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1.
Whittaker P Fry FS Curtis SK Al-Khaldi SF Mossoba MM Yurawecz MP Dunkel VC 《Journal of agricultural and food chemistry》2005,53(9):3735-3742
Capillary gas chromatography (GC) with flame ionization detection was used to determine the cellular fatty acid profiles of various food-borne microbial pathogens and to compare the fatty acid profiles of spores and vegetative cells of the same endospore-forming bacilli. Fifteen bacteria, representing eight genera (Staphylococcus, Listeria, Bacillus, Yersinia, Salmonella, Shigella, Escherichia, and Vibrio) and 11 species were used to compare the extracted fatty acid methyl esters (FAMEs). Endospore-forming bacilli were processed to obtain pure spores and whole cell FAMEs for GC analysis. A data set for each bacterial agent was prepared using fatty acid profiles from five replicates prepared on different days. The results showed that these fatty acid intensity profiles were unique for each of the 11 species and that they could be used as a fingerprint for the organisms. The cellular fatty acid profiles for Bacillus anthracis and Bacillus cereus show that there are two branched chain fatty acids, iso 17:1 omega10c and 17:1 anteiso, which are unique in these species. Iso 17:1 omega10c is present in B. cereus vegetative cells and spores but is not observed in B. anthracis. The 17:1 anteiso fatty acid is present in B. anthracis cells but not in B. cereus cells. Fatty acids 16:0 2OH and 17:0 iso 3OH are present in B. anthracis and B. cereus spores but not in the vegetative cells. In summary, analysis of FAMEs from bacteria and spores can provide a sensitive procedure for the identification of food-borne pathogens. 相似文献
2.
Araújo FD Esper LM Kuaye AY Sircili MP Marsaioli AJ 《Journal of agricultural and food chemistry》2012,60(2):585-592
A chemical study of acyl-homoserine lactones (acyl-HSLs) produced by Enterobacter sakazakii resulted in the identification of three molecules: (S)-N-heptanoyl-HSL, (S)-N-dodecanoyl-HSL and (S)-N-tetradecanoyl-HSL. Mixed cultures of E. sakazakii and Bacillus cereus depleted E. sakazakii acyl-HSLs, suggesting acyl-HSL degradation by B. cereus hydrolases (hydrolysis of the lactone or amide moiety). The expression of B. cereus acyl-HSL lactonase and acyl-homoserine acylase was confirmed by monitoring the biotransformation of (S)-N-dodecanoyl-HSL into (S)-N-dodecanoyl-homoserine, dodecanoic acid and homoserine in the presence of B. cereus whole cells, using electrospray-mass spectrometry (ESI-MS). 相似文献
3.
Ten lots of mapará (Hypophthalmus sp.), captured from the Amazon River, Brazil, were analyzed for their lipid content and fatty acid composition. This knowledge would allow for the development of adequate processing methods and the formulation of therapeutic diets. Separation into neutral and phospholipids was accomplished by silica-gel column chromatography. Fat from the muscular tissue and from the orbital cavity of the mapará was analyzed by high-resolution gas chromatography-mass spectrometry in two different seasonal periods. There were high levels of saturated and monounsaturated fatty acids in the total and neutral lipid with the principal components 16:0, 18:1omega9, 18:0, 16:1omega7, 14:0, 18:3omega3, and 18:1omega7 in both seasons. In the phospholipids there was a high level of polyunsaturated fatty acids, including primarily 16:0, 18:1omega9, 18:0, 16:1omega7, 22:6omega3, 20:4omega6, 18:3omega3, and 20:5omega3. The ratio omega3/omega6 was the same in the muscular tissue and in the orbital cavity, in both seasonal periods. The muscle tissue could be used in diets that need high levels of polyunsaturated fatty acids, but use of the head to produce an omega3 fatty-acid-rich oil still requires greater study with respect to its economic viability. 相似文献
4.
