Phospholipid Fatty Acid Profiles of Chinese Red Soils with Varying Fertility Levels and Land Use Histories

Analysis of phospholipid fatty acids (PLFAs) was used to estimate the microbial community structures of eight Chinese red soils with different fertility levels and land use histories. The total amounts of PLFAs in the soils were significantly correlated with soil organic carbon, total nitrogen, microbial biomass C and basal respiration, indicating that total PLFA was closely related to fertility and sustainability in these highly weathered soils. Soils for the eroded wasteland were rich in Gram-positive species. When the eroded soils were planted with citrus trees, the soil microbial population had changed little in 4 years but took up to 8-12 years before it reached a significantly different population. Multivariate analysis of PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure. However, the difference of soil microbial community structure in the paddy field compared to other land uses was not larger than expected in this experiment.

Effect of copper on phospholipid fatty acid composition of microbial communities in two red soils

The phospholipid fatty acid （PLFA） composition was analyzed in two red soils experimentally contaminated with copper at different concentrations. The total amounts ofphospholipid fatty acids （PLFAs） in both red soils were significantly correlated with soil microbial biomass C and N, which decreased consistently with increasing levels of copper. The relative quantities of the PLFAs 17：0 （10 Me）, i16：0, il 5：0 and 16：1w5c, decreased with increasing heavy metal concentration, while those of cyl7：0, which is an indicator of gram-negative bacteria, increased. The Shannon index calculated from the PLFA data indicated that Cu addition in the red soils decreased the population diversity of soil microbial communities. Multivariate analysis of PLFA data demonstrated that high levels of Cu application had a significant impact on microbial community structure and there is a threshold metal concentration for PLFA composition. Comparatively higher toxic effect on microbial biomass and community structure were found in the red sandy soil than those in the red clayey soil. The differential effect of Cu addition on microbial communities in the two soils may be due to differences in soil texture and cation exchange capacity.

Using Phospholipid FattyAcid Technique toAnalysis the Rhizosphere Specific Microbial Community of Seven Hybrid Rice Cultivars

To analyze the intrinsic relationship between rhizosphere microbial community structure and variety of rice, the microbial community structures in rhizosphere of different hybrid rice cultivars were determined with phospholipid fatty acids （PLFA） analysis. Three series of new-breeding hybrid rice cultivars in China were tested in the experiment, Ilyouming 86 （II-32A/Minghui 86）, Ilyouhang 1 （II-32A/Hang 1）, and Ilyouhang 2 （II-32A/Hang 2） with H-32A as female parent, XinyouHK02 （XinA/HK02） and YiyouHK02 （YXA/HK02） with HK02 as male parent, Chuanyou 167 （ChuanxiangA/MR167） and 44you167 （Hunan44A/MR167） with MR167 as male parent. The results showed that the microbial community in rhizosphere of the hybrid rice comprised bacteria, fungi, actinomycetes, and protozoa, according to the 40 PLFA biomarkers detected. Bacteria were more abundant than fungi and actinomycetes in rhizosphere of the hybrid rice tested. Both sulfate-reducing and methane-oxidizing bacteria were found to exist in the hybrid rice rhizosphere. It was also found that the characteristics of PLFA biomarkers had correlation with the biological traits of rice. The cluster analysis suggested that microbial community structure and activity in rhizosphere were associated with genetic background of the rice cultivar.

Hatching egg polyunsaturated fatty acids and the broiler chick

Transgenerational effects of certain nutrients such as essential fatty acids are gaining increased attention in the field of human medicine and animal sciences as a new tool to improve health and animal performance during perinatal life.Omega-3(n-3)and omega-6(n-6)fatty acids are denoted by the position of the first double bond from methyl end of the hydrocarbon chain.Alpha-linolenic acid(18:3 n-3)and linoleic acid(18:2 n-6)are essential n-3 and n-6 fatty acids and cannot be synthesized by the vertebrates including chickens.Alpha-linolenic acid and linoleic acid are the parent fatty acids of long chain(>20–22C)n-3 and n-6 polyunsaturated fatty acids(PUFA)such as eicosapentaenoic acid(20:5 n-3,EPA),docosapentaenoic acid(22:5 n-3/or 22:5 n-6,DPA),docosahexaenoic acid(22:6 n-3,DHA)and arachidonic acid(20:4 n-6).As components of cell membrane phospholipids,PUFA serves as precursors of eicosa-noids,act as ligands for membrane receptors and transcription factors that regulate gene expression and are pivotal for normal chick growth and development.Considering the role of egg lipids as the sole source of essential fatty acids to the hatchling,dietary deficiencies or inadequate in ovo supply may have repercussions in tissue PUFA incorpora-tion,lipid metabolism,chick growth and development during pre and early post-hatch period.This review focus on studies showing how maternal dietary n-3 or n-6 fatty acids can lead to remodeling of long chain n-3 and n-6 PUFA in the hatching egg and progeny chick tissue phospholipid molecular species and its impact on chick growth and PUFA metabolism during early life.

