巨大芽孢杆菌(Bacillus megaterium)解磷机理的研究(1)——解磷能力与磷素影响

以透明圈法定性地判定巨大芽孢杆菌(Bacillusmegaterium)分解有机磷的能力,并以摇瓶法定量地测定了影响该菌的解磷条件。结果表明,该菌对卵磷脂有一定的分解能力,且接种量和卵磷脂添加量对该菌分解卵磷脂能力有着重要的影响。

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.

Molecular cloning and characterization of a threonine/serine protein kinase lvakt from Litopenaeus vannamei

The phosphatidylinositol 3-kinase(PI3K)-AKT pathway is involved in various cellular functions, including anti-apoptosis, protein synthesis, glucose metabolism and cell cycling. However, the role of the PI3K-AKT pathway in crustaceans remains unclear. In the present study, we cloned and characterized the AKT gene lvakt from Litopenaeus vannamei. The 511-residue LVAKT was highly conserved; contained a PH domain, a catalytic domain and a hydrophobic domain; and was highly expressed in the heart and gills of L. vannamei. We found, using Real-Time Quantitative PCR(Q-PCR) analysis, that lvakt was upregulated during early white spot syndrome virus(WSSV) infection. Moreover, the PI3K-specific inhibitor, LY294002, reduced viral gene transcription, implying that the PI3K-AKT pathway might be hijacked by WSSV. Our results therefore suggest that LVAKT may play an important role in the shrimp immune response against WSSV.

LOW MOLECULAR WEIGHT HEPARIN ENHANCES THE EFFECT OF aFGF IN ACCELERATING NEOVASCULA-RIZATION

Objective To explore the potential of low molecular weight heparin (LMWH) in combination cooperated with aFGF in accelerating neovascularization in vivo. Methods Ischemic model was set up in the right hindlimbs of 28 New Zealand white rabbits. Four groups of animals treated with saline, LMWH, aFGF and aFGF plus LMWH were allocated equally in group Ⅰ, group Ⅱ, group Ⅲ and group Ⅳ respectively. Vascular neovascularization and smooth muscular thickness of the ischemic hindlimb vessels of each animal in different groups were compared with each other on the 28th day postoperatively by angiography with DSA and the standard immunoperoxidase technique. Results No significant neovascularization was seen when aFGF adiministered in low dosage by venous infusion. But when the same dosage of aFGF plus LMWH were administered by venous infusion, a significant neovascularization was observed. Conclusion LMWH can potentiate aFGF in accelerating neovascularization.

The Development of Soybean Byproducts in Heilongjiang, China

The Heilongjiang Soybean Research Institute not only focuses on improving yield and quality of soybean, but also exploring the development of various high quality soybean byproducts. Currently, the institute uses advanced extraction technology, the institute also produces new soybean chips and vitamin E from soybean pulp, soybean peptides, phosphatides and oligosaccharides. 120 broilers were randomly divided into 4 groups with 6 replicates in each group and 5 chicken in each replicate. The authors studied influence on performance and body quality of broiler chicken by using soybean phosphatides to take the place of 0.5%, 1% and 1.5% corn of basal daily grain. Conclusion indicated that rates of broiler chicken weight gain were 2.1%, 4.4% and 8.7%, feed utilization rates raised 3.5%, 5.2% and 8.1%, costs reduced 2.3%, 3.5% and 5.8%, chest muscle rates improved 14.7%, 0.9% and -0.49%, belly fat rates improved 11.06%, 20.28% and 44.75% by using soybean phosphatides to take place of corn in daily grain after 42 days. More recently, the study is also involved in the research on improving the meat quality of chicken by adding extracted soybean peptide and phosphatides into feed. Furthermore, nearly 98% post-consumer waste oil with high acid value can be converted into biodiesel by using an effective supercritical methanol method.