This study investigated the possibility of fingerprinting different organic wastes (cow, pig and horse manure) and the vermicomposts produced by different earthworm species (Eisenia andrei, Eudrilus eugeniae and Lumbricus rubellus) analyzing the profiles of fatty acid methyl esters (FAMEs). We found clear differences between their microbial communities, demonstrating the power and sensitivity of the total FAME analysis. In addition, qualitative and quantitative analyses of specific biomarkers permitted to determine differences between samples and to evaluate the effect of earthworms in the decomposition of organic matter. Fatty acid profiles were largely determined by the different vermicomposting earthworm species. Fatty acid 18:2ω6 increased significantly in horse manure vermicomposted by L. rubellus and in cow manure vermicomposted by the three earthworm species, whereas it decreased significantly in pig manure vermicomposted by L. rubellus and E. eugeniae. Fatty acid 20:4ω6 increased significantly in all vermicomposts obtained with the three earthworm species. 相似文献
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6.
J.M. Meriles S. Vargas Gil C. Conforto G. Figoni E. Lovera G.J. March C.A. Guzmn 《Soil & Tillage Research》2009,103(2):271
This work analyzes the direct effect of soil management practices on soil microbial communities, which may affect soil productivity and sustainability. The experimental design consisted of two tillage treatments: reduced tillage (RT) and zero tillage (ZT), and three crop rotation treatments: continuous soybean (SS), corn–soybean (CS), and soybean–corn (SC). Soil samples were taken at soybean planting and harvest. The following quantifications were performed: soil microbial populations by soil dilution plate technique on selective and semi-selective culture media; microbial respiration and microbial biomass by chloroform fumigation-extraction; microbial activity by fluorescein diacetate hydrolysis; and fatty acid methyl ester (FAME) profiles. Soil chemical parameters were also quantified. Soil organic matter content was significantly lower in RT and SS sequence crops, whereas soil pH and total N were significantly higher in CS and SC sequence crops. Trichoderma and Gliocladium populations were lower under RTSS and ZTSS treatments. Except in a few cases, soil microbial respiration, biomass and activity were higher under zero tillage than under reduced tillage, both at planting and harvest sampling times. Multivariate analyses of FAMEs clearly separated both RT and ZT management practices at each sampling time; however, separation of sequence crops was less evident. In our experiments ZT treatment had highest proportion of 10Me 16:0, an actinomycetes biomarker, and 16:1ω9 and 18:1ω7, two fatty acids associated with organic matter content and substrate availability. In contrast, RT treatment had highest content of branched biomarkers (i15:0 and i16:0) and of cy19:0, fatty acids associated with cell stasis and/or stress. As cultural practices can influence soil microbial populations, it is important to analyze the effect that they produce on biological parameters, with the aim of conserving soil richness over time. Thus, in a soybean-based cropping system, appropriate crop management is necessary for a sustainable productivity without reducing soil quality. 相似文献
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8.
Two complementary studies were performed to examine (1) the effect of 18 years of nitrogen (N) fertilization, and (2) the effects of N fertilization during one growing season on soil microbial community composition and soil resource availability in a grassland ecosystem. N was added at three different rates: 0, 5.44, and 27.2 g N m−2 y−1. In both studies, Schizachyrium scoparium was the dominant plant species before N treatments were applied. Soil microbial communities from each experiment were characterized using fatty acid methyl ester (FAME) analysis. Discriminant analysis of the FAMEs separated the three N fertilizer treatments in both experiments, indicating shifts in the composition of the microbial communities. In general, plots that received N fertilizer at low or high application rates for 18 years showed increased proportions of bacterial FAMEs and decreased fungal FAMEs. In particular, control plots contained a significantly higher proportion of fungal FAMEs C18:1(cis9) and C18:2(cis9,12) and of the arbuscular mycorrhizal fungal (AMF) FAME, C16:1(cis11), than both of the N addition treatment plots. A significant negative effect of N fertilization on the AMF FAME, C16:1(cis11), was measured in the short-term experiment. Our results indicate that high rates of anthropogenic N deposition can lead to significant changes in the composition of soil microbial communities over short periods and can even disrupt the relationship between AMF and plants. 相似文献
9.