Temperature-Dependent Fatty Acid Composition Change of Phospholipid in Steelhead Trout (Oncorhynchus mykiss) Tissues

In this study, the changes of the fatty acid composition of phospholipid in different tissues(muscle, heart, brain and spleen) of steelhead trout(Oncorhynchus mykiss) were analyzed when the water temperature decreased gradually from 16 to 12℃℃, 8℃, 6℃, 4℃, 2 and 1℃℃. Three fish individuals each tank(average weight 70.32 g ± 9.12 g) were collected and used to analysis at each designed temperatures. At normal temperature(16℃), the fatty acid composition of phospholipid of muscle and heart was similar each other. The highest concentration of saturate fatty acids(SFA) was found in the phospholipid of spleen. The brain phospholipid contained higher oleic acid(18:1 n9) than the phospholipid of other tissues at 16℃. When the environmental temperature decreased, the concentration of unsaturated fatty acids of phospholipids in all tissues increased, and accordingly the ratio pf the unsaturated to saturated fatty acids(U/S) and unsaturation index(UI) increased, indicating that steelhead trout can compensate temperature-dependent changes in membrane fluidity by remodeling the fatty acid composition of phospholipids. The changes in the fatty acid composition of phospholipid were tissue-specific. At the early stages of the experiment(16 to 8℃℃), the fatty acid composition of phospholipid changed remarkably in muscle, heart, and spleen. When temperature decreased to less than 8℃, an obvious response of phospholipid fatty acid was observed in all tissues. The change of phospholipid composition of steelhead trout tissues may be affected by both cold stress and starvation when the temperature decreased to 2℃, and the change of phospholipid composition of muscle was very obvious.

Optimization of High EPA Structured Phospholipids Synthesis from （u-3 Fatty Acid Enriched Oil and Soy Lecithin

The molecular structure of phospholipids can be changed enzymatically to obtain different tailor-made phospholipids. Incorporation of ω-3 fatty acids into phospholipids structure increased their oxidative stability, suggesting more health beneficial phospholipids. This study aimed to optimize eicosapentaenoic acid （EPA） incorporation into phospholipids structure by acidolysis reaction using free lipase （EC 3.1.1.3） from Rhizomucor miehei. Deoiled soy lecithin from anjasmoro variety was used as phospholipids source, while ω-3 fatty acid enriched oil was used as acyl source. Oil enriched with ω-3 fatty acids was obtained from low temperature solvent crystallization of lemuru （Sardinella longiceps） by-product. Response surface methodology （RSM） was used in this study to determine the relationship between the three factors （enzyme concentration, reaction time and substrate ratio） and their effects on EPA incorporation into soy lecithin structure. The results showed that the relation between EPA content with three factors （reaction time, enzyme concentration and substrate ratio） was quadratic. The significant factors were substrate ratio and reaction time. Optimum conditions at a ratio of 3.77：1 between ω-3 fatty acids enriched oil and soy lecithin, 30% lipase concentration, and 24.08 h reaction time, gave 22.81% of EPA content of structured phospholipids.

