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61.
Vieira RP Clementino MM Cardoso AM Oliveira DN Albano RM Gonzalez AM Paranhos R Martins OB 《Microbial ecology》2007,54(3):460-468
Guanabara Bay is an eutrophic estuarine system located in a humid tropical region surrounded by the second largest metropolitan
area of Brazil. This study explores the contrasting environmental chemistry and microbiological parameters that influence
the archaeaplankton diversity in a pollution gradient in Guanabara Bay ecosystem. The environments sampled ranged from completely
anoxic waters in a polluted inner channel to the adjacent, relatively pristine, coastal Atlantic Ocean. Partial archaeal 16S
rDNA sequences in water samples were retrieved by polymerase chain reaction (PCR) and analyzed using denaturing gradient gel
electrophoresis (DGGE), cloning, and sequencing. Sequences were subjected to phylogenetic and diversity analyses. Community
structure of the free-living archaeal assemblages was different from that of the particle-attached archaea according to DGGE.
Gene libraries revealed that phylotype identification was consistent with environmental setting. Archaeal phylotypes found
in polluted anoxic waters and in more pristine waters were closely related to organisms that have previously been found in
these environments. However, inner bay archaea were related to organisms found in oil, industrial wastes, and sewage, implying
that water pollution controls archaea communities in this system. The detection of a substantial number of uncultured phylotypes
suggests that Guanabara Bay harbors a pool of novel archaeaplankton taxa. 相似文献
62.
Marielle Cascaes Inácio Tiago Antunes Paz Ana Maria Soares Pereira Maysa Furlan 《Plant Cell, Tissue and Organ Culture》2017,131(1):15-26
The root bark of Peritassa campestris (Cambess.) A.C. Sm. (Celastraceae) accumulates quinonemethide triterpenes (QMTs), an important class of bioactive compounds that shows potent antitumor activity. The production of these metabolites is difficult by both chemical synthesis, because of the complex molecular structure, and extraction from plant resources, because of the low yield. Thus, the aim of this work was to evaluate the influence of some important factors on the synthesis of QMTs to increase their production in adventitious roots grown in vitro. The effects of luminosity, mechanical damage to the tissue, source and concentration of carbon, auxins, macronutrient and micronutrient concentrations and the elicitation with its endophytic microorganism, Bacillus megaterium, isolated from roots grown in vitro were evaluated. Additionally, we compared the production of QMTs of roots in vitro with that of P. campestris roots bark in natura. Our results showed that all stimulating agents affected the biosynthesis of QMTs, with the exception of luminosity. The pattern of QMTs produced was different for the in vitro and in natura roots, including the accumulation of the majority QMTs: the in vitro roots accumulated maytenin (1) and 22β-hydroxy-maytenin (2), and the in natura roots showed the accumulation of maytenin (1), 22β-hydroxy-maytenin (2), 20α-hydroxy-maytenin (3), and maytenol (4). Therefore, we concluded that the biosynthesis of QMTs by P. campestris roots is affected by biotic and abiotic factors. 相似文献
63.
A genomic view of sugar transport in Mycobacterium smegmatis and Mycobacterium tuberculosis 总被引:1,自引:0,他引:1 下载免费PDF全文
Titgemeyer F Amon J Parche S Mahfoud M Bail J Schlicht M Rehm N Hillmann D Stephan J Walter B Burkovski A Niederweis M 《Journal of bacteriology》2007,189(16):5903-5915
We present a comprehensive analysis of carbohydrate uptake systems of the soil bacterium Mycobacterium smegmatis and the human pathogen Mycobacterium tuberculosis. Our results show that M. smegmatis has 28 putative carbohydrate transporters. The majority of sugar transport systems (19/28) in M. smegmatis belong to the ATP-binding cassette (ABC) transporter family. In contrast to previous reports, we identified genes encoding all components of the phosphotransferase system (PTS), including permeases for fructose, glucose, and dihydroxyacetone, in M. smegmatis. It is anticipated that the PTS of M. smegmatis plays an important role in the global control of carbon metabolism similar to those of other bacteria. M. smegmatis further possesses one putative glycerol facilitator of the major intrinsic protein family, four sugar permeases of the major facilitator superfamily, one of which was assigned as a glucose transporter, and one galactose permease of the sodium solute superfamily. Our predictions were validated by gene expression, growth, and sugar transport analyses. Strikingly, we detected only five sugar permeases in the slow-growing species M. tuberculosis, two of which occur in M. smegmatis. Genes for a PTS are missing in M. tuberculosis. Our analysis thus brings the diversity of carbohydrate uptake systems of fast- and a slow-growing mycobacteria to light, which reflects the lifestyles of M. smegmatis and M. tuberculosis in their natural habitats, the soil and the human body, respectively. 相似文献
64.
Gonzalez AM Vieira RP Cardoso AM Clementino MM Albano RM Mendonça-Hagler L Martins OB Paranhos R 《Molecular biology reports》2012,39(4):3401-3407
A culture-independent molecular phylogenetic analysis was carried out to study for the first time the diversity of bacterial
ammonia monooxygenase subunit A (amoA) and nitrogenase reductase subunit H (nifH) genes from Urca inlet at Guanabara Bay in Rio de Janeiro, Brazil. Most bacterial amoA and nifH sequences exhibited identities of less than 95% to those in the GenBank database revealing that novel ammonia-oxidizing bacteria
and nitrogen-fixing microorganisms may exist in this tropical marine environment. The observation of a large number of clones
related to uncultured bacteria also indicates the necessity to describe these microorganisms and to develop new cultivation
methodologies. 相似文献
65.
Jacobsen NE Wijeratne EM Corsino J Furlan M Bolzani Vda S Gunatilaka AA 《Bioorganic & medicinal chemistry》2008,16(4):1884-1889
Reaction of pristimerin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) resulted in a biomimetic-type coupling leading to xuxuarines Ealpha and Ebeta and not the previously reported Rzedowskia bistriterpenoids I and II suggesting that the structures proposed for these natural products need revision. A product obtained in this reaction by an unusual Diels-Alder addition followed by retro-Diels-Alder-type elimination was characterized as pristimerin dicyanophenalenedione. Complete 1H, and 13C NMR spectral assignments of xuxuarines Ealpha and Ebeta have been made by the application of 1D and 2D NMR techniques. 相似文献