Fluorescence characterization of metal ion–humic acid interactions in soils amended with composted municipal solid wastes

Fluorescence spectroscopy has been used to probe the structural properties and Cu(II), Zn(II), Cd(II), and Pb(II)-binding behavior of humic acid (HA)-like fractions isolated from a municipal solid waste compost (MSWC) and HAs from unamended and MSWC-amended soils. The main feature of the fluorescence spectra, in the form of emission-excitation matrix (EEM) plots, was a broad peak with the maximum centered at an excitation/emission wavelength pair that was much shorter (340/437 nm) for MSWC-HA than for unamended and MSWC-amended soil HAs (455/513 and 455/512 nm, respectively). Fluorescence intensity for MSWC-amended soil HA was less than that for unamended soil HA. These results were indicative of more aromatic ring polycondensation and humification of soil HAs, and of partial incorporation of simple and low-humified components of MSWC-HA into native soil HA, as a result of MSWC amendment. Titrations of HAs with Cu(II), Zn(II), Cd(II), and Pb(II) ions at pH 6 and ionic strength 0.1 mol L⁻¹ resulted in a marked decrease of the fluorescence intensities of untreated HAs. By successfully fitting a single-site fluorescence-quenching model to titration data, the metal ion complexing capacities of each HA and the stability constants of metal ion-HA complexes were obtained. The binding capacities and stability constants of MSWC-HA were smaller than those of the unamended soil HA. Application of MSWC to soil slightly reduced the metal-ion-binding capacities and affinities of soil HAs.     

Effects of Tebuconazole Application on Soil Microbiota and Enzymes

Identification of pesticide impact on the soil microbiome is of the utmost significance today. Diagnosing the response of bacteria to tebuconazole, used for plant protection, may help isolate the most active bacteria applicable in the bioaugmentation of soils contaminated with this preparation. Bearing in mind the above, a study was undertaken to test the effect of tebuconazole on the diversity of bacteria at all taxonomic levels and on the activity of soil enzymes. It was conducted by means of standard and metagenomic methods. Its results showed that tebuconazole applied in doses falling within the ranges of good agricultural practice did not significantly disturb the biological homeostasis of soil and did not diminish its fertility. Tebuconazole was found to stimulate the proliferation of organotrophic bacteria and fungi, and also the activities of soil enzymes responsible for phosphorus, sulfur, and carbon metabolism. It did not impair the activity of urease responsible for urea hydrolysis, or cause any significant changes in the structure of bacterial communities. All analyzed soil samples were mainly populated by bacteria from the phylum Proteobacteria, Actinobacteria, Firmicutes, Gemmatimonadetes, Acidobacteria, Planctomycetes, and Chloroflexi. Bacteria from the genera Kaistobacter, Arthrobacter, and Streptomyces predominated in the soils contaminated with tebuconazole, whereas these from the Gemmata genus were inactivated by this preparation.     

Characterization of humic acids in sediments from dam reservoirs by pyrolysis-gas chromatography/mass spectrometry using tetramethylammonium hydroxide: Influence of the structural features of humic acids on iron(II) binding capacity

The structural features of humic acids (HAs) isolated from sediments on the bottom of dam reservoirs that can affect their binding capacities for Fe(II) were investigated by pyrolysis-gas chromatography/mass spectroscopy using tetramethylammonium hydroxide (TMAH-py-GC/MS). The binding capacities for Fe(II) increased with increasing O/C molar ratio, suggesting that the oxygen-containing functional group content plays a role in the binding of Fe(II). However, it was not possible to identify specific binding-sites for Fe(II) by TMAH-py-GC/MS analysis. Although C_16:1ω7, iso-C_15:0 and anteiso-C_17:0 fatty acids, which serve as molecular markers of anaerobic microbial activity, were detected in all of the HA samples, the contents of these acids were not correlated with binding capacities for Fe(II). However, the ratio of C_16:0 to C_16:1ω7 fatty acids, which is used as an index of anaerobic bacterial activity, increased with increasing Fe(II) binding capacities of the HAs. It thus appears likely that the activities of anaerobic bacteria on the bottom of dam reservoirs contribute to alterations in the structural features for HAs, and that this process results in increased binding capacities for Fe(II).     