基于组成特性的肉骨粉种属鉴别标志性变量挖掘 总被引：1，自引：1，他引：0
为了全面表征不同种属肉骨粉的组成特性，并进一步挖掘肉骨粉种属鉴别标志性变量，研究基于166个来源可靠的不同种属肉骨粉样本（猪、鸡、牛、羊源），从基本组分、元素组成、脂肪酸组成和氨基酸组成4个方面全面获取物料组成特性信息。对比分析不同种属肉骨粉的69个组成变量，其中31个组成变量在种属间差异性显著（P<0.05）。主成分分析（Principal Component Analysis，PCA）结合偏最小二乘判别分析（Partial Least Square-Discriminant Analysis，PLS-DA）对肉骨粉种属间特异性进行探索性分析。结果表明，元素组成和脂肪酸组成可以为猪、鸡、牛、羊肉骨粉提供特异性组成标志变量；氨基酸组成是反刍动物肉骨粉的特异性组成标志变量来源。综合PLS-DA和单因素方差分析结果，以VIP值大于1，P<0.05为指标，研究获取了不同种属肉骨粉之间的特异性组成标志变量，分别为：C10∶0、C18∶0、C18∶2n6c（猪肉骨粉）；Ca、K、Zn、C18∶0、C18∶2n6c（鸡肉骨粉）；Sr、C14∶1、C17∶0、C17∶1、C18∶0、C18∶2n6t（牛肉骨粉）；H、Mg、Sr、C10∶0、C16∶0、C17∶0、C17∶1、C18∶0（羊肉骨粉）；Sr、Ba、C14∶1、C17∶0、C15∶0、C17∶1、C18∶0、C18∶2n6t、C18∶2n6c、丝氨酸（反刍动物肉骨粉）；K、Zn、C18∶0、C18∶2n6c（哺乳动物肉骨粉）。该研究可以为肉骨粉种属鉴别方法及其多元应用机理分析提供数据支持，并可以为肉骨粉多元应用细化至不同种属提供理论基础。 相似文献
10.
Factors affecting reduction of selenate to elemental selenium in agricultural drainage water by Enterobacter taylorae 总被引：1，自引：0，他引：1
Microbial reduction of selenate [Se(VI)] to elemental selenium [Se(0)] is a useful technique for removing Se from agricultural drainage water. A series of batch experiments were conducted in the laboratory to determine the effects of yeast extract (50-1000 mg/L), salinity (EC, 5-75 dS/m), and NO(3)(-) (5-100 mg/L) on the removal of Se(VI) (2000 microg/L) from drainage water by Enterobacter taylorae. Results showed that relatively high amounts of yeast extract (500 mg/L) were needed for E. taylorae to effectively reduce Se(VI) to Se(0). During a 7-day experiment, approximately 95% of added Se(VI) was reduced to Se(0) in the low-salinity drainage water (5 dS/m) with NO(3)(-) values of 5-50 mg/L. In the high-salinity drainage water (50-75 dS/m), reduction of Se(VI) to Se(0) was limited. E. taylorae was also capable of reducing Se(VI) to Se(0) in the San Joaquin Valley drainage water, with a reduction of the added Se(VI) to Se(0) (73.8%) and Se(-II) (20%). This study suggests that E. taylorae may be used to treat Se(VI)-contaminated drainage water in the field. 相似文献
11.
Turner C Whitehand LC Nguyen T McKeon T 《Journal of agricultural and food chemistry》2004,52(1):26-32
The aim of this work was to optimize a supercritical fluid extraction (SFE)/enzymatic reaction process for the determination of the fatty acid composition of castor seeds. A lipase from Candida antarctica (Novozyme 435) was used to catalyze the methanolysis reaction in supercritical carbon dioxide (SC-CO(2)). A Box-Behnken statistical design was used to evaluate effects of various values of pressure (200-400 bar), temperature (40-80 degrees C), methanol concentration (1-5 vol %), and water concentration (0.02-0.18 vol %) on the yield of methylated castor oil. Response surfaces were plotted, and these together with results from some additional experiments produced optimal extraction/reaction conditions for SC-CO(2) at 300 bar and 80 degrees C, with 7 vol % methanol and 0.02 vol % water. These conditions were used for the determination of the castor oil content expressed as fatty acid methyl esters (FAMEs) in castor seeds. The results obtained were similar to those obtained using conventional methodology based on solvent extraction followed by chemical transmethylation. It was concluded that the methodology developed could be used for the determination of castor oil content as well as composition of individual FAMEs in castor seeds. 相似文献
12.
