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1.
Absalón AE Fernández FJ Olivares PX Barrios-González J Campos C Mejía A 《Biotechnology letters》2007,29(6):951-958
The rifamycin gene cluster in Amycolatopsis mediterranei includes the gene rifP, whose role in antibiotic production has not yet been established. In this work, the rifP gene was silenced and the results indicated that it codes for a protein to export rifamycin, avoiding its accumulation inside
the cell. An antisense cassette was constructed by inserting the rifP gene in an antisense orientation downstream from the modified ermE* promoter, and upstream of the Tasd terminator (aspartate semialdehyde dehydrogenase of A. lactamdurans). Partial silencing of the rifP gene by the use of the antisense cassette, cloned in the plasmid pUAMAE5, resulted in a 70% decrease in the extracellular
rifamycin B. A protein of 53 kDa was absent in the membrane fraction of the silenced strain. This is the same size of the
expected product from the rifP gene. The 2D structure analysis indicated it belongs to a Drug:H+ antiporter family which includes a wide number of membrane transport proteins. 相似文献
2.
Amycolatopsis, genus of a rare actinomycete, produces many clinically important antibiotics, such as rifamycin and vancomycin. Although
GlnR of Amycolatopsis mediterranei is a direct activator of the glnA gene expression, the production of GlnR does not linearly correlate with the expression of glnA under different nitrogen conditions. Moreover, A. mediterranei GlnR apparently inhibits rifamycin biosynthesis in the absence of nitrate but is indispensable for the nitrate-stimulating
effect for its production, which leads to the hyper-production of rifamycin. When glnR of A. mediterranei was introduced into its phylogenetically related organism, Streptomyces coelicolor, we found that GlnR widely participated in the host strain’s secondary metabolism, resemblance to the phenotypes of a unique
S. coelicolor
glnR mutant, FS2. In contrast, absence or increment in copy number of the native S. coelicolor glnR did not result in a detectable pleiotrophic effect. We thus suggest that GlnR is a global regulator with a dual functional
impact upon nitrogen metabolism and related antibiotics production. 相似文献
3.
The actinomycete Amycolatopsis mediterranei produces the commercially and medically important polyketide antibiotic rifamycin, which is widely used against mycobacterial infections. The rifamycin biosynthetic (rif) gene cluster has been isolated, cloned and characterized from A. mediterranei S699 and A. mediterranei LBGA 3136. However, there are several other strains of A. mediterranei which also produce rifamycins. In order to detect the variability in the rif gene cluster among these strains, several strains were screened by PCR amplification using oligonucleotide primers based on the published DNA sequence of the rif gene cluster and by using dEBS II (second component of deoxy-erythronolide biosynthase gene) as a gene probe. Out of eight strains of A. mediterranei selected for the study, seven of them showed the expected amplification of the DNA fragments whereas the amplified DNA pattern was different in strain A. mediterranei DSM 46095. This strain also showed striking differences in the banding pattern obtained after hybridization of its genomic DNA against the dEBS II probe. Initial cloning and characterization of the 4-kb DNA fragment from the strain DSM 46095, representing a part of the putative rifamycin biosynthetic cluster, revealed nearly 10% and 8% differences in the DNA and amino acid sequence, respectively, as compared to that of A. mediterranei S699 and A. mediterranei LBGA 3136. The entire rif gene cluster was later cloned on two cosmids from A. mediterranei DSM 46095. Based on the partial sequence analysis of the cluster and sequence comparison with the published sequence, it was deduced that among eight strains of A. mediterranei, only A. mediterranei DSM 46095 carries a novel rifamycin biosynthetic gene cluster. 相似文献
4.
Strain B31T is a Gram-staining-negative, motile, and extremely halophilic archaeon that was isolated from salt-fermented seafood. Its
morphology, physiology, biochemical features, and 16S rRNA gene sequence were determined. Phylogenetic analysis of its 16S
rRNA gene sequence and composition of its major polar lipids placed this archaeon in the genus Halorubrum of the family Halobacteriaceae. Strain B31T showed 97.3, 97.2, and 96.9 % 16S rRNA similarity to the type strains of Halorubrum alkaliphilum, Hrr. tibetense, and Hrr. vacuolatum, respectively. Its major polar lipids were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me)
and sulfated diglycosyl diether (S-DGD). Genomic DNA from strain B31T has a 61.7 mol% G+C content. Analysis of 16S rRNA gene sequences, as well as physiological and biochemical tests, identified
genotypic and phenotypic differences between strain B31T and other Halorubrum species. The type strain of the novel species is B31T (=JCM 15757T =DSM 19504T). 相似文献
5.
