507,245 research outputs found
Applications of Essential Oils as Antibacterial Agents in Minimally Processed Fruits and Vegetables - A Review
Microbial foodborne diseases are a major health concern. In this regard, one of the major
risk factors is related to consumer preferences for “ready-to-eat” or minimally processed (MP) fruits
and vegetables. Essential oil (EO) is a viable alternative used to reduce pathogenic bacteria and
increase the shelf-life of MP foods, due to the health risks associated with food chlorine. Indeed,
there has been increased interest in using EO in fresh produce. However, more information about
EO applications in MP foods is necessary. For instance, although in vitro tests have defined EO
as a valuable antimicrobial agent, its practical use in MP foods can be hampered by unrealistic
concentrations, as most studies focus on growth reductions instead of bactericidal activity, which, in
the case of MP foods, is of utmost importance. The present review focuses on the effects of EO in MP
food pathogens, including the more realistic applications. Overall, due to this type of information,
EO could be better regarded as an added value to the food industryinfo:eu-repo/semantics/publishedVersio
Apparatus and process for microbial detection and enumeration
An apparatus and process for detecting and enumerating specific microorganisms from large volume samples containing small numbers of the microorganisms is presented. The large volume samples are filtered through a membrane filter to concentrate the microorganisms. The filter is positioned between two absorbent pads and previously moistened with a growth medium for the microorganisms. A pair of electrodes are disposed against the filter and the pad electrode filter assembly is retained within a petri dish by retainer ring. The cover is positioned on base of petri dish and sealed at the edges by a parafilm seal prior to being electrically connected via connectors to a strip chart recorder for detecting and enumerating the microorganisms collected on filter
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Optimised production and extraction of astaxanthin from the yeast Xanthophyllomyces dendrorhous
Currently, astaxanthin demand is fulfilled by chemical synthesis using petroleum-based feedstocks. As such, alternative pathways of natural astaxanthin production attracts much research interest. This study aimed at optimising bioreactor operation parameters for astaxanthin production and evaluated strategies for its subsequent extraction. The effect of pH and agitation were evident as significant reduction in both biomass and astaxanthin production was observed when the culture pH was not controlled, and low agitation speed was applied. At controlled pH condition and high agitation speed, significant increase in biomass (16.4 g/l) and astaxanthin production (3.6 mg/l) were obtained. Enzymatic yeast cell lysis using two commercial enzymes (Accellerase 1500 and Glucanex) was optimised using central composite design of experiment (DoE). Accellerase 1500 led to mild cell disruption and only 9% (w/w) of astaxanthin extraction. However, glucanex treatment resulted in complete astaxanthin extractability, compared to standard extraction method (DMSO/acetone). When supercritical CO2 was employed as an extraction solvent in accellerace pre-treated Xanthophyllomyces dendrorhous cells, astaxanthin extraction increased 2.5-fold. Overall, the study showed that extraction conditions can be tailored towards targeted pigments present in complex mixtures, such as in microbial cells
A culture collection of Maltese microorganisms for application in biotechnology, biomedicine and industry
Over the years, very few studies have been conducted
on microorganisms growing in the Maltese islands, and
these have rarely resulted in the description of new gen-
era, species or serovars. Two important exceptions are
the studies on Brucella melitensis, by Sir Temi Zammit
in 1905 (Wyatt, 2005) and a new serovar of Salmonella
from Gozo (Vella & Cuschieri, 1995).
Ten years ago, sampling of microorganisms growing
as bio lms on di erent substrates around the Maltese
islands was initiated. The microorganisms consisted
mainly of chemoorganotrophic bacteria, cyanobacteria
and microalgae. Today the culture collection of Maltese
microorganisms contains over a hundred new microbial
strains that are new to science and which include fresh-
water, marine, soil and subaerophytic microorganisms.
The aim of the research is twofold. Firstly, it is im-
portant to characterise the Maltese microbial strains
and describe new taxa as required. Secondly, the ex-
traction of important metabolites for application in bi-
otechnology, biomedicine and industrypeer-reviewe
Biogasification of soma lignite by microorganisms
The main scopes of this study are to analyze the bacterial activity on the coal samples which come from Soma basin in Turkey and investigation of the bacterial gas production of these samples. For that purpose, characterization of the coal samples was performed by using FTIR, STA, BET, SAM and ICP
Chemosensing in microorganisms to practical biosensors
Microorganisms like bacteria can sense concentration of chemo-attractants in
its medium very accurately. They achieve this through interaction between the
receptors on their cell surface and the chemo-attractant molecules (like
sugar). But the physical processes like diffusion set some limits on the
accuracy of detection which was discussed by Berg and Purcell in the late
seventies. We have a re-look at their work in order to assess what insight it
may offer towards making efficient, practical biosensors. We model the
functioning of a typical biosensor as a reaction-diffusion process in a
confined geometry. Using available data first we characterize the system by
estimating the kinetic constants for the binding/unbinding reactions between
the chemo-attractants and the receptors. Then we compute the binding flux for
this system which Berg and Purcell had discussed. But unlike in microorganisms
where the interval between successive measurements determines the efficiency of
the nutrient searching process, it turns out that biosensors depend on long
time properties like signal saturation time which we study in detail. We also
develop a mean field description of the kinetics of the system.Comment: 6 pages, 7 figure
Hydrodynamic phase-locking of swimming microorganisms
Some microorganisms, such as spermatozoa, synchronize their flagella when
swimming in close proximity. Using a simplified model (two infinite, parallel,
two-dimensional waving sheets), we show that phase-locking arises from
hydrodynamics forces alone, and has its origin in the front-back asymmetry of
the geometry of their flagellar waveform. The time-evolution of the phase
difference between co-swimming cells depends only on the nature of this
geometrical asymmetry, and microorganisms can phase-lock into conformations
which minimize or maximize energy dissipation
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