Characterization of alditol oxidase from Streptomyces coelicolor and its application in the production of rare sugars

A synthetic platform for the cascade synthesis of rare sugars using Escherichia coli whole cells was established. In the cascade, the donor substrate dihydroxyacetone phosphate (DHAP) was generated from glycerol by glycerol kinase (GK) and glycerol phosphate oxidase (GPO). The acceptor d-glyceraldehyde was directly produced from glycerol by an alditol oxidase. Then, the aldol reaction between DHAP and d-glyceraldehyde was performed by l-rhamnulose-1-phosphate aldolase (RhaD) to generate the corresponding sugar-1-phosphate. Finally, the phosphate group was removed by fructose-1-phosphatase (YqaB) to obtain the rare sugars d-sorbose and d-psicose. To accomplish this goal, the alditol oxidase from Streptomyces coelicolor (AldO_S.coe) was expressed in E. coli and the purified AldO_S.coe was characterized. Furthermore, a recombinant E. coli strain overexpressing six enzymes including AldO_S.coe was constructed. Under the optimized conditions, it produced 7.9 g/L of d-sorbose and d-psicose with a total conversion rate of 17.7% from glycerol. This study provides a useful and cost-effective method for the synthesis of rare sugars.     

Single-cell oil production by Mortierella isabellina DSM 1414 using different sugars as carbon source

Pure carbon sources, especially carbohydrates which are raw materials deriving from agro-industrial processes, are often used for small-scale single-cell oil production by fermentation. The aim of this study was to investigate the effects of different pure carbon sources on cell growth, lipid accumulation, and γ-linolenic acid (GLA) production by the filamentous fungus Mortierella isabellina DSM 1414 (Deutsche Sammlung von Mikroorganismen). The sugars utilized in this study are found extensively and abundantly in nature, especially in food raw materials and, in consequence, in agro-food industry wastes or surpluses. Thus, the potential of many waste materials containing these sugars to be used in the production of single-cell oil by fermentation could also be evaluated. The effects of the sugars utilized on cell growth, biomass production, and lipid production were investigated. Fatty acids were also analysed in the lipids produced at the end of the fermentations. Results showed that the maximum biomass production was 10.80 g/L in lactose-based media, while the maximum oil production was 5.44 g/L in maltose-based media. Oleic (20.42%–42.94%), palmitic (14.96%–22.19%), and stearic (9.00%–26.92%) acids were the major fatty acids along with linoleic acid (11.35%–18.67%) and GLA (3.56%–8.04%). The production of GLA as the target fatty acid was remarkable. This study indicates that agro-industrial waste including most of the sugars utilized (except for arabinose and sucrose with lipid production of 0.81 and 0.28 g/L, respectively) can be employed for production of single-cell oil by M. isabellina DSM 1414 which contains a high amount of GLA.     

Development of multi-component non-sex pheromone blends to monitor both sexes of Cydia pomonella (Lepidoptera: Tortricidae)

Nineteen host plant volatiles (HPVs) were screened for attractivity to adult codling moth Cydia pomonella (L.) as a fourth component of core blends (3K) including (E,Z)-2,4-ethyl decadienoate, (E)-4,8-dimethyl-1,3,7-nonatriene and acetic acid. Each new quaternary combination was compared with a previously reported attractive bisexual lure (4K), consisting of the 3K blend plus 6-ethenyl-2,2,6-trimethyloxan-3-ol (pyranoid linalool oxide, pyrLOX). All lure evaluations were conducted in apple, Malus domestica (Borkhausen). Several compounds were found to significantly lower total and/or female catches when added to the 3K blend, including (Z)-3-hexenol, (E)-2-hexanal and hexyl butanoate (female and total moths), and (Z)-3-hexenyl acetate and linalool (female moths). Other compounds when added to the 3K blend did not increase or decrease moth catches, including methyl salicylate, (E)-β-ocimene, limonene, β-caryophyllene, butyl hexanoate, farnesol, terpineol, terpinen-4-ol and α-pinene. A few added compounds significantly increased moth catches compared with the 3K blend, including β-pinene (male moths), (Z)-jasmone (male and total moths), (E)-β-farnesene and β-myrcene (female and total moths), and (E,E)-α-farnesene (male, female, and total moths). In addition, each of these five compounds when added to the 3K core blend performed similarly to the 4K lure (male, females, and total moths). Further studies should expand these results through tests of these and other new blends with a range of component ratios and total loading amounts. Field trials should also be replicated within all host crops of codling moth and across major geographical production regions.     

