Enhanced removal of polychlorinated biphenyls from alfalfa rhizosphere soil in a field study: The impact of a rhizobial inoculum

Polychlorinated biphenyls (PCB) are persistent pollutants in soil environments where they continue to present considerable human health risks. Successful strategies to remediate contaminated soils are needed that are effective and of low cost. Bioremediation approaches that include the use of plants and microbial communities to promote degradation of PCB have significant potential but need further assessment under field conditions. The effects of growth of alfalfa (Medicago sativa L.) and inoculation with a symbiotic nitrogen fixing bacterium (Rhizobium meliloti) on the removal of polychlorinated biphenyls (PCB) from rhizosphere soil were evaluated in a field experiment. The initial PCB content of the soil ranged from 414 to 498 µg kg⁻¹. PCB removal for the rhizosphere soil was enhanced in the planted treatments, an average of 36% decrease in PCB levels compared to a 5.4% decrease in the unplanted soil, and further enhanced when plants were inoculated with the symbiotic Rhizobium (an average of 43% decrease) when evaluated at 90 days after planting. Plant biomass production was higher in the inoculated treatment. The total PCB content was increased from 3.30 µg kg⁻¹ to 26.72 µg kg⁻¹ in plant shoots, and from 115.07 µg kg⁻¹ to 142.23 µg kg⁻¹ in roots in the inoculated treatment compared to the planted treatment. Increased colony forming units (cfu) of total heterotrophic bacteria, biphenyl-degrading bacteria and fungi were observed in the rhizosphere of inoculated plants. PCB removal from the rhizosphere soil was not significantly correlated with the direct PCB uptake by the plants in any of the treatments but was significantly correlated with the stimulation of rhizosphere microflora. Changes in the soil microbial community structure in the planted and inoculated treatment were observed by profiling of bacterial ribosomal sequences. Some bacteria, such as Flavobacterium sp., may have contributed to the effective degradation of PCB and deserve further investigation.     

Efficacy of combinations of high pressure treatment, temperature and antimicrobial compounds to improve the microbiological quality of alfalfa seeds for sprout production

The effect of combined treatments of pressure, temperature and two disinfectant agents (hypochlorite and carvacrol) applied on alfalfa seeds, on their germination capability as well as on the reduction of the native microbial load of sprouts developed from treated seeds was evaluated by using response surface methodology (RSM). The germination percentage decreased as pressure and carvacrol concentration increased, while calcium hypochlorite concentration had no significant impact on seed viability. The counts of total aerobic mesophilic bacteria, total and faecal coliforms and moulds and yeast were reduced with increasing pressure and hypochlorite and carvacrol concentrations. The optimal conditions for improving the microbiological quality of alfalfa seeds (reductions between 4.5 and 5 log CFU/g) for sprouts production were 200 MPa and hypochlorite concentration of 18,000 ppm. On the contrary, the process parameters of the combined treatment HP/carvacrol that ensure the microbial safety of sprouts (250 MPa and 1500 ppm of carvacrol) reduced the germination percentage to unacceptable levels.     

黄土区废弃钻井液对苜蓿产量和品质的影响

以长庆油田废弃钻井液回填法处理后井场生长的苜蓿为研究对象，研究了废弃钻井液对苜蓿的产量、重金属含量、品质和氨基酸的影响。结果表明，废弃钻井液处理场生长的苜蓿Pb、Cd、Cr、As、Hg和Cu等重金属含量均在GB13078-2017安全范围内，重金属未超标；废弃钻井液对苜蓿有明显的增产作用，苜蓿产量增加了730.20 kg/hm2，增长了21.6%。苜蓿品质也得到明显提升，其中粗蛋白总量增加24.87 kg/hm2，粗脂肪总量增加3.34 kg/hm2，淀粉总量增加9.61kg/hm2，还原性糖总量增加45.92 kg/hm2，粗纤维含量有所降低。氨基酸总量增加3.6%，必需氨基酸和非必需氨基酸含量分别增长了1.2%和2.3%。      

Influence of pulsed electric field energy on the damage degree in alfalfa tissue

The objectives of this study were to investigate the influence of pulsed electric field (PEF) parameters on the damage degree of alfalfa mash, and to determine the relationship between the maximum damage degree and the energy used. Alfalfa mash was treated with PEF at various electric field strengths of 1.25, 1.90, and 2.50 kV/cm. The capacitance of the discharge capacitor was varied from 0.5 to 1.5 μF in steps of 0.5 μF. The pulse number was increased gradually to the point where the impedance became constant. There was no significant increase in the rate of damage beyond 0.5 kJ applied energy. The rate of change of the damage degree at 0.5 kJ was highest when the capacitance was 1.5 μF for all the voltages. Increase in the electric field strength led to decrease in energy needed to obtain the maximum damage degree. To achieve an efficient result for alfalfa juice extraction, the capacitance of the discharge capacitor should preferably be 1 μF or more. In order to minimize energy consumption for a given damage degree in alfalfa, it is desirable to have the highest energy per pulse and fewer number of pulses.     