脂多糖（LPS）在革兰氏阴性细菌中的功能作用在不同菌株中已有研究,但尚未有对肠杆菌属LPS结构与功能的报道。本研究试图构建能引起肥胖的阴沟肠杆菌B29菌株waaL和waaG基因的缺失突变株,以了解突变体菌株产生的LPS结构与活性与野生菌株产生的LPS的差异。根据同源重组技术原理,利用广宿主自杀性质粒构建成敲除载体pKNG101△waaL和pKNG101△waaG,转化E.coli SM10菌株,并与B29菌株进行双亲杂交,再以抗生素和蔗糖筛选条件筛选waaL和waaG基因缺失突变株;利用多重PCR、ERICPCR、PCR-DGGE、DNA测序结果均证实突变株B29△waaL和B29△waaG构建成功;最后,对野生菌株B29与两个突变株生物学特性的差异进行了比较。银染实验结果表明野生型B29菌株的脂多糖为光滑型结构,突变株的LPS结构明显缺失O抗原,B29△waaG突变株同时还缺失了外部核心部分;用鲎试剂法检测LPS的内毒素活性显示,突变株的内毒素活性与野生型相比有较大幅度下降;B29△waaL突变株的生长速率与野生型相当,而B29△waaG突变株的生长速率则相对降低。本研究成功构建两种内毒素活性下降的突变株,为下一步利用突变株研究B29菌株在肥胖发生中的机制奠定基础。 相似文献
13.
Fatty acid methyl ester (FAME) profiles, together with Biolog substrate utilization patterns, were used in conjunction with
measurements of other soil chemical and microbiological properties to describe differences in soil microbial communities induced
by increased salinity and alkalinity in grass/legume pastures at three sites in SE South Australia. Total ester-linked FAMEs
(EL-FAMEs) and phospholipid-linked FAMEs (PL-FAMEs), were also compared for their ability to detect differences between the
soil microbial communities. The level of salinity and alkalinity in affected areas of the pastures showed seasonal variation,
being greater in summer than in winter. At the time of sampling for the chemical and microbiological measurements (winter)
only the affected soil at site 1 was significantly saline. The affected soils at all three sites had lower organic C and total
N concentrations than the corresponding non-affected soils. At site 1 microbial biomass, CO2-C respiration and the rate of cellulose decomposition was also lower in the affected soil compared to the non-affected soil.
Biomarker fatty acids present in both the EL- and PL-FAME profiles indicated a lower ratio of fungal to bacterial fatty acids
in the saline affected soil at site 1. Analysis of Biolog substrate utilization patterns indicated that the bacterial community
in the affected soil at site 1 utilized fewer carbon substrates and had lower functional diversity than the corresponding
community in the non-affected soil. In contrast, increased alkalinity, of major importance at sites 2 and 3, had no effect
on microbial biomass, the rate of cellulose decomposition or functional diversity but was associated with significant differences
in the relative amounts of several fatty acids in the PL-FAME profiles indicative of a shift towards a bacterial dominated
community. Despite differences in the number and relative amounts of fatty acids detected, principal component analysis of
the EL- and PL-FAME profiles were equally capable of separating the affected and non-affected soils at all three sites. Redundancy
analysis of the FAME data showed that organic C, microbial biomass, electrical conductivity and bicarbonate-extractable P
were significantly correlated with variation in the EL-FAME profiles, whereas pH, electrical conductivity, NH4-N, CO2-C respiration and the microbial quotient were significantly correlated with variation in the PL-FAME profiles. Redundancy
analysis of the Biolog data indicated that cation exchange capacity and bicarbonate-extractable K were significantly correlated
with the variation in Biolog substrate utilization patterns.
Received: 8 March 2000 相似文献
14.