三江平原湿地开垦对土壤氨基糖积累特征的影响

微生物残体在土壤有机质的形成和稳定过程中发挥着重要作用,但湿地开垦对土壤微生物残体积累特征的影响尚不清楚。本研究以三江平原小叶章湿地为对象,采集原始自然湿地和开垦改种豆科作物后不同耕作年限(5年、10年和25年)的土壤,以氨基糖为微生物残体的标识物,探讨湿地开垦对土壤微生物残体积累特征的影响。结果表明: 自然湿地开垦为农田后显著降低了土壤中氨基糖的含量,且随着开垦年限的增加,氨基糖的损失比例也增加。与自然湿地相比,开垦25年后土壤中的氨基葡萄糖、氨基半乳糖和胞壁酸含量分别下降38.0%、38.1%和35.9%,且在开垦最初5年中细菌来源的胞壁酸下降速率(25.8%)远高于真菌来源的氨基葡萄糖(14.9%),说明短期内湿地开垦对细菌的影响较真菌更加迅速。湿地开垦为农田5、15和25年后,土壤氨基糖总量分别下降21.1%、34.0%和38.0%;同时,氨基糖总量占土壤有机质的比例也受到湿地开垦的显著影响,由自然湿地中的4.8%降至开垦25年后的4.4%。这说明长期湿地开垦加速了土壤有机质中微生物来源有机组分的分解转化,进而改变土壤有机质的组成。这些变化将影响湿地生态系统中土壤有机质的长期稳定和功能演变。     

β-Carboline-Based pH Fluorescent Probe and Its Application for Monitoring Enzymatic Ester Hydrolysis

A novel pH-activatable fluorescent probe, 1-(propan-2-yl)-9H-pyrido[3,4-b]indole-3-carboxylic acid ( L-1 ), based on β-carboline derivatives, has been developed, which displays significant fluorescent response toward pH variation with high selectivity, good photo-stability and favorable pKa value. Moreover, L-1 can dynamically monitor the release of protons during ester hydrolysis reaction in consistent with enzymatic kinetics manner.     

晋西黄土区典型乔灌木短期水分利用效率对环境因子的响应

为明确晋西黄土区植物的水分利用规律及对半干旱区的适应策略, 提高黄土地区植被建设效益, 该研究对该地区典型乔灌木短期水分利用效率随环境因子的变化进行了探究。以典型乔木油松(Pinus tabuliformis)、刺槐(Robinia pseudoacacia)及其林下灌木黄刺玫(Rosa xanthina)、杠柳(Periploca sepium)为研究对象, 测定叶片可溶性糖稳定碳同位素比值(δ¹³C_leaf)与枝条渗出液稳定碳同位素比值(δ¹³C_branch), 使用δ¹³C_leaf推导计算7-10月叶片尺度下植物短期水分利用效率(WUE_leaf)变化趋势, 使用δ¹³C_branch明确植物光合作用后分馏情况, 确定半干旱区植物在生长季的水分变化规律对环境因子变化的响应。结果表明: (1) 7-10月4种植物δ¹³C_leaf总体呈现降低趋势, δ¹³C_branch呈现先升高后降低趋势。δ¹³C_leaf在种间和生活型中均存在差异。具体表现为: 灌木>乔木, 常绿乔木(油松) >落叶乔木(刺槐)。研究过程中未发现明显的碳同位素在光合作用后发生分馏的情况。(2) 4种植物WUE_leaf在7-8月保持稳定, 9-10月逐渐升高。21.5 ℃、0.9 kPa、52.4%分别为WUE_leaf随温度(T_a)、饱和水汽压差(VPD)、相对湿度(RH)变化的突变点, 突变点之后4种植物WUE_leaf均表现出稳定的变化趋势, 不再随T_a、VPD、RH升高而降低。(3) WUE_leaf与T_a、RH、VPD之间存在显著负相关关系, T_a通过非气孔因素, 即酶的作用改变光合速率, 引起WUE_leaf变化。RH、VPD等水分因子则通过改变气孔开度, 影响蒸腾, 进而改变WUE_leaf。随着土壤含水量(SWC)的升高, WUE_leaf呈现先升高后降低的趋势。油松林和刺槐林在SWC分别达到15%-18%、13%-14%时, WUE_leaf达到最高值。经过混合线性模型(LMM)分析得到, 油松和刺槐WUE_leaf主导环境因子分别为RH和VPD, 黄刺玫和杠柳WUE_leaf主导环境因子均为T_a。该研究得到了黄土地区典型乔灌木生长季水分利用效率变化的规律和主要环境影响因子, 明确了黄土地区植物对气候因子变化的适应机制。     

Effects of caffeic acid phenethyl ester (CAPE) on angiogenesis,apoptosis and oxidatıve stress ın various cancer cell lines

ABSTRACT

Cancer is a common cause of death worldwide. Approximately 80% of cancer patients use complementary or alternative medicines for treatment. Caffeic acid phenethyl ester (CAPE), the main active component of propolis, exhibits cytotoxic, antiproliferative and anti-cancer effects. Despite its anticancer effects CAPE exhibits no known harmful effects toward normal cells. We investigated the effects of CAPE on angiogenesis, apoptosis and oxidative stress using MDA MB-231, N2a and COLO 320 cell lines and CAPE treatments at 24 and 48 h. A two dimensional cell culture system was used and the findings were evaluated by an indirect immunohistochemical method and H-scores were calculated. CAPE was effective for all three cancer cell lines. After 24 and 48 h, we found a significant decrease in live cells and increased stress in the cells based on e-NOS and i-NOS levels.     