Ottem KF Nylund A Karlsbakk E Friis-Møller A Krossøy B Knappskog D 《Archives of microbiology》2007,188(5):547-550
A Francisella strain, GM2212, previously isolated from moribund farmed Atlantic cod (Gadus morhua) in Norway, is closely related to Francisella philomiragia among Francisella spp. according to its complete 16S rDNA, 16S-23S intergenic spacer, 23S rDNA, 23S–5S intergenic spacer, 5S rDNA, FopA, lipoprotein
TUL4 (LpnA), malate dehydrogenase and hypothetical lipoprotein (LpnB) sequences. A comparison between GM2212 and the type
strain of Francisella philomiragia were performed by DNA–DNA hybridization and fatty acid analysis. The DNA–DNA hybridization showed a 70% similarity. The fatty
acid analysis showed only minor differences between the Francisella isolates. Due to the inconclusive result from the DNA–DNA hybridisation, major emphasis concerning the status of this isolate
is made on previously published molecular, phenotypic and biochemical characters. All characteristics taken together support
the establishment of GM2212 as a novel species, for which the name Francisella piscicida sp. nov. is proposed (=CNCM I-3511T = DSM 18777T = LMG registration number not yet
available). 相似文献
6.
Ekman J Kosonen M Jokela S Kolari M Korhonen P Salkinoja-Salonen M 《Journal of industrial microbiology & biotechnology》2007,34(3):203-211
Colored biofilms cause problems in paper industry. In this work we used real-time PCR to detect and to quantitate members
of the genus Meiothermus from the process samples and end products from 24 machines manufacturing pulp, paper and board in four countries. The results
obtained from 200 samples showed the importance of members of the genus Meiothermus as ubiquitous biofoulers in paper machines. This genus was the dominant biofouler in some mills. From ≤104 to 1011 copies of Meiothermus 16S rRNA genes were found per gram of process deposit (wet weight). Meiothermus spp. were found in paper and board products with colored defects and connection between deposit-forming microbes and end-product
spots was shown. 16S rRNA gene sequences of 29 biofilm producing bacterial isolates from different mills were determined.
Based on sequence data, 25 of the isolates were assigned to the genus Meiothermus, with Meiothermus silvanus and M. ruber as the most frequent species. 相似文献
7.
A bacterium identified as Pseudomonas fluorescence was isolated from Taxus baccata rhizosphere. Ethyl acetate extract from its culture filtrate yielded an active antimicrobial compound that was purified by
TLC. The active metabolites were resolved by column chromatography on silica gel (60–120 mesh). The compound was further characterized
on the basis of spectral data (UV, IR and 1HNMR), which indicated the presence of an aromatic ring and phenolic functionality. The compound showed significant antimicrobial
activity against two-gram positive bacteria (B. subtilis and S. aureus), four-gram negative bacteria (E. coli, K. pneumoniae, S. flexneri and P. aeruginosa), and one pathogenic fungus (Candida albicans). The minimum inhibitory concentration (MIC) of the compound ranged between 75μg to 250 μg/ml. 相似文献
8.
Md. Harun-ur-Rashid Kaname Togo Minoru Ueda Taku Miyamoto 《World journal of microbiology & biotechnology》2007,23(1):125-133
We isolated a total of 266 strains of lactic acid bacteria (LAB) from 28 dahi samples that were collected from different areas in Bangladesh. The isolated strains were identified on basis of their morphological,
physiological and biochemical characteristics, the lactic acid isomer produced, the ability to ferment sugars and 16S rDNA
analysis. Among the isolates, the cocci (73%) were dominant over the rods (27%). The distribution of the isolates by genus
was as follows: Streptococcus (50%), Lactobacillus (27%), Enterococcus (9%), Leuconostoc (5%), Lactococcus (5%) and Pediococcus (4%). In this study, S. bovis was the most predominant species as this species represents 47.0% of the total isolates in dahi. The other species we isolated were identified as Lb. fermentum, Lb. delbrueckii ssp. bulgaricus, Lb. delbrueckii ssp. lactis, Lb. sp., Ec. faecium, S. thermophilus, Leuc. mesenteroides ssp. mesenteroides, Leuc. mesenteroides ssp. dextranicum, Lc. lactis ssp. lactis, Lc. raffinolactis and P. pentosaceus. 相似文献
9.
