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1.
Suspension cultured cells of Caragana chamlagu (Leguminosae) converted zerumbone (1) into zerumbone epoxide (2) as the intermediate, (2R,3R,7R)-2,3-epoxy-9-humulen-8-one (3) and (2R,3S,7R)-2,3-epoxy-9-humulen-8-one (4) as new sesquiterpenes in 11%, 36% and 21% yields, respectively. 相似文献
2.
Burkholderia sp. C3 was isolated from a polycyclic aromatic hydrocarbon (PAH)-contaminated site in Hilo, Hawaii, USA, and studied for
its degradation of phenanthrene as a sole carbon source. The initial 3,4-C dioxygenation was faster than 1,2-C dioxygenation
in the first 3-day culture. However, 1-hydroxy-2-naphthoic acid derived from 3,4-C dioxygenation degraded much slower than
2-hydroxy-1-naphthoic acid derived from 1,2-C dioxygenation. Slow degradation of 1-hydroxy-2-naphthoic acid relative to 2-hydroxy-1-naphthoic
acid may trigger 1,2-C dioxygenation faster after 3 days of culture. High concentrations of 5,6-␣and 7,8-benzocoumarins indicated
that meta-cleavage was the major degradation mechanism of phenanthrene-1,2- and -3,4-diols. Separate cultures with 2-hydroxy-1-naphthoic
acid and 1-hydroxy-2-naphthoic acid showed that the degradation rate of the former to naphthalene-1,2-diol was much faster
than that of the latter. The two upper metabolic pathways of phenanthrene are converged into naphthalene-1,2-diol that is
further metabolized to 2-carboxycinnamic acid and 2-hydroxybenzalpyruvic acid by ortho- and meta-cleavages, respectively. Transformation of naphthalene-1,2-diol to 2-carboxycinnamic acid by this strain represents the first
observation of ortho-cleavage of two rings-PAH-diols by a Gram-negative species. 相似文献
3.
Bacterial and fungal contaminants of enset (Ensete ventricosum) cultures and microbes associated with surface-sterilized field material were identified by 16S/26S rDNA sequencing. Ten bacterial species were identified in 16 isolates from in vitro cultures and seven in 10 isolates from field clones. Three yeast species and one filamentous fungus were recorded as in vitro contaminants, whereas five yeast species were isolated from the field material. The bacterium, Pseudomonas reactans (6 isolates), and the yeast, Torulaspora delbrueckii (8 isolates), were the most frequent in vitro contaminants. Most of the bacterial species isolated from in vitro enset were Gram-positive and hitherto unrecorded as in vitro contaminants. The difficulty in controlling the in vitro contaminants is due to their apparent endogenous nature and their resistance to antimicrobial drugs. 相似文献
4.
Wentzel A Ellingsen TE Kotlar HK Zotchev SB Throne-Holst M 《Applied microbiology and biotechnology》2007,76(6):1209-1221
Degradation of alkanes is a widespread phenomenon in nature, and numerous microorganisms, both prokaryotic and eukaryotic,
capable of utilizing these substrates as a carbon and energy source have been isolated and characterized. In this review,
we summarize recent advances in the understanding of bacterial metabolism of long-chain n-alkanes. Bacterial strategies for accessing these highly hydrophobic substrates are presented, along with systems for their
enzymatic degradation and conversion into products of potential industrial value. We further summarize the current knowledge
on the regulation of bacterial long-chain n-alkane metabolism and survey progress in understanding bacterial pathways for utilization of n-alkanes under anaerobic conditions. 相似文献
5.
A Candida rugosa lipase immobilized on polypropylene powder was employed as the biocatalyst for the enantioselective hydrolysis of (R, S)-suprofen 2,2,2-trifluorothioester in cyclohexane, in which trioctylamine was added as the catalyst to perform in situ racemization of the remaining (R)-thioester. A hollow-fiber membrane was also integrated with the dynamic kinetic resolution process in order to continuously extract the desired (S)-suprofen into an aqueous solution containing NaOH. A kinetic model for the whole process (operating in batch and feed-batch modes) was developed, in which enzymatic hydrolysis and deactivation, lipase activation, racemization and non-enantioselective hydrolysis of the substrate by trioctylamine, and reactive extraction of (R)- and (S)-suprofen into the aqueous phase in the membrane were considered. Theoretical predictions from the model for the time-course variations of substrate and product concentrations in each phase were compared with experimental data. 相似文献
6.