Non-phospholipid liposomes with high sterol content display a very limited permeability

We demonstrate that it is possible to form non-phospholipid fluid bilayers in aqueous milieu with a mixture of palmitic acid (PA),cholesterol (Chol),and cholesterol sulfate (Schol) in a molar proportion of 30/28/42.These self-assemblies are shown to be bilayers in the liquid ordered phase.They are stable between pH 5 and 9.Over this pH range,the protonation/deprotonation of PA carboxylic group is observed but this change does not appear to alter the stability of these bilayers,a behavior contrasting with that observed for binary mixtures of PA/Chol,and PA/Schol.The multilamellar dispersions formed spontaneously from the PA/Chol/Schol mixture could be successfully extruded to form Large Unilamellar Vesicles (LUVs).These LUVs show interesting permeability properties,linked with their high sterol content.These non-phospholipid liposomes can sustain a pH gradient (pH internal 8/pH external 6) 100 times longer than LUVs made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol,with a molar ratio of 60/40.Moreover,the non-phospholipid LUVs are shown to protect ascorbic acid from an oxidizing environment (1 mM iron(III)).Once entrapped in liposomes,ascorbic acid displays a degradation rate similar to that obtained in the absence of iron(III).These results show the possibility to form novel nanocontainers from a mixture of a monoalkylated amphiphile and sterols,with a good pH stability and showing interesting permeability properties.

Response of Microbial Communities in Soil to Multi-level Warming in a Highland Barley System of the Lhasa River

No studies have examined the effect of experimental warming on the microbial biomass and community composition of soil in agricultural ecosystem on the Qinghai-Tibet Plateau. Thus it is unclear whether the influences of experimental warming on microbial communities in soil are related to warming magnitude in croplands on this Plateau. This study performed warming experiment(control, low-and high-level) in a highland barley system of the Lhasa River in May 2014 to examine the correlation between the response of microbial communities in soil to warming and warming magnitude. Topsoil samples(0–10 and 10–20 cm) were collected on September 14, 2014. Experimental warming at both low and high levels significantly increased soil temperature by 1.02 ℃ and 1.59 ℃, respectively at the depth of 15 cm. Phospho lipid fatty acid(PLFA) method was used to determine the microbial community in soil. The low-level experimental warming did not significantly affect the soil’s total PLFA, fungi, bacteria, arbuscular mycorrhizal fungi(AMF), actinomycetes, gram-positive bacteria(G+), gram-negative bacteria(G–), protozoa, the ratio of fungi to bacteria(F/B ratio), and ratio of G+ to G–(G+/G– ratio) at the 0–10 and 10–20 cm depth. The low-level experimental warming also did not significantly alter the composition of microbial community in soil at the 0–10 and 10–20 cm depth. The high-level experimental warming significantly increased total PLFA by 74.4%, fungi by 78.0%, bacteria by 74.0%, AMF by 66.9%, actinomycetes by 81.4%, G+ by 67.0% and G– by 74.4% at the 0–10 cm depth rather than at 10–20 cm depth. The high-level experimental warming significantly altered microbial community composition in soil at the 0–10 cm depth rather than at 10-20 cm depth. Our findings suggest that the response of microbial communities in soil to warming varied with warming magnitudes in the highland barley system of the Lhasa River.

Effcts of Irrigation Patterns and Nitrogen Fertilization on Rice Yield and Microbial Community Structure in Paddy Soil

Water and nitrogen （N） are considered the most important factors affecting rice production and play vital roles in regulating soil microbial biomass, activity, and community. The effects of irrigation patterns and N fertilizer levels on the soil microbial community structure and yield of paddy rice were investigated in a pot experiment. The experiment was designed with four N levels of 0 （NO）, 126 （N1）, 157.5 （N2）, and 210 kg N ha^（-1） （N3） under two irrigation patterns of continuous water-logging irrigation （WLI） and water- controlled irrigation （WCI）. Phospholipid fatty acid （PLFA） analysis was conducted to track the dynamics of soil microbial communities at tillering, grain-filling, and maturity stages. The results showed that the maximums of grain yield, above-ground biomass, and total N uptake were all obtained in the N2 treatment under WCI. Similar variations in total PLFAs, as well as bacterial and fungM PLFAs, were found, with an increase from the tillering to the grain-filling stage and a decrease at the maturity stage except for actinomycetic PLFAs, which decreased continuously from the tillering to the maturity stage. A shift in composition of the microbial community at different stages of the plant growth was indicated by principal component analysis （PCA）, in which the samples at the vegetative stage （tillering stage） were separated from those at the reproductive stage （grain-filling and maturity stages）. Soil microbial biomass, measured as total PLFAs, was significantly higher under WCI than that under WLI mainly at the grain-filling stage, whereas the fungal PLFAs detected under WCI were significantly higher than those under WLI at the tillering, grain-filling, and maturity stages. The application of N fertilizer also significantly increased soil microbial biomass and the main microbial groups both under WLI and WCI conditions. The proper combination of irrigation management and N fertilizer level in this study was the N2 （157.5 kg N ha^（-1）） treatment under the water-controlled irrigation pattern.