An improved analytical method for determination of heterocyclic amines in chicken legs

Summary Several extraction, separation and detection methods for heterocyclic amines (HAs) in chicken legs were evaluated by liquid chromatography. Results showed that the most appropriate extraction method includes the removal of macrosubstances by centrifugation and subsequent purification using a PRS (propylsulfonic acid silica gel) and a C₁₈ cartridge, and the recovery obtained ranged between 51 and 89 %. For HPLC separation, a binary solvent system consisting of acetonitrile and 0.05 M ammonium acetate solution (pH 3.6) with gradient elution with flow rate of 1.0 mL min⁻¹ and detection at 258 nm was used to resolve 16 HAs. With fluorescence nine HAs could be detected by employing a programmable wavelength, and the sensitivity was 100–400 times higher than that by UV detection. The detection limits for UV and fluorescence detection were 0.02≈0.5 ng and 0.05≈3 pg respectively, with a signal-to-noise ratio 3. The presence of HAs in fried chicken legs was also determined.     

Structural alterations of humic acid fractions in a steel slag-compost fertilizer during fertilization. Analysis by pyrolysis/methylation-gas chromatography/mass spectrometry

Alterations in the structural features of humic acids (HAs) in a steel slag-compost fertilizer for supplying soluble Fe(II) to barren ground in coastal areas were monitored during a 6-month period of fertilization. HAs, the major organic fractions in the fertilizer, were extracted at different periods of time (2, 4 and 6 months) in the absence and presence of steel slag. To focus on the polymeric structure of the HA-backbone and the organic fractions, which are sorbed onto the HA-polymeric matrix (e.g., lipids), the extracted HA samples were analyzed by pyrolysis-gas chromatography/mass spectrometry under conditions where the sample is methylated with tetramethylammonium hydroxide (TMAH-py-GC/MS). The structural features analyzable by TMAH-py-GC/MS for the HA were dramatically altered in the presence of steel slag during the fertilization period. The major modification involved a decrease in phenolic moieties and a significant increase in the sulfur-containing pyrolysate compounds. These results indicate that the steel slag has a significant effect in altering the structure of HA in the fertilizer. TMAH-py-GC/MS analysis of the HAs indicated that the sulfur in the HAs was present in an organic form and not as elemental sulfur. Significant increases in the levels of biomarker fatty acids (iso- and anteiso-C_15:0 and C_17:0 carboxylic acids), which are related to the activity of sulfate reducing bacteria, suggests that the significant alterations in the HA structures in the presence of steel slag can be attributed to the sulfurization of organic matter in the fertilizer to form hydrogen polysulfides by the reduction of sulfate ions in seawater and/or steel slag via microbial processes.     

Bioreduction of hexavalent chromium: Effect of compost-derived humic acids and hematite

Composting can enhance the nutrient elements cycling and reduce carbon dioxide production. However, little information is available regarding the application of compost for the remediation of the contaminated soil. In this study, we assess the response of the redox capacities (electron accepting capacities (EAC) and electron donating capacities (EDC)) of compost-derived humic acids (HAs) to the bioreduction of hexavalent chromium (Cr(VI)), especially in presence of hematite. The result showed that the compost-derived HAs played an important role in the bioreduction of Cr(VI) in presence and absence of hematite under the anoxic, neutral (pH 7) and motionless conditions. Based on the pseudo-first order kinetic model, the rate constants of Cr(VI) reduction increased by 1.36–2.0 times when compost-derived HAs was added. The redox capacity originating from the polysaccharide structure of compost-derived HAs made them effective in the direct Cr(VI) reduction (without MR-1) at pH 7. Meanwhile, the reduction rates were inversely proportional to the composting treatment time. When iron mineral (Fe₂O₃) and compost-derived HAs were both present, the rate constants of Cr(VI) reduction increased by 2.35–5.09, which were higher than the rate of Cr(VI) reduction in HA-only systems, indicating that the hematite played a crucial role in the bioreduction process of Cr(VI). EAC and quinonoid structures played a major role in enhancing the bioreduction of Cr(VI) when iron mineral and compost-derived HAs coexisted in the system. The results can extend the application fields of compost and will provide a new insight for the remediation of Cr(VI)-contaminated soil.     

