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1.
The carotenoid synthetic genes, crtM and crtN, derived from Staphylococcus aureus, were introduced into B. subtilis, resulting in yellow pigmentation. Absorption maxima of pigments and MALDI-TOF mass spectrometry demonstrated that the pigmented
strain accumulated two C30 carotenoids, 4,4′-diapolycopene and 4,4′-diaponeurosporene. A survival test using H2O2 revealed that the pigmented strain was more resistant to oxidative stress than the strain harboring an empty-vector. These
findings indicate that B.
subtilis can produce carotenoids, and the strain accumulating the carotenoids, CarotenoBacillus, will become a basal host for production
of C30 carotenoids and evaluation of their antioxidative effects. 相似文献
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D. Stassi D. Post M. Satter M. Jackson G. Maine 《Applied microbiology and biotechnology》1998,49(6):725-731
The erythromycin producer, Saccharopolyspora erythraea ER720, was genetically engineered to produce 6,12-dideoxyerythromycin A, a novel erythromycin derivative, as the major macrolide
in the fermentation broth. Inspection of the biosynthetic pathway for erythromycin would suggest that production of this compound
could be achieved simply through the disruption of two genes, that encoding the erythromycin C-6 hydroxylase (eryF ) and that encoding the erythromycin C-12 hydroxylase (eryK ). The double mutant, however, was found to produce a mixture of 6,12-dideoxyerythromycin A and the precursor, 6-deoxyerythromycin
D. Complete conversion to the desired product (to the limit of detection by TLC) was achieved by inserting an additional copy
of the eryG gene, encoding the erythromycin 3′′-O-methyltransferase and driven by the ermE* promoter, into the S. erythraea chromosome.
Received: 6 October 1997 / Received revision: 27 January 1998 / Accepted: 24 February 1998 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
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Makio Kobayashi 《Biotechnology and Bioprocess Engineering》2003,8(6):322-330
The unicellular green algaHaematococcus pluvialis has recently attracted great interest due to its large amounts of ketocarotenoid astaxanthin, 3,3′-dihydroxy-β,β-carotene-4,4′-dione,
widely used commercially as a source of pigment for aquaculture. In the life cycle ofH. pluvialis, astaxanthin biosynthesis is associated with a remarkable morphological change from green motile vegetative cells into red
immotile cyst cells as the resting stage. In recent years we have studied this morphological process from two aspects: defining
conditions governing astaxanthin biosynthesis and questioning the possible function of astaxanthin in protecting algal cells
against environmental stress. Astaxanthin accumulation in cysts was induced by a variety of environmental conditions of oxidative
stress caused by reactive oxygen species, intense light, drought, high salinity, and high temperature. In the adaptation to
stress, abscisic acid induced by reactive oxygen species, would function as a hormone in algal morphogenesis from vegetative
to cyst cells. Furthermore, measurements of bothin vitro andin vivo antioxidative activities of astaxanthin clearly demonstrated that tolerance to excessive reactive oxygen species is greater
in astaxanthin-rich cysts than in astaxanthin-poor cysts or astaxanthin-less vegetative genesis and carotenogenesis, and the
accumulated astaxanthin in cysts can function as a protective agent against oxidative stress damage. In this study, the physiological
roles of astaxanthin in stress response and cell protection are reviewed. 相似文献
7.
