Production of Induced Secondary Metabolites by a Co-Culture of Sponge-Associated Actinomycetes,Actinokineospora sp. EG49 and Nocardiopsis sp. RV163

Two sponge-derived actinomycetes, Actinokineospora sp. EG49 and Nocardiopsis sp. RV163, were grown in co-culture and the presence of induced metabolites monitored by ¹H NMR. Ten known compounds, including angucycline, diketopiperazine and β-carboline derivatives 1–10, were isolated from the EtOAc extracts of Actinokineospora sp. EG49 and Nocardiopsis sp. RV163. Co-cultivation of Actinokineospora sp. EG49 and Nocardiopsis sp. RV163 induced the biosynthesis of three natural products that were not detected in the single culture of either microorganism, namely N-(2-hydroxyphenyl)-acetamide (11), 1,6-dihydroxyphenazine (12) and 5a,6,11a,12-tetrahydro-5a,11a-dimethyl[1,4]benzoxazino[3,2-b][1,4]benzoxazine (13a). When tested for biological activity against a range of bacteria and parasites, only the phenazine 12 was active against Bacillus sp. P25, Trypanosoma brucei and interestingly, against Actinokineospora sp. EG49. These findings highlight the co-cultivation approach as an effective strategy to access the bioactive secondary metabolites hidden in the genomes of marine actinomycetes.     

Metabolomic Tools for Secondary Metabolite Discovery from Marine Microbial Symbionts

Marine invertebrate-associated symbiotic bacteria produce a plethora of novel secondary metabolites which may be structurally unique with interesting pharmacological properties. Selection of strains usually relies on literature searching, genetic screening and bioactivity results, often without considering the chemical novelty and abundance of secondary metabolites being produced by the microorganism until the time-consuming bioassay-guided isolation stages. To fast track the selection process, metabolomic tools were used to aid strain selection by investigating differences in the chemical profiles of 77 bacterial extracts isolated from cold water marine invertebrates from Orkney, Scotland using liquid chromatography-high resolution mass spectrometry (LC-HRMS) and nuclear magnetic resonance (NMR) spectroscopy. Following mass spectrometric analysis and dereplication using an Excel macro developed in-house, principal component analysis (PCA) was employed to differentiate the bacterial strains based on their chemical profiles. NMR ¹H and correlation spectroscopy (COSY) were also employed to obtain a chemical fingerprint of each bacterial strain and to confirm the presence of functional groups and spin systems. These results were then combined with taxonomic identification and bioassay screening data to identify three bacterial strains, namely Bacillus sp. 4117, Rhodococcus sp. ZS402 and Vibrio splendidus strain LGP32, to prioritize for scale-up based on their chemically interesting secondary metabolomes, established through dereplication and interesting bioactivities, determined from bioassay screening.     

微孢子虫糖蛋白的研究进展

随着蛋白质组学和糖组学研究的迅速发展,糖蛋白已成为众多研究的中心.糖蛋白的糖链结构直接影响其功能,因此糖蛋白中糖链的结构研究成为糖生物学研究的重点之一.就糖蛋白研究的基本策略方法作了简要介绍,并且简要概括了近年来微孢子虫糖蛋白的研究进展.     

Unfrozen water content moderates temperature dependence of sub-zero microbial respiration

Abrupt increases in the temperature sensitivity of soil respiration below 0 °C have been interpreted as a change in the dominance of other co-dependent environmental controls, such as the availability of liquid-state water. Yet the relationship between unfrozen water content and soil respiration at sub-zero temperatures has received little attention because of difficulties in measuring unfrozen water contents. Using a recently-developed semi-solid ²H NMR technique the unfrozen water content present in seasonally frozen boreal forest soils was quantified and related to biotic CO₂ efflux in laboratory microcosms maintained at temperatures between −0.5 and −8 °C. In both soils the unfrozen water content had an exponential relationship with temperature and was increased by addition of KCl solutions of defined osmotic potential. Approximately 13% unfrozen water was required to release the dependence of soil respiration on unfrozen water content. Depending on the osmotic potential of soil solution, this threshold unfrozen water content was associated with temperatures down to −6 °C; yet if temperature were the predictor of CO₂ efflux, then the abrupt increase in the temperature sensitivity of CO₂ efflux was associated with −2 °C, except in soils amended with −1500 kPa KCl which did not show any abrupt changes in temperature sensitivity. The KCl-amendments also had the effect of decreasing Q₁₀ values and activation energies (Ea) by factors of 100 and three, respectively, to values comparable with those for soil respiration in unfrozen soil. The disparity between the threshold temperatures and the reductions in Q₁₀ values and activation energies after KCl amendment indicates the significance of unfrozen water availability as an environmental control of equal importance to temperature acting on sub-zero soil respiration. However, this significance was diminished when soils were supplied with abundant labile C (sucrose) and the influences of other environmental controls, allied to the solubility and diffusion of respiratory substrates and gases, are considered to increase.     