Fluorescence analysis of humic and fulvic acids from two Brazilian oxisols as affected by biosolid amendment

Conventional monodimensional fluorescence spectroscopy in the emission, excitation, and synchronous-scan modes and total luminescence spectroscopy have proven to be sensitive techniques for characterization and differentiation of humic acid (HA) and fulvic acid (FA) fractions isolated from an aerobically and anaerobically digested and limed biosolid, two layers of a sandy and a clayey Brazilian oxisol, and the corresponding biosolid-amended soils. The spectral patterns and the relative fluorescence intensities suggest greater molecular heterogeneity, less aromatic polycondensation, and less humification of biosolid HA and FA compared with soil HA and FA. However, the differences are smaller for the FA fractions than for the HA fractions. Fluorescence properties of soil HA and FA differ slightly as a function of soil type and soil layer. Biosolid application causes a shift to shorter wavelengths of the main fluorescence peaks and marked variation of the relative fluorescence intensities of HA and FA isolated from amended soils. These results suggest that molecular components of relatively small molecular size, with a low level of aromatic polycondensation, and low degree of humification present in biosolid HA and FA are partially and variously incorporated into amended soil HA and FA. In general, these modifications seem to be smaller in HA and FA from the clayey soil layers than in those from the sandy soil layers, possibly because of protective effects exerted by clay minerals of native soil HA and FA against disturbances caused by biosolid application.     

Combining electrophoresis with detection under ultraviolet light and multiple ultrafiltration for isolation of humic fluorescence fractions

Polyacrylamide gel electrophoresis of chernozem soil humic acids (HAs) followed by observation under UV (312 nm) excitation light reveals new low molecular weight (MW) fluorescent fractions. Ultrafiltration of HAs sample in 7 M urea on a membrane of low nominal MW retention (NMWR, 5 kDa) was repetitively used for separation of fluorescent and non-fluorescent species. Thirty ultrafiltrates and the final retentate R were obtained. Fluorescence maxima of separate ultrafiltrates were different and non-monotonously changed in the range of 475–505 nm. Fluorescence maxima of less than 490 nm were detected only in the four first utrafiltrates. For further physical–chemical analyses all utrafiltrates were combined into a fraction called UF < 5 (NMW < 5 kDa). Retentate R demonstrated very weak fluorescence under 270 nm excitation, while fluorescence intensity of UF < 5 was about six times higher than of the bulk HAs. Fraction UF < 5 was further ultrafiltrated on membranes of MNWR 3 kDa and 1 kDa, yielding three subfractions UF3-5, UF1-3 and UF < 1 with NMW 3–5 kDa, 1–3 kDa and <1 kDa, respectively. The validation of the UF procedure was performed by size exclusion chromatography on Sephadex G-25 column. The fluorescence maxima were found to be at 505, 488 and 465 nm for UF3-5, UF1-3 and UF < 1, respectively, with increasing of fluorescence intensity from UF3-5 to UF1-3 to UF < 1 fraction. EPR analysis showed that the amount of free radicals was the largest in retentate R and drastically decreased in fluorescent ultrafiltrates. The results demonstrate that more than one fluorophore is present in chernozem soil HAs complex.     

