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1.
Moonen MJ Rietjens IM van Berkel WJ 《Journal of industrial microbiology & biotechnology》2001,26(1-2):35-42
The biological Baeyer–Villiger oxidation of acetophenones was studied by 19F nuclear magnetic resonance (NMR). The 19F NMR method was used to characterise the time-dependent conversion of various fluorinated acetophenones in either whole cells
of Pseudomonas fluorescens ACB or in incubations with purified 4′-hydroxyacetophenone monooxygenase (HAPMO). Whole cells of P. fluorescens ACB converted 4′-fluoroacetophenone to 4-fluorophenol and 4′-fluoro-2′-hydroxyacetophenone to 4-fluorocatechol without the
accumulation of 4′-fluorophenyl acetates. In contrast to 4-fluorophenol, 4-fluorocatechol was further degraded as evidenced
by the formation of stoichiometric amounts of fluoride anion. Purified HAPMO catalysed the strictly NADPH-dependent conversion
of fluorinated acetophenones to fluorophenyl acetates. Incubations with HAPMO at pH 6 and 8 showed that the enzymatic Baeyer–Villiger
oxidation occurred faster at pH 8 but that the phenyl acetates produced were better stabilised at pH 6. Quantum mechanical
characteristics explained why 4′-fluoro-2′-hydroxyphenyl acetate was more sensitive to base-catalysed hydrolysis than 4′-fluorophenyl
acetate. All together, 19F NMR proved to be a valid method to evaluate the biological conversion of ring-substituted acetophenones to the corresponding
phenyl acetates, which can serve as valuable synthons for further production of industrially relevant chemicals. Journal of Industrial Microbiology & Biotechnology (2001) 26, 35–42.
Received 20 April 2000/ Accepted in revised form 16 September 2000 相似文献
2.
M. A. Ivanov G. S. Ludva A. V. Mukovnya S. N. Kochetkov V. L. Tunitskaya L. A. Alexandrova 《Russian Journal of Bioorganic Chemistry》2010,36(4):488-496
4′-Fluoro-2′,3′-O-isopropylidenecytidine was synthesized by the treatment of 5′-O-acetyl-4′-fluoro-2′,3′-O-isopropylideneuridine with triazole and 4-chlorophenyl dichlorophosphate followed by ammonolysis. The interaction of 4′-fluoro-2′,3′-O-isopropylidenecytidine with hydroxylamine resulted in 4′-fluoro-2′,3′-O-isopropylidene-5′-O-acetyl-N
4-hydroxycytidine. The removal of the 2′,3′-O-isopropylidene groups led to acetyl derivatives of 4′-fluorouridine, 4′-fluorocytidine, and 4′-fluoro-N
4-hydroxycytidine. 4′-Fluorouridine 5′-O-triphosphate was obtained in three steps starting from 4′-fluoro-2′,3′-O-isopropylideneuridine. 4′-Fluorouridine 5′-O-triphosphate was shown to be an effective inhibitor of HCV RNA-dependent RNA polymerase and a substrate for the NTPase reaction
catalyzed by the HCV NS3 protein, the hydrolysis rate being similar to that of ATP. It could also activate a helicase reaction
with an efficacy of only threefold lower than that for ATP. 相似文献
3.
