The molecular composition of lignin in spruce decayed by white-rot fungi (Phanerochaete chrysosporium and Trametes versicolor) using pyrolysis-GC–MS and thermochemolysis with tetramethylammonium hydroxide

Pyrolysis-gas chromatography-mass spectrometry (Py-GC–MS) and off-line thermochemolysis with tetramethylammonium hydroxide followed by GC–MS were used in the molecular characterisation of lignin in spruce wood decayed by Phanerochaete chrysosporium and Trametes versicolor. Mono-methoxyphenols were the main pyrolysis products from the undegraded lignin. Py-GC–MS provided qualitative evidence that 2-methoxy-4-(prop-2-enal)phenol and trans-2-methoxy-4-(1-hydroxy-prop-2-enyl)phenol content decreased whereas 1,2-dihydroxybenzene increased in intensity relative to other products upon fungal decay. Comparison of methylated phenols from thermochemolysis revealed that ratio of methyl 3,4-dimethoxybenzoate to 3,4-dimethoxybenzaldehyde increased from 0.69 in control spruce to 2.3 after decay by P. chrysosporium and 3.7 following growth of T. versicolor. The results indicate that white-rot fungi cleave alkyl side chains of β-O-4 linked mono-methoxyphenylpropane structures between the α–β carbon atoms to give lignin residues enriched in carboxylic acids as well as demethylating methoxy groups attached to aromatic nuclei to give dihydroxybenzene products. Py-GC–MS and thermochemolysis are complementary methods for tracking demethylation of aromatic nuclei and oxidation of alkyl side chains caused by white-rot fungi.     

NMR,HS‐SPME‐GC/MS,and HPLC/MSn Analyses of Phytoconstituents and Aroma Profile of Rosmarinus eriocalyx

In this work, a comprehensive study on the chemical constituents of the aerial parts of Rosmarinus eriocalyx (Lamiaceae), an aromatic shrub traditionally consumed as a food and herbal remedy in Algeria, is presented. The aroma profile was analysed by headspace solid phase microextraction (HS‐SPME) coupled with gas chromatography‐mass spectrometry (GC/MS), whereas the crude extract constituents were analyzed by ¹H‐NMR and by high performance liquid chromatography coupled with mass spectrometry (HPLC/MSⁿ). Thirty‐nine volatile compounds, most of them being monoterpenes, have been identified, with camphor, camphene, and α‐pinene as the most abundant constituents. ¹H‐NMR analysis revealed the presence of phenolic compounds and betulinic acid while HPLC/MSⁿ allowed the identification of glycosilated and aglyconic flavonoids as well as phenylpropanoid derivatives. Some of these constituents, namely as betulinic acid, rosmanol, and cirsimaritin were reported for the first time in R. eriocalyx.     

Biological controls upon the physical taphonomy of exceptionally preserved salamanders from the Miocene of Rubielos de Mora,northeast Spain

McNamara, M.E., Orr, P.J., Manzocchi, T., Alcalá, L., Anadón, P. & Peñalver, E. 2011: Biological controls upon the physical taphonomy of exceptionally preserved salamanders from the Miocene of Rubielos de Mora, northeast Spain. Lethaia, Vol. 45, pp. 210–226. The middle Miocene Rubielos de Mora Konservat‐Lagerstätte of northeast Spain is hosted within profundal, finely laminated, lacustrine mudstones. The diverse biota includes abundant salamanders. Most individuals died during separate episodes and sank rapidly postmortem. Specimens are typically preserved in dorso‐ventral aspect, the most hydrodynamically stable orientation. The near‐cylindrical morphology of the body, however, allowed some carcasses to settle in or subsequently re‐orientate into, lateral orientations. Loss of skeletal elements (i.e. reduced completeness) reflects their location within the body and followed a distal to proximal trend. Two stages are identified: initial loss of a small number of phalanges, followed by loss of more proximal limb bones plus additional phalanges. Disarticulation is more complex: it occurred via several mechanisms (notably, abdominal rupture and re‐orientation of part of the body and limbs during decay) and shows no consistent pattern among specimens. The physical taphonomy of the salamanders is controlled predominantly by intrinsic biological factors, i.e. the geometry of the body and of individual skeletal elements, the orientation, inherent strength and location of specific joints and the extent to which soft tissues, particularly the skin, persist during decay. These biological factors probably control patterns of physical taphonomy of other fossil tetrapods with a similar skeletal configuration. □Articulation, completeness, Konservat‐Lagerstätten, orientation, quantitative taphonomy, salamanders.     