Hee Sook Kim Jae-Hwa Lee Sunghoon Park Eun Yeol Lee 《Biotechnology and Bioprocess Engineering》2004,9(1):62-64
The use of enantioselective hydrolysis for preparing chiral epichlorohydrins was investigated using recombinantPichia pastoris with the enantioselective epoxide hydrolase ofRhodotorula glutinis. The rate of the recombinant epoxide hydrolase-catalyzed enantioselective hydrolysis of racemic epichlorohydrins was enhanced
by the addition of 5% (v/v) Tween 20. Enantiopure (R)-epichlorohydrins with an enantiopurity of 100%ee and a yield of 26% were obtained within 5 min from 50 mM racemates. 相似文献
7.
Zhengfang Zhang Yanming Sheng Keyi Jiang Zhao Wang Yuguo Zheng Qing Zhu 《Biotechnology letters》2010,32(4):513-516
A newly isolated Bacillus megaterium with epoxide hydrolase activity resolved racemic glycidyl (o, m, p)-methylphenyl ethers to give enantiopure epoxides in 84–99% enantiomeric excess and with 21–73 enantiomeric ratios. The (S)-enantiomer was obtained from rac-glycidyl (o or m)-methylphenyl ether while the (R)-epoxides was obtained from glycidyl p-methylphenyl ether. The observations are explained at the level by enzyme-substrate docking studies. 相似文献
8.
Fuhong Xie Yapeng Chao Zhiquan Xue Xiuqing Yang Guoqing Zhang Jiaji Shi Shijun Qian 《Journal of industrial microbiology & biotechnology》2009,36(5):739-746
In industry, fosfomycin is mainly prepared via chemical epoxidation of cis-propenylphosphonic acid (cPPA). The conversion yield of fosfomycin is less than 50% in the whole process and a large quantity
of waste is produced. Biotransformation by microorganisms is an alternative method of preparation. This kind of conversion
is more delicate, environmentally friendly, and the conversion yield of fosfomycin would be higher. In this work, an aerobic
bacterium capable of transforming cPPA to fosfomycin was isolated. The organism, designated as strain S101, was identified
as Bacillus simplex by morphological and physiological characteristics as well as by analysis of the gene encoding the 16S rRNA. Fosfomycin was
assayed by two means, bioassay and gas chromatography (GC). Glycerol was a good carbon source for growth and cPPA conversion
of strain S101. When cPPA was used as the sole carbon source, neither growth nor conversion to fosfomycin occurred. The optimum
cPPA concentration in the conversion medium was 2,000 μg ml−1. After 6 days of incubation, the concentration of fosfomycin reached its maximum level (1,838.2 μg ml−1), with a conversion ratio of 81.3%. Air was indispensable for the growth but not for the conversion to fosfomycin. Furthermore,
vanadium ions were found to be essential for the conversion. High concentrations of cPPA had fewer inhibitory effects on the
growth of strain S101. 相似文献
9.
Sarawood Sungkaew Atchara Teerawatananon John A. N. Parnell Chris M. A. Stapleton Trevor R. Hodkinson 《Kew Bulletin》2008,63(4):669-673
Summary A new monotypic bamboo genus Phuphanochloa (Poaceae: Bambusoideae) from north-eastern Thailand is described, together with a new species, P. speciosa. 相似文献
10.
Soils contaminated with o-xylene were more difficult to bioremediate than those contaminated with other BTEX hydrocarbons (benzene, toluene, ethylbenzene,
m-xylene and p-xylene). In order to identify microorganisms responsible for o-xylene degradation in soil, microbial community structure analyses were carried out with two soil samples in the presence
of o-xylene and mineral nutrients. In two different soil samples, Rhodococcus
opacus became abundant. We were also able to isolate o-xylene degrading Rhodococcus species from these soil samples. A primer set was developed to specifically detect a cluster of this Rhodococcus group including isolated Rhodococcus strains, Rhodococcus opacus and Rhodococcus koreensis. The growth of this bacterial group in an o-xylene-contaminated soil was followed by competitive PCR (cPCR). The decrease in o-xylene clearly paralleled the growth of the Rhodococcus group. 相似文献
11.