Toxic coplanar polychlorinated biphenyls (Co-PCBs) were used as substrates for a degradation experiment with white-rot fungus, Phlebia brevispora TMIC33929, which is capable of degrading polychlorinated dibenzo-p-dioxins. Eleven PCB congener mixtures (7 mono-ortho- and 4 non-ortho-PCBs) were added to the cultures of P. brevispora and monitored by high resolution gas chromatography and mass spectrometry (HRGC/HRMS). Five PCB congeners, 3,3′,4,4′-tetrachlorobiphenyl, 2,3,3′,4,4′-pentachlorobiphenyl, 2,3′,4,4′,5-pentachlorobiphenyl, 3,3′,4,4′,5-pentachlorobiphenyl, and 2,3′,4,4′,5,5′-hexachlorobiphenyl were degraded by P. brevispora. To investigate the fungal metabolism of PCB, each Co-PCB was treated separately by P. brevispora and the metabolites were analyzed by gas chromatography and mass spectrometry (GC/MS) and identified on the basis of the GC/MS comparison with the authentic compound. Meta-methoxylated metabolite was detected from the culture containing each compound. Additionally, para-dechlorinated and -methoxylated metabolite was also detected from the culture with 2,3,3′,4,4′-pentachlorobiphenyl, 2,3′,4,4′,5-pentachlorobiphenyl, and 2,3′,4,4′,5,5′-hexachlorobiphenyl, which are mono-ortho-PCBs. In this paper, we identified the congener specific degradation of coplanar PCBs by P. brevispora, and clearly proved for the first time by identifying the metabolites that the white-rot fungus, P. brevispora, transformed recalcitrant coplanar PCBs. 相似文献
4.
Degradation experiment of model polychlorinated biphenyl (PCB) compound 4,4′-dichlorobiphenyl (4,4′-DCB) and its metabolites by the white-rot fungus Phanerochaete chrysosporium and newly isolated 4,4′-DCB-degrading white-rot fungus strain MZ142 was carried out. Although P. chrysosporium showed higher degradation of 4,4′-DCB in low-nitrogen (LN) medium than that in potato dextrose broth (PDB) medium, Phanerochaete sp. MZ142 showed higher degradation of 4,4′-DCB under PDB medium condition than that in LN medium. The metabolic pathway of 4,4′-DCB was elucidated by the identification of metabolites upon addition of 4,4′-DCB and its metabolic intermediates. 4,4′-DCB was initially metabolized to 2-hydroxy-4,4′-DCB and 3-hydroxy-4,4′-DCB by Phanerochaete sp. MZ142. On the other hand, P. chrysosporium transformed 4,4′-DCB to 3-hydroxy-4,4′-DCB and 4-hydroxy-3,4′-DCB produced via a National Institutes of Health shift of 4-chlorine. 3-Hydroxy-4,4′-DCB was transformed to 3-methoxy-4,4′-DCB; 4-chlorobenzoic acid; 4-chlorobenzaldehyde; and 4-chlorobenzyl alcohol in the culture with Phanerochaete sp. MZ142 or P. chrysosporium. LN medium condition was needed to form 4-chlorobenzoic acid, 4-chlorobenzaldehyde, and 4-chlorobenzyl alcohol from 3-hydroxy-4,4′-DCB, indicating the involvement of secondary metabolism. 2-Hydroxy-4,4′-DCB was not methylated. In this paper, we proved for the first time by characterization of intermediate that hydroxylation of PCB was a key step in the PCB degradation process by white-rot fungi. 相似文献
5.
The modulation of the calmodulin-induced inhibition of the calcium release channel (ryanodine receptor) by two sulfhydryl
oxidizing compounds, 4-(chloromercuri)phenyl–sulfonic acid (4-CMPS) and 4,4′-dithiodipyridine (4,4′-DTDP) was determined by
single channel current recordings with the purified and reconstituted calcium release channel from rabbit skeletal muscle
sarcoplasmic reticulum (HSR) and [3H]ryanodine binding to HSR vesicles. 0.1 μm CaM reduced the open probability (P
o
) of the calcium release channel at maximally activating calcium concentrations (50–100 μm) from 0.502 ± 0.02 to 0.137 ± 0.022 (n= 28), with no effect on unitary conductance. 4-CMPS (10–40 μm) and 4,4′-DTDP (0.1–0.3 mm) induced a concentration dependent increase in P
o (> 0.9) and caused the appearance of longer open states. CaM shifted the activation of the calcium release channel by 4-CMPS
or 4,4′-DTDP to higher concentrations in single channel recordings and [3H]ryanodine binding. 40 μm 4-CMPS induced a near maximal (P
o
> 0.9) and 0.3 mm 4,4′-DTDP a submaximal (P
o
= 0.74) channel opening in the presence of CaM, which was reversed by the specific sulfhydryl reducing agent DTT. Neither
4-CMPS nor 4,4′-DTDP affected Ca-[125I]calmodulin binding to HSR. 1 mm MgCl2 reduced P
o
from 0.53 to 0.075 and 20–40 μm 4-CMPS induced a near maximal channel activation (P
o
> 0.9). These results demonstrate that the inhibitory effect of CaM or magnesium in a physiological concentration is diminished
or abolished at high concentrations of 4-CMPS or 4,4′-DTDP through oxidation of activating sulfhydryls on cysteine residues
of the calcium release channel.