Nitrogen Addition Decreases Soil Respiration without Changing the Temperature Sensitivity in a Semiarid Grassland

The mechanisms underlying the response of soil respiration(Rs) to nitrogen(N) addition remain to be explored in semiarid ecosystems. This study was conducted to determine the effect of N addition on soil microbial composition, Rs and the temperature sensitivity of Rs(Q10). The N addition experiment was carried out in a semiarid grassland in China, with N fertilizer application rates of 0, 2, 4, 8, 16, or 32 gN m-2yr-1. Microbial phospholipid fatty acids(PLFAs), Rs and Q10 were measured, and their relationships with soil properties were determined for three growing seasons. The results showed that N addition significantly increased the content of soil dissolved organic carbon(DOC) and inorganic nitrogen(IN), and decreased soil p H. With respect to soil microbes, N addition reduced soil PLFAs, reduced the fungi to bacteria ratio(F:B) and increased the gram-positive bacteria to gram-negative bacteria ratio(G+:G–). Rs under the N2, N4, N8, N16 and N32 treatments decreased by 2.58%, 14.86%, 22.62%, 23.97% and 19.87%, respectively, compared to the N0(control) treatment. The results of structural equation models showed that N addition reduced Rs by lowering soil PLFAs and altering the microbial composition. However, N addition had no significant effect on either Q10, soil total organic carbon(TOC) or total nitrogen(TN), indicating that N addition alleviated soil carbon loss and was unlikely to change the potential for a bigger loss under global warming.

Microbial Biomass and PLFA Profile Changes in Rhizosphere of Pakchoi(Brassica chinensis L.) as Affected by External Cadmium Loading

The effects of root activity on microbial response to cadmium(Cd) loading in the rhizosphere are not well understood.A pot experiment in greenhouse was conducted to investigate the effects of low Cd loading and root activity on microbial biomass and community structure in the rhizosphere of pakchoi(Brassica chinensis L.) on silty clay loam and silt loamy soil.Cd was added into soil as Cd(NO_3)_2 to reach concentrations ranging from 0.00 to 7.00 mg kg^(-1).The microbial biomass carbon(MBC) and community structure were affected by Cd concentration,root activity,and soil type.Lower Cd loading rates(<1.00 mg kg^(-1)) stimulated the growth of pakchoi and microorganisms,but higher Cd concentrations inhibited the growth of microorganisms.The content of phospholipid fatty acids(PLFAs) was sensitive to increased Cd levels.MBC was linearly correlated with the total PLFAs.The content of general PLFAs in the fungi was positively correlated with the available Cd in the soil,whereas those in the bacteria and actinomycetes were negatively correlated with the available Cd in the soil.These results indicated that fungi were more resistant to Cd stress than bacteria or actinomycetes,and the latter was the most sensitive to Cd stress.Microbial biomass was more abundant in the rhizosphere than in the bulk soil.Root activity enhanced the growth of microorganisms and stabilized the microbial community structure in the rhizosphere.PLFA analysis was proven to be sensitive in detecting changes in the soil microbial community in response to Cd stress and root activity.

Response of Soil Microbial Community to a High Dose of Fresh Olive Mill Wastewater

An incubation experiment was designed in order to determine the further microbiological response to an addition （500 m3 ha-1） of fresh olive mill wastewater （FOMWW） in a soil that has been frequently amended with uncontrolled doses of OMWW since the 1990s in an active disposal site （ADS soil）. To achieve this aim, the phospholipid fatty acid （PLFA） profiles, microbial biomass C （Cmic）, and dehydrogenase （DHA） and urease activities （URA） were monitored at the beginning （To）, 3 h （T1） and 97 d （Tf, i.e., the end） of incubation after FOMWW addition. After the FOMWW addition, an increase in the ratio of fungal to bacterial PLFAs was observed in ADS soil. Moreover, a relative increase of monounsaturated fatty acids （MUFAs） with respect to saturated fatty acids （SATFA） was found in the ADS soil. An increase of the Gram-positive to Gram-negative ratio was observed in this soil at the end of the incubation. While DHA and Cmic increased in the ADS soil after FOMWW addition, URA showed a decrease. Fungi and Gram-positive bacterial biomass experienced an increase after addition of a high dose of FOMWW in laboratory conditions.