Selection of Variovorax paradoxus-like bacteria in the mycosphere and the role of fungal-released compounds

At two occasions (2004 and 2006), a similar cluster of culturable bacteria was found to be selected in the mycosphere of the basidiomycetous fungus Laccaria proxima (Agaricales, Tricholomataceae) in the field. The bacteria, identified as related to Variovorax paradoxus, comprised 7.3-9% of the total culturable bacterial community in the L. proxima mycosphere, but were not found in corresponding bulk soil (<0.3%). One strain, denoted HB44, was selected in order to unravel the basis of the V. paradoxus mycosphere competence in in vitro experiments with the former Laccaria laccata, which was recently reclassified as Lyophyllum sp. strain Karsten (Agaricales, Tricholomataceae). In liquid culture experiments, L. strain Karsten was shown to be an avid producer of glycerol, next to acetate and formate, which constituted the most abundant carbonaceous compounds released. Strain HB44 was able to grow avidly at the expense of the glycerol liberated by the fungus, as evidenced by proton NMR analysis of the fungal exudates in the medium before and after bacterial growth. In sterilized field soil, strain HB44 survived significantly better in the presence than in the absence of L. strain Karsten. Addition of a glycerol series to the sterilized soil (without the fungus) resulted in the persistence or growth of strain HB44, but only if the pH of this soil was previously set at 5.5. Thus, we provide evidence for the contention that tricholomataceous fungi can create specific niches in soil for the V. paradoxus-related strain HB44 and that glycerol may be a main carbon source that drives the selection of this organism.     

The effects of compost in a rice–wheat cropping system on aggregate size,carbon and nitrogen content of the size–density fraction and chemical composition of soil organic matter,as shown by 13C CP NMR spectroscopy

We investigated whether the long‐term application of compost from agricultural waste improved soil physical structure, fertility and soil organic matter (SOM) storage. In 2006, we began a long‐term field experiment based on a rice–wheat rotation cropping system, having a control without fertilizer (NF) and three treatments: chemical fertilizers (CF), pig manure compost (PMC) and a prilled mixture of PMC and inorganic fertilizers (OICF). Following the harvest of wheat in 2010, the mean‐weight diameter (MWD) of water‐stable aggregates and the concentration of C and N in bulk soil (0–20 cm; <2 mm fraction) were significantly greater (P < 0.05) in PMC and NF plots than in CF or OICF plots. Pig manure compost significantly increased the proportion of >5‐mm aggregates, whereas CF significantly increased the proportion of 0.45‐ to 1‐mm aggregates. The C and N contents of all density fractions were greater in PMC than in other treatments with levels decreasing in the following order: free particulate organic matter (fPOM) >occluded particulate organic matter (oPOM) > mineral‐combined SOM (mineral–SOM). Solid‐state ¹³C CPMAS NMR spectra showed that alkyl C/O‐alkyl C ratios and aromatic component levels of SOM were smaller in PMC and OICF plots than in CF plots, suggesting that SOM in PMC and OICF plots was less degraded than that in CF plots. Nevertheless, yields of wheat in PMC and NF plots were smaller than those in CF and OICF plots, indicating that conditions for producing large grain yields did not maintain soil fertility.     

Carbon Sequestration in Restored Soils by Applying Organic Amendments

The study of different natural carbon sinks has become especially important because of climate change effects. The restoration of contaminated areas can be an ideal strategy for carbon sequestration. The studied area was affected by toxic Aznalcóllar mine spill in 1998. Restoration process of the contaminated area was based, mainly, on the use of two organic amendments: leonardite (LE) and biosolid compost (BC). The objective of this study was to verify whether the application of these amendments promotes the long‐term carbon sequestration in this soil. Five treatments were established: untreated control, biosolid compost (doses 4 and 2) and leonardite (doses 4 and 2). The addition of amendments implied an improvement in soil quality that was directly related to the amendment dose: decrease in bulk density, increase in pH, higher respiration rates and an improvement in the stratification ratio. Dose‐dependent changes in the molecular composition of soil organic matter were shown by nuclear magnetic resonance analysis. Both amendments promoted carbon retention, although because of the low mineralization rates of soil organic matter in LE treatments, the carbon storage was higher. The dosage effect on the carbon balance was more important in LE treatments, whereas in the BC treatments, the balance was similar for both doses. Our findings suggest that LE4 significantly increased the total organic carbon and it was the most suitable treatment for long‐term carbon storage, because of its molecular composition rich in relatively stable aromatic and lignin‐derived compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

面制品加工和贮藏的NMR研究

近年来,核磁共振NMR及其成像技术在食品工业上的运用日益广泛而重要。这就为设计和优化食品,特别是面制品加工和贮藏过程的技术创新提供了崭新的领域,同时在更基础的层面上,利用NMR技术来研究食品内部传热、传质过程及许多影响食品品质的因素,将会取得对其更好的理解。     

应用核磁共振技术测定油菜籽含油量的方法研究

本文建立了系统的应用核磁共振技术测定油菜种子含油量的方法。首次报道了样品前处理，最适工作参数选择和校正方法的系统研究结果。 50份不同含油量的种子样品用于核磁共振法与经典索氏抽提法比较试验，两方法相关系数r=0.9823。核磁共振仪对纯菜籽油的线性响应r=0.9994。最少种子需要量为0.5克。测定环境温度和种子样