酸法破壁条件对法夫酵母虾青素提取效果的影响

为了评价酸法破壁在法夫酵母虾青素提取中的应用价值，从酸的种类、酸的浓度、液料比、破壁温度及时间等方面研究了条件因子对破壁后法夫酵母虾青素提取的影响并对破壁条件进行了优化。试验结果表明：乳酸比盐酸和醋酸更适合用于法夫酵母的破壁处理；酸的浓度、破壁温度等因素对虾青素的提取得率影响较大，而酸处理时间和液料比对虾青素的提取得率影响不大。用正交试验方法得到优化的乳酸破壁法夫酵母的条件为：乳酸浓度6 mol/L、破壁温度30℃、破壁时间5 min、酸加量15 mL/g(干菌体)，优化后虾青素的提取得率为1374.7 μg/g(干菌体)，总类胡萝卜素的提取得率为1709.9 μg/g(干菌体)，提取物中虾青素占总类胡萝卜素80.4%。优化的破壁条件温和，不会引起残留毒性，能获得良好的虾青素提取效果，具有较好的工业应用前景。     

利用薄层色谱法快速筛选法夫酵母突变株

法夫酵母（Phaffia rhodozyma）是一种极具产业化前景的天然虾青素资源（Johnson,2003）.本实验从溶剂极性、溶剂组成等方面优选法夫酵母类胡萝卜素薄层分析的溶剂,并对薄层色谱在法夫酵母类胡萝卜素突变株筛选中的应用进行了研究.     

利用农业废弃物碳源的红法夫酵母生产虾青素研究进展

利用红法夫酵母产虾青素工艺具有绿色、安全、低成本等优点,但培养红法夫酵母的培养基(尤其是碳源)成本是制约该工艺实现大规模生产的主要因素之一。传统的利用纯糖如葡萄糖、蔗糖、木糖等作为红法夫酵母生产虾青素的碳源,效果虽好,但因其价格较高,仅适用于实验室研究和小型发酵生产,不适于大规模工业化生产。如何寻找来源广、价廉且发酵效果好的碳源,降低虾青素的生产成本是发展虾青素产业亟待解决的课题。利用廉价且来源广泛的原料如水果类原料、糖质原料、甘油及废弃木质纤维素类原料等作为碳源能有效降低成本。但这些原料都存在一些问题,比如水果类原料存在季节性及地域性限制,糖蜜类原料供应稳定性方面存在问题,甘油类原料杂质多且存在食品安全隐患,木质纤维素类原料来源广泛、价格低廉,不存在占用耕地等问题,是最有希望用于规模化低成本发酵生产虾青素的原料,但其利用存在一些技术瓶颈。该文介绍了目前利用红法夫酵母生产虾青素的基本情况,并系统地对国内外不同碳源条件下利用红法夫酵母生产虾青素的研究状况进行了综述、比较及分析。最后,对利用红法夫酵母生产虾青素在碳源方面的未来发展趋势及重点研究方向进行了展望。     

超声波辅助提取石榴叶单宁的工艺

为探究提取石榴叶单宁的最佳工艺条件,在比较了不同溶剂、不同处理方式提取效果的基础上,采用正交试验研究了以70%丙酮溶液为溶剂超声波辅助提取的最佳条件;结果为:料液比1∶20(g/mL),超声波功率100W,频率为40kHz,提取温度40℃,提取时间50min,最优条件下的提取量为225.12mg/g,提取率为94.63%。     

啤酒花多酚类化合物提取工艺的优化研究

从提取溶剂及提取条件等方面对啤酒花多酚提取工艺进行了优化研究。用单因子试验对提取溶剂进行了筛选，结果表明丙酮和水组成的复合体系是理想的提取溶剂。用析因试验对提取条件进行了分析研究，结果表明丙酮浓度、提取温度、提取时间、料液比都对啤酒花多酚提取产生一定的影响，其中丙酮浓度和提取温度的影响最为显著。通过最陡爬坡试验和中心组合设计试验，优化得到最佳的多酚类化合物提取条件为：丙酮浓度为62％，提取温度为47℃，在此条件下啤酒花中多酚的最大提取量为47.40 mg·g^-1。     