The taphonomic fate of isorenieratene in Lower Jurassic shales—controlled by iron?

Fossil derivatives of isorenieratene, an accessory pigment in brown‐colored green sulfur bacteria, are often used as tracers for photic zone anoxia through Earth's history, but their diagenetic behavior is still incompletely understood. Here, we assess the preservation of isorenieratene derivatives in organic‐rich shales (1.5–8.4 wt.% TOC) from two Lower Jurassic anoxic systems (Bächental oil shale, Tyrol, Austria; Posidonia Shale, Baden‐Württemberg, Germany). Bitumens and kerogens were investigated using catalytic hydropyrolysis (HyPy), closed‐system hydrous pyrolysis (in gold capsules), gas chromatography–mass spectrometry (GC–MS) and gas chromatography combustion isotope ratio‐mass spectrometry (GC‐C‐IRMS). Petrography and biomarkers indicate a syngenetic relationship between bitumens and kerogens. All bitumens contain abundant isorenieratane, diverse complex aromatized isorenieratene derivatives, and a pseudohomologous series of 2,3,6‐trimethyl aryl isoprenoids. In contrast, HyPy and mild closed‐system hydrous pyrolysis of the kerogens yielded only minor amounts of these compounds. Given the overall low maturity of the organic matter (below oil window), it appears that isorenieratene and its abundant derivatives from the bitumen had not been incorporated into the kerogens. Accordingly, sulfur cross‐linking, the key mechanism for sequestration of functionalized lipids into kerogens in anoxic systems, was not effective in the Jurassic environments studied. We explain this by (i) early cyclization/aromatization and (ii) hydrogenation reactions that have prevented effective sulfurization. In addition, (iii) sulfide was locally removed via anoxygenic photosynthesis and efficiently trapped by the reaction with sedimentary iron, as further indicated by elevated iron contents (4.0–8.7 wt.%) and the presence of abundant pyrite aggregates in the rock matrix. Although the combined processes have hampered the kerogen incorporation of isorenieratene and its derivatives, they may have promoted the long‐term preservation of these biomarkers in the bitumen fraction via early defunctionalization. This particular taphonomy of aromatic carotenoids has to be considered in studies of anoxic iron‐rich environments (e.g., the Proterozoic ocean).     

1‐Acetyl‐3‐[(3R)‐hydroxyfatty acyl]glycerols: Lipid Compounds from Euphrasia rostkoviana Hayne and E. tetraquetra (Bréb.) Arrond.

Five homologous acetylated acylglycerols of 3‐hydroxyfatty acids (chain lengths C(14) – C(18)), named euphrasianins A – E, were characterized for the first time in Euphrasia rostkoviana Hayne (Orobanchaceae) by gas chromatography/mass spectrometry (GC/MS) and high‐performance liquid chromatography/atmospheric pressure chemical ionization‐mass spectrometry (HPLC/APCI‐MSⁿ). In addition to mass spectrometric data, structures of euphrasianins were verified via a three‐step total synthesis of one representative homologue (euphrasianin A). The structure of the latter was confirmed by 1D‐ and 2D‐NMR experiments as well as high‐resolution electrospray ionization‐mass spectrometry (HR‐ESI‐MS). The absolute configuration of the 3‐hydroxyfatty acid moiety at C(3) was found to be R in the natural euphrasianins, which was determined by alkaline hydrolysis and methylation of a purified fraction, followed by chiral GC analysis. Furthermore, in extracts of Euphrasia tetraquetra (Bréb .) Arrond . euphrasianins C and E were detected exclusively, indicating that this subclass of lipid constituents is possibly valuable for fingerprinting methods.     

