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Characterisation and antimicrobial activity of epibiotic bacteria from Petrosia ficiformis (Porifera, Demospongiae)
No full textNumerous natural products from marine invertebrates show striking structural similarities to known metabolites of microbial origin, suggesting that microorganisms (bacteria, microalgae) are at least involved in their biosynthesis or are in fact the true sources of these respective metabolites.
The viable epibiotic microbial community of the marine sponge Petrosia ficiformis was screened and characterised using classical and molecular techniques. Fifty-seven aerobic heterotrophic bacterial strains were isolated and presumptively identified by their phenotypic characters. Random Amplified Polymorphic DNA (RAPD) analysis of the non-fermentative Gram-negative strains and Corynebacteria was performed. Cluster analysis of RAPD data showed genetic relatedness among sponge isolates. Antimicrobial activity was found in several isolates, two of which were identified as Rhodococcus sp. and Pseudomonas sp. by partial 16S rRNA gene sequencing. The recovery of strains with antimicrobial activity suggests that marine sponges represent an ecological niche which harbours a largely uncharacterised microbial diversity and a yet unexploited potential in the search for new secondary metabolites
Bacterial community structure and activity in fish farm sediments of the Ligurian sea (Western Mediterranean)
No full textThe environmental impact of a well-established fish farm has beeninvestigated in surface sediments of the Ligurian Sea in order to assess thebiodeposition, bacterial community structure and dynamics at a mature stage oforganic enrichment.The Biopolymeric carbon (BPC) fraction of organic matter and phytopigmentconcentrations displayed very high values beneath the fish cages. In particularlipid, carbohydrate and chlorophyll-a concentrations werehigher in farm sediment while protein concentrations did not show significantchange between farm sediment and control.Benthic bacteria were closely related to organic enrichment and their densitywas three times higher (up to 3 × 1010 cellsg–1) in stations beneath the cages being positivelycorrelated with BPC (n = 10, p < 0.05) and lipid (n = 10, p < 0.05)concentrations. Colony forming units (CFU) counts of heterotrophic bacteriaindicate a shift in the relative importance of the gram negative bacterialfraction, displaying the predominance of theCytophaga/Flexibacter-like bacteria (CBF), as well as theoccurrence of pathogenic bacteria (such as Vibrio) insediments beneath the farm. In contrast, Gram positive bacteria were moreprevalent in control site where they represented up to 90% of total isolates.Aminopeptidase activity displayed higher values in sediment beneath the cages,whereas the enzymatic activity per bacterial cell was lower. These data suggesta functional stress of bacterial degradation rates and represent a potentialvaluable environmental index of imbalance between supply and removal of organicmatter in eutrophicated environments.Data presented in this study also suggest that either the biochemicalcomposition of sedimentary organic matter as well as the selected microbialvariables may represent useful tools for evaluating the effects of organicenrichment due to fish farming and could be proposed as new environmentalindices of aquaculture impact on marine sediment
2007 Bacteria with antimicrobial properties from the Mediterranean sponges Chondrilla nucula and Petrosia ficiformis.
No full textCharacterisation and antimicrobial activity of epibiotic bacteria from Petrosia ficiformis (Porifera, Demospongiae).
No full textNumerous natural products from marine invertebrates show striking structural similarities to known metabolites of microbial origin, suggesting that microorganisms (bacteria, microalgae) are at least involved in their biosynthesis or are in fact the true sources of these respective metabolites. The viable epibiotic microbial community of the marine sponge Petrosia ficiformis was screened and characterised using classical and molecular techniques. Fifty-seven aerobic heterotrophic bacterial strains were isolated and presumptively identified by their phenotypic characters. Random Amplified Polymorphic DNA (RAPD) analysis of the non-fermentative Gram-negative strains and Corynebacteria was performed. Cluster analysis of RAPD data showed genetic relatedness among sponge isolates. Antimicrobial activity was found in several isolates, two of which were identified as Rhodococcus sp. and Pseudomonas sp. by partial 16S rRNA gene sequencing. The recovery of strains with antimicrobial activity suggests that marine sponges represent an ecological niche which harbours a largely uncharacterised microbial diversity and a yet unexploited potential in the search for new secondary metabolites. (C) 2004 Elsevier B.V. All rights reserved
Antibiotic resistance of benthic bacteria in fish farm and control sediments of the Western Mediterranean
No full textThe effects of fish farming on bacterial density, biomass, community structure and their possible link to antibiotic resistance have been investigated in coastal sediments of the Ligurian Sea (Western Mediterranean). The top 2 cm of the sediment under a fish farm and control areas were analysed during summer 2000. Bacterial density and biomass were three folds higher (up to 3×1010 cells/g and 2602.7 μC/g) (ANOVA, p<0,01) in sediments beneath the fish cages compared to the control sediments. The number of Colony Forming Units (CFUs) for culturable bacteria and microbiological investigations indicated a shift in the relative importance of the Gram-negative bacteria in impacted sediments. Gram-positive bacteria increased their relevance in the control site where they represented up to 90% of total isolates.
Antibiotic sensitivity tests showed a high percentage of resistant strains in both control and impacted sediments, which indicates a widespread antibiotic resistance within bacterial populations in areas surrounding fish farms. A high frequency of antibiotic resistance was observed for ampicillin (AMP) in impacted sediments (ANOVA, p<0.05). Gram-negative bacteria displayed the highest resistance to ampicillin, and streptomycin (STR) (ANOVA, p<0.05) and the shift in the structure of microbial assemblage was apparently related to the presence of Gram-negative resistant strains in fish-farm sediments. The incidence of multiple resistance patterns in bacterial isolates was also greater in impacted sediments and the presence of Bacillus strains producing antimicrobial compounds may be related to the high level of drug resistance.
This study highlighted a major change occurring in the structure of the benthic bacterial community most probably due to fish farming and its close association with antibiotic resistance patterns
The marine sponge Chondrilla nucula Schmidt, 1862 as an elective candidate for bioremediation in integrated aquaculture
No full textThe use of sponges for marine bioremediation in a farming scenario has been investigated focusing on Chondrilla nucula. We
report experiments examining clearance and retention rates of the bacterium Escherichia coli . Despite low values expressed for
clearance tests, C. nucula exhibited a marked ability to retain high quantities of bacteria. One square meter patch of this sponge can
filter up to 14 l/h of sea water retaining up to 7/1010 bacterial cells/h. This suggests that C. nucula is a suitable species for marine
environmental bioremediatio
Microbial diversity in Petrosia ficiformis investigated by different technical approaches
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
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