Carotenoids represent a group of valuable molecules for the pharmaceutical, chemical, food and feed industries, not only because
they can act as vitamin A precursors, but also for their coloring, antioxidant and possible tumor-inhibiting activity. Animals
cannot synthesize carotenoids, and these pigments must therefore be added to the feeds of farmed species. The synthesis of
different natural commercially important carotenoids (β-carotene, torulene, torularhodin and astaxanthin) by several yeast
species belonging to the genera Rhodotorula and Phaffia has led to consider these microorganisms as a potential pigment sources. In this review, we discuss the biosynthesis, factors
affecting carotenogenesis in Rhodotorula and Phaffia strains, strategies for improving the production properties of the strains and directions for potential utility of carotenoid-synthesizing
yeast as a alternative source of natural carotenoid pigments. 相似文献
12.
Yuko Kurihara Nampiah Sukarno Muhammad Ilyas Erny Yuniarti Wibowo Mangunwardoyo Ju-Young Park Rasti Saraswati Yantyati Widyastuti Katsuhiko Ando 《Mycoscience》2008,49(4):250-257
Four species belonging to Kickxellales (Kickxellomycotina) isolated from soil of Indonesia are described and illustrated.
Two new species of Coemansia, C. asiatica and C. javaensis, were discovered in South Sulawesi and West Java, and two known species of Linderina, L. pennispora and L. macrospora, were discovered in East Kalimantan and South Sulawesi, respectively. These four species are newly added to the Indonesian
mycobiota. A technique for inducing sporulation of C. javaensis and L. macrospora by adding substances derived from invertebrates such as aphids, nereids, or cladocerans to culture media is described. 相似文献
13.
Young Tae Kim Kang Seon Lee Moon Jung Kim Seung Bum Kim 《Journal of microbiology (Seoul, Korea)》2009,47(1):33-39
The effects of Chinese cabbage (Brassica rapa subsp. pekinensis) carrying cry1AC derived from Bacillus thuringiensis (Bt) on leaf bacterial community were examined by analyzing the horizontal transfer of trans-gene fragments from plants to
bacteria. The effect of plant pathogenic bacteria on the gene transfer was also examined using Pseudomonas syringae pathovar. maculicola. The frequency of hygromycin-resistant bacteria did not alter in Bt leaves, though slight increase was observed in Pseudomonas-infected Bt leaves with no statistical significance. The analysis of bacterial community profiles using the denaturing gradient
gel electrophoresis (DGGE) fingerprinting indicated that there were slight differences between Bt and control Chinese cabbage,
and also that infected tissues were dominated by P. syringae pv. maculicola. However, the cultured bacterial pools were not found to contain any transgene fragments. Thus, no direct evidence of immediate
gene transfer from plant to bacteria or acquisition of hygromycin resistance could be observed. Still, long-term monitoring
on the possibility of gene transfer is necessary to correctly assess the environmental effects of the Bt crop on bacteria. 相似文献
14.
Five isolates of a species of Colletotrichum were collected from Japanese barnyard millet (Echinochloa utilis) in Japan. Although the fungus had once been identi-fied as C. graminicola sensu lato, it was clearly different from C. graminicola isolated from maize (Zea mays) in its falcate and short conidia, 18.0–22.2 μm in length, cultural characteristics, and specific pathogenicity to E. utilis. Moreover, molecular phylogenetic analyses using sequences of rDNA-ITS, HMG, and SOD2 indicated a monophyly of the isolates.
A new species, Colletotrichum echinochloae, is then proposed based on the morphological, pathological, and molecular characteristics. 相似文献
15.