Comprehensive Characterisation of n‐Alkylresorcinols and Other Lipid Constituents of Mercurialis tomentosa L. from Alicante,Spain

Mercurialis tomentosa L. has been used in Spanish ethnomedicine. In the present study the first phytochemical characterisation of a lipid fraction from M. tomentosa was performed. The CHCl₃ extraction of aerial parts from M. tomentosa and GC/MS investigations revealed the occurrence of cuticular lipid and wax constituents, like long chain n‐alcohols and n‐aldehydes (C₂₂ – C₃₀), besides several aromatic constituents, i.e., phenylpropanoids and n‐alkylresorcinols. The latter were further purified by CC and analysed by LC/MSⁿ. In contrast to other Mercurialis species, i.e., M. annua, M. perennis, which exclusively contain 5‐n‐alkylresorcinols ( 1a  –  j , C_n), mainly 5‐n‐alkyl‐2‐methylresorcinols ( 2a  –  j , C_n*) with side chain lengths of C₁₅ – C₂₅ were found in M. tomentosa, in addition to 1a  –  j . Thus, the latter compounds may be utilised for analytical characterisation and authentication of M. tomentosa based on fingerprinting methods. For structure elucidation a novel facile total synthesis of one representative 5‐n‐alkyl‐2‐methylresorcinol homologue ( 2d , C₁₉*) was developed, starting with a Grignard reaction from a substituted benzoic acid chloride ( 19 ). The compound obtained by synthesis was identical to the natural product 2d in terms of its chromatographic and spectroscopic features. Futhermore, 2d exhibited satisfactory DPPH free radical scavenging activity (IC₅₀ = 37.8 μm ) when compared to trolox (IC₅₀ = 21.0 μm ), corroborating the antioxidant features of these amphipathic molecules.     

GPIomics: global analysis of glycosylphosphatidylinositol‐anchored molecules of Trypanosoma cruzi

Glycosylphosphatidylinositol (GPI) anchoring is a common, relevant posttranslational modification of eukaryotic surface proteins. Here, we developed a fast, simple, and highly sensitive (high attomole‐low femtomole range) method that uses liquid chromatography‐tandem mass spectrometry (LC‐MSⁿ) for the first large‐scale analysis of GPI‐anchored molecules (i.e., the GPIome) of a eukaryote, Trypanosoma cruzi, the etiologic agent of Chagas disease. Our genome‐wise prediction analysis revealed that approximately 12% of T. cruzi genes possibly encode GPI‐anchored proteins. By analyzing the GPIome of T. cruzi insect‐dwelling epimastigote stage using LC‐MSⁿ, we identified 90 GPI species, of which 79 were novel. Moreover, we determined that mucins coded by the T. cruzi small mucin‐like gene (TcSMUG S) family are the major GPI‐anchored proteins expressed on the epimastigote cell surface. TcSMUG S mucin mature sequences are short (56–85 amino acids) and highly O‐glycosylated, and contain few proteolytic sites, therefore, less likely susceptible to proteases of the midgut of the insect vector. We propose that our approach could be used for the high throughput GPIomic analysis of other lower and higher eukaryotes.     

HS‐SPME‐GC‐FID method for detection and quantification of Bacillus cereus ATCC 10702 mediated 2‐acetyl‐1‐pyrroline

