1,720,997 research outputs found
Innovative ready to use carrier-bacteria devices for bioremediation of oil contaminated water
Full text linkBioremediation, that uses microorganisms to remove environmental pollutants, is the best way of restoring
the environment due to its low cost and sustainability. Immobilization of microorganisms capable of
degrading specific contaminants significantly promotes bioremediation processes. An innovative ready to
use bioremediation system to clean up oil-contaminated water was developed immobilizing highly
performant marine and soil HC degrading bacteria, on biodegradable oil-absorbing carriers. Two soil
Actinobacteria (Gordonia sp. SoCg, Nocardia sp. SoB) and two marine Gammaproteobacteria (Alcanivorax
sp. SK2, Oleibacter sp.5), were immobilized on biopolymeric membranes prepared by electrospinning
(polylactic acid, PLA and polycaprolactone, PCL). These carriers are characterized by high uptake capacity,
oil retention, buoyancy, durability, reusability and recoverability of the oil absorbed. The morphology of the
carriers and microbial adhesion and proliferation were evaluated using scanning electron microscopy (SEM).
A high capacity of adhesion and proliferation of bacterial cells was observed on membranes after 5 days. The
bioremediation efficiency of the carrier-bacteria systems was tested on crude oil by GC-FID analysis and
compared whit planktonic cells. The bacterial immobilization on PLA and PCL membranes was a
promoting factor for biodegradation, increasing hydrocarbon removal up to 20%, in respect to planktonic
cells. Biofilm-mediated bioremediation is a versatile tool to be developed for in situ and ex situ
bioremediation of aquatic systems. Several applications can be designed to exploit both the high oil uptake
capacity of the carriers, and the biodegradation potential of autochtonous microrganisms and/or of selected
microorganisms that are immobilized on the carriers before exposure to the contaminated site
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
Isolation and Characterization of Oil-Degrading Bacteria from Bilge Water
Full text linkTwenty-one oil-degrading bacteria were isolated from bilge water. Based on a high growth rate on crude oil and on hydrocarbon degradation ability, 7 strains were selected (from 21 isolated) for further studies. 16S rRNA gene sequencing showed that isolated strains were affiliated to Bacillus, Pseudomonas and Halomonas genera; in particular, isolate BW-B12 (Bacillus sp., 99%), BW-C12 (Halomonas boliviensis, 99%) and BW-E12 (Halomonas boliviensis, 98%) were the best crude-oil degraders; after 10 days of cultivation in ONR 7a mineral medium supplemented with crude oil as single carbon source BW-B12, BW-C12 and BW-E12 showed a degradation rate of 80, 60 and 59%, respectively. The strains showed also a high emulsification activity and biosurfactants production. Obtained results give an important contribution in order to utilize these bilge water autochthonous microorganisms in processes of bioremediation of marine environment chronically polluted from saline oily wast
Biodegradation Potential of Oil-degrading Bacteria Related to the Genus Thalassospira Isolated from Polluted Coastal Area in Mediterranean Sea
Full text linkThree bacterial species related to the genus Thalassospira
(T. lucentensis, T. xianhensis and T. profundimaris), isolated from polluted sediment and seawater samples collected from Priolo Bay (eastern coast of Sicily, Ionian Sea), were analyzed for their biotechnological
potential. For this purpose, the presence of specific catabolic genes
associated to aliphatic and aromatic hydrocarbon metabolism, the
production of biosurfactants and emulsification activity, the capability
to degrade oil-derived linear, branched, cyclic alkanes, and polycyclic
aromatic hydrocarbons (PAHs) were evaluated. Alkane hydroxylase
gene (alkano-monoxygenase alkb and citocrome P450) were present
in genome of all strains, confirming their hydrocarbons degrading
capability. All strains of Thalassospira produced biosurfactants and
showed emulsification activity. The two-dimensional gas chromatography analysis (GC×GC) showed that they were able to degrade oil
fractions with the capacity ranging between 77% and 91%. The data
obtained in this study demonstrated the biodegradation ability of
Thalassospira and suggest that these strains play an important role in
marine contaminated ecosystem
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
BIODEGRADING BIOFILMS ON INNOVATIVE BIOPOLYMERIC SUPPORTS
No full textABSTRACT
Water bioremediation is traditionally carried out using ‘ free ’ bacterial cells, however, in recent years, utilization of ‘immobilized’ bacterial cells on adsorbing matrices, has gained attention as a promising technique due to biotechnological and economic benefits (Sonawane et al., 2022). Bacterial biofilms show greater resilience, survival and degradative activity for longer periods than cells in the planktonic state (Alessandrello et al., 2017); moreover immobilization reduces bioremediation costs, eliminate cell dilution and dispersion in the environment (Bayat et al., 2015). Possible applications of immobilized biodegrading bacteria require long-term survival and maintenance of biodegrading performances. In this study, combinations of polylactic acid (PLA) and polycaprolactone (PCL) biodegradable membrane carriers hosting selected HC-biodegrading marine and soil bacterial biofilms were tested after different incubation periods and their survival was monitored over time, simulating storage effects.