Quantitative comparison of the nitrogen-containing pyrolysis products and amino acid composition of soil humic acids

Pyrrole and acetonitrile, major pyrolysis products of soil humic substances, vary characteristically in abundance with the degree of humification of the organic matter in the soil. Their origin, however, is uncertain because of the large amount of unidentifiable soil nitrogen. A quantitative relationship between amino acid composition and pyrrole and acetonitrile abundances has been established by Curie-point pyrolysis-gas chromatography of a group of test proteins, using polystyrene as an internal standard. The pyrolysis yields of these products from three humic acids extracted from the surface horizons of Scottish brown forest soils (Cambisols or Ochrepts) were entirely accounted for by the known hydrolysable amino acid content and composition, and the products were related to individual amino acids. The peptide amino acid was also found to be the overall source of the aromatic pyrolysis products toluene, phenol and p-cresol.     

Simultaneous extraction and determination of fluoroquinolones,tetracyclines and sulfonamides antibiotics in soils using optimised solid phase extraction chromatography-tandem mass spectrometry

An analytical method was developed for the simultaneous extraction and determination of 18 fluoroquinolones (FQs), tetracyclines (TCs) and sulfonamides (SAs) antibiotics from soils using solid phase extraction and liquid chromatography-tandem mass spectrometry. The soils were extracted by different solvents with the help of mechanical shaking and ultrasonic treatment at 59?kHz, followed by a strong anion exchange (SAX) cartridge to clean up soil samples and a hydrophilic lipophilic balance (HLB) cartridge as enrichment. The method was evaluated by testing the following variables: extraction solvents, the type of SPE cartridges, solvent volumes, initial spiking levels and soil types (silty clay loam and clay loam soils). The soil extraction method was validated using these two types of soils, representing two typical agricultural soils in northern China. For 2?g soil, the extraction steps with the mixture of potassium phosphate buffer and acetonitrile (ACN) (1/1, v/v, pH 3.2) provided satisfactory recoveries. In the clay loam soil, the recoveries of all the compounds were from 56% to 89% at the spiking level of 50?µg?kg^?1 soil, and from 69% to 97% at the spiking level of 200?µg?kg^?1 soil, respectively. Recoveries in silty clay loam soil were similar to that in clay loam. The method was successfully employed using soil samples collected from a farmland and afforestion area irrigated with sewage in northern China. The result indicates that trace antibiotics in sewage may accumulate in soil irrigated by river water containing sewage.     

The natural abundance of 13C, 15N, 34S and 14C in archived (1923-2000) plant and soil samples from the Askov long-term experiments on animal manure and mineral fertilizer

The Askov field experiment (Denmark), established in 1894, provides a unique opportunity to examine long-term effects of animal manure and mineral fertilizer on soil organic matter quality and turnover. This sandy loam soil is classified as Alfisol (Typic Hapludalf). Soil C, N, S, 13C, 15N, 34S and 14C contents were measured in a selection of archived soil samples (1923, 1938, 1945, 1953, 1964, 1976, 1985, 1996 and 2000) from unfertilized (O), animal manure (1 AM) and mineral fertilizer (1 NPK) treatments. These treatments are imbedded in a four-course crop rotation of winter cereals, root crops, spring cereals and a clover/grass mixture. The contents of C, N, S, 13C, 15N and 34S in selected crop samples (1953-1996) and in contemporary samples of animal feed and manure were also determined. Temporal soil nutrient and isotope trends between fertilizer treatments were significantly different, except for S content in 1 AM and 1 NPK. The total soil C and S was higher in 1 AM and 1 NPK than in the O treatment. The total soil N content (1 AM>1 NPK>O) and the delta15N content (1 AM>1 NPK and O) were also different. Analyses of plant, animal feed and manures confirmed that differences in soil 15N values were related to delta15N values of added source inputs. Soil and crop delta13C values were similar, but manures had slightly lower values. The variation of soil delta34S (and total S) from 1923 to 1996 was larger in the O than 1 AM and 1 NPK plots reflecting changes in atmospheric S inputs. The total contents of soil C, N and S were significantly correlated, but their isotopic signatures were not, suggesting that the C, N, S turnovers in soil are subject to different controls. The 14C content was generally higher in the 1 AM than 1 NPK and O, with bomb-14C incorporation modelling indicating that mean residence time (MRT) was ca. 170 years in the 1 AM, but closer to 250-290 years in the 1 NPK and O treatments. The measured trends in soil C and 14C during 1923-1996 were successfully modelled using the RothC model. The OM accumulation in the Askov soils was generally dominated by microbial decomposition products rather than by recalcitrant components of the various inputs.     

