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

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

How do microorganisms reach the stratosphere?

A number of studies have demonstrated that bacteria and fungi are present in the stratosphere. Since the tropopause is generally regarded as a barrier to the upward movement of particles it is difficult to see how such microorganisms can reach heights above 17 km. Volcanoes provide an obvious means by which this could be achieved, but these occur infrequently and any microorganisms entering the stratosphere from this source will rapidly fall out of the stratosphere. Here, we suggest mechanisms by which microorganisms might reach the stratosphere on a more regular basis; such mechanisms are, however, likely only to explain how micrometre to submicrometre particles could be elevated into the stratosphere. Intriguingly, clumps of bacteria of size in excess of 10 μm have been found in stratospheric samples. It is difficult to understand how such clumps could be ejected from the Earth to this height, suggesting that such bacterial masses may be incoming to Earth. We suggest that the stratospheric microflora is made up of two components: (a) a mixed population of bacteria and fungi derived from Earth, which can occasionally be cultured; and (b) a population made up of clumps of, viable but non-culturable, bacteria which are too large to have originated from Earth; these, we suggest, have arrived in the stratosphere from space. Finally, we speculate on the possibility that the transfer of bacteria from the Earth to the highly mutagenic stratosphere may have played a role in bacterial evolution