Results
Soil hydrocarbon (HC) degrading actinobacteria and marine hydrocarbonoclastic bacteria were immobilized on absorbent biodegradable biopolymeric polylactic acid (PLA) and polycaprolactone (PCL) membranes (Scaffaro et al., 2017, Catania et al., 2020). Combinations of HC-degrading bacteria and biopolymers were obtained and tested on hexadecane. After 5, 10 and 15 days incubation, the capacity of adhesion and proliferation of bacterial cells into the biopolymers was verified by scanning electron microscopy (SEM); PLA and PCL nanofibers were covered by bacterial cells already after 5 days incubation; Total biomass (estimated as total dsDNA) extracted from biofilms confirmed the colonization up to 15 days incubation. Viable plate counts showed that survival of the bacterial strains was high for the entire experimental period. HC biodegradation ability of biofilms was assessed by high resolution GC-FID analysis, after extraction of total residual HC from the liquid medium and from biopolymers, incubated for different times. HC degradation was observed during the whole experiment and resulted higher in respect to the free-living bacterial cultures. Survival tests of bacterial biofilms adsorbed on biopolymers for up to 30 days are in progress.
Conclusions
The synergistic exploitation of the high absorbent capacity of biodegradable nanofiber membranes and the catabolic capacity of HC-degrading bacteria allow to obtain biodegrading biofilms endowed with higher removal capacity of hexadecane in respect to free-living bacterial cultures. The survival and biodegrading performances of the biofilm-carrier systems is maintained after 30 days incubation. A green, low-cost, biodegradable and reusable bioremediation tool is obtained without negative impacts on the environment.
References:
Alessandrello, M. J., Tomás, M. S. J., Raimondo, E. E., Vullo, D. L. and Ferrero, M. A. “Petroleum oil removal by immobilized bacterial cells on polyurethane foam under different temperature conditions”, Marine pollution bulletin, 122(1-2), 156-160 (2017).
Bayat, Z., Hassanshahian, M. and Cappello, S. “Immobilization of microbes for bioremediation of crude oil polluted environments: a mini review”, The open microbiology journal, 9, 48 (2015).
Catania, V., Lopresti, F., Cappello, S., Scaffaro, R. and Quatrini, P. “Innovative, ecofriendly biosorbent-biodegrading biofilms for bioremediation of oil-contaminated water”, New Biotechnology, 58, 25-31 (2020).
Scaffaro, R., Lopresti, F., Catania, V., Santisi, S., Cappello, S., Botta, L. and Quatrini, P. “Polycaprolactone-based scaffold for oil-selective sorption and improvement of bacteria activity for bioremediation of polluted water: Porous PCL system obtained by leaching melt mixed PCL/PEG/NaCl composites: Oil uptake performance and bioremediation efficiency”, European Polymer Journal, 91, 260-273 (2017).
Sonawane, J. M., Rai, A. K., Sharma, M., Tripathi, M. and Prasad, R. “Microbial biofilms: Recent advances and progress in environmental bioremediation”, Science of The Total Environment, 153843 (2022).
Catania, V., Santisi, S., Signa, G., Vizzini, S., Mazzola, A., Cappello, S., ... & Quatrini, P. (2015). Intrinsic bioremediation potential of a chronically polluted marine coastal area. Marine Pollution Bulletin, 99(1-2), 138-149.
Lo Piccolo, L., De Pasquale, C., Fodale, R., Puglia, A. M., & Quatrini, P. (2011). Involvement of an alkane hydroxylase system of Gordonia sp. strain SoCg in degradation of solid n-alkanes. Applied and environmental microbiology, 77(4), 1204-1213.
Quatrini, P., Scaglione, G., De Pasquale, C., Riela, S., & Puglia, A. M. (2008). Isolation of Gram‐positive n‐alkane degraders from a hydrocarbon‐contaminated Mediterranean shoreline. Journal of applied microbiology, 104(1), 251-259
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