In situ fluorescence imaging of fungi via (1,3)-β-d-glucan aptamer and tyramide signal amplification technology

Fungal infections are hazardous to human health that has drawn wide attention. In this work, a specific and sensitive method combing the recognition of aptamer to (1,3)-β-d-glucan and tyramide signal amplification technology was proposed for the in situ fluorescence imaging of fungi. Fungi could be distinctly observed by fluorescence microscope rapidly. This method provides morphology and diagnostic information for identifying fungi. The combination of aptamer and tyramide signal amplification technology is a promising tool for the detection of fungi, bacteria and even eukaryotic cell with the virtue of biomarkers.     

Potential bioactive secondary metabolites of Actinomycetes sp. isolated from rocky soils of the heritage village Rijal Alma,Saudi Arabia

The present study was designed to discover novel secondary antibiotic metabolites from Actinomycetes species from the soil of Rijal Almaa, Saudi Arabia. A laboratory-scale benchtop fermentation was utilized for the demonstration of antibiotics from the soil actinomycetes. Fourier transform-infrared spectroscopy (FT-IR) spectroscopy analysis of the fermented product (FP) was carried out, which showed unique fingerprint regions indicating the presence of phenolic hydroxyl groups, aliphatic compounds, carboxylic groups, esters, isothiocyanate, etc. GC-MS analysis of the FP depicted the unique structures of secondary metabolites, such as cyclononasiloxane octadecamethyl, cercosporin, ethyl iso-allocholate, octadecane, 3-ethyl-5-(2-ethylbutyl), dasycarpidan-1-methanol (acetate), heptadecane, 9-hexyl-, phthalic acid-butyl, and octadecane, 3-ethyl-5-(2-ethylbutyl). The TGA analysis showed the thermal stability of FP and the initial weight loss in FP was observed at 277.29 °C. The ¹H NMR and ¹³C NMR spectra of FP analysis demonstrated the various characteristic peaks presence of secondary metabolites. The XRD analysis at 2θ revealed distinct particles based on specific diffraction peaks. A set of six human bacterial pathogens, namely, the Gram-positive bacteria Staphylococcus aureus (S. aureus), Streptococcus pyogenes (S. pyogenes), and Bacillus subtilis (B. subtilis) and Gram-negative bacteria Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), and Klebsiella pneumoniae (K. pneumoniae), were utilized for screening. The FP exhibited promising antibacterial effects against both Gram-positive and Gram-negative bacterial organisms. The antibacterial spectrum of activity was greater for E. coli and B. subtilis than for K. pneumoniae.     

Photoinduced transformation of camptothecin in the presence of iron(III) ions

To obtain the information on the photoactivated action of camptothecin (CPT) promoted by transition metals, CPT was UVA irradiated (λ = 365 nm) in dimethylsulfoxide (DMSO) solutions. Fe(III) ions present were efficiently reduced to Fe(II) under argon and also in the presence of oxygen. The photoinduced electron transfer under argon resulted into the generation of carbon-centered radicals identified by EPR spin trapping evidencing the cleavage of CPT skeleton. Whereas the absorption UV/vis experiments with equimolar ratio Fe(III):CPT excluded the formation of charge-transfer complexes, the fluorescence spectra of CPT in the presence of Fe(III) revealed a significant fluorescence quenching indicating the probability of physical association between Fe(III) and CPT species in DMSO solutions confirming Fe(III) involvement in the photoinduced transformation.     