Nectar sugar composition of European Caryophylloideae (Caryophyllaceae) in relation to flower length,pollination biology and phylogeny

Floral nectar composition has been explained as an adaptation to factors that are either directly or indirectly related to pollinator attraction. However, it is often unclear whether the sugar composition is a direct adaptation to pollinator preferences. Firstly, the lower osmolality of sucrose solutions means that they evaporate more rapidly than hexose solutions, which might be one reason why sucrose‐rich nectar is typically found in flowers with long tubes (adapted to long‐tongued pollinators), where it is better protected from evaporation than in open or short‐tubed flowers. Secondly, it can be assumed that temperature‐dependent evaporation is generally lower during the night than during the day so that selection pressure to secrete nectar with high osmolality (i.e. hexose‐rich solutions) is relaxed for night‐active flowers pollinated at night. Thirdly, the breeding system may affect selection pressure on nectar traits; that is, for pollinator‐independent, self‐pollinated plants, a lower selective pressure on nectar traits can be assumed, leading to a higher variability of nectar sugar composition independent of pollinator preferences, nectar accessibility and nectar protection. To analyse the relations between flower tube length, day vs. night pollination and self‐pollination, the nectar sugar composition was investigated in 78 European Caryophylloideae (Caryophyllaceae) with different pollination modes (diurnal, nocturnal, self‐pollination) using high‐performance liquid chromatography (HPLC). All Caryophylleae species (Dianthus and relatives) were found to have nectar with more than 50% sucrose, whereas the sugar composition of Sileneae species (Silene and relatives) ranged from 0% to 98.2%. In the genus Silene, a clear dichotomous distribution of sucrose‐ and hexose‐dominant nectars is evident. We found a positive correlation between the flower tube length and sucrose content in Caryophylloideae, particularly in day‐flowering species, using both conventional analyses and phylogenetically independent contrasts.     

Enrichment of pinolenic acid from pine nut oil via lipase-catalyzed ethanolysis with an immobilized Candida antarctica lipase

Abstract

Pinolenic acid (PLA) enrichment as an ethyl ester from pine nut oil was successfully accomplished in a batch reactor by lipase-catalyzed ethanolysis using Novozym 435 lipase from Candida antarctica as a biocatalyst. PLA is predominantly an sn-3 substituent of the pine nut oil triacylglycerol (TAG), where it accounts for about 39 mol% of the fatty acids esterified at that position. In the presence of ethanol, Novozym 435 exhibited sn-3 regiospecificity with respect to the TAG of pine nut oil. The effect of the molar ratio of reactants on PLA enrichment by ethanolysis was investigated. The molar ratios of pine nut oil to ethanol were varied from 1:20 to 1:100. A fatty acid ethyl ester (FAEE) fraction with higher PLA content was obtained in the early stage of the reaction, although the yield of PLA was small. However, the PLA content of the FAEEs decreased with increasing reaction time, while the yield of PLA increased. The molar ratio of pine nut oil to ethanol that produced the optimum content and yield of PLA in FAEEs was 1:80.     

Modeling and optimization of lipase-catalyzed esterification of policosanols with conjugated linoleic acid by response surface methodology

Abstract

The aim of this study was to model the lipase-catalyzed esterification of policosanols with conjugated linoleic acid (CLA) in a solvent-free system to produce wax esters which had a lower melting point than that of their corresponding policosanol forms and to optimize the reaction conditions by response surface methodology (RSM). Novozym 435 was selected as a suitable biocatalyst for the reaction. The molar ratio of substrates (policosanols to CLA) was 1:2. A well-fitting quadratic polynomial regression model for the degree of esterification (DE) of policosanols with CLA was established with regard to temperature (35–65°C), enzyme loading (1–5% of weight of total substrates), and reaction time (10–50 min). Optimal reaction conditions were 61.3°C for temperature, 3.7% for enzyme loading, and 34.1 min for reaction time, and the DE was ? 95 mol% under these conditions. The policosanols and wax esters synthesized under optimal conditions had melting points of 79°C and 57°C, respectively.