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Caratterizzazione fenotipica di mutanti di Trametes trogii a ridotta attività endoglucanasica
No full textMessa a punto di una tecnica di diagnosi per discriminare le alterazioni litiche di origine biotica ed abiotica attraverso l'analisi frattale
No full textBiogenicity and characterization of moonmilk in the Grotta Nera (Majella National Park, Abruzzi, Central Italy)
No full textAbstract: Observations and hypotheses on the possible influence of unidentified
calcifying bacteria on moonmilk speleothem formation in the Grotta Nera are reported
for the first time. The Majella Massif hosts a complex karst system of several caves; the
accessible Grotta Nera is the most interesting one. Despite its name, the cave is
characterized by particularly abundant ivory-white deposits of moonmilk. Two samples
of moonmilk were analyzed to determine the geochemistry, fabric, depositional setting,
and extent of biogenicity. For this, we combined geochemical, scanning electron
microscopic, microbiological, and in vitro precipitation studies. X-ray diffraction of the
moonmilk deposits gave clear evidence for the presence of calcite. Scanning electron
microscopy showed that moonmilk in the Grotta Nera consists of a network of calcite
fibers oriented in all directions, resembling a felted mat. The cultivation on specific
medium of moonmilk and drip-water samples showed the presence of fungi,
actinomycetes, and other bacteria, but the dominant cultivable microorganisms were
bacteria, which produced significant crystallization. Examination of Gram-stained
smears taken from the fifteen different colony types showed that the majority (66.7%) of
the bacterial isolates were Gram-negative. Single small rods and rod chains were the most
common bacteria isolated from the Grotta Nera. None of the molds isolated from the
Grotta Nera samples were able to precipitate CaCO3 crystals, suggesting a major
bacterial contribution to moonmilk deposition in the cave. Bacteria were capable of
precipitating CaCO3 on B-4 solid medium at 15 (cave temperature), 22, and 32 uC. The
calcifying bacteria isolated from the Grotta Nera showed a greater capability to
solubilize CaCO3 than those associated with consolidated stalactites sampled from
previously studied caves. The electron microscopy and microbiological evidences,
together with the geochemistry and environmental data, allowed us to postulate the biogenic nature of the moonmilk in the Grotta Ner
Isolamento di matrici organiche da batteri calcificanti finalizzato al biorecupero di beni culturali
No full textA biosensor for Escherichia coli based on a potentiometric alternating biosensing (PAB) transducer
No full textIn the present paper, we describe a biosensor for the detection of bacterial contamination in drinking water based on an immunoassay test.
The biological component was made by a rabbit polyclonal antibody obtained utilising an environmental strain of Escherichia coli, DH5a.
This strain, showed a capsular protein pattern typical of this species. Cells present in water samples were detected by a complete
potentiometric alternating biosensor (PAB). The PAB system consists of a measuring chamber, acquisition and driving electronics and the
appropriate software: the apparatus is computer controlled in order to obtain on-line acquisitions and recording of data. The transducer
principle is based on a light addressable potentiometric sensor (LAPS) technology which, in our case, reveals the production of NH3 by a
urease–E. coli antibody conjugate. The proposed system appears to be very sensitive and fast, in comparison with conventional methods:
concentrations of 10 cells per ml were detected in an assay time of ca. 1.5 h. No signals were detected from other potential water polluting
bacteria, such as Pseudomonas marina and Sphaerotilus natans and also from bacteria such as Klebsiella oxytoca phyletically related to
E. coli. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Biosensor; E. coli; Water pollution; Light addressable potentiometric sensor (LAPS); Immunoassa
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