A rapid micro‐scale solid‐phase micro‐extraction (SPME) procedure coupled with gas‐chromatography with flame ionized detector (GC‐FID) was used to extract parts per billion levels of a principle basmati aroma compound “2‐acetyl‐1‐pyrroline” (2‐AP) from bacterial samples. In present investigation, optimization parameters of bacterial incubation period, sample weight, pre‐incubation time, adsorption time, and temperature, precursors and their concentrations has been studied. In the optimized conditions, detection of 2‐AP produced by Bacillus cereus ATCC10702 using only 0.5 g of sample volume was 85 μg/kg. Along with 2‐AP, 15 other compounds produced by B. cereus were also reported out of which 14 were reported for the first time consisting mainly of (E)?2‐hexenal, pentadecanal, 4‐hydroxy‐2‐butanone, n‐hexanal, 2–6‐nonadienal, 3‐methoxy‐2(5H) furanone and 2‐acetyl‐1‐pyridine and octanal. High recovery of 2‐AP (87 %) from very less amount of B. cereus samples was observed. The method is reproducible fast and can be used for detection of 2‐AP production by B. cereus. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1356–1363, 2014     

Characterization of Secondary Metabolites in Flowers of Sanguisorba officinalis L. by HPLC‐DAD‐MSn and GC/MS

The investigations reported here focus on an in‐depth characterization of the secondary metabolite profile of Sanguisorba officinalis flowers. For this purpose, fresh flowers were extracted with MeOH/H₂O and EtOH/H₂O and the resulting crude extracts fractionated using CH₂Cl₂, AcOEt, and BuOH. Individual compounds were characterized by high performance liquid chromatography and gas chromatography coupled with mass spectrometric detection (HPLC‐DAD‐MSⁿ and GC/MS). MeOH/H₂O extraction and LC/MSⁿ investigations revealed the occurrence of flavonoid glycosides (quercetin, kaempferol), ellagitannin glycosides and four anthocyanins. Among the latter, two components, i. e., cyanidin‐malonyl‐glucose and cyanidin‐galloyl‐hexose, have not been reported for S. officinalis so far. Furthermore, phenylethylamine was characterized for the first time in Sanguisorba by pH value dependent extraction with CH₂Cl₂. In addition, AcOEt and BuOH extracts were analyzed by GC/MS both prior to and after acid hydrolysis of secondary metabolites. For this purpose, the extracts were treated with 1 n HCl solution (105 °C, 1 h) and derivatized with BSTFA. Analyses revealed the occurrence of several classes of phenolic compounds, such as gallic acid, hydroxybenzoic acid, hydroxycinnamic acid and ellagic acid derivatives. Additionally, the most prominent ursane‐type triterpenoid (ziyu‐glycoside I) from Sanguisorba and its corresponding aglycone isomers were detected and assigned based on their characteristic fragmentation patterns.     

Electrophysiological responses of Batocera horsfieldi (Hope) adults to plant volatiles

The olfactory stimuli from the maturation feeding‐plant, Rosa multiflora Thunb., and larval‐host plant, Populus deltoides, of the longhorned beetle, Batocera horsfieldi (Hope), were investigated by using TCT‐GC/MS (Thermal desorption and cold trap, and GC/MS) and electroantennogram recordings (EAG). A total of 20 plant compounds were identified from plant headspace volatile, including aliphatic, aromatic and terpenoid compounds. Five compounds were common to both plants. Eight compounds eliciting strong EAG response were E‐3‐hexenyl acetate, 3‐carene, 1‐penten‐3‐ol, 3‐pentanol, Z‐2‐penten‐1‐ol, hexanal and E‐2‐hexenal. Female and male B. horsfieldi exhibited broad overlap in their EAG responses to individual plant odour, and there was no clear pattern of difference between responses of female and male antennae to different compounds. Mating status had little effect on the EAG responses of females.     

Chemical Composition,Antibacterial, Antibiofilm and Synergistic Properties of Essential Oils from Eucalyptus globulus Labill. and Seven Mediterranean Aromatic Plants