Xiang-Jing Wang Xiao-Chong Wang Wen-Sheng Xiang 《World journal of microbiology & biotechnology》2009,25(6):1051-1056
Milbemycin antibiotics are produced by Streptomyces
hygroscopicus subsp. aureolacrimosus and a newly isolated Streptomyces bingchenggensis, respectively. According to the biosynthetic pathway of milbemycins generated by S.
hygroscopicus subsp. aureolacrimosus, a rational screening procedure with UV irradiation and N-methyl-N′-nitroso-N-nitrosoguanidine (NTG) mutation was performed to obtain high milbemycin-producing S. bingchenggensis. Aminoacetic acid (Glycine)-resistant mutants (AAr), propionate-resistant mutants (PRPr), streptomycin-resistant mutants (STRr) and 2-deoxy-d-glucose-resistant mutants (DOGr) were selected successively. A strain S. bingchenggensis BC-109-6 with AAr, PRPr, STRr and DOGr was obtained and its production of milbemycin A3 and A4 reached 1,450 μg/ml, which was 80% higher than that of the ancestral
strain S. bingchenggensis BC-101-4. The subculture experiments indicated that the hereditary characteristic of high productivity of S. bingchenggensis BC-109-6 was stable. The production of milbemycin A3 and A4 by S. bingchenggensis BC-109-6 in a 50-l fermentor could reach 1,380 μg/ml after 360 h batch fermentation. 相似文献
10.
11.
Derekova A Sjøholm C Mandeva R Kambourova M 《Extremophiles : life under extreme conditions》2007,11(4):577-583
Three strains of a novel thermophilic, strictly aerobic, Gram-positive, spore-forming hemo-organotrophic bacterium were isolated
from three hot springs in the region of Rupi basin, Bulgaria as producers of amylolytic enzymes. Their 16S rRNA gene sequences
(first 500 nucleotides) were very similar (99.8%). Strains were able to ferment a wide spectrum of carbohydrates such as sugars,
polyols, and polysaccharides like xylan, glycogen and starch. Optimal growth was observed at 55–58°C, and pH at 6.0–6.5. Phylogenetic
analysis of the whole 16S rRNA gene sequence clustered the strain R270T with the representatives of the genus Anoxybacillus and with Geobacillus tepidamans. The G + C content of the genomic DNA was 41.7%. DNA–DNA hybridization analysis revealed low homology with the closest relatives
(32.0 mol% homology to Geobacillus tepidamans). Fatty acid profile (major fatty acids iso-C15:0 and iso-C17:0) confirmed the affiliation of the strain to the genus Anoxybacillus. On the basis of the data presented here, we propose that strain R270T, represents a new species of the genus Anoxybacillus for which, we recommend the name Anoxybacillus rupiensis sp. nov. (=DSM 17127T = NBIMCC 8387T). The 16S rRNA gene sequence data of a strain R270T have been deposited in the EMBL databases under the accession number AJ879076. 相似文献
12.
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
13.
14.
Zhi-Ping Zhuang Mei-Ping Kung William Clarke Saul Maayani Mu Mu Hank F. Kung 《Chirality》1995,7(6):452-458
(R,S)-trans-8-Hydroxy-2-[N-n-propyl-N-(3′-iodo-2′-propenyl)amino]tetralin 7 , a new radioiodinated ligand based on 8-OH-DPAT, was reported as a potential ligand for 5-HT1A receptors. The optically active (+)-(R)- and (?)-(S)- 7 were prepared to investigate the stereoselectivity of (R,S)- 7 . Racemic intermediate 8-methoxy-2-N-n-propyltetralin was reacted with the acyl chloride of (?)-(R)-O-methylmandelic acid to form a mixture of (S,R)- and (R,R)-diastereoisomers, which were separated by flash column chromatography. After removing the N-acyl group from the diastereoisomers, the desired (+)-(R)-or (?)-(S)- 7 was obtained by adding an N-iodopropenyl group. In vitro homogenate binding studies showed the stereoselectivity of this new compound for 5-HT1A receptors. (+)-(R)- 7 isomer displayed 100-fold higher affinity than the (?)-(S)- 7 isomer. Biochemical study indicated that (+)-(R)- 7 potently inhibited forskolin-stimulated adenylyl cyclase activity in hippocampal membranes (Emax and EC50 were 24.5% and 5.4 nM, respectively), while (?)-(S)- 7 showed no effect at 1 μM. The radioiodinated (+)-(R)- and (?)-(S)-[125I] 7 were confirmed by coelution with the resolved unlabeled compound on HPLC (reverse phase column PRP-1, acetonitrile/pH 7.0 buffer, 80/20). The active isomer, (+)-(R)-[125I] 7 , displayed high binding affinity to 5-HT1A receptors (Kd = 0.09 ± 0.02 nM). In contrast, the (?)-(S)- 7 isomer displayed a significantly lower affinity to the 5-HT1A receptor (Kd > 10 nM). Thus, (+)-(R)-[125I]trans-8-OH-PIPAT, (+)-(R)- 7 , an iodinated stereoselective 5-HT1A receptor agonist, is potentially useful for study of in vivo and in vitro function and pharmacology of 5-HT1A receptors in the central nervous system. © 1995 Wiley-Liss, Inc. 相似文献
15.