The Isolation and Characterization of Antagonist Trichoderma spp. from the Soil of Abha,Saudi Arabia

Background: The genus Trichoderma is widely spread in the environment, mainly in soils. Trichoderma are filamentous fungi and are used in a wide range of fields to manage plant patho-genic fungi. They have proven to be effective biocontrol agents due to their high reproducibility, adaptability, efficient nutrient mobilization, ability to colonize the rhizosphere, significant inhibitory effects against phytopathogenic fungi, and efficacy in promoting plant growth. In the present study, the antagonist Trichoderma isolates were characterized from the soil of Abha region, Saudi Arabia. Methodology: Soil samples were collected from six locations of Abha, Saudi Arabia to isolate Trichoderma having the antagonistic potential against plant pathogenic fungi. The soil dilution plate method was used to isolate Trichoderma (Trichoderma Specific Medium (TSM)). Isolated Trichoderma were evaluated for their antagonistic potential against Fusarium oxysporum, Alternaria alternata and Helminthosporium rostratum. The antagonist activity was assessed by dual culture assay, and the effect of volatile metabolites and culture filtrate of Trichoderma. In addition, the effect of different temperature and salt concentrations on the growth of Trichoderma isolates were also evaluated. Results: The most potent Trichoderma species were identified by using ITS4 and ITS 5 primers. Total 48 Trichoderma isolates were isolated on (TSM) from the soil samples out of those six isolates were found to have antagonist potential against the tested plant pathogenic fungi. In general, Trichoderma strains A (1) 2.1 T, A (3) 3.1 T and A (6) 2.2 T were found to be highly effective in reducing the growth of tested plant pathogenic fungi. Trichoderma A (1) 2.1 T was highly effective against F. oxysporum (82%), whereas Trichoderma A (6) 2.2 T prevented the maximal growth of H. rostratum (77%) according to the dual culture data. Furthermore, Trichoderma A (1) 2.1 T volatile metabolites hindered F. oxysporum growth. The volatile metabolite of Trichoderma A (6) 2.2 T, on the other hand, had the strongest activity against A. alternata (45%). The Trichoderma A (1) 2.1 T culture filtrate was proven to be effective in suppressing the growth of H. rostratum (47%). The temperature range of 26 °C to 30 °C was observed to be optimum for Trichoderma growth. Trichoderma isolates grew well at salt concentrations (NaCl) of 2%, and with the increasing salt concentration the growth of isolates decreased. The molecular analysis of potent fungi by ITS4 and ITS5 primers confirmed that the Trichoderma isolates A (1) 2.1 T, A (3) 3.1 and A (6) 2.2 T were T. harzianum, T. brevicompactum, and T. velutinum, respectively. Conclusions: The study concludes that the soil of the Abha region contains a large population of diverse fungi including Trichoderma, which can be explored further to be used as biocontrol agents.     

New method for the quantification of dequalinium cations in pharmaceutical samples by absorption and fluorescence diode array thin-layer chromatography

A diode array HPTLC method for dequalinium chloride in pharmaceutical preparations is presented. For separation a Nano TLC silica gel plate (Merck) is used with the mobile phase methanol—7.8% aqueous NH₄⁺CH₃COO⁻ (17:3, v/v) over a distance of 6 cm. Dequalinium chloride shows an R_F value of 0.58. Pure dequalinium chloride is measured in the wavelength range from 200 to 500 nm and shows several by-products, contour plot visualized in absorption, fluorescence and using the Kubelka–Munk transformation. Scanning of a single track in absorption and fluorescence measuring 600 spectra in the range from 200 to 1100 nm takes 30 s. As a sample pre-treatment of an ointment it is simply dissolved in methanol and can be quantified in absorption from 315 to 340 nm. The same separation can also be quantified using fluorescence spectrometry in the range from 355 to 370 nm. A new staining method for dequalinium chloride, using sodium tetraphenyl borate/HCl in water allows a fluorescence quantification in the range from 445 to 485 nm. The linearity range of absorption and fluorescence measurements is from 10 to 2000 ng. Sugar-containing preparations like liquids or lozenges with a reduced sample pre-treatment can be reliably quantified only in fluorescence. The total for the quantification of an ointment sample (measuring four standards and five samples), including all sample pre-treatment steps takes less than 45 min!     