Essential oils (EOs) from Eucalyptus globulus Labill . ssp. globulus and from Mediterranean autochthonous aromatic plants – Thymus mastichina L., Mentha pulegium L., Rosmarinus officinalis L., Calamintha nepeta (L.) Savi ssp. nepeta, Cistus ladanifer L., Foeniculum vulgare L., Dittrichia viscosa (L.) Greuter ssp. viscosa – were extracted by hydrodistillation and characterized by GC‐FID and NMR spectroscopy. EOs were evaluated for antimicrobial properties against several bacterial strains, using diverse methods, namely, the agar disc‐diffusion method, the microdilution method, the crystal violet assay and the Live/Dead staining for assessment of biofilm formation. Potential synergy was assessed by a checkerboard method. EOs of R. officinalis and C. ladanifer showed a predominance in monoterpene hydrocarbons (> 60%); EOs of C. nepeta, M. pulegium, T. mastichina, E. globulus and F. vulgare were rich in oxygenated monoterpenes (62 – 96%) whereas EO of D. viscosa was mainly composed of oxygenated sesquiterpenes (54%). All EOs showed antimicrobial activity; M. pulegium and E. globulus generally had the strongest antimicrobial activity. EO of C. nepeta was the most promising in hampering the biofilm formation. The combinations D. viscosa/C. nepeta and E. globulus/T. mastichina were synergistic against Staphylococcus aureus. These results support the notion that EOs from the aromatic plants herein reported should be further explored as potential pharmaceuticals and/or food preservatives.     

A freshwater analog for the production of Epiphyton‐like microfossils

Calcified microbial microfossils—often interpreted as cyanobacteria—were important components of Precambrian and Paleozoic limestones, but their paucity in modern marine environments complicates our ability to make conclusive interpretations about their taxonomic affinity and geologic significance. Freshwater spring‐associated limestones (e.g., travertine and tufa) serve as terrestrial analogs to investigate mineralization in and around aquatic biofilms on observable timescales. We document the diagenesis of calcite fabrics associated with the freshwater algae Oocardium stratum, an epiphytic colonial green algae (desmid) known for producing stalks of extracellular polymeric substances (EPS) and passively producing a bifurcating tubular calcite monocrystal. Bifurcating EPS stalks produced by Oocardium colonies can become calcified and preserved in ancient carbonate deposits. Calcified micritic EPS stalks have a filamentous morphology, show evidence of branching, and maintain uniformity in diameter thickness throughout the mm‐scale colony, much like the enigmatic calcimicrobe Epiphyton. We provide a mechanism by which calcification associated with a colonial semispherical micro‐organism produces microfossils that deceptively resemble filamentous forms. These findings have implications for the use of morphological traits when assigning taxonomic affinities to extinct microfossil groups and highlight the utility of calcifying freshwater modern environments to investigate microbial taphonomy.     

Variation in volatile leaf oils of five Eucalyptus species harvested from Jbel Abderrahman arboreta (Tunisia)

Hydrodistillation of the dried leaves of five species of the genus Eucalyptus L' Hér ., viz., E. dundasii Maiden , E. globulus Labill ., E. kitsoniana Maiden , E. leucoxylon F. Muell ., and E. populifolia Hook ., harvested from Jbel Abderrahman arboreta (region of Nabeul, northeast of Tunisia) in April 2006, afforded essential oils in yields varying from 0.9±0.3 to 3.8±0.6%, dependent on the species. E. globulus and E. Kitsoniana provided the highest and the lowest percentage of essential oil amongst the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 127 compounds, representing 93.8 to 98.7% of the total oil composition. The contents of the different samples varied according to the species. The main components were 1,8‐cineole ( 2 ; 4.7–59.2%), followed by α‐pinene ( 1 ; 1.9–23.6%), trans‐pinocarveol ( 6 ; 3.5–21.6%), globulol ( 8 ; 4.3–12.8%), p‐cymene ( 3 ; 0.5–6.7%), α‐terpineol (1.5–4.5%), borneol (0.2–4.4%), pinocarvone (1.1–3.8%), aromadendrene (1.4–3.4%), isospathulenol (0.0–1.9%), fenchol ( 4 ; 0.1–2.5%), limonene (1.0–2.4%), epiglobulol (0.6–2.1%), viridiflorol ( 9 ; 0.8–1.8%), and spathulenol (0.1–1.6%). E. leucoxylon was the richest species in 2 . Principal component analysis (PCA) and hierarchical cluster analysis (HCA) separated the five Eucalyptus leaf essential oils into four groups, each constituting a chemotype.     