The effect of high fat food on erythrocyte phospholipids, fatty acids composition and glutathione redox-system of rats with alimentary dyslipidemia

To evaluate the effects of high fat food consisted of tallow (19% of total diets) and cholesterol (2%) on modification of erythrocyte phospholipids, fatty acids composition and glutathione redox- system of male Wistar rats with alimentary dysli- pidemia. The results demonstrated that after 30 and 180 days of high-fat feed erythrocyte phos- phatidylinositol and phosphatidylcholine levels were reduced, phosphatidylserine were in-creased. Only on the 90 days of the experiment phosphatidylinositol level increased. In all grow- ups the erythrocyte 18:0 saturated fatty acids and 20:4n6, 22:4n6 polyunsaturated fatty acids (PUFA) were increased. Deficit of n3 PUFA- 20:5n3 and 22:6n3 after 90 and 180 days high fat feed promoted compensatory synthesis from 18:1n9 on 20:3n9. Erythrocyte maleic dialde-hyde increased, glutathione level decreased in all groups of rats after fed with high-fat feed. Glutathione reductase and glutathione peroxi-dase activity decreased in erythrocytes after 30 and 180 days of high-fat feed. In conclusion: high-fat diet during 30-90 days started adaptive answer in lipids of membrane and glutathione redox-system. Important mechanism of adapta-tion of a cellular membrane to high-fat diet is increase major, structuring a membrane phos-phatidylethanolamine and minor, most meta-bolic significant fractions phospholipids (phos- phatidylinositol), keeps homeostasis of 18:2n6 and 22:6n3, 20:3n9 compensatory synthesis, decrease in activity of processes lipid peroxi-dation, activation of enzymes of redox-system glutathione. But prolonging the high-fat feeding (180 days and more) formed failure compensa-tory processes (dysadaptation). It is a risk factor of developmening atherosclerosis, diabetes, steatogepatitis and other diseases.

Effects of Dietary Phospholipids on Na^+-K^+-ATPase Activity and Cell Membrane Fatty Acid Composition in Gill of Catfish (Pangasius sutchi)

[ Objective] The aim of this study was to determine the effects of dietary phospholipids on Na＋ - K＋ - ATPase activity and cell mem- brane fatty acid composition in the gill of catfish （Pangasius sutchi）. [Method] 900 healthy catfish （1.4 ±0.08 g of average weight） were randomly divided into five groups. Dietary phospholipids level of group PL0 was 0%, and 1%, 2%, 3%, 4% for group PL1, PL2, PL3, PL4, respectively. The experiment lasted for 56 days. [Result] The results showed that the Na＋ -K＋ -ATPase activity in gill decreased gradually with the increase of the dietary phospholipids level （ P 〈0.05）. Cell membrane fatty acid composition was affected significantly by dietary phospholipids. The content of saturated fatty acids and monounsaturated fatty acids of group PLO was the highest （ P 〈 0.05）, however, it had the lowest content of highlyunsatu- rated fatty acids （ P 〈 0.05）. The content of polyunsaturated fatty acids of group 3 was higher than group 0 and group 1 （ P 〈 0.05）. E Conclusion] The results indicated that there is obvious compensation effects on Na＋ -K＋ -ATPase activity with phospholipids content changes in gills of catfish （ Pangasius sutchi） to maintain stable physiological level and normal basal metabolism and the increase of HUFA and ∑PUFA is necessary for gill cell membrane to better maintain and perform normal physiological function.

Olive and Corn Oil Enriched Diets Changed the Phospholipid Fatty Acid Composition in Mice Liver after One-Thirds Hepatectomy

We examined the effect of dietary fats on the kinetics of liver regeneration after one-third partial hepatectomy (PH) in male Balb/c mice. Corn and olive supplemented diets were chosen as a model of n-6 and n-9 diets. Phospholipid fatty acids were determined by gas chromatography (GC) after previous fractionation by solid-phase extraction using aminopropyl (NH2) column, and data were analysed by nonparametric Kruskal-Wallis test. Diet enriched with corn and olive oil did not affect the balance of lipid disorders during liver regeneration after 1/3 PH. Desaturases activity direction has changed depending on the used diet. The key role in the alteration of the polar fatty acids profile at all stages of liver regeneration and examined dietary fats is played by activity of stearoyl-CoA desaturase (SCD).