Comparison between CP/MAS 13C-NMR and pyrolysis-GC/MS in the structural characterization of humins and humic acids of soil and sediments

The chemical structure of humins (HUs) and humic acids (HAs) of terrestrial and marine environments was investigated by cross-polarization magic angle spinning ¹³C-nuclear magnetic resonance spectroscopy (CP/ MAS ¹³C-NMR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Samples of HUs and HAs were obtained from sediments of the Adriatic Sea, the Lagoon of Ravenna (Adriatic Sea) and the Bubano Lake as well as from an agricultural soil. HUs displayed pyrograms and NMR spectra different from those of related HAs. According to NMR spectra HUs were more aliphatic and contained fewer carboxyl groups than HAs, while pyrolysates of HUs were characterized by higher levels of products arising from carbohydrates and lower levels of lignin methoxyphenols with respect to HAs. The relative content of paraffinic carbons determined by NMR was in good agreement with the relative abundance of unbranched aliphatic hydrocarbons released by pyrolysis. Both techniques evidenced the importance of polymethylene structures in HUs. Received: 5 January 1998 / Revised: 24 March 1998 / Accepted: 25 March 1998     

Regio‐selective Reduction of Oxysophoridine by Microorganism Isolated from Soil

Oxysophoridine (OSR), an alkaloid extracted from a traditional Chinese medicine, attracted more and more attention because of remarkable biological activities. Biocatalysis of OSR by 86 stains including soil microbes and endophytic fungi were investigated. Incubation of OSR with soil bacteria T003 identified as Escherichia coli could lead to only one reductive product with highly regio‐selectivity. The structural elucidations of transformation product were achieved mainly by the NMR spectroscopic methods and references. Effect of pH, substrate concentration, conversion time and strain concentration was studied, the optimization of reaction was analyzed by LC‐MS. The production of sophoridine (SR) from OSR was highest at pH 7.0, 36 h of incubation and in presence of 625 μg/mL substrate concentration, 50 μL/mL strain concentration respectively. Biocatalysis was considered the alternatives to preparation of sophoridine with green and sustainable synthetic processes except for less time‐consuming and more environmentally friendly.     

Comparison between CP/MAS 13C-NMR and pyrolysis-GC/MS in the structural characterization of humins and humic acids of soil and sediments

The chemical structure of humins (HUs) and humic acids (HAs) of terrestrial and marine environments was investigated by cross-polarization magic angle spinning ¹³C-nuclear magnetic resonance spectroscopy (CP/ MAS ¹³C-NMR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Samples of HUs and HAs were obtained from sediments of the Adriatic Sea, the Lagoon of Ravenna (Adriatic Sea) and the Bubano Lake as well as from an agricultural soil. HUs displayed pyrograms and NMR spectra different from those of related HAs. According to NMR spectra HUs were more aliphatic and contained fewer carboxyl groups than HAs, while pyrolysates of HUs were characterized by higher levels of products arising from carbohydrates and lower levels of lignin methoxyphenols with respect to HAs. The relative content of paraffinic carbons determined by NMR was in good agreement with the relative abundance of unbranched aliphatic hydrocarbons released by pyrolysis. Both techniques evidenced the importance of polymethylene structures in HUs. Received: 5 January 1998 / Revised: 24 March 1998 / Accepted: 25 March 1998     

Anthracene-9-methanol—a novel fluorescent phototrigger for biomolecular caging

Photoexcitation of a solution of anthracene-9-methanol derived esters at ∼386 nm in CH₃CN/H₂O (3:2 v/v) results in fluorescence emission in the 380-480 nm range, with quantum yields of fluorescence (Φ_f) in the 0.01-0.09 range and releases of the carboxylic acids in good chemical yields (43-100%), with quantum yields of photoreaction (Φ_PR, i.e., the photodisappearance of the esters) in the 0.067-0.426 range.