Fungal biosolubilization of Rhenish brown coal monitored by Curie-point pyrolysis/gas chromatography/mass spectrometry using tetraethylammonium hydroxide

Residues and coal fractions that remained after the biosolubilization of Rhenish brown coal by strains of Lentinula edodes and Trametes versicolor have been studied by Curie-point pyrolysis/gas chromatography/mass spectrometry using tetraethylammonium hydroxide (NEt₄OH) at 610 °C. To differentiate methyl derivatives of esters and ethers from free or bound hydroxyl and carboxyl groups NEt₄OH was used in the thermochemolysis experiments instead the commonly used tetramethylammonium hydroxide. A comparison of humic acid fractions before and after fungal attack shows considerable alteration of the soluble macromolecules of coal. Depending on the coal fraction studied and the fungi used, the assortment of fatty acid esters released during the pyrolysis varies significantly. Furthermore, dicarbonic acid ethyl diesters as well as ethyl derivatives of aromatic ethers and acids yield information about humic acid structure and the biosolubilization of brown coal. Variations in the mixture produced are possibly caused by differences in the pattern of extracellular enzymes secreted that attack the macromolecular structural elements of brown coal. Therefore pyrolysis of native and microbiologically altered geomacromolecules using NEt₄OH allows one to differentiate between free hydroxyl groups as well as substances that are attached to humic substances via ester or ether bridges, and their methylated counterparts. Received: 13 July 1998 / Received revision: 12 October 1998 / Accepted: 16 October 1998     

Essential oils from wild populations of Algerian Lavandula stoechas L.: composition, chemical variability, and in vitro biological properties

In an effort to develop local productions of aromatic and medicinal plants, a comprehensive assessment of the composition and biological activities of the essential oils (EOs) extracted from the aerial flowering parts of wild growing Lavandula stoechas L. collected from eleven different locations in northern Algeria was performed. The oils were characterized by GC‐FID and GC/MS analyses, and 121 compounds were identified, accounting for 69.88–91.2% of the total oil compositions. The eleven oils greatly differed in their compositions, since only 66 compounds were common to all oils. Major EO components were fenchone ( 2 ; 11.27–37.48%), camphor ( 3 , 1.94–21.8%), 1,8‐cineole ( 1 ; 0.16–8.71%), and viridiflorol ( 10 ; 2.89–7.38%). The assessed in vitro biological properties demonstrated that the DPPH‐based radical‐scavenging activities and the inhibition of the β‐carotene/linoleic acid‐based lipid oxidation differed by an eight‐fold factor between the most and the least active oils and were linked to different sets of molecules in the different EOs. The eleven EOs exhibited good antimicrobial activities against most of the 16 tested strains of bacteria, filamentous fungi, and yeasts, with minimum inhibitory concentrations (MICs) ranging from 0.16 to 11.90 mg/ml.     

Quantitative and Qualitative Aspects of Dissolved Organic Carbon Leached from Senescent Plants in an Oligotrophic Wetland