M M Rebolloso-Fuentes A Navarro-Pérez F García-Camacho J J Ramos-Miras J L Guil-Guerrero 《Journal of agricultural and food chemistry》2001,49(6):2966-2972
The nutritional composition of the marine eustigmatophyte Nannochloropsis spp. cultured in an indoor chemostat under continuous illumination was analyzed. Proximate composition, (moisture, ash, crude protein, available carbohydrates, fiber, lipids, and energy), nitrate, nucleic acid, mineral element (Na, K, Ca, Mg, Fe, Cu, Zn, Mn, Pb, Cd, Cr, Ni, Co, and S), fatty acid, and pigment (carotenoids and chlorophyll) concentrations were determined. On average, the biomass contained 37.6% (w/w) available carbohydrates, 28.8% crude protein, and 18.4% total lipids. Mineral in 100 g of dry biomass were as follows: Ca (972 mg), K (533 mg), Na (659 mg), Mg (316 mg), Zn (103 mg), Fe (136 mg), Mn (3.4 mg), Cu (35.0 mg), Ni (0.22 mg), and Co (<0.1 mg). Toxic heavy metal contents (Cd and Pb) were negligible. Fatty acid content was as follows (on percent dry weight): 0.6% of 14:0, 5.0% of 16:0; 4.7% of 16:1omega7, 3.8% of 18:1omega9, 0.4% of 18:2omega6; 0.7% of 20:4omega6, and 2.2% of 20:5omega3. Nutrient composition of the biomass was highly influenced by residence time in the photobioreactor. The biomass harvested for short residence times was richer in protein and eicosapentaenoic acid than biomass harvested for high residence time. 相似文献
15.
Robert P Larkin 《Soil biology & biochemistry》2003,35(11):1451-1466
The effects of 11 different 2- and 3-yr potato crop rotations on soil microbial communities were characterized over three field seasons using several techniques. Assessments included microbial populations determined by soil dilution plate counts on various general and selective culture media, microbial activity by fluorescein diacetate (FDA) hydrolysis, single carbon source substrate utilization (SU) profiles, and fatty acid methyl ester (FAME) profiles. Potato rotation crops evaluated in research plots at Newport, ME, included barley/clover, canola, green bean, millet, soybean, sweet corn, and a continuous potato control. Soil populations of culturable bacteria and overall microbial activity tended to be highest following barley, canola, and sweet corn rotations, and lowest with continuous potato. Differences among rotations were less apparent during the potato phase of the rotations. Populations of actinomycetes and fluorescent pseudomonads tended to be greater in barley rotations than in most other rotations. SU profiles derived from BIOLOG GN2 plates indicated that certain rotations, including barley, canola, and sweet corn tended to have higher overall microbial activity, and barley and sweet corn rotations averaged higher substrate richness and diversity. Soybean and potato rotations tended to have lower substrate richness and diversity. Principal component analyses of SU data revealed differences among rotation soil communities in their utilization of individual carbon sources and substrate guilds, including carbohydrates, carboxylic acids, amines/amides, and amino acids. Analyses of soil FAME profiles demonstrated distinct differences among all the rotation soils in their relative composition of fatty acids, indicating differences in their microbial community structure. Fatty acids most responsible for differentiation among rotation soils included 16:1 ω5c, 16:1 ω7c, 18:2 ω6c, 18:1 ω9c, 12:0, and 13:0 anteiso, with 16:1 ω5c being the single greatest determinant. Overall, monounsaturated fatty acids, particularly 16:1 ω5c, were most prevalent in sweet corn rotations and polyunsaturates were highest in barley and millet rotations. Straight chain saturated fatty acids comprised the greatest proportion of fatty acids in soils under continuous potato. FAME biomarkers for microorganism groups indicated barley and millet rotations had the highest ratio of fungi to bacteria, and soybean and continuous potato had the lowest ratio. This research has demonstrated that different crop rotations have distinctive effects on soil microbial communities that are detectable using a variety of techniques. Further studies will identify more specific changes associated with particular rotations and relate these changes to potential effects on disease management, crop health, and crop productivity. 相似文献
16.
