1,721,114 research outputs found
Biotechnological advances in the synthesis of modified chondroitin towards novel biomedical applications
No full textChondroitin sulfate (CS) is a well-known glycosaminoglycan present in a large variety of animal tissues, with an outstanding structural heterogeneity mainly related to molecular weight and sulfation pattern. Recently, few microorganisms, eventually engineered, proved able to synthesize the CS biopolymer backbone, composed of D- glucuronic acid and N-acetyl-D-galactosamine linked through alternating & beta;-(1-3)-and & beta;-(1-4)-glycosidic bonds, and secrete the biopolymers generally unsulfated and possibly decorated with other carbohydrates/molecules. Enzyme catalyzed/assisted methods and chemical tailored protocols allowed to obtain a variety of macromol-ecules not only resembling the natural extractive ones, but even enlarging the access to unnatural structural features. These macromolecules have been investigated for their bioactivity in vitro and in vivo establishing their potentialities in an array of novel applications in the biomedical field. This review aims to present an overview of the advancements in: i) the metabolic engineering strategies and the biotechnological processes towards chon-droitin manufacturing; ii) the chemical approaches applied to obtain specific structural features and targeted decoration of the chondroitin backbone; iii) the biochemical and biological properties of the diverse biotechnological-sourced chondroitin polysaccharides reported so far, unraveling novel fields of applications
Production of Succinic Acid From Basfia succiniciproducens
Full text linkBasfia succiniciproducens is a facultative anaerobic capnophilic bacterium, isolated
from rumen, that naturally produces high amounts of succinic acid by fixing CO2 and
using fumarate as final electron acceptor. This metabolic feature makes it one of the
ideal candidates for developing biotechnological industrial routes that could
eventually replace the polluting and environment unfriendly petrochemical ones
that are still main sources for the production of this value-added compound. In
fact, due to the large number of applications of succinic acid that range from the more
traditional ones as food additive or pharmaceutical intermediate to the most recent as
building block for biopolymers and bioplastic, increasing demand and market size growth
are expected in the next years. In line with a “green revolution” needed to preserve our
environment, the great challenge is the establishment of commercially viable production
processes that exploit renewable materials and in particular preferably non-food
lignocellulosic biomasses and waste products. In this review, we describe the currently
available literature concerning B. succiniciproducens since the strain was first isolated,
focusing on the different renewable materials and fermentation strategies used to improve
succinic acid production titers to date. Moreover, an insight into the metabolic engineering
approaches and the key physiological characteristics of B. succiniciproducens deduced
from the different studies are presented
IMMAGINI AD ALTA RISOLUZIONE PER LA GOVERNANCE AMBIENTALE NELLA ZONA TAMPONE DELLA RISERVA DI BIOSFERA TRANSFRONTALIERA “W”, AFRICA
No full textMicrobial polysaccharides: optimisation of production exploiting novel fermentation strategies. 83, Abstract book of
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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
Microbioreactor (micro-Matrix) potential in aerobic and anaerobic conditions with different industrially relevant microbial strains
Full text linkMicroscale fermentation systems are important high throughput tools in clone selection, and bioprocess set up and optimization, since they provide several parallel experiments in controlled conditions of pH, temperature, agitation, and gas flow rate. In this work we evaluated the performance of biotechnologically relevant strains with different respiratory requirements in the micro-Matrix microbioreactor. In particular Escherichia coli K4 requires well aerated fermentation conditions to improve its native production of chondroitin-like capsular polysaccharide, a biomedically attractive polymer. Results from batch and fed-batch experiments demonstrated high reproducibility with those obtained on 2 L reactors, although highlighting a pronounced volume loss for longer-term experiments. Basfia succiniciproducens and Actinobacillus succinogenes need CO2 addition for the production of succinic acid, a building block with several industrial applications. Different CO2 supply modes were tested for the two strains in 24 h batch experiments and results well compared with those obtained on lab-scale bioreactors. Overall, it was demonstrated that the micro-Matrix is a useful scale-down tool that is suitable for growing metabolically different strains in simple batch process, however, a series of issues should still be addressed in order to fully exploit its potential
Modeling and measurements of rainfall by ground-based multispectral microwave radiometry
No full textAbstract—The potential of ground-based multispectral microwave
radiometers in retrieving rainfall parameters is investigated
by coupling physically oriented models and retrieval methods
with a large set of experimental data. Measured data come from
rain events that occurred in the USA at Boulder, Colorado, and
at the Atmospheric Radiation Measurement (ARM) Program’s
Southern Great Plains (SGP) site in Lamont, OK. Rain cloud
models are specified to characterize both nonraining clouds,
stratiform and convective rainfall. Brightness temperature numerical
simulations are performed for a set of frequencies from
20 to 60 GHz at zenith angle, representing the channels currently
deployed on a commercially available ground-based radiometric
system. Results are illustrated in terms of comparisons between
measurements and model data in order to show that the observed
radiometric signatures can be attributed to rainfall scattering
and absorption. A new statistical inversion algorithm, trained by
synthetic data and based on principal component analysis is also
developed to classify the meteorological background, to identify the
rain regime, and to retrieve rain rate from passive radiometric observations.
Rain rate estimate comparisons with simultaneous rain
gauge data and rain effect mitigation methods are also discussed
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