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
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Takashi Akagi Ayako Ikegami Yasuhiko Suzuki Junya Yoshida Masahiko Yamada Akihiko Sato Keizo Yonemori 《Planta》2009,230(5):899-915
Persimmon fruits accumulate a large amount of proanthocyanidin (PA) during development. Fruits of pollination-constant and
non-astringent (PCNA) type mutants lose their ability to produce PA at an early stage of fruit development, while fruits of
the normal (non-PCNA) type remain rich in PA until fully ripened. To understand the molecular mechanism for this difference,
we isolated the genes involved in PA accumulation that are differentially expressed between PCNA and non-PCNA, and confirmed
their correlation with PA content and composition. The expression of structural genes of the shikimate and flavonoid biosynthetic
pathways and genes encoding transferases homologous to those involved in the accumulation of phenolic compounds were downregulated
coincidentally only in the PCNA type. Analysis of PA composition using the phloroglucinol method suggested that the amounts
of epigallocatechin and its 3-O-gallate form were remarkably low in the PCNA type. In the PCNA type, the genes encoding flavonoid 3′5′ hydroxylase (F3′5′H)
and anthocyanidin reductase (ANR) for epigallocatechin biosynthesis showed remarkable downregulation, despite the continuous
expression level of their competitive genes, flavonoid 3′ hydroxylation (F3′H) and leucoanthocyanidin reductase (LAR). We
also confirmed that the relative expression levels of F3′5′H to F3′H, and ANR to LAR, were considerably higher, and the PA composition corresponded to the seasonal expression balances in both types. These results
suggest that expressions of F3′5′H and ANR are important for PA accumulation in persimmon fruit. Lastly, we tested enzymatic activity of recombinant DkANR in vitro,
which is thought to be an important enzyme for PA accumulation in persimmon fruits. 相似文献
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Two new loci have been found to be clustered with five other genes for the nitrate assimilation pathway in the Chlamydomonas reinhardtii genome. One gene, located close to the 3′-end of the high-affinity nitrate transporter (HANT) gene Nrt2;2, corresponds to the nitrite reductase (NiR) structural gene Nii1. This is supported by a number of experimental findings: (i) NiR-deficient mutants have lost Nii1 gene expression; (ii) Nii1 mRNA accumulation is co-regulated with the expression of other structural genes of the nitrate assimilation pathway; (iii)
nitrite (nitrate) utilization ability is recovered in the NiR mutants by functional complementation with a wild-type Nii1 gene; (iv) the elucidated NII1 amino acid sequence is highly similar to that of the cyanobacterial and higher-plant enzyme,
and contains the predicted domains for plastidic ferredoxin-NiRs. Thus, the mutant phenotype and the mRNA sequence and expression
of the Nii1 gene have been unequivocally related. Accumulation of mRNA for the second locus identified, Lde1 (light-dependent expression), was not regulated by nitrogen, but like nitrate-assimilation clustered genes, its expression
was down-regulated in the dark.
Received: 27 November 1997 / Accepted: 19 January 1998 相似文献
12.
Nitric oxide (NO), a gaseous free radical that is synthesized in organisms by nitric oxide synthases, participates in a critical
fashion in the regulation of diverse physiological functions such as vascular and neuronal signal transduction, host defense,
and cell death regulation. Two major pathways of NO signaling involve production of the second messenger guanosine 3′,5′-cyclic
monophosphate (cGMP) and posttranslational modification (PTM) of redox-sensitive cysteine thiols of proteins. We recently
clarified the physiological formation of 8-nitroguanosine 3′,5′-cyclic monophosphate (8-nitro-cGMP) as the first demonstration,
since the discovery of cGMP more than 40 years ago, of a new second messenger derived from cGMP in mammals. 8-Nitro-cGMP is
electrophilic and reacts efficiently with sulfhydryls of proteins to produce a novel PTM via cGMP adduction, a process that
we named protein S-guanylation. 8-Nitro-cGMP may regulate electrophilic signaling on the basis of its electrophilicity through induction of
S-guanylation of redox sensor proteins. Examples include S-guanylation of the redox sensor protein Kelch-like ECH-associated protein 1 (Keap1), which leads to activation of NF-E2-related
factor 2 (Nrf2)-dependent expression of antioxidant and cytoprotective genes. This S-guanylation-mediated activation of an antioxidant adaptive response may play an important role in cytoprotection during bacterial
infections and oxidative stress. Identification of new redox-sensitive proteins as targets for S-guanylation may help development of novel therapeutics for oxidative stress- and inflammation-related disorders and vascular
diseases as well as understanding of cellular protection against oxidative stress. 相似文献
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Rainer-B. Volk 《Journal of applied phycology》2007,19(5):491-495
Changes in the content of exometabolites excreted by the cyanobacterium Nostoc insulare during batch cultivation were determined. During linear growth, only the non-toxic compound N,N′-(4,5-dimethyl-1,2-phenylene)-bis-acetamide
was detectable in appreciable quantities in the medium, whereas during stationary growth the antimicrobial and cytotoxic exometabolites
4,4′-dihydroxybiphenyl and 9H-pyrido(3,4-b)indole (norharmane) were also present to an increasing degree. Hence it is proposed
that biosynthesis of N,N′-(4,5-dimethyl-1,2-phenylene)bis-acetamide in N. insulare is associated with cell proliferation and primary metabolism of this organism. 4,4′-Dihydroxybiphenyl and norharmane, however,
are proposed to be products of secondary metabolism that are excreted by N. insulare primarily under nutrient-restricted conditions and under increased pressure of competition with other organisms. 相似文献
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S. Takaichi Kazuhito Inoue Mitsuhiro Akaike Masami Kobayashi Hirozo Oh-oka Michael T. Madigan 《Archives of microbiology》1997,168(4):277-281
The carotenoids of five species of heliobacteria (Heliobacillus mobilis, Heliophilum fasciatum, Heliobacterium chlorum, Heliobacterium modesticaldum, and Heliobacterium gestii) were examined by spectroscopic methods, and the C30 carotene 4,4′-diaponeurosporene was found to be the dominant pigment; heliobacteria were previously thought to contain the
C40 carotenoid neurosporene. In addition, trace amounts of the C30 diapocarotenes diapolycopene, diapo-ζ-carotene, diapophytofluene, and diapophytoene were also found. Up to now, diapocarotenes
have been found in only three species of chemoorganotrophic bacteria, but not in phototropic organisms. Furthermore, the esterifying
alcohol of bacteriochlorophyll g from all known species of heliobacteria was determined to be farnesol (C15) instead of the usual phytol (C20). Heliobacteria may be unable to produce geranylgeranyol (C20).