We conducted a series of experiments whereby dissolved organic matter (DOM) was leached from various wetland and estuarine plants, namely sawgrass (Cladium jamaicense), spikerush (Eleocharis cellulosa), red mangrove (Rhizophora mangle), cattail (Typha domingensis), periphyton (dry and wet mat), and a seagrass (turtle grass; Thalassia testudinum). All are abundant in the Florida Coastal Everglades (FCE) except for cattail, but this species has a potential to proliferate in this environment. Senescent plant samples were immersed into ultrapure water with and without addition of 0.1% NaN₃ (w/ and w/o NaN₃, respectively) for 36 days. We replaced the water every 3 days. The amount of dissolved organic carbon (DOC), sugars, and phenols in the leachates were analyzed. The contribution of plant leachates to the ultrafiltered high molecular weight fraction of DOM (>1 kDa; UDOM) in natural waters in the FCE was also investigated. UDOM in plant leachates was obtained by tangential flow ultrafiltration and its carbon and phenolic compound compositions were analyzed using solid state ¹³C cross-polarization magic angle spinning nuclear magnetic resonance (¹³C CPMAS NMR) spectroscopy and thermochemolysis in the presence of tetramethylammonium hydroxide (TMAH thermochemolysis), respectively. The maximum yield of DOC leached from plants over the 36-day incubations ranged from 13.0 to 55.2 g C kg⁻¹ dry weight. This amount was lower in w/o NaN₃ treatments (more DOC was consumed by microbes than produced) except for periphyton. During the first 2 weeks of the 5 week incubation period, 60–85% of the total amount of DOC was leached, and exponential decay models fit the leaching rates except for periphyton w/o NaN₃. Leached DOC (w/ NaN₃) contained different concentrations of sugars and phenols depending on the plant types (1.09–7.22 and 0.38–12.4 g C kg⁻¹ dry weight, respectively), and those biomolecules comprised 8–34% and 4–28% of the total DOC, respectively. This result shows that polyphenols that readily leach from senescent plants can be an important source of chromophoric DOM (CDOM) in wetland environments. The O-alkyl C was found to be the major C form (55±9%) of UDOM in plant leachates as determined by ¹³C CPMAS NMR. The relative abundance of alkyl C and carbonyl C was consistently lower in plant-leached UDOM than that in natural water UDOM in the FCE, which suggests that these constituents increase in relative abundance during diagenetic processing. TMAH thermochemolysis analysis revealed that the phenolic composition was different among the UDOM leached from different plants, and was expected to serve as a source indicator of UDOM in natural water. Polyphenols are, however, very reactive and photosensitive in aquatic environments, and thus may loose their plant-specific molecular characteristics shortly. Our study suggests that variations in vegetative cover across a wetland landscape will affect the quantity and quality of DOM leached into the water, and such differences in DOM characteristics may affect other biogeochemical processes.     

Antifungal and Herbicidal Effects of Fruit Essential Oils of Four Myrtus communis Genotypes

The chemical composition of the essential oils isolated by hydrodistillation from the fruits of four selected Myrtus communis L. genotypes from Turkey was characterized by GC‐FID and GC/MS analyses. 1,8‐Cineole (29.20–31.40%), linalool (15.67–19.13%), α‐terpineol (8.40–18.43%), α‐pinene (6.04–20.71%), and geranyl acetate (3.98–7.54%) were found to be the major constituents of the fruit essential oils of all M. communis genotypes investigated. The oils were characterized by high amounts of oxygenated monoterpenes, representing 73.02–83.83% of the total oil compositions. The results of the fungal growth inhibition assays showed that the oils inhibited the growth of 19 phytopathogenic fungi. However, their antifungal activity was generally lower than that of the commercial pesticide benomyl. The herbicidal effects of the oils on the seed germination and seedling growth of Amaranthus retroflexus L., Chenopodium album L., Cirsium arvense (L.) Scop ., Lactuca serriola L., and Rumex crispus L. were also determined. The oils completely or partly inhibited the seed germinations and seedling growths of the plants. The findings of the present study suggest that the M. communis essential oils might have potential to be used as natural herbicides as well as fungicides.     

Essential Oil Composition of Three Globularia Species

The chemical composition of the essential oils obtained by hydrodistillation from the aerial parts of Globularia cordifolia L., G. meridionalis (Podp.) O.Schwarz , and G. punctata Lapeyr . was characterized by GC‐FID and GC/MS analyses. Among the 33 identified compounds, the most abundant present in all investigated samples were oct‐1‐en‐3‐ol (2.9–47.0%), 6‐(1,5‐dimethylhex‐4‐enyl)‐3‐methylcyclohex‐2‐enone (8.2–40.9%), and fukinanolid (7.4–31.6%). Multivariate statistical analyses (PCA and HCA) of the hitherto studied Globularia volatile compounds confirmed to some extent the assumed phylogenetic relationships of the Globularia species studied, including the close relationship between the morphologically similar species G. cordifolia and G. meridionalis, but also evidenced several discrepancies in the current classification of Globularia species.     