Received: 22 July 1999/Revised: 15 November 1999 相似文献
6.
The reactive disulfide 4,4′-dithiodipyridine (4,4′DTDP) was added to single cardiac ryanodine receptors (RyRs) in lipid bilayers.
The activity of native RyRs, with cytoplasmic (cis) [Ca2+] of 10−7
m (in the absence of Mg2+ and ATP), increased within ∼1 min of addition of 1 mm 4,4′-DTDP, and then irreversibly ceased 5 to 6 min after the addition. Channels, inhibited by either 1 mm
cis Mg2+ (10−7
m
cis Ca2+) or by 10 mm
cis Mg2+ (10−3
m
cis Ca2+), or activated by 4 mm ATP (10−7
m
cis Ca2+), also responded to 1 mm
cis 4,4′-DTDP with activation and then loss of activity. P
o
and mean open time (T
o
) of the maximally activated channels were lower in the presence of Mg2+ than in its absence, and the number of openings within the long time constant components of the open time distribution was
reduced. In contrast to the reduced activation by 1 mm 4,4′-DTDP in channels inhibited by Mg2+, and the previously reported enhanced activation by 4,4′-DTDP in channels activated by Ca2+ or caffeine (Eager et al., 1997), the activation produced by 1 mm
cis 4,4′-DTDP was the same in the presence and absence of ATP. These results suggest that there is a physical interaction between
the ATP binding domain of the cardiac RyR and the SH groups whose oxidation leads to channel activation.
Received: 8 September 1997/Revised: 20 January 1998 相似文献
7.
Inhibitor studies and mutant analysis revealed a C30 pathway via 4,4′-diapophytoene and 4,4′-diaponeurosporene to 4,4′-diaponeursoporene-4-oic acid esters related to staphyloxanthin
in Halobacillus halophilus. Six genes may be involved in this biosynthetic pathway and could be found in two adjacent gene clusters. Two genes of this
pathway could be functionally assigned by functional pathway complementation as a 4,4′-diapophytoene synthase and a 4,4′-diapophytoene
desaturase gene. These genes were organized in two operons together with two putative oxidase genes, a glycosylase and an
acyl transferase ortholog. Pigment mutants were obtained by chemical mutagenesis. Carotenoid analysis showed that a white
mutant accumulated 4,4′-diapophytoene due to a block in desaturation. In a yellow mutant carotenogenesis was blocked at the
stage of 4,4′-diaponeurosporene and in an orange mutant at the stage of 4,4′-diaponeurosporene-4-oic acid. The protective
function of these pigments could be demonstrated for H. halophilus after inhibition of carotenoid synthesis by initiation of oxidative stress. A degree of oxidative stress which still allowed
50% growth of carotenogenic cells resulted in the death of the cells devoid of colored carotenoids. 相似文献
8.
Three NAD(P)H-dependent nitroreductases that can transform 2,4,6-trinitrotoluene (TNT) by two reduction pathways were detected
in Klebsiella sp. C1. Among these enzymes, the protein with the highest reduction activity of TNT (nitroreductase I) was purified to homogeneity
using ion-exchange, hydrophobic interaction, and size exclusion chromatographies. Nitroreductase I has a molecular mass of
27 kDa as determined by SDS-PAGE, and exhibits a broad pH optimum between 5.5 and 6.5, with a temperature optimum of 30–40°C.