Plasma Phospholipid Omega-3 Fatty Acids and Freshwater Fish Consumption in the Brazilian Amazon

Background: Amazonian riverside communities consume large quantities of freshwater fish, comparable to marine fish consumption of Inuit, Scandinavian and Japanese populations. Few studies have considered the relation of high freshwater fish consumption and intake of omega-3 fatty acids (FA). Objective: The objective of the present study was to determine the profile of the concentrations of plasma phospholipid FAs and its relation with freshwater fish intake in 12 riverside communities in the Tapajós River basin (State of Pará, Brazilian Amazon). Design: This cross-sectional study included 333 adults (15 - 86 years old). Fish meal frequency was determined using a 7-day interview-administered dietary recall questionnaire. Fish were categorized as piscivorous and non-piscivorous fish on trophic level. Plasma phospholipid FAs were measured by capillary gas-liquid chromatography. Results: Participants consumed 5 to 6 fish meals a week, with twice as many non-piscivorous fish than piscivorous fish (4.4 fish/week vs 2.2 fish/week, respectively). The omega-3 FA levels in plasma phospholipids were low (EPA + DHA = 31.21 mg/L;%EPA + DHA = 2.59%). Omega-3 FAs increased with frequency of fish intake, and particularly with piscivorous fish, controlling for sociodemographic, anthropometric and lifestyle characteristics. DHA levels were greater in women than in men. Conclusions: Omega-3 FA in this Amazonian population increased with fish consumption, but although they consumed freshwater fish almost daily, the concentrations of omega-3 FA were relatively low and comparable to fish-eater communities for which fish is not a dietary mainstay. It is possible that nutrients present in marine, but not in certain freshwater fish species, may facilitate absorption of omega-3 FA. Sex and/or gender differences must be taken into account when assessing the relationship between fish consumption and plasma phospholipid omega-3 FA levels.

Comparison of the fatty acid composition of the serum phospholipids of controls, prediabetics and adults with type 2 diabetes

Objective: Although abnormalities in the fatty acid composition of serum and red cell membrane phospholipids of patients with type 2 diabetes are well-documented, lacking are studies of this issue in prediabetic individuals. Materials/Methods: For this cross-sectional study, we recruited 180 subjects (30 - 80 years), 56 of whom were normal with regard to glucose control (HbA1c, 6.5%). Serum phospholipids were isolated and analyzed for fatty acids. Results: Most importantly, the fatty acid compositions of the controls and prediabetic subjects were not different for 19 fatty acids. However, the fatty acid profile of the phospholipids of the patients with diabetes differed from the other two groups;the 14 to 18-carbon saturated fatty acids were decreased by 12% - 26% whereas the unsaturated fatty acids 16:1n-7, 18:1n-9, 18:2n-6, 20:3n-6 and 20:4n-6 were increased by 45% - 64%. Of note, the docosahexaenoic acid (DHA) status of individuals in all three study groups was remarkably low compared with international values, as indicated by DHA proportions in the 1.62% - 2.07% range, and there were no differences between groups. The mean melting point of the phospholipid fatty acids of the diabetic patients (32.2℃) was significantly lower (p < 0.001) than that of the prediabetic subjects (38.1℃) and the controls (39.9℃) which were not different from each other. Conclusion: These observations indicate that the fatty acid changes associated with type 2 diabetes follow the onset of the disease as opposed to being a causative factor of poor glucose control and insulin insensitivity.

Effects of Subcutaneous Fat Stores on Serum Phospholipids and Nonesterified Fatty Acid Lipid Fractions in Periparturient Dairy Cows

Negative energy balance in early lactating dairy cows results in a massive release of fatty acids （FA） into the blood in nonesterified fatty acids （NEFA） form. Large quantities of circulating NEFA may alter the serum FA profile of phospholipids （PL） fraction, which is responsible for cellular plasma membrane integrity and intercellular signaling. The objective of this study was to determine the effects of subcutaneous fat stores, as assessed by body condition score （BCS） on a scale of one to five, around the time of calving and the subsequent lipomobilization on FA profile of serum NEFA and PL lipid fractions, and on productive performance. Based on BCS, cows were retrospectively dichotomized into two groups： over-conditioned （BCS _〉 3.25） and control （BCS _〈 3.0）. 22 cows had serum samples obtained at -28, -7, 8, 18 and 28 d relative to parturition and analyzed for the FA profile of the NEFA and PL fractions. As expected, over-conditioned cows had greater total plasma NEFA concentrations and decreased dry matter intake. Milk yield and composition did not differ between groups. More importantly however, several FA in the NEFA fraction of plasma lipids varied significantly, including C14：1, C16：0, C18：0 and C20：3n3. In the PL fraction, other FA varied significantly by BCS around time of parturition, including C16：0, C17：0, total C18：2 cis, and C20：2. In summary, BCS did affect FA profile of serum NEFA and PL lipid fractions. This may have drastic consequences for circulating immune cells and their ability to fight infection by altering their FA profile.