超临界CO2萃取南美白对虾虾青素的工艺优化

为提高虾青素萃取物得率和虾青素纯度,采用超临界CO2萃取南美白对虾虾头废弃物中的虾青素,皂化后用高效液相色谱对虾青素含量进行测定。单因素试验确定萃取参数对虾青素萃取物得率和虾青素纯度的影响,然后进一步运用响应面法对萃取工艺参数进行优化。结果表明：超临界CO2萃取工艺参数对虾青素萃取物得率影响不显著（P＞0.05）,但对虾青素纯度影响显著（P＜0.05）;物料粒径40目,质量含水率9%时,响应面理论优化最佳萃取参数为萃取压力403.95 Pa,萃取温度39.95℃,CO2流量1.16 L/min,虾青素纯度为796.3 mg/g。结合实际应用,验证试验在萃取压力400 Pa,萃取温度40℃,流量1.2 L/min时,虾青素纯度为789.61 mg/g。研究结果可为虾青素的提取和纯化提供参考。     

溶剂法提取丹皮酚的工艺优化

以筛选从丹皮中提取丹皮酚的理想溶剂及最佳工艺参数为目的，通过高效液相色谱测定研究了不同溶剂提取丹皮酚的效果，通过正交试验设计研究了四氯化碳提取丹皮酚的最佳条件。结果表明，溶剂法提取丹皮中丹皮酚的理想溶剂为四氯化碳。以牡丹根皮为材料，以四氯化碳为溶剂，最佳工艺参数为料液比1∶25(w/v)、丹皮粒径0.90 mm、浸提时间6h。按此最佳工艺参数，一次提取，丹皮酚提取量11.428 g/kg，占提取总量的89.857%；两次提取合计丹皮酚提取量12.30 g/kg，占提取总量的96.79%。     

超声波辅助提取木薯皮活性物质工艺

木薯皮乙醇提取物同时具有抗乙酰胆碱酯酶（AChE）和抗丁酰胆碱酯酶（BuChE）的活性,为了能充分提取和利用其抗胆碱酯酶活性物质,研究了超声波提取木薯皮活性物质的工艺。通过单因素试验和Box-Behnken Design法设计的响应面优化试验确定了超声波辅助乙醇提取木薯皮中抗胆碱酯酶活性物质的最优工艺条件,并比较了超声波提取与传统溶剂浸提的提取效果。试验结果表明：超声波辅助乙醇提取木薯皮中抗胆碱酯酶活性物质的最优工艺条件为：乙醇体积分数为95%,超声波功率550W,提取时间90min,提取温度60℃,液料比12mL/g,在此工艺条件下,木薯皮活性物质的平均得率为8.97%,质量浓度为0.5mg/mL时的AChE抑制率为54.62%,BuChE抑制率为45.7%;影响木薯皮活性物质得率的4个主要因素的显著程度排列顺序为：超声波提取功率＞提取温度＞提取时间＞液料比;与传统溶剂浸提法相比,超声波提取法具有提取速度快,得率高,提取物活性好,溶剂用量少等明显优势。     

响应面法优化盐渍藠头蒜素提取工艺参数

为了获得在自然pH值条件下利用果胶酶提取盐渍藠头中的风味物质蒜素的最佳工艺参数,以浸提温度、时间和果胶酶添加比为试验因子,蒜素含量为响应值,采用三元二次回归正交旋转组合设计进行了试验.结果表明,3个因素对蒜素含量的影响大小依次为提取温度＞保温时间＞果胶酶添加比;边际效应大小为提取温度＞保温时间＞果胶酶添加比;通过典形分析和岭脊分析确定果胶酶提取盐渍菖头中蒜素的最佳工艺参数为:浸提温度47℃、浸提时间3.3 h、果胶酶添加比0.77%,蒜素最高含量为0.274 g/(100 mL).所得回归模型拟合情况良好,达到设计要求.     

超声辅助萃取芒果叶中芒果苷提取条件优化

为优化芒果叶中芒果苷的提取条件,以溶剂用量、超声时间、超声温度和超声功率为考察因素,采用单因素试验和正交试验对提取条件进行优化;在优选出的超声萃取条件下测定了6个品种芒果叶中芒果苷的含量,并与常规浸渍提取法进行对比。结果表明,超声波辅助提取芒果叶中芒果苷时,影响提取效果大小的顺序依次为溶剂用量超声温度超声功率超声时间;用超声波辅助提取芒果苷的最优组合为:样品量1.0 g,乙醇用量20 mL,超声时间40 min,超声温度50 ℃,超声功率160 W;超声萃取法不但缩短了提取时间,还提高了提取效率,与浸渍提取法相比,超声萃取提取芒果苷量增加了21.60%～26.69%。     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.