Flavin mononucleotide is most likely the natural flavin cofactor of this enzyme. The N-terminal amino acid sequence of this
enzyme does not show a high degree of sequence similarity with nitroreductases from other enteric bacteria. This enzyme catalyzed
the two-electron reduction of several nitroaromatic compounds with very high specific activities of NADPH oxidation. In the
enzymatic transformation of TNT, 2-amino-4,6-dinitrotoluene and 2,2′,6,6′-tetranitro-4,4′-azoxytoluene were detected as transformation
products. Although this bacterium utilizes the direct ring reduction and subsequent denitration pathway together with a nitro
group reduction pathway, metabolites in direct ring reduction of TNT could not easily be detected. Unlike other nitroreductases,
nitroreductase I was able to transform hydroxylaminodinitrotoluenes (HADNT) into aminodinitrotoluenes (ADNT), and could reduce
ortho isomers (2-HADNT and 2-ADNT) more easily than their para isomers (4-HADNT and 4-ADNT). Only the nitro group in the ortho position of 2,4-DNT was reduced to produce 2-hydroxylamino-4-nitrotoluene by nitroreductase I; the nitro group in the para position was not reduced. 相似文献
9.
N,N′-Pyromelliticdiimido-di-l-amino acids (1a–1d) were prepared from the reaction of pyromellitic dianhydride with the corresponding l-amino acids in a solution of glacial acetic acid/pyridine (3:2) at refluxing temperature. 4,4′-sulfonyl bis(4,1-phenylene)
bis(diazene-2,1-diyl) diphenol, 4,4′-oxy bis(4,1-phenylene) bis(diazene-2,1-diyl) diphenol and 4,4′-methylene bis(4,1-phenylene)
bis(diazene-2,1-diyl) diphenol, were prepared from 4,4′-diamino diphenyl sulfone, 4,4′-diamino diphenyl ether, 4,4′-diamino
diphenyl methane, sodium nitrite and phenol following the general procedure of diazo coupling. Interfacial polycondensation
method was used to prepare the corresponding poly(azo-ester-imid)s (PAEI
1–12
) in biphasic solution of water/dichloromethane. The resulting polymers (PAEIs) have been obtained in high yields having good inherent viscosities (0.32–0.57 dl g−1), optical activities and thermal stabilities. 相似文献
10.
The location of reactive cysteine residues on the ryanodine receptor (RyR) calcium release channel was assessed from the
changes in channel activity when oxidizing or reducing reagents were added to the luminal or cytoplasmic solution. Single
sheep cardiac RyRs were incorporated into lipid bilayers with 10−7
m cytoplasmic Ca2+. The thiol specific-lipophilic-4,4′-dithiodipyridine (4,4′-DTDP, 1 mm), as well as the hydrophilic thimerosal (1 mm), activated and then inhibited RyRs from either the cis (cytoplasmic) or trans (luminal) solutions. Activation was associated with an increase in the (a) mean channel open time and (b) number of exponential
components in the open time distribution from one (∼2 msec) to three (∼1 msec; ∼7 msec; ∼15 msec) in channels activated by
trans 4,4′-DTDP or cis or trans thimerosal. A longer component (∼75 msec) appeared with cis 4,4′-DTDP. Activation by either oxidant was reversed by the thiol reducing agent, dithiothreitol. The results suggest that
three classes of cysteines are available to 4,4′-DTDP or thimerosal, SHa or SHa* activating the channel and SHi closing the
channel. SHa is either distributed over luminal and cytoplasmic RyR domains, or is located within the channel pore. SHi is
also located within the transmembrane domain. SHa* is located on the cytoplasmic domain of the protein.
Received: 17 March 1998/Revised: 26 October 1998 相似文献
11.
