Fatty acid ethyl esters in the liverwort Conocephalum conicum

A series of fatty acid ethyl esters ranging from C₁₄ to C₂₄ was isolated from a hexane extract of the liverwort Conocephalum conicum, these esters accounted for 77% of the extract. The ethyl esters consisting of even-numbered fatty acids were predominant and ethyl palmitate was the major constituent.     

Cometabolic turnover of aniline,phenol and some of their monochlorinated derivatives by the Rhodococcus mutant strain AM 144

One-step conversion of aniline, phenol and some of their monochlorinated derivatives into the corresponding catechols by resting pre-adapted cells of the Rhodococcus mutant strain AM 144 (defective in synthesis of catechol 1,2-dioxygenase) was shown to depend on the availability of an additional metabolizable carbon substrate, e.g. glucose or acetate. A stoichiometric relation existed between the amount of the latter compounds added and the amount of aniline (or phenol, respectively) converted into catechol suggesting that the primary function of the cosubstrates was to provide reducing power to the oxygenative transformation reaction. The observed cosubstrate-dependence generally parallels that seen in previous studies on turnover of different monochloroaromatic non-growth substrates by aromatics-utilizing Rhodococcus wildtype-strains. Cell cultures of strain AM 144 growing at the expense of acetate also proved able to convert aniline into catechol. Typically, growth of the cells was retarded during the phase of aniline transformation as compared to the respective control cultures. Based on the results of these model experiments, it was concluded that (i) in natural microbial communities cometabolically active bacteria would hardly enrich under cometabolic conditions over fast-growing non-cometabolizing bacteria if the latter organisms will tolerate the particular non-growth substrate, and (ii) cometabolizing bacteria would have a selective advantage only if the non-growth substrate to be transformed is a toxic one or if it can serve as a potential nutrient source (e.g., of nitrogen or sulfur).Abbreviations MCA monochloroaniline - MCP monochlorophenol - MCC monochlorocatechol - TLC thin-layer chromatography - MS mass spectrometry - GLC gas-liquid chromatography - UV ultraviolet (range of the spectrum)     

Profiling the Lipophilic Fractions of Pithecellobium dulce Bark and Leaves Using GC/MS and Evaluation of Their Antioxidant,Antimicrobial and Cytotoxic Activities

Pithecellobium dulce has been used in traditional medicine to treat various ailments owing to its restorative properties. The biological activities and chemical profiles of the lipophilic fraction of P. dulce bark and leaves were assessed herein. Fatty acid methyl esters (FAME) and unsaponifiable matter (USM) were prepared and analyzed by GC/MS. A total of 40 compounds were identified in the bark saponifiable fraction, whereas 9 compounds were annotated in the leaves. Palmitic acid methyl ester was the major compound identified accounting for 41.48 % of the bark and 19.03 % of the leaves composition. Besides, linolenic acid methyl ester (22.40 %) and linoleic acid (12.69 %) were annotated in the leaves saponifiable fraction. A total of 63 compounds were detected in the bark USM and 4 compounds were identified in the leaves. Phytol represented the major component in the leaves (52.57 %) followed by lupeol (20.68 %) and lupenone (8.60 %). Meanwhile, n‐dodecane dominated in the bark USM accounting for 24.69 % of the total composition. The leaves and bark lipophilic fractions revealed moderate antioxidant and antibacterial activities. Both extracts showed no antifungal activity. No cytotoxicity was observed for both lipophilic fractions. P. dulce offers a good source of antioxidant compounds that can be introduced to food and pharmaceutical industry.     

Selective synthesis of panthenyl esters by a kinetically controlled enzymatic process

Abstract

Panthenyl esters (panthenyl monoacetate and panthenyl diacetate) were synthesized in high yields (≈100%) by a kinetic reaction control using a commercial immobilized Candida Antarctica lipase B (Novozyme 435) in acetonitrile. The enzyme showed excellent synthetic activity, regioselectivity, and operational stability under the conditions used.     

Occurrence of Fatty Acid Short‐Chain‐Alkyl Esters in Fruits of Celastraceae Plants

Small amounts of a mixture of fatty acid short‐chain‐alkyl esters (FASCAEs) were obtained from the fruits of twelve plant species of Celastraceae family, and in five of them the FASCAEs were present not only in the arils but also in the seeds. These mixtures contained 32 individual FASCAE species, which formed four separate fractions, viz. FA methyl, ethyl, isopropyl, and butyl esters (FAMEs, FAEEs, FAIPEs, and FABEs, resp.). The FASCAE acyl components included the residues of 16 individual C₁₄–C₂₄ saturated, mono‐, di‐, and trienoic FAs. Linoleic, oleic, and palmitic acids, and, in some cases, also α‐linolenic acid predominated in FAMEs and FAEEs, while myristic acid was predominant in FAIPEs. It can be suggested that, in the fruit arils of some plant species, FAMEs and FAEEs were formed at the expense of a same FA pool characteristic of a given species and were strongly different from FAIPEs and FABEs esters regarding the mechanism of their biosynthesis. However, as a whole, the qualitative and quantitative composition of various FASCAE fractions, as well as their FA composition, varied considerably depending on various factors. Therefore, separate FASCAE fractions seem to be synthesized from different FA pools other than those used for triacylglycerol formation.     