Paulin Azokpota Joseph D. Hounhouigan Nana T. Annan Mathurin C. Nago Mogens Jakobsen 《World journal of microbiology & biotechnology》2008,24(6):879-885
Volatile compounds in afitin, iru and sonru, three traditional food condiments produced in Benin by natural fermentation of the African locust bean (Parkia biglobosa) were identified and quantified, using the Likens-Nickerson simultaneous distillation-extraction method and GC-MS analysis.
A total of 13 chemical groups of volatile compounds were identified and classified in six major groups: pyrazines, aldehydes,
ketones, alcohols, esters and benzene derivatives. From these groups, 2,5–dimethylpyrazine, tetramethylpyrazine, 3-methylbutanal,
2-decanone, 3,5-dimethylphenylmethanol, ethyl linoleate and chlorobenzene were found in higher amounts in the three condiments.
Afitin was characterized by high concentration of 2-decanone, whereas 2,5-dimethylpyrazine, tetramethylpyrazine, 3-methylbutanal
and ethyl linoleate were found particularly in higher concentration, both in iru and sonru. 相似文献
16.
P. Selvakumar S. Rajasekar K. Periasamy N. Raaman 《World journal of microbiology & biotechnology》2008,24(10):2125-2131
Melanins are enigmatic pigments that are produced by a wide variety of microorganisms including several species of bacteria
and fungi. For more than 40 years, fungi have been known to produce pigments called melanins. Melanin pigment production by
mushrooms was not intensively studied. The present study was carried out on isolation and characterization of melanin from
an edible mushroom Pleurotus
cystidiosus var. formosensis. The mushroom produced dark mucous mass of hyaline arthrospores on mycelium. The coremia exclusively produced dikaryotic
arthrospores with the remnant of a clamp connection. Continuous cell extension and division in the coremium stipe supplied
cells for arthroconidiation at the coremium apex, which is surrounded by a liquid droplet (coremioliquid). The black coloured
coremea (conidia) were produced by Antromycopsis macrocarpa (anamorph of P. cystidiosus) when cultured on potato dextrose agar medium. The agar plate was incubated at continuous light illumination for high amount
of pigment (coremea) production. The slimy layer of the coremea was extracted and partially purified by alkaline and acid
treatment. The black pigment was confirmed as melanin based on UV, IR and EPR spectra apart from chemical analysis. This is
the first report on characterization of melanin obtained from Pleurotus
cystidiosus var. formosensis. 相似文献
17.
Xin Xu N. Hayashi C. T. Wang H. Kato T. Fujimura S. Kawasaki 《Molecular breeding : new strategies in plant improvement》2008,22(2):289-299
The Pik-h gene in rice confers resistance to several races of rice blast fungus (Magnaporthe oryzae), and has been classified as a member of the Pik cluster, one of the most resistance (R) gene-dense regions in the rice genome. However, the loss of a key mutant isolate has long made it difficult to differentiate
Pik-h from other Pik group genes especially from Pik-m. We identified new natural isolates enabling the differentiation between Pik-h and Pik-m genes, and first confirmed the authenticity of the International Rice Research Institute (IRRI) “monogenic” line IRBLkh-K3,
and then fine-mapped the Pik-h gene in the Pik cluster. Using 701 susceptible individuals among 3,060 siblings from a cross of IRBLkh-K3×CO39, the Pik-h region was delimited to 270 kb, the narrowest interval among the Pik group genes reported to date, in the cv. Nipponbare genome. Annotation of this genome region first revealed 6 NBS-LRR type
R-gene analogs (RGAs), clustered within the central 120 kb, as possible counterparts of Pik-h and 6 other Pik group R genes. Interestingly, the Pik-h region and the cluster of RGAs were shown to be located 130 kb and 230 kb apart from Xa4 and Xa2 bacterial blight resistance genes, respectively, once classified as belonging to the Pik cluster. The closest recombination events were limited to the margins of the Pik-h region, and recombination was suppressed in the core interval with the RGA cluster. This fine-mapping, performed in a short
time using an HEGS system, will facilitate utilization of the cluster’s genetic resources and help to elucidate the mechanism
of evolution of R-genes. The presence of natural isolates also confirmed that evolution of Pik-h corresponds to pathogen evolution. 相似文献
18.