Kawai Masao Yamamoto Tatsuo Yamada Keiichi Yamaguchi Masashi Kurobe Shigehiro Yamamura Hatsuo Araki Shuki Butsugan Yasuo Kobayashi Kyoko Katakai Ryoichi Saito Kazuki Nakajima Terumi 《International journal of peptide research and therapeutics》1998,5(1):5-12
Summary Derivatives of gramicidin S (GS) and its mono- and di-d-cyclohexylalanined-Cha) analogs possessing various protecting groups on Orn side chains were prepared.1H NMR spectra of the unsymmetrically protected analogs [Orn(X)2, Orn(X′)2′,d-Cha4]GS were similar to the composites of the spectra of the symmetrical derivatives [Orn(X)2,2′,d-Cha4,4′]GS and [Orn(X′)2,2′]Gs, revealing the proximity of the protecting groups of NδH of Orn residues at the 2 and 2′ positions to the side chains ofd-Phe (ord-Cha) residues at the 4 and 4′ positions, respectively. The results indicated the presence of H-bonds between the N°H of Orn and the carbonyl ofd-Phe residues in the i→i+2 sense and not in i→i-3, which was also supported by the ROESY analysis. The substantially strong
H-bonds can explain the observed resistance of the urethane NH of the Orn side chains in the GS derivatives to the N-methylation
with CH3I−Ag2O in DMF. 相似文献
12.
Su-Il Kang Seo-Young Kang Robert A. Kanaly Eunjung Lee Yoongho Lim Hor-Gil Hur 《Archives of microbiology》2009,191(6):509-517
The hypolipidemic agent gemfibrozil (GEM), which has been studied for its metabolism in humans and animals, was investigated
to elucidate its primary metabolism by Cunninghamella elegans. The fungus produced ten metabolites (FM1–FM9 and FM6′) from the biotransformation of GEM. Based on LC/MS/MS and NMR analyses,
a major metabolite, FM7, was identified as 2′-hydroxymethyl GEM. FM6 was considered to be 5′-hydroxymethyl GEM, after comparison
of results LC/MS, LC/MS/MS, and UV absorption spectra to FM7. The combined concentration of FM6 and FM7 was found to increase
up to 0.83 mM by day 2, and then decreased gradually with incubation time, followed by a noticeable increase in the biotransformation
product, FM1, up to 0.86 mM by day 15. NMR analyses confirmed that FM1 was 2′,5′-dihydroxymethyl GEM. Further minor oxidations
of the aromatic ring and carboxylic acid intermediates were also detected. Based upon these findings, the major fungal metabolic
pathway for GEM is likely to occur via production of 2′,5′-dihydroxymethyl GEM from 2′-hydroxymethyl GEM. These relatively
rapid and diverse biotransformations of GEM by C. elegans suggest that depending upon conditions, it may also follow a similar biodegradation fate when released into the natural environment. 相似文献
13.
Neil K. O’Connor Alex S. Hudson Steven L. Cobb Deborah O’Neil Jennifer Robertson Vanessa Duncan Cormac D. Murphy 《Amino acids》2014,46(12):2745-2752
While attempting to improve production of fluoro-iturin A in Bacillus sp. CS93 new mono- and di-fluorinated fengycins were detected in culture supernatants by 19F NMR and tandem mass spectrometry, after incubation of the bacterium with 3-fluoro-l-tyrosine. The fluorinated amino acid was presumably incorporated in place of one or both of the tyrosyl residues in fengycin. Investigations to generate additional new fluorinated derivatives were undertaken using commercially available fluorinated phenylalanines and 2-fluoro- and 2,3-difluoro-tyrosine that were synthesised by Negishi cross-coupling of iodoalanine and fluorinated bromo-phenols. The anti-fungal activity of the fluorinated lipopeptides was assayed against Trichophyton rubrum and found to be similar to that of the non-fluorinated metabolites. 相似文献
14.