为了改善奶酪品质,奶酪生产过程中通常会添加脂肪酶或者产脂肪酶乳酸菌来提升产品品质。该研究以前期筛选的4株高产脂肪酶乳酸菌为发酵剂,分别随机选取3株乳酸菌复配制作酸凝奶酪。试验组：A组T1-5和T1-3属融合魏斯氏菌（Weissella confusa）、H1-6属瑞士乳杆菌（Lactobacillus helveticus）,B组H1-6、T1-5、B2-5属植物乳杆菌（Lactobacillus plantarum）,C组H1-6、T1-3、B2-5,D组T1-3、T1-5、B2-5,对照组（E组）（添加商业发酵剂）,分析发酵剂对传统奶酪pH值、滴定酸度和脂肪氧化情况的影响,并利用气相色谱法（Gas Chromatography,GC）检测奶酪中脂肪酸变化、利用气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Chromatography,GC-IMS）分析奶酪中风味物质的变化。结果表明：A,B,C,D组4组奶酪的pH值、过氧化值（Peroxide value,POV值）明显低于E组（对照组）（P < 0.05）,A,B组奶酪滴定酸度比对照E组高（P < 0.05）;A,B,C,D组奶酪中饱和脂肪酸（Saturated Fatty Acids,SFA）含量、单不饱和脂肪酸（Monounsaturated Fatty Acids,MUFA）含量和多不饱和脂肪酸（Polyunsaturated Fatty Acids,PUFA）含量均显著高于E组（P < 0.05）;4个试验组样品中亚油酸（C18∶2n6c）含量明显高于对照组（E组）（P < 0.05）。GC-IMS及主成分分析结果显示,A、B组奶酪挥发性风味物质种类多,且相似度较高,其中2-庚酮、丁醛、乙酸丁酯是主要呈味物质;C、E两组奶酪中风味物质比较相似,风味物质主要以乙酸乙酯、乙酸丙酯、己酸乙酯等酯类为主;D组与其他4组有所差异,主要挥发性风味物质为乙酸丁酯、3-辛酮、庚醛等。结合感官评定,A、B两组奶酪整体风味和口感较好,评分较高。筛选得到的产脂肪酶乳酸菌可以作为发酵剂用于提升新疆传统奶酪品质。 相似文献
17.
Integrated crop and livestock (ICL) agroecosystems are characterized by a mixture of perennial or annual vegetation grazed by livestock and annual harvested crops. Compared to annual crops, ICLs hold the potential to enhance soil organic matter (OM) inputs, carbon sequestration, nutrient cycling, and water conservation. Soil fungi play an essential role in the transformation of OM and nutrients and soil structure stabilization; however their specific role in OM transformations in ICL agroecosystems has not been studied. This study evaluated mycorrhizal and saprophytic fungal populations (via fatty acid methyl ester profiles; FAME) and saprophytic fungal functionality (via FungiLog analysis) under two ICL agroecosystems and a continuous cotton (Gossypium hirsutum L.) system in the Southern High Plains of the U.S. The first ICL system included non-irrigated perennial native grasses, an annual cotton and foxtail millet (Setaria italica) rotation and deficit-irrigated ‘WW-B. Dahl’ old world bluestem (Bothriochloa bladhii; OWB). The second ICL agroecosystem consisted of deficit-irrigated OWB and bermudagrass (Cynodon dactylon). The effect of grazing by cattle was evaluated via grazing exclusion areas. Abundance of saprophytic fungal FAMEs (10–26% of total FAMEs) and mycorrhizal FAMEs (2–24% of total FAMEs) were higher under ICLs compared to the continuous-cotton system at 0–5 cm. Overall, vegetation impacted the distribution of the fungal FAME markers, whereas the fungal saprophytic functionality was more sensitive to grazing. Perennial vegetation of ICLs was associated with an increase in fungal markers (saprophytic and mycorrhizal) as well as increased soil OM content. Greater utilization of multiple C sources and increased saprophytic fungal functional indices were found under cotton, non-grazed perennial vegetation (with exception of bermudagrass) and the rotation under millet. Among the grazed perennial vegetation, bermudagrass showed the highest fungal FAMEs abundance and functional diversity values. These fungal improvements were also reflected in the highest OM content under this grass, potentially indicating improved sustainability under the OWB and bermudagrass agroecosystem. 相似文献
18.
