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Degradation of chlorophenois and phenol mixtures by cooperative activities of chlorophenol-degrading strains
No full textThree strains capable of degrading a chlorophenol were isolated by selective enrichment from soils contaminated with industrial wastewater. A Pseudomonas solanacaccam TCP114 could use 2,4,6-tri- chlorophenol (TCP) as sole carbon and energy source, while two strains of Pseudomonas testosteroni CPW301 and Arthrobacter ureafaciens CPR706 could use 4-CP. All isolates also grew well on phenol. The degradation of one component by a pure strain was strongly affected by the presence of other compounds in the medium. CPW301 and CPR706 entirely lost the ability to degrade 4-CP and phenol in the presence of TCP. TCP114 also lost the ability to degrade phenol when 4-CP was added to the culture medium. These restrictions on the degradability could be overcome by employing defined mixed cultures (TCP114 and one strain of 4-CP degrading strains). All three components were successfully degraded by defined mixed cultures through their cooperative activities. It was also demonstrated that defined mixed cultures could be immobilized by using calcium alginate for the semi-continuous degradation of the three component mixture. Immobilization could not only accelerate the degradation rate, but also allowed the reuse of the cell mass several times without loss of the cells degrading capabilities
Simultaneous degradation of p-nitrophenol and phenol by a newly isolated Nocardioides sp.
No full textA p-nitrophenol (PNP)- and phenol-mineralizing bacterium (strain NSP41) was isolated from an industrial wastewater and identified as a member of the genus Nocardioides, PNP was degraded via a hydroquinone pathway, and phenol was degraded through a catechol pathway in strain NSP41, Both enzyme systems for the degradation of PNP and phenol were induced simultaneously in the presence of both compounds. Although both enzyme systems were induced at the same time, PNP and phenol were degraded by the hydroquinone and catechol pathway, respectively. However, during the simultaneous degradation in the low phenol concentration, after the exhaustion of phenol, some PNP was transformed by the catechol pathway and 4-nitrocatechol was transiently accumulated. Kinetically, the addition of phenol greatly enhanced the apparent PNP degradation rate, which may be due to the increased cell mass by the assimilation of phenol
Treatment of metal-contaminated water and vertical distribution of metal precipitates in an upflow anaerobic bioreactor
No full textA lab-scale upflow anaerobic bioreactor filled with granular sludge and cow manure was operated for 140 days to determine the mechanism of metal removal and the vertical distribution of metal precipitates. Heavy metal ions were removed in the order of Cu2+, Cd2+, ZnZ(2+), Fe2+ and Mn2+ with respect to the height in the reactor. The solid phase analysis showed that the heavy metals were mostly precipitated in the form of metal sulfides by sulfate reduction. The contents of metal precipitates in the reactor were as follows: (i) Cd and Zn were highest in the bottom, (ii) Fe was highest at the low-middle layer, and (iii) Mn was increased with the height in the reactor. The vertical distribution of metal sulfides in the reactor was directly related to the solubility product (Ksp). Results obtained in this study suggest a feasibility of the application to separate precipitation of metal ions and recovery of valuable metals from metal-containing wastewater
Rhodococcus pyridinivorans sp. nov., a pyridine-degrading bacterium
No full textThe taxonomic position of a bacterial strain (PDB9 ) that is capable of degrading pyridine was clarified by a polyphasic taxonomic approach using phenotypic, chemotaxonomic and genetic methods. The cells, which are rods and branched filaments during the early growth phase, fragment into short rods or cocci, thereby completing the growth cycle. Strain PDB9 was found to have a cell wall of chemotype IV, MK-8(H 2) as the predominant menaquinone, mycolic acids with 36-46 carbon atoms and C 16:0, C 18:1 cis9, 10-methyl-C 18:0(TBSA) as the major fatty acids. The G+C content of the DNA was 66 mol%. The phylogenetic tree showed that strain PDB9 falls within an evolutionary radiation comprising Rhodococcus species and is most closely related to the type strain of Rhodococcus rhodochrous, sharing 99% 16S rDNA similarity. The differences in some phenotypic characteristics and the genetic distinctiveness distinguish strain PDB9 from the Rhodococcus species described previously. Therefore, strain PDB9 should be placed in the genus Rhodococcus as a new species, for which the new name Rhodococcus pyridinivorans sp. nov. is proposed. The type strain of the new species is strain PDB9 (= KCTC 0647BP = KCCM 80005 )
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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