Seidel V Windhövel J Eaton G Alfermann AW Arroo RR Medarde M Petersen M Woolley JG 《Planta》2002,215(6):1031-1039
Cell cultures of Linum album Kotschy ex Boiss. (Linaceae) showing high accumulation of the lignan podophyllotoxin (PTOX) were established. Enzymological
studies revealed highest activities of phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, 4-hydroxycinnamate:CoA
ligase and cinnamoyl-CoA:NADP oxidoreductase immediately prior to PTOX accumulation. To investigate PTOX biosynthesis, feeding
experiments were performed with [2-13C]3′,4′-dimethoxycinnamic acid, [2-13C]3′,4′-methylenedioxycinnamic acid (MDCA), [2-13C]3′,4′,5′-trimethoxycinnamic acid, [2-13C]sinapic acid, [2-13C]- and [2,3-13C2]ferulic acid. Analysis of the metabolites by HPLC coupled to tandem mass spectrometry revealed incorporation of label from
ferulic acid into PTOX and deoxypodophyllotoxin (DOP). In addition, MDCA was also unambiguously incorporated intact into PTOX.
These observations suggest that in L. album both ferulic acid and methylenedioxy-substituted cinnamic acid can be incorporated into lignans. Furthermore, it appears
that, in this species, the hydroxylation of DOP is a rate-limiting point in the pathway leading to PTOX.
Electronic supplementary material to this article is available at and is accessible for authorized users.
Electronic Publication 相似文献
15.
Anastassia Kanavarioti David H. White 《Origins of life and evolution of the biosphere》1987,17(3-4):333-349
We have undertaken a complete kinetic analysis of the template-directed oligoguanylate synthesis originated in Orgel's laboratory
(Inoue and Orgel, 1982). The reaction of guanosine 5′-phospho-2-methylimidazolide, 2-MelmpG, with ribooligoguanylates all
3′–5′ linked, designatedn
3 withn=7−12, was studied in the presence/absence of the complementary template polycytidylic acid, poly(C). Conditions were chosen
where poly(C) and 2-MelmpG are in large excess over the oligoguanylate. In the absence of the template at 37 °C the reaction
leads to three isomeric oligomers that are elongated by one monomer unit. They are the 3′–5′ linked, (n+1)3, the 2′–5′ linked, (n+1)2, and the pyrophosphate product, (n+1)
p
, formed in an approximate ratio 1:2:5. In the presence of the template the reaction is 20-fold faster and yields productsn+1,n+2,n+3 etc. as long as 2-MelmpG is available. Most importantly the formation of the natural, 3′–5′ linked isomer, is enhanced
selectively by 140-fold at 37 °C. Qualitative observations allow the conclusion that this enhancement is temperature dependent
and increases with decreasing temperature. For example, at 1 °C only the 3′–5′ linked isomers were detected. Initial rates
for the disappearance of then
3 oligoguanylate were determined at 1, 23, and 37 °C. It was found that the pseudo-first order rate constant for oligoguanylate
elongation was linearly proportional to the 2-MelmpG concentration. This implies that the reaction complex poly(C)·n
3·2-MelmpG does not accumulate under the reaction conditions, a conclusion which is also supported by infrared data (Miles
and Frazier, 1982). The implication of the above results with respect to chemical evolution is that lower temperatures, i.e.,
close to freezing, enhance the regioselectivity of these template-directed reactions and that one way to improve replication
models may be sought in finding conditions that favor stable reaction complexes.
NASA — National Research Council Research Fellow. 相似文献
16.