Long-Term Effects of Docosahexaenoic Acid-Bound Phospholipids and the Combination of Docosahexaenoic Acid-Bound Triglyceride and Egg Yolk Phospholipid on Lipid Metabolism in Mice

The bioavailability of docosahexaenoic acid(DHA) and eicosapentaenoic acid(EPA) depends on their chemical forms. This study investigated the long-term effects of DHA-bound triglyceride(TG-DHA), DHA-bound phospholipid(PL-DHA), and the combination of TG-DHA and egg yolk phospholipid(Egg-PL) on lipid metabolism in mice fed with a high-fat diet(fat levels of 22.5%). Male C57BL/6J mice were fed with different formulations containing 0.5% DHA, including TG-DHA, PL-DHA, and the combination of TG-DHA and Egg-PL, for 6 weeks. Serum, hepatic, and cerebral lipid concentrations and the fatty acid compositions of the liver and brain were determined. The concentrations of serum total triglyceride(TG), total cholesterol(TC), high-density lipoprotein cholesterol(HDL-c), and hepatic TG in the PL-DHA group and the combination group were significantly lower than those in the high-fat(HF) group(P < 0.05). Atherogenic index(AI) of the PL-DHA group was significantly lower than that of the combination group(P < 0.05). Hepatic TC level in the combination group was significantly lower than that in the HF group(P < 0.05), but no significant difference was observed between the combination group and the PL-DHA group. Both the PL-DHA and the combination groups showed significantly increased DHA levels in the liver compared with the HF group(P < 0.05). However, there were no obvious increases in the cerebral DHA levels in all DHA diet groups. These results suggest that PL-DHA was superior to the combination of TG-DHA and Egg-PL in decreasing the AI. Long-term dietary supplementation with low amount of DHA(0.5%) may improve hepatic DHA levels, although cerebral DHA levels may not be enhanced.

Lipid and Fatty Acid Compositions of Cod (Gadus morhua),Haddock (Melanogrammus aeglefinus) and Halibut (Hippoglossus hippoglossus)

This study was conducted to compare lipid and fatty acid composition of cod,haddock and halibut.Three groups of cod（276 g±61 g）,haddock（538 g±83 g）and halibut（3704 g±221 g）were maintained with commercial feeds mainly based on fish meal and marine fish oil for 12 weeks prior to sampling.The fatty acid compositions of muscle and liver were determined by GC/FID after derivatization of extracted lipids into fatty acid methyl esters（FAME）.Lipids were also fractionated into neutral and polar lipids using Waters silica Sep-Pak（R）.The phospholipid fraction was further separated by high-performance thin-layer chromatography（HPTLC）and the FAME profile was obtained.Results of the present study showed that cod and haddock were lean fish and their total muscle lipid contents were 0.8% and 0.7%,respectively,with phospholipid constituting 83.6% and 87.5% of the total muscle lipid,respectively.Halibut was a medium-fat fish and its muscle lipid content was 8%,with 84% of the total muscle lipid being neutral lipid.Total liver lipid contents of cod,haddock and halibut were 36.9%,67.2% and 30.7%,respectively,of which the neutral lipids accounted for the major fraction（88.1%-97.1%）.Polyunsaturated fatty acids were the most abundant in cod and haddock muscle neutral lipid.Monounsaturated fatty acid level was the highest in halibut muscle neutral lipid.Fatty acid compositions of phospholipid were relatively constant.In summary,the liver of cod and haddock as lean fish was the main lipid reserve organ,and structural phospholipid is the major lipid form in flesh.However,as a medium-fat fish,halibut stored lipid in both their liver and muscle.