黑河流域盐渍土资源及紫花苜蓿改土培肥和生态恢复效应的研究

在黑河流域草甸盐土上种植了紫花苜蓿,改土培肥效果十分明显。3年生紫花苜蓿产鲜草55.20 t hm-2,折干草18.40 t hm-2,与CK比较0~20 cm土层中自然含水量增加90.65g kg-1,>0.25mm团粒结构增加32.34%,总孔度增加9.06%,土壤容重降低0.24g cm-3,pH由8.45降到8.20,全盐含量降低4.63g kg-1,脱盐率达到56.60%,有机质、速效N、P、K亦随之增加。     

Assessment of the microbiological safety of edible dried seeds from retail premises in the United Kingdom with a focus on Salmonella spp.

Sesame seed products have recently been associated with a number of Salmonella outbreaks in the UK and elsewhere. Aside from sesame seeds, there is little published information on the prevalence of Salmonella spp. in edible seeds. A study of 3735 samples of retail edible dried seeds in the UK was therefore carried out between October 2007 and March 2008 to assess their microbiological safety in relation to Salmonella contamination and levels of Escherichia coli, an indicator of faecal contamination. Overall, Salmonella was detected in 23 samples (0.6%), of which over half (57%) were sesame seeds. Other seeds contaminated with Salmonella were linseed (1 sample), sunflower (1 sample), alfalfa (1 sample), melon (4 samples) and mixed seeds (3 samples). E. coli was detected in 9% of samples, with 1.5% containing unsatisfactory levels (≥10²/g). These included melon, pumpkin, sesame, hemp, poppy, linseed, sunflower and mixed seeds. The UK retailers affected by the detection of Salmonella in their products recalled the contaminated batches, and Food Standards Agency food alerts were issued to advise against the consumption of affected seed products. This study highlights the importance of good hygiene practices and effective decontamination procedures during the production of these products.     

Thermo-Mechanical Fractionation of Green Biomass

Green biomass can efficiently be separated into a fiber-rich fraction and a green juice with the TAMD process. This process combines a mechanical pressing and a moderate heating of the walls of the apparatus. This work aims to investigate the influence of the biomass water potential on the kinetic and to identify the optimal processing conditions. If the TAMD process is used as a pre-treatment for fodder dewatering, 70°C and 300 kPa are the optimum conditions to reach a high separation yield (+25.5% compared to current processes) in short times. For biorefining purposes, a lower wall temperature is required.     

Influence of fresh alfalfa supplementation on fat skatole and indole concentration and chop odour and flavour in lambs grazing a cocksfoot pasture

We investigated the influence of the level of fresh alfalfa supplementation on fat skatole and indole concentration and chop sensory attributes in grazing lambs. Four groups of nine male Romane lambs grazing a cocksfoot pasture were supplemented with various levels of alfalfa for at least 60 days before slaughter. Perirenal fat skatole concentration was higher for lambs that consumed alfalfa than for those that consumed only cocksfoot. The intensity of ‘animal’ odour in the lean part of the chop and of ‘animal’ flavour in both the lean and fat parts of the chop, evaluated by a trained sensory panel, increased from the lowest level of alfalfa supplementation onwards and did not increase further with increasing levels of alfalfa supplementation. The outcome of this study therefore suggests that these sensory attributes may reach a plateau when perirenal fat skatole concentration is in the range 0.16–0.24 μg/g of liquid fat.     

苜蓿叶蛋白资源的开发和利用

重点介绍了苜蓿叶蛋白的营养特点和国内外研究现状。苜蓿叶蛋白因苜蓿草产量高、适应性强、蛋白含量高、氨基酸平衡而倍受人们的重视并在欧洲得到开发和应用。     

Identification of female sex pheromone in alfalfa blotch leafminer,Agromyza frontella (Rondani)(Diptera: Agromyzidae)

Gas chroinatography of hexane extracts of 3-day-old virgin A.frontella adults revealed a branched saturated hydrocarbon present only in females. This compound was isolated by argentation chromotography and preparative GC, identified by GC and GC-MS as 3,7-dimethylnonadecane, and subsequently synthesized. Three-day-old virgin females contained 54.1 ± 3.5 ng (± SEM;N = 48) of 3,7-dimethylnonadecane. Male cadavers do not elicit male courtship behavior, but when treated with 18 ng of 3,7-dimethylnonadecane they were as attractive as cadavers of 3-day-old virgin females. Black cotton knots were less attractive than male cadavers when treated with 3,7-dimethylnonadecane, but all bioassays indicated that this compound is an important semiochemical modulating male mating behavior.