1 or 4°C. The presence of monogalactosyl diglyceride stimulated chlorophyll-a degradation. In addition the level of linolenic acid was decreased in liposomal dispersions containing chlorophyll-a, dipalmitoyl phosphatidyl choline, and monogalactosyl diglyceride, indicating that monogalactosyl diglyceride and chlorophyll-a were coupled in the preparations. In liposomal dispersions containing equal (molar) quantities of a-tocopherol, monogalactosyl diglyceride, and chlorophyll-a, a-tocopherol fully protected linolenic acid against photo-oxidative degradation, while chlorophyll-a degradation was only slightly reduced. In liposomal preparations containing a-tocopherol, chlorophyll-a and phosphatidyl choline, a-tocopherol catalyzed degradation of chlorophyll-a. Absorption spectra of the liposomal dispersions showed that the presence of a-tocopherol caused increased absorption in red light, which was attributed to structural changes in the liposomal preparations and thus could explain the noted effects. Tocopherol itself was rapidly degraded in chlorophyll-a containing liposomal preparations. Complex formation between chlorophyll-a and monogalactosyl diglyceride in chloroplasts is suggested and protection by a-tocopherol against photo-oxidation in chilling-sensitive plants; a suggestion which is founded on the similarities that exist between chloroplast preparations and liposomal preparations containing chlorophyll-a and monogalactosyl diglyceride as regards photo-oxidative degradation of chlorophyll-a, a-tocopherol and linolenic acid.     

Degradation Kinetics of Caffeine and Related Methylxanthines by Induced Cells of <Emphasis Type="Italic">Pseudomonas</Emphasis> sp.

In this study, the kinetics of degradation of caffeine and related methylxanthines by induced cells of Pseudomonas sp. was performed. The kinetics data showed that degradation of caffeine, theobromine, and 7-methylxanthine followed Michealis–Menten kinetics. The values of K _m are low for caffeine and 7-methylxanthine and high for theobromine. Degradation of caffeine and theobromine was enhanced in the presence of NADH and NADPH, whereas the degradation of 7-methylxanthine was unaffected. Among the various metal ions tested, Fe²⁺ was found to enhance the rate of degradation for all three substrates, whereas Zn²⁺ and Cu²⁺ inhibited the degradation of caffeine and theobromine but not 7-methylxanthine. The differences in kinetic parameters and cofactor requirement suggest the possibility of the involvement of more than one N-demethylases in the caffeine catabolic pathway in Pseudomonas sp. The induced cells can serve as effective biocatalysts for the development of biodecaffeination techniques.     

Biodegradation of 4-chlorobiphenyl by using induced cells and cell extract of Burkholderia xenovorans

This study aimed to evaluate the efficiency of Burkholderia xenovorans LB400 cells and their cell extract to remediate 4-chlorobiphenyl (4-CB). The bacterium previously induced with 4-CB was able to degrade up to 98% of initial 50 mg L^?1 of 4-CB from mineral medium within 96 h of incubation. The degradation of 4-CB occurred through the formation of meta-cleavage product 2-hydroxy-6-oxo-6phenylhexa-2,4-dienoic acid (HOPDA), as revealed through enzymatic assay of 2,3-dihydroxybiphenyl 1,2-dioxygenase (2,3-DHBD). A derivative of 1,2-benzenedicarboxylic acid was observed as one of the major intermediate metabolites of 4-CB degradation. Time course production of 2,3-DHBD during growth corresponds with the degradation pattern of 4-CB by the bacterium. In vitro degradation of 4-CB using cell extract of B. xenovorans showed complete degradation of initial 25 mg L^?1 of 4-CB within 6 h of incubation. To the best of the authors' knowledge, this is the first report in which in vitro degradation of 4-CB using cell extract of Burkholderia xenovorans is presented.     

Metabolism of α-Glyceryl Ethers by Crithidia fasciculata. I. Study of the In Vivo Degradation of Exogenous Chimyl and Batyl Alcohols1

ABSTRACT. [¹⁴C]chimyl and [³H]batyl alcohols were added to Crithidia fasciculata cultures during the mid-log phase of cell growth, and the lipid extracts of the cells were analyzed for degradation products. C. fasciculata cells were able to take up exogenous glyceryl ethers, and in amounts as high as the endogenous lipid content. The glyceryl ether taken up by the cells was incorporated into lipids either prior to the ether bond cleavage or after degradation to fatty acid. The extent of degradation and the degree of incorporation of degradation products into cellular lipid were higher for chimyl than for batyl alcohol. Batyl alcohol was not metabolized efficiently, leading to the formation of large intracellular pools of free substrate. One product of glyceryl ether degradation was identified as alkyl-dihydroxy acetone, and was detected inside and outside of the cells. The data strongly suggest that this product is the first stable intermediate in the degradation process and indicate that the extracellular formation of alkyl-dihydroxy acetone is due to the action of exocnzyme; ecteted by the cells. The constant detection of alk I cnyl glycerol among the degradation products indicates the existence of a second mechantsm in C. fasciculata for converting the alkyl-to alkenyl-glycerol.     

Protein degradation in C3 and C4 plants with particular reference to ribulose bisphosphate carboxylase and glycolate oxidase

Determining the degradation characteristics of proteins is difficult due to the lack of appropriate methodologies, particularly in the case of leaf proteins. Previous studies suggest that ribulose bisphosphate carboxylase (RuBP carboxylase; EC 4.1.1.39) proteolysis may be fundamentally different in C3 and C4 plants. To test this hypothesis, the relative degradation rates of the total soluble protein, RuBP carboxylase and glycolate oxidase (EC 1.1.3.1) in the second leaves of intact C3 (Triticum aestivum L.) and C4 (Zea mays L) and Sorghum bicolor L.)plants was measured. The methodology utilized involved an efficient procedure to label the leaf proteins, the use of a double-labelling method to measure protein degradation and a single-step purification of the labelled proteins under study. RuBP carboxylase is subjected to continuous degradation in all plants investigated. Its rate of degradation is higher for Z. mays, intermediate for T. aestivum and lower for S. bicolor. When the rate of RuBP carboxylase degradation was compared with that of the total soluble protein a differential pattern was obtained for the plant species examined: whereas maize presents a faster rate of RuBP carboxylase degradation than of the total soluble protein, wheat and sorghum show similar rates. However, the rate of RuBP carboxylase proteolysis in the three plant species studied is much lower than the rate of glycolate oxidase degradation. The results obtained indicate that, under the conditions of study, the degradation characteristics of plant RuBP carboxylase, as those of glycolate oxidase, are species specific, in a way suggesting that they do not depend on the type of photosynthetic metabolism of the species considered (C3 or C4).