The Global Research Progress of Enzymatic Processing of Oils with Omega 3 Polyunsaturated Fatty Acids

This paper has reviewed that Omega 3 polyunsaturated fatty acids (PUFAs), as an essential fatty acids (EFAs), mainly come from fish oil of marine products, has positive effects on treatment and/or prevention of several diseases. In this review, the recent developments by 2019 in the field of enzymatic modification of oils rich in omega 3 PUFAs have summarized. Several different products, such as structured lipids with a variety of FA compositions, nutritional aspects, omega 3 PUFA concentrates and phospholipids,have discussed from the point of process technology as well as possible applications. Enhancing omega 3 PUFA content in diet involves a number of strategies aiming to modify the content of such FAs in fats and oils. Due to the mild reaction conditions used, especially the lipase specificity, the position as well as content of omega 3 PUFAs in lipid molecules being of importance from the point of bioavailability, enzymatic processing of omega 3 PUFA oil is safe, efficient and preferred over chemical treatments.

Potential Roles of Fatty Acids and Lipids in Postharvest Needle Abscission Physiology

Our understanding of postharvest needle abscission physiology in conifers has greatly improved in the last decade. Abscission is initially triggered by root detachment, which begins a cascade of changes such as decreased water uptake, water potential, and auxins and increased membrane injury, ethylene, abscisic acid, volatile terpenes, and catalytic enzymes. Needle abscission is also affected by environmental factors. For example, a period of cold acclimation generally delays postharvest abscission. The aforementioned pieces of evidence, along with previous studies, strongly points to a role for plant lipids and fatty acids. Studies from other species have pointed out key roles in abscission and stress responses for a variety of phospholipids and galactolipids, which has not been studied in balsam fir. It is imperative to have an understanding of the role of plant lipids and fatty acids to further our overall understanding of the physiological mechanisms of postharvest abscission and needle abscission resistance. This review is an overview of membrane lipids and fatty acids, changes that occur postharvest and the interaction that lipids may have in the phenomenon of postharvest abscission.

Effects of Different Chinese Hickory Husk Returning Modes on Soil Nutrition and Microbial Community in Acid Forest Soil

Chinese hickory(Carya cathayensis Sarg.)is an important economic forest in Southeastern China.A large amount of hickory husk waste is generated every year but with a low proportion of returning.Meanwhile,intensive management has resulted in soil degradation of Chinese hickory plantations.This study aims to investigate the effects of three Chinese hickory husk returning modes on soil amendment,including soil acidity,soil nutrition,and microbial community.The field experiment carried out four treatments:control(CK),hickory husk mulching(HM),hickory husk biochar(BC),and hickory husk organic fertilizer(OF).The phospholipid fatty acid(PLFA)biomarker method was employed to determine the soil microbial community.After one year of treatment,the results showed that:(i)HM and BC significantly increased soil pH by 0.33 and 1.71 units,respectively;(ii)HM,BC and OF treatments significantly increased the soil organic carbon,alkaline nitrogen,available phosphorous,and available potassium.The OF treatment demonstrated the most significant improvement in the soil nutrient;(iii)The soil microbial biomass significantly increased in the HM,BC and OF treatments,and all microbial groups showed an increasing trend.HM treatment increased the fungal/bacterial ratio(F/B).The OF treatment significantly decreased the Shannon-Wiener diversity(H’)and evenness index(J)of the microbial community(P<0.05).Considering the treatments effects,costs,and ease of operation,our recommended returning modes of Chinese hickory husk are mulching and organic fertilizer produced by composting with manure.

草原苏尼特羊脑中磷脂型DHA萃取及其结构特性研究

旨在为绿色天然草原羊脑中磷脂型二十二碳六烯酸(DHA-PL)的开发利用提供科学数据,以苏尼特冻干羊脑为原料,采用溶剂萃取其中的粗脂肪,用冰丙酮沉淀得到磷脂,再采用硅胶柱层析法分离其中的磷脂酰胆碱(PC)和磷脂酰丝氨酸(PS)。测定了粗脂肪中胆固醇含量,以及磷脂中PC和PS的含量,分析了粗脂肪、磷脂、PC和PS中DHA含量,以及PC和PS中sn-2位的DHA含量。结果表明:采用体积比2∶1乙醇-正己烷萃取冻干苏尼特羊脑中粗脂肪,粗脂肪得率较高,为45%;羊脑粗脂肪中胆固醇含量为29.42mg/g,粗脂肪的脂肪酸组成中DHA含量为8.89%;磷脂的脂肪酸组成中DHA含量为11.41%;磷脂中PC和PS含量分别为27.67μg/g和10.69μg/g,PC和PS的sn-2位脂肪酸组成中DHA含量分别为8.06%和2.59%。综上,可以从苏尼特羊脑中制备易于吸收的DHA-PL。