Received: 10 March 1997 / Accepted: 3 June 1997 相似文献
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Sarrou I Khan Z Cowgill J Lin S Brune D Romberger S Golbeck JH Redding KE 《Photosynthesis research》2012,111(3):291-302
We have developed a purification protocol for photoactive reaction centers (HbRC) from Heliobacterium modesticaldum. HbRCs were purified from solubilized membranes in two sequential chromatographic steps, resulting in the isolation of a
fraction containing a single polypeptide, which was identified as PshA by LC–MS/MS of tryptic peptides. All polypeptides reported
earlier as unknown proteins (in Heinnickel et al., Biochemistry 45:6756–6764, 2006; Romberger et al., Photosynth Res 104:293–303, 2010) are now identified by mass spectrometry to be the membrane-bound cytochrome c
553 and four different ABC-type transporters. The purified PshA homodimer binds the following pigments: 20 bacteriochlorophyll
(BChl) g, two BChl g′, two 81-OH-Chl a
F, and one 4,4′-diaponeurosporene. It lacks the PshB polypeptide binding the FA and FB [4Fe–4S] clusters. It is active in charge separation and exhibits a trapping time of 23 ps, as judged by time-resolved fluorescence
studies. The charge recombination rate of the P800
+FX− state is 10–15 ms, as seen before. The purified HbRC core was able to reduce cyanobacterial flavodoxin in the light, exhibiting
a K
M of 10 μM and a k
cat of 9.5 s−1 under near-saturating light. There are ~1.6 menaquinones per HbRC in the purified complex. Illumination of frozen HbRC in
the presence of dithionite can cause creation of a radical at g = 2.0046, but this is not a semiquinone. Furthermore, we show that high-purity HbRCs are very stable in anoxic conditions
and even remain active in the presence of oxygen under low light. 相似文献
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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
20.
Hong Lu Jiti Zhou Jing Wang Guangfei Liu Lihong Zhao 《World journal of microbiology & biotechnology》2008,24(7):1147-1152
Sphingomonas xenophaga QYY from sludge samples could effectively decolorize 1-aminoanthraquinone-2-sulfonic acid (ASA-2), one kind of anthraquinone
dye intermediate, under aerobic conditions. More than 98% of ASA-2 could be removed within 120 h at the dye concentration
from 200 mg l−1 to 1,000 mg l−1 due to oxidative degradation. The strain converted ASA-2 to 2-(2′-hydroxy-3′-amino-4′-sulfo-benzoyl)-benzoic acid, 2-(2′-amino-3′-sulfo-6′-hydroxy-benzoyl)-benzoic
acid, o-phthalic acid and 2-amino-3-hydroxy-benzenesulfonic acid, which were identified using HPLC-MS and NMR. A possible
initial decolorization pathway was proposed according to these metabolites. The decolorization of ASA-2 by cells in the basal
salt medium was induced by ASA-2, and was due to soluble cytosolic enzymes. Combined initial decolorization pathway and the
analysis of decolorization enzyme(s), the major enzyme responsible for ASA-2 decolorization was a NADH-dependent oxygenase. 相似文献