Production of sophorolipids from whey 总被引:5,自引:0,他引:5
Otto RT Daniel HJ Pekin G Müller-Decker K Fürstenberger G Reuss M Syldatk C 《Applied microbiology and biotechnology》1999,52(4):495-501
Sophorolipids, obtained by a two-stage process starting from deproteinized whey concentrate using Cryptococcus curvatus ATCC 20509 and Candida bombicola ATCC 22214, were compared to products from one-stage processes, using different lipidic compounds as substrates. Results
showed that above all carbon source and not cultivation conditions had a distinct influence on the composition of the crude
product mixture and therefore on the physicochemical and biological properties of the sophorolipids, such as, for example,
surface activity, cytotoxicity and stability against hydrolases. The results were completed by corresponding data for purified
mono- and diacetylated (17-hydroxyoctadecenoic)-1′,4′′-lactonized sophorolipids. Crude sophorolipid mixtures showed moderate
to good surface active properties (SFTmin 39 mN m−1, CMC 130 mg l−1), water solubilities (2–3 g l−1) and low cytotoxicities (LC50 300–700 mg l−1). In contrast, purified sophorolipids were more surface active (SFTmin 36 mN m−1, CMC 10 mg l−1), less water soluble (max. 70 mg l−1) and showed stronger cytotoxic effects (LC50 15 mg l−1). Incubation of crude sophorolipid mixtures with different hydrolases demonstrated that treatment with commercially available
lipases such as from Candida rugosa and Mucor miehei distinctly reduced the surface active properties of the sophorolipids, while treatment with porcine liver esterase and glycosidases
had no effect.
Received: 23 February 1999 / Received revision: 27 May 1999 / Accepted: 28 May 1999 相似文献
17.
Doreen Waldau Annett Mikolasch Michael Lalk Frieder Schauer 《Applied microbiology and biotechnology》2009,83(1):67-75
Different 9H-carbazole derivatives have been investigated within the last decades due to their broad range of pharmacological applications.
While the metabolism of 9H-carbazole has previously been reported, nothing was known about the bacterial transformation of 2,3,4,9-tetrahydro-1H-carbazole and 9-methyl-9H-carbazole. Thus, for the first time, the bacterial biotransformation of 2,3,4,9-tetrahydro-1H-carbazole and 9-methyl-9H-carbazole was analyzed using biphenyl-grown cells of Ralstonia sp. strain SBUG 290 expressing biphenyl 2,3-dioxygenase. This strain accumulated 3-hydroxy-1,2,3,5,6,7,8,9-octahydrocarbazol-4-one
and 6′-iminobicyclohexylidene-2′,4′-dien-2-one as major products during the incubation with 2,3,4,9-tetrahydro-1H-carbazole. Carbazol-9-yl-methanol was verified as the primary oxidation product of 9-methyl-9H-carbazole. In addition, 9H-carbazol-1-ol, 9H-carbazol-3-ol, and 3-hydroxy-1,2,3,9-tetrahydrocarbazol-4-one where detected in lower concentrations during the transformation
of carbazol-9-yl-methanol and 9-methyl-9H-carbazole. Products were identified by high-performance liquid chromatography, gas chromatography–mass spectrometry, liquid
chromatography–mass spectrometry, as well as 1H and 13C nuclear magnetic resonance analyses. 相似文献
18.
The seasonal variations in biomass, abundance and species composition of zooplankton in relation to hydrography and chlorophyll
a were studied in the subarctic waters north of Iceland. The sampling was carried out at approximately monthly intervals from
February 1993 to February 1994 at eight stations arranged along a transect extending from 66°16′N–18°50′W to 68°00′N–18°50′W.
The mean temperature at 50 m depth showed a clear seasonal pattern, with lowest water temperatures in February (∼1.1°C) and
the highest in July (∼5.4°C). The spring growth of the phytoplankton began in late March and culminated during mid-April (∼7.0 mg
Chl a m−3). Both the biomass and the abundance of total zooplankton were low during the winter and peaked once during the summer in
late May (∼4 g m−2 and ∼38,000 individuals m−2). A total of 42 species and taxonomic groups were identified in the samples. Eight taxa contributed ∼90% of the total zooplankton
number. Of these Calanus finmarchicus was by far the most abundant species (∼60% of the total zooplankton). Less important groups were ophiuroid larvae (∼9%),
Pseudocalanus spp. (∼8%), Metridia longa (∼4%), C. hyperboreus (∼3%), Acartia longiremis (∼2%), chaetognaths (∼2%) and euphausiid larvae (∼2%). The dominant copepods showed two main patterns in seasonal abundance:
C. finmarchicus, C. hyperboreus and C. glacialis had one annual peak in numbers in late May, while Pseudocalanus spp., M. longa and A. longiremis showed two maxima during the summer (July) and autumn (October/November). Ophiuroid larvae and chaetognaths (mainly Sagitta elegans) peaked during the middle of July, while the number of euphausiid eggs and larvae was greatest from May to July. The succession
in population structure of C. finmarchicus indicated its main spawning to be in April and May, coincident with the phytoplankton spring bloom. A minor spawning was
also observed sometime between August and October. However, the offspring from this second spawning contributed only insignificantly
to the overwintering stock of C. finmarchicus.