水分条件对水稻土微生物群落多样性及活性的影响 总被引：10，自引：0，他引：10
采用BIOLOG碳素利用法、磷脂脂肪酸（PLFA）法和土壤酶活性测定等方法比较了三种水分条件（淹育、淹育晾干、非淹育）对水稻土微生物群落多样性及活性的影响。结果表明，淹育处理水稻土的脱氢酶、蔗糖酶活性明显高于淹育晾干和非淹育处理，并导致该土壤的基础呼吸升高。BIOLOG碳素利用法表明，非淹育处理的微生物群落平均吸光值（AWCD）显著低于淹育和淹育晾干处理。磷脂脂肪酸（PLFA）实验发现，淹育水稻土的真菌特征脂肪酸（18：2w6，9c）所占比例减少，真菌特征脂肪酸（18：2w6，9c）与细菌特征脂肪酸（15：0i＋15：0a＋16：0i＋16：1w5c＋17：0i＋17：0a＋17：0cy＋17：0＋18：1w7c＋19：0cy）的比值下降；水分条件变化没有改变土壤微生物环丙基脂肪酸19：0cy的相对丰度，但非淹育处理的环丙基脂肪酸17：0cy相对丰度明显高于另外二种处理。BIOLOG碳素利用法的群落水平生理剖面（CLPP）和磷脂脂肪酸（PLFA）测定结果经聚类分析后，发现淹育和淹育晾干处理的土壤微生物多样性在较低的距离尺度可聚成一类，且与非淹育土壤具有明显差异。淹育水稻土与淹育晾干相比，尽管土壤微生物群落结构和功能多样性有一定的相似性，但微生物的种群组成和活性仍发生了较大的变化。 相似文献
19.
Zhang Y Zahir ZA Amrhein C Chang A Frankenberger WT 《Journal of agricultural and food chemistry》2007,55(14):5714-5717
Acceleration of bacterial reduction of selenate [Se(VI)] to insoluble elemental Se [Se(0)] plays an important role in Se bioremediation. Anthraquinone-2,6-disulfonate (AQDS), a redox mediator, was assessed for its ability to enhance the reduction of Se(VI) (2000 microg/L) to Se(0) by Enterobacter taylorae in various media. The results showed that addition of AQDS did not increase Se(VI) reduction in the media containing 50 and 250 mg/L yeast extract, suggesting that E. taylorae cannot directly use anthrahydroquinone-2,6-disulfonate (AHQDS, a reduced form of AQDS) to respire Se(VI). An increase of yeast extract concentration from 50 to 250 mg/L in the medium dramatically enhanced the AQDS function for rapid reduction of selenite [Se(IV)] to Se(0). During an 8-day experiment, 85-91% of the added Se was reduced to Se(0) in the AQDS-amended medium in comparison to formation of 46% of Se(0) in the medium without AQDS. These results show that redox mediators have great application potential in bioremediation of Se in Se-contaminated water. 相似文献
20.
J.C. Aciego Pietri 《Soil biology & biochemistry》2009,41(7):1396-1405
Our aim was to determine whether the smaller biomasses generally found in low pH compared to high pH arable soils under similar management are due principally to the decreased inputs of substrate or whether some factor(s) associated with pH are also important. This was tested in a soil incubation experiment using wheat straw as substrate and soils of different pHs (8.09, 6.61, 4.65 and 4.17). Microbial biomass ninhydrin-N, and microbial community structure evaluated by phospholipid fatty acids (PLFAs), were measured at 0 (control soil only), 5, 25 and 50 days and CO2 evolution up to 100 days. Straw addition increased biomass ninhydrin-N, CO2 evolution and total PLFA concentrations at all soil pH values. The positive effect of straw addition on biomass ninhydrin-N was less in soils of pH 4.17 and 4.65. Similarly total PLFA concentrations were smallest at the lowest pH. This indicated that there is a direct pH effect as well as effects related to different substrate availabilities on microbial biomass and community structure. In the control soils, the fatty acids 16:1ω5, 16:1ω7c, 18:1ω7c&9t and i17:0 had significant and positive linear relationships with soil pH. In contrast, the fatty acids i15:0, a15:0, i16:0 and br17:0, 16:02OH, 18:2ω6,9, 17:0, 19:0, 17:0c9,10 and 19:0c9,10 were greatest in control soils at the lowest pHs. In soils given straw, the fatty acids 16:1ω5, 16:1ω7c, 15:0 and 18:0 had significant and positive linear relationships with pH, but the concentration of the monounsaturated 18:1ω9 PLFA decreased at the highest pHs. The PLFA profiles indicative of Gram-positive bacteria were more abundant than Gram-negative ones at the lowest pH in control soils, but in soils given straw these trends were reversed. In contrast, straw addition changed the microbial community structures least at pH 6.61. The ratio: [fungal PLFA 18:2w6,9]/[total PLFAs indicative of bacteria] indicated that fungal PLFAs were more dominant in the microbial communities of the lowest pH soil. In summary, this work shows that soil pH has marked effects on microbial biomass, community structure, and response to substrate addition. 相似文献