Characterisation of a thermo-alkali-stable lipase from oil-contaminated soil using a metagenomic approach

Lipases are widely used for a variety of biotechnological applications. Screening these industrial enzymes directly from environmental microorganisms is a more efficient and practical approach than conventional cultivation-dependent methods. Combined with activity-based functional screening, six clones with lipase activity were detected and a gene (termed lipZ01) isolated from a target clone with the highest lipase activity was cloned from an oil-contaminated soil-derived metagenomic library and then sequenced. Gene lipZ01 was expressed in Pichia pastoris GS115 and the molecular weight of the recombinant lipase LipZ01 was estimated by electrophoresis analysis to be approximately 50 kDa. The maximum activity of the purified lipase was 42 U/mL, and the optimum reaction temperature and pH value were 45 °C and 8.0, respectively. The enzyme was highly stable in the temperature range 35–60 °C and under alkaline conditions (pH 7–10). The presence of Ca²⁺ and Mn²⁺ ions could significantly enhance the activity of the lipase. The purified lipase preferentially hydrolysed triacylglycerols with acyl chain lengths ≥8 carbon atoms, and the conversion degree of biodiesel production was nearly 92% in a transesterification reaction using olive oil and methanol. Some attractive properties suggested that the recombinant lipase may be valuable in industrial applications.     

农业土壤中邻苯二甲酸酯污染研究进展

由邻苯二甲酸酯(PAEs)引起的环境污染和食品安全问题已经引起全球性关注.我国既是邻苯二甲酸酯生产大国,又是消费大国,其环境污染问题不容忽视.本文综述了美国国家环保署所列出的6种优先控制PAEs污染物在我国农田土壤中的污染现状,分析了其来源,重点阐述了不同类型农作物对PAEs化合物的吸收累积特征及PAEs类污染物的生物毒害效应.我国多数地区农业土壤中PAEs的含量显著高于美国和欧洲等国家.大气沉降、农用薄膜、施用污泥和污水灌溉是我国农业土壤中PAEs的主要来源.不同作物对PAEs的吸收、累积和分配特征具有显著的差异性.PAEs不但影响土壤质量、作物生长和生理生化性质,而且具有生物累积效应.最后指出了当前研究中的不足及对今后研究的展望,建议扩大PAEs污染调查范围,深入揭示PAEs对农作物的毒害机理,重点研发PAEs污染土壤的原位修复技术.     

Chemical Constituents of a Heat-dried Chinese Mushroom,Hohenbuehelia serotina

Several compounds were isolated from a Chinese mushroom, Huangmo, the heat-dried fruiting body of Hohenbuehelia serotina. They were identified as linoleic acid (I), hexadecanoic acid (II), β-sitosterol (IV), benzoic acid (V), D-mannitol (VI), sucrose (VII), and L-rhamnose (VIII). In addition, six acidic substances were identified. (Table I). Also, ethyl linoleate, hexadecanoic acid, and 9,12-octadecadienoic acid (Z-Z) ethyl esters, IV, V, and VI were identified for the first time from this mushroom.     

Purification and Characterization of an Esterase from Micrococcus sp. YGJ1 Hydrolyzing Phthalate Esters

An esterase hydrolyzing phthalate esters has been purified from Micrococcus sp. YGJ1. The enzyme, a monomeric protein (M_r=56 kDa) with a pI of 4.0, hydrolyzes various aliphatic and aromatic carboxylesters. The medium chain (C₃-C₄) esters are the most preferred substrates. The enzyme is inhibited by HgCl₂ and p-chloromercuribenzoate but not by phenylmethyl-sulfonyl fluoride.     

Astaxanthin preparation by fermentation of esters from Haematococcus pluvialis algal extracts with Stenotrophomonas species

Natural astaxanthin (Ax) is an additive that is widely used because of its beneficial biochemical functions. However, the methods used to produce free Ax have drawbacks. Chemical saponification methods produce several by‐products, and lipase‐catalyzed hydrolysis methods are not cost effective. In this study, a bacterial strain of Stenotrophomonas sp. was selected to enzymatically catalyze the saponification of Ax esters to produce free all‐trans‐Ax. Through single‐factor experiments and a Box–Behnken design, the optimal fermentation conditions were determined as follows: a seed culture age of 37.79 h, an inoculum concentration of 5.92%, and an initial broth pH of 6.80. Under these conditions, a fermentation curve was drawn, and the optimal fermentation time was shown to be 60 h. At 60 h, the degradation rate of the Ax esters was 98.08%, and the yield of free all‐trans‐Ax was 50.130 μg/mL. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:649–656, 2016