Received: 12 September 1997 / Accepted: 1 March 1998 相似文献
19.
The occurrence of reductive dechlorination processes towards pre-existing PCBs and five exogenous coplanar PCBs were investigated
in a contaminated sediment of Porto Marghera (Venice Lagoon, Italy) suspended, under strictly anaerobic conditions, in water
collected from the same site. PCB dechlorination started after five months of incubation, when sulfate initially occurring
in the microcosms was completely depleted and methanogenesis was in progress. It was ascribed to sulfate-reducing bacteria.
Several pre-existing hexa-, penta- and tetra-chlorinated biphenyls were slowly bioconverted into tri- and di-, ortho-substituted PCBs from the 5th to the 16th month of experiment. Spiked coplanar PCBs, i.e., 3,3′,4,4′-tetrachlorobiphenyl,
3,3′,4,4′,5- and 2,3′,4,4′,5-pentachlorobiphenyls, 3,3′,4,4′,5,5′- and 2,3,3′,4,4′,5-hexachlorobiphenyls, were extensively
transformed (by about 90%) into lower chlorinated congeners, such as 3,3′,5,5′-/2,3′,4,4′-tetrachlorobiphenyl, 3,3′,5-, 2,4,4′-,
2,3′,4- and 2,3′,5-trichlorobiphenyl, 3,4-/3,4′- and 3,3′-dichlorobiphenyl and 2-chlorobiphenyl. The reductive dechlorination
of spiked PCBs did not influence significantly the biotransformation rate and extent of pre-existing PCBs. 相似文献
20.
Kyung-Ja Jung Eungbin Kim Jae-Seong So Sung-Cheol Koh 《Biotechnology and Bioprocess Engineering》2001,6(1):61-66
The aim of this study was to examine how plant terpenoids, as natural growth substrates or inducers, would affect the biodegradation
of PCB congeners. Various PCB degraders that could grow on biphenyl and several terpenoids were tested for their PCB degradation
capabilities. Degradation activities of the PCB congeners, 4,4′-dichlorobiphenyl (4,4′-DCBp) and 2,2′-dichlorobiphenyl (2,2′-DCBp),
were initially monitored through a resting cell assay technique that could detect their degradation products. The PCB degraders,Pseudomonas sp. P166 andRhodococcus sp. T104, were found to grow on both biphenyl and terpenoids ((S)-(−) limonene,p-cymene and α-terpinene) whereasArthrobacter sp. B1B could not grow on the terpenoids as a sole carbon source. The B1B strain grown on biphenyl exhibited good degradation
activity for 4,4′-DCBp and 2,2′-DCBp, while the activity of strains P166 and T104 was about 25% that of the B1B strain, respectively.
Concomitant GC analysis, however, demonstrated that strain T104, grown on (S)-(−) limonene,p-cymene and α-terpinene, could degrade 4,4′-DCBp up to 30%, equivalent to 50% of the biphenyl induction level. Moreover, strain
T104 grown on (S)-(−) limonene, could also degrade 2,2′-DCBp up to 30%. This indicates that terpenoids, widely distributed
in nature, could be utilized as both growth and/or inducer substrate(s) for PCB biodegradation in the environment. 相似文献