A Gram-negative, aerobic, rod shaped, non-spore-forming bacterial strain, designated Dae08T, was isolated from sediment of the stream near Daechung dam in South Korea, and was characterized in order to determine its
taxonomic position, using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain Dae08T belongs to the family Xanthomonadaceae of the Gammaproteobacteria, and is related to Lysobacter brunescens ATCC 29482T (97.3%). The phylogenetic distances from any other species with validly published names within the genus Lysobacter were greater than 3.7%. The G+C contents of the genomic DNA of strain Dae08T was 69.3 mol%. The detection of a quinone system with Q-8 as the predominant compound and a fatty acid profile with iso-C15:0, iso-C17:1, ω9c, iso-C17:0, iso-C16:0, and iso-C11:0 3-OH as the major acids supported the affiliation of strain Dae08T to the genus Lysobacter. DNA-DNA relatedness between strain Dae08T and its phylogenetically closest neighbour was 28%. On the basis of its phenotypic properties and phylogenetic distinctiveness,
strain Dae08T (= KCTC 12600T) should be classified in the genus Lysobacter as the novel species, for which the name Lysobacter daecheongensis sp. nov. is proposed. 相似文献
16.
Interactions between the necrotrophic fungus Sclerotinia sclerotiorum and one of its hosts, Helianthus annuus L., were analyzed during fungal colonization of plant tissues. Metabolomic analysis, based on 13C- and 31P-NMR spectroscopy, was used to draw up the profiles of soluble metabolites of the two partners before interaction, and to
trace the fate of metabolites specific of each partner during colonization. In sunflower cotyledons, the main soluble carbohydrates
were glucose, fructose, sucrose and glutamate. In S. sclerotiorum extracts, glucose, trehalose and mannitol were the predominant soluble carbon stores. During infection, a decline in sugars
and amino acids was observed in the plant and fungus total content. Sucrose and fructose, initially present almost exclusively
in plant, were reduced by 85%. We used a biochemical approach to correlate the disappearance of sucrose with the expression
and the activity of fungal invertase. The expression of two hexose transporters, Sshxt1 and Sshxt2, was enhanced during infection. A database search for hexose transporters homologues in the S. sclerotiorum genome revealed a multigenic sugar transport system. Furthermore, the composition of the pool of reserve sugars and polyols
during infection was investigated. Whereas mannitol was produced in vitro and accumulated in planta, glycerol was exclusively produced in infected tissues and increased during colonization. The hypothesis that the induction
of glycerol synthesis in S. sclerotiorum exerts a positive effect on osmotic protection of fungal cells and favors fungal growth in plant tissues is discussed. Taken
together, our data revealed the importance of carbon–nutrient exchanges during the necrotrophic pathogenesis of S. sclerotiorum. 相似文献
17.
Crude extracts of the leaves of Spiraea prunifolia Sieb. showed high plant-growth-inhibiting activity comparable to that of S. thunbergii extracts. To isolate the causal compound in S. prunifolia, we performed bioassay-directed purification by monitoring the biological activity per unit weight of the organism containing the bioactive compound (total activity). We isolated 1-O-cis-cinnamoyl-β-D-glucopyranose (cis-CG) and identified it as the most important growth-inhibiting constituent in the crude extracts. We did not detect 6-O-(4′-hydroxy-2′-methylenebutyroyl)-1-O-cis-cinnamoyl-β-D-glucopyranose (cis-BCG) in S. prunifolia, though it is a major plant growth inhibitor in S. thunbergii together with cis-CG. We estimated the cis-CG content in S. prunifolia to be 3.84 mmol kg−1 F.W. This amount is comparable to the cis-CG plus cis-BCG content in S. thunbergii (3.59 mmol kg−1 F.W.). This indicates that S. prunifolia and S. thunbergii have equally high potential to inhibit plant growth, and cis-CG acts as the most important plant-growth inhibitor in S. prunifolia extracts. 相似文献
18.