林分改变驱动的优势菌根真菌类型变化影响土壤有机碳积累

马尾松林(PinusmassonianaLamb.)是典型的外生菌根(Ectomycorrhiza,ECM)优势林,但是近年来受到松材线虫病的影响,生态服务功能下降,逐渐被丛枝菌根(Arbuscularmycorrhiza,AM)占优势的阔叶林所替代,但亚热带地区马尾松林转变为阔叶林过程中,优势菌根类型的改变对土壤有机碳积累的影响仍不清楚。以建德市马尾松林和阔叶林为研究对象,通过高效液相色谱和中性脂肪酸、磷脂脂肪酸等技术,测定优势菌根真菌生物量、球囊霉素相关土壤蛋白(GRSP)含量以及土壤胞外酶活性和微生物群落特征。结果表明:AM真菌占优势的阔叶林(AMD)取代ECM真菌占优势的马尾松林(ECMD),土壤有机碳显著提高了36.81%,微生物碳利用效率(CUE)显著提高了53.85%,AM真菌生物量提高了25.57%,ECM真菌生物量下降45.04%,并且ECM真菌占优势的马尾松林受到更严重的氮限制。磷脂脂肪酸分析显示,相比于AM真菌占优势的阔叶林,ECM真菌占优势的马尾松林革兰氏阳性细菌(G^(+))以及革兰氏阳性与阴性细菌之比(G^(+)/G^(–))分别显著下降了21.47%和6.46%。冗余分析(Redundancy analysis,RDA)结果表明,AM真菌占优势和ECM真菌占优势的森林之间土壤微生物群落结构存在显著差异(P<0.05),其中AM真菌生物量和土壤有机碳与微生物群落结构变异显著相关。GRSP含量下降以及不同类型菌根真菌招募微生物类群不同是导致ECM真菌占优势森林土壤有机碳下降的重要原因。因此,亚热带地区马尾松林被阔叶林替代后增加森林土壤有机碳含量,提高森林碳汇功能。

长期不同施肥措施对盐碱地稻田土壤微生物数量和群落结构的影响

为阐明盐碱地稻田长期不同施肥对表层土壤微生物数量和群落结构的影响,以大安站盐碱地水稻长期定位施肥试验土壤为对象,采用磷脂脂肪酸(PLFA)分析法研究了单施氮肥(N)、无机肥配施(NPK)、有机肥单施(M)、有机肥与无机肥配施(MNPK)和秸秆还田配施无机肥(RNPK)对土壤微生物数量和群落结构的影响。结果表明:不同施肥处理土壤中共检测出57种PLFA生物标记,M、MNPK、RNPK和NPK处理的PLFA含量较N处理分别增加26.47%、29.76%、25.07%和13.20%,其中M、MNPK和RNPK处理显著高于N处理(P<0.05)。MNPK处理土壤中的真菌/细菌的比值最大,较二者之比最小的M处理高6.00%,说明有机肥配施化肥对盐碱地稻田土壤生态系统的稳定性具有更好的改善作用。RNPK处理土壤中革兰氏阳性菌与革兰氏阴性菌之比最小,较二者之比最大的M处理降低了13.71%,说明秸秆还田配施化肥处理的土壤营养胁迫小,能有效改善土壤的营养状况。不同施肥处理微生物群落多样性大小表现为N处理土壤的Shannon-Wiener多样性指数(H)、Pielou均匀度指数(J)和Simpson优势度指数(D)最大,分别较3项指数最小的NPK处理增加10.91%、12.00%和13.79%。冗余分析结果表明,盐分电导率(EC)、有机质和pH对土壤微生物群落变化具有显著影响,解释量分别为54.8%、39.8%和33.1%。因此,长期有机肥与化肥配施、有机肥单施和秸秆还田配施无机肥能有效增加土壤微生物生物量并优化微生物群落结构,进而改善土壤生态环境。