Antibacterial and antifungal activities of pyroligneous acid from wood of Eucalyptus urograndis and Mimosa tenuiflora

Aims

This work aimed to evaluate the antibacterial and antifungal activities of two types of pyroligneous acid (PA) obtained from slow pyrolysis of wood of Mimosa tenuiflora and of a hybrid of Eucalyptus urophylla × Eucalyptus grandis.

Methods and Results

Wood wedges were carbonized on a heating rate of 1·25°C min^?1 until 450°C. Pyrolysis smoke was trapped and condensed to yield liquid products. Crude pyrolysis liquids were bidistilled under 5 mmHg vacuum yielding purified PA. Multi‐antibiotic‐resistant strains of Escherichia coli, Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923) had their sensitivity to PA evaluated using agar diffusion test. Two yeasts were evaluated as well, Candida albicans (ATCC 10231) and Cryptococcus neoformans. GC‐MS analysis of both PAs was carried out to obtain their chemical composition. Regression analysis was performed, and models were adjusted, with diameter of inhibition halos and PA concentration (100, 50 and 20%) as parameters. Identity of regression models and equality of parameters in polynomial orthogonal equations were verified. Inhibition halos were observed in the range 15–25 mm of diameter.

Conclusions

All micro‐organisms were inhibited by both types of PA even in the lowest concentration of 20%.

Significance and Impact of the Study

The feasibility of the usage of PAs produced with wood species planted in large scale in Brazil was evident and the real potential as a basis to produce natural antibacterial and antifungal agents, with real possibility to be used in veterinary and zootechnical applications.     

Microbial biofilms and the preservation of the Ediacara biota

Laflamme, M., Schiffbauer, J.D., Narbonne, G.M., & Briggs, D.E.G. 2011: Microbial biofilms and the preservation of the Ediacara biota. Lethaia, Vol. 44, pp. 203–213. The terminal Neoproterozoic Ediacaran Period is typified by the Ediacara biota (ca. 579–542 Ma), which includes the first morphologically complex macroscopic organisms. Both the taphonomic setting that promoted the preservation of the soft‐bodied Ediacara biota in coarse‐grained sediments, and the influence of associated microbial coatings on this process, have generated debate. Specimens of Ediacaran discs (Aspidella) from the Fermeuse Formation of Newfoundland, Canada, were analysed using environmental scanning electron microscopy (ESEM) and focused ion beam electron microscopy (FIB‐EM) to determine the relationship between the fossil specimens and the surrounding sediment. The presence of chemically distinct (Al–Mg–Fe–K‐ and to a lesser extent S‐rich), finer‐grained sediment (with organized iron sulphides) surrounding the upper and lower margins of the Ediacaran fossils is consistent with elemental analyses of well preserved bacterial biofilms from other localities. ESEM analyses reveal a contrast in the composition of the sediment bound within the discs, which contains a higher concentration of Al, Ca and K, and the purer Si‐rich sediment that forms the surrounding matrix. This suggests that the coarse grained sediment was incorporated into the organism during life. Ediacaran discs were likely surrounded by a bacterial biofilm or thin microbial mat composed primarily of extracellular polymeric substances (or exopolysaccharide) during life, which added structural stability to these frond holdfasts, and facilitated their fossilization. Microbially mediated preservation in Fermeuse‐style Ediacaran taphonomy provides an explanation for the dominance of Aspidella holdfasts in these settings, and suggests that preservation of Ediacaran fossils in the round may be much more prevalent than previously recognized. We suggest that the overwhelming dominance of circular to bulbous forms such as Aspidella in Ediacaran biotas around the world is a direct result of the interplay between microbial ecology and microbially mediated taphonomy. □Aspidella, Ediacaran preservation, environmental scanning electron microscopy, focused ion beam electron microscopy, palaeoecology, taphonomic bias.