A novel actinobacterium designated as MSL-26T was isolated from soil in Bigeum Island Korea. A polyphasic study was undertaken to establish the taxonomic position of isolate
MSL-26T. Strain MSL-26T was found to have chemical and morphological characteristics similar to Nocardioides. The strain grew optimally at pH 7·5 and 28°C. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain
MSL-26T forms a distinct line of descent within the radiation enclosed by the genus Nocardioides. The cell wall of strain MSL-26T contained LL-2, 6-diaminopimelic acid. The principal menaquinone was MK-8 (H4). The phospholipids detected were diphosphatidylglycerol, phosphatidylglycerol and some unidentified lipids. C18:1 w7c (50.38%) was the major fatty acid. The DNA G + C content of strain MSL-26T was 71.4 mol%. The 16S rRNA gene sequence of strain MSL-26T shares the highest sequence similarity with Nocardioides kribbensis KCTC 19038T (95.78%) and Nocardioides aquaticus DSM 11439T (95.52%). Based on the morphological, physiological, biochemical and chemotaxonomical data presented in this study, strain
MSL-26T should be classified as a novel species, for which the name Nocardioides islandiensis sp. nov. is proposed. The type strain is MSL-26T (=KCTC 19275T =DSM 19321T) 相似文献
19.
Cryptococcus neoformans var. grubii and C. gattii were repeatedly isolated from decaying wood of trunk hollows in living trees growing in Jabalpur City in Central India. The
isolation of C.␣gattii has been reported from decayed wood inside trunk hollow of Tamarindus indica (15.6%), Mangifera indica (2.2%), Pithecolobium dulce (12.5%), Syzygium cumini (14%), and one from bark of S.␣cumini. C. n. var. grubii was isolated from decaying wood debris of T. indica (4.4%), M. indica (13.3%), Terminalia arjuna (25%), S. cumini (2%), Cassia fistula (4.5%), and two from bark of S. cumini. The two varieties never co-occurred in the same hollow. C. gattii and C. n. var. grubii isolates belonged to serotype B and serotype A respectively. The data strongly supported the colonization of the pathogen
in␣decaying wood hollow of all six-tree species. Evidence of this was found by repeated isolation up to 820 days. P. dulce is being reported for the first time as natural habitat of C. gattii and T.␣arjuna and C. fistula as natural habitat for C. n. var. grubii. M. indica is being reported for the second time as the natural habitat of both varieties (C. n. var. grubii and C. gattii). The population density of these pathogens from decaying wood debris of various tree species ranged between 0.5 × 103 cells/g and 6 × 105 cells/g. The seasonal variation has been seen in isolation of this yeast. Our result further reinforce the recently emerging
evidence that the natural habitat of C. n. var. grubii and C. gattii is more generalized. 相似文献
20.
Ok-Sun?Lee Young-Min?Kang Hee-Young?Jung Ji-Yun?Min Seung-Mi?Kang Chandrakant?S.?Karigar D.?Theertha?Prasad Jung-Dong?Bahk Myung-Suk?Choi
Summary In wild-type Scopolia parvilfora (Solanaceae) tissues, only the roots express the enzyme putrescine N-methyltransferase (PMT; EC 2.1.1.53), which is the first specific precursor of the tropane alkaloids. Moreover, the tropanane
alkaloid levels were the highest in the root (0.9 mg g−1 on a dry weight basis), followed by the stem and then the leaves. We metabolically engineered S. parviflora by introducing the tobacco pmt gene into its genome by a binary vector system that employs disarmed Agrobacterium rhizogenes. The kanamycin-resistant hairy root lines were shown to bear the pmt gene and to overexpress its mRNA and protein product by at least two-fold, as determined by polymerase chain reaction (PCR)
and Northern and Western blottings, respectively. The transgenic lines also showed higher PMT activity and were morphologically
aberrant in terms of slower growth and the production of lateral roots. The overexpression of pmt markedly elevated the scopolamine and hyoscyamine levels in the transgenic lines that showed the highest pmt mRNA and PMT protein levels. Thus, overexpression of the upstream regulator of the tropane alkaloid pathway enhanced the
biosynthesis of the final product. These observations may be useful in establishing root culture systems that generate large
yields of tropane alkaloids.
These authors contributed equally to this paper (co-first authors). 相似文献