1,721,023 research outputs found
Growth phase-dependent expression of an endoglucanase encoding gene (eglS) in Streptomyces rochei A2
No full textDifferent growth phases of Streptomyces rochei A2, a cellulolytic strain isolated from termite gut, were determined in liquid culture. The strain exhibited a multiphasic growth curve typical of streptomycetes. In S. rochei A2, the secreted endoglucanase EglS is coded by a TTA-containing gene, conserved in other Streptomyces. The onset of S. rochei A2 eglS gene expression was determined by RT-PCR using total RNA extracted at different growth phases. The eglS gene was expressed only during transition, second rapid growth and stationary phases, the timing of expression being transcriptionally regulated
Selezione e caratterizzazione di ceppi batterici per il miglioramento del processo di macerazione della canapa
No full textRestriction enzyme and DNA hybridization analysis of cellulolytic Streptomyces isolates of different origin
No full textStreptomyces rochei A2 endoglucanase (eglS) and β-glucosidase (bgs1) genes were used as probes to survey their distribution among 16 Streptomyces strains isolated from different sources and characterized for their cellulolytic activities. The eglS probe hybridized to the genomic DNA of 12 strains with a restriction pattern different from that of S. rochei A2. The DNA from all strains, except one, hybridized with the bgs1 probe and one strain showed the same restriction pattern as seen in S. rochei A2. The sequence localized by the eglS probe in S. thermoviolaceus and the one localized by the bgs1 probe in strain EC1 were cloned and expressed in E. coli in plasmids pTAE and pCSF203, respectively. The restriction maps showed that the cloned genes were identical to eglS and bgs1. The restriction enzyme analysis of genomic DNA from all the strains identified nine different groups, each characterized by a distinctive pattern and in agreement with the results of the hybridization experiments
A putative Streptomyces sigma factor can activate the expression of the cryptic operon bgl in Escherichia coli K-12.
No full textStreptomyces sp A21 is a cellulolytic strain isolated from soil which was assigned to the genus Streptomyces on the basis of distinctive morphological features. A genomic library of A21 DNA has been constructed and transformed into Escherichia coli K-12 using a high-copy-number vector. One of the recombinant plasmids activates the cryptic bgl operon when inserted into appropriate strains. The complete sequence of the 1629-bp A21 DNA fragment has been determined. The analysis revealed the presence of an ORF whose putative product shows a high degree of similarity to RNA polymerase sigma factors; we therefore designated the gene psfS (Putative sigma factor, Streptomyces). Mapping of the 5' terminus of transcript by primer extension indicated that PsfS induces transcription initiation within the bgl promoter-silencer region
A putative sigma factor from Streptomyces sp. strain A21 can activate the expression of the cryptic operon bgl in Escherichia coli K-12
No full textStreptomyces sp A21 is a cellulolytic strain isolated from soil which was assigned to the genus Streptomyces on the basis of distinctive morphological features. A genomic library of A21 DNA has been constructed and transformed into Escherichia coli K-12 using a high-copy-number vector. One of the recombinant plasmids activates the cryptic bgl operon when inserted into appropriate strains. The complete sequence of the 1629-bp A21 DNA fragment has been determined. The analysis revealed the presence of an ORF whose putative product shows a high degree of similarity to RNA polymerase sigma factors; we therefore designated the gene psfS ((P) under bar utative (s) under bar igma (f) under bar actor, (S) under bar treptomyces). Mapping of the 5' terminus of transcript by primer extension indicated that PsfS induces transcription initiation within the bgl promoter-silencer region
Characterization of bacterial pectinolytic strains involved in the water retting process
No full text[Compulsory and additional parameters in water control]
No full textThe authors have analyzed 22 water samples from the Arno River (both river and drinking samples), as well as 11 effluent samples from an urban plant. Chemical and microbiological features of river samples were in line with the A3 class, needing treatment for drinking use (Executive Order n. 152/99); drinkable water met requirements (Presidents Decree n degrees 236/1988 and Executive Order n degrees 31/2001). As regards chemical parameters, effluents complied with the law (Executive Order n. 152/1999) but their bacteriological figures exceeded the standards set by the Authorities due to a lack in chlorination. Enteric viruses reacted to the RT-PCR test in 5 of the samples, including a Coxsackievirus Type B2 and a Poliovirus. No association was shown between bacteriophage parameters and virus
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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