Nádia Skorupa Parachin Magnus Carlquist Marie F. Gorwa-Grauslund 《Applied microbiology and biotechnology》2009,84(3):487-497
In this study, the production of enantiomerically pure (1R,4S,6S)-6-hydroxy-bicyclo[2.2.2]octane-2-one ((−)-2) through stereoselective bioreduction was used as a model reaction for the comparison of engineered Saccharomyces cerevisiae and engineered Escherichia coli as biocatalysts. For both microorganisms, over-expression of the gene encoding the NADPH-dependent aldo-keto reductase YPR1
resulted in high purity of the keto alcohol (−)-2 (>99% ee, 97–98% de). E. coli had three times higher initial reduction rate but S. cerevisiae continued the reduction reaction for a longer time period, thus reaching a higher conversion of the substrate (95%). S. cerevisiae was also more robust than E. coli, as demonstrated by higher viability during bioreduction. It was also investigated whether the NADPH regeneration rate was
sufficient to supply the over-expressed reductase with NADPH. Five strains of each microorganism with varied carbon flux through
the NADPH regenerating pentose phosphate pathway were genetically constructed and compared. S. cerevisiae required an increased NADPH regeneration rate to supply YPR1 with co-enzyme while the native NADPH regeneration rate was
sufficient for E. coli.
Nádia Skorupa Parachin and Magnus Carlquist have contributed equally to the paper. 相似文献
19.
Woo JH Hwang YO Kang SG Lee HS Cho JC Kim SJ 《Applied microbiology and biotechnology》2007,76(2):365-375
Previously, we reported that ten strains belonging to Erythrobacter showed epoxide hydrolase (EHase) activities toward various epoxide substrates. Three genes encoding putative EHases were
identified by analyzing open reading frames of Erythrobacter litoralis HTCC2594. Despite low similarities to reported EHases, the phylogenetic analysis of the three genes showed that eeh1 was similar to microsomal EHase, while eeh2 and eeh3 could be grouped with soluble EHases. The three EHase genes were cloned, and the recombinant proteins (rEEH1, rEEH2, and
rEEH3) were purified. The functionality of purified proteins was proved by hydrolytic activities toward styrene oxide. EEH1
preferentially hydrolyzed (R)-styrene oxide, whereas EEH3 preferred to hydrolyze (S)-styrene oxide, representing enantioselective hydrolysis of styrene oxide. On the other hand, EEH2 could hydrolyze (R)- and (S)-styrene oxide at an equal rate. The optimal pH and temperature for the EHases occurred largely at neutral pHs and 40–55
°C. The substrate selectivity of rEEH1, rEEH2, and rEEH3 toward various epoxide substrates were also investigated. This is
the first representation that a strict marine microorganism possessed three EHases with different enantioselectivity toward
styrene oxide. 相似文献
20.
Hartung de Capriles C Mata-Essayag S Pérez C Colella MT Roselló A Olaizola C Abate SM 《Mycopathologia》2005,160(3):227-234
Over the past decades there has been a significant increase in fungal infections caused by Candida species, and continues to be common in immunocompromised individuals infected with the human immunodeficiency virus (HIV).
Although Candida albicans remains the fungal species most frequently isolated as an opportunistic oral pathogen, other non-albicans are often identified in this cohort of patients, including C. dubliniensis. This yeast is closely related to and shares many phenotypic characteristics with C. albicans. Colonies of these two species appear morphologically identical when not grown on special media. The shared phenotypic characteristics
of C. dubliniensis and C. albicans suggest that many C. dubliniensis isolates may have been misidentified as C. albicans in the past. The present studies aim is to recover and identify C. dubliniensis, and presumptive clinical C. albicans, from the oral cavities of HIV-seropositive individuals, comparing conventional media to obtain a simple, low-cost and reliable
identification system for C. dubliniensis. A total of 16 isolates (3,98%) had been obtained from 402 HIV infected individuals with recurrent oropharyngitis and were
identified as C. dubliniensis. Out of these C. dubliniensis isolates 19% were resistant, with MICs above 64 μg/ml to fluconazole. This constitutes, to the authors knowledge the first
recovery of this organism in Venezuela. 相似文献