The Production of Aquatic Fluorescent Organic Matter in a Simulated Freshwater Laboratory Model.

Dissolved organic matter (DOM) is ubiquitous throughout aquatic systems. Fluorescence techniques can be used to characterize the fluorescing proportion of DOM, aquatic fluorescent organic matter (AFOM). AFOM is conventionally named in association with specific fluorescence "peaks," which fluoresce in similar optical regions as microbially-derived proteinaceous material (Peak T), and terrestrially-derived humic-like compounds (Peaks C/C+), with Peak T previously being investigated as a tool for bacterial enumeration within freshwaters.

Real-time detection of volatile metabolites enabling species-level discrimination of bacterial biofilms associated with wound infection.

Aims: The main aim of this study was to investigate the real-time detection of volatile metabolites for the species-level discrimination of pathogens associated with clinically relevant wound infection, when grown in a collagen wound biofilm model.

Methods And Results: This work shows that Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes produce a multitude of volatile compounds when grown as biofilms in a collagen-based biofilm model. The real-time detection of these complex volatile profiles using selected ion flow tube mass spectrometry and the use of multivariate statistical analysis on the resulting data can be used to successfully differentiate between the pathogens studied.

Laboratory In-Situ Production of Autochthonous and Allochthonous Fluorescent Organic Matter by Freshwater Bacteria.

This work investigates the origin and range of fluorescent organic matter (FOM) produced in-situ by environmentally sourced freshwater bacteria. Aquatic FOM is an essential component in global carbon cycling and is generally classified as either autochthonous, produced in-situ via microbial processes, or allochthonous, transported into aquatic systems from external sources. We have demonstrated that, within laboratory model systems, environmentally sourced mixed microbial communities and bacterial isolates can produce and/or export FOM associated with both autochthonous and allochthonous material.

An in vitro collagen perfusion wound biofilm model; with applications for antimicrobial studies and microbial metabolomics.

Background: The majority of in vitro studies of medically relevant biofilms involve the development of biofilm on an inanimate solid surface. However, infection in vivo consists of biofilm growth on, or suspended within, the semi-solid matrix of the tissue, whereby current models do not effectively simulate the nature of the in vivo environment. This paper describes development of an in vitro method for culturing wound associated microorganisms in a system that combines a semi-solid collagen gel matrix with continuous flow of simulated wound fluid.

Microbial volatile compounds in health and disease conditions.

Microbial cultures and/or microbial associated diseases often have a characteristic smell. Volatile organic compounds (VOCs) are produced by all microorganisms as part of their normal metabolism. The types and classes of VOC produced is wide, including fatty acids and their derivatives (e.

Application of bacterial bioluminescence to assess the efficacy of fast-acting biocides.

Traditional microbiological techniques are used to provide reliable data on the rate and extent of kill for a range of biocides. However, such techniques provide very limited data regarding the initial rate of kill of fast-acting biocides over very short time domains. This study describes the application of a recombinant strain of Escherichia coli expressing the Photorhabdus luminescens lux operon as a whole-cell biosensor.

Multivariate analysis of bacterial volatile compound profiles for discrimination between selected species and strains in vitro.

Volatile compounds (VCs) are produced by all microorganisms as part of their normal metabolism. The aim of this study was to determine whether bacterial VC profiles could be used to discriminate between selected bacterial species and strains in vitro. Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) was used to quantify the concentration of 23 microbial VCs within the head-space of various bacterial monocultures, during both the logarithmic and stationary growth phases.

In vitro diffusion bed, 3-day repeat challenge 'capacity' test for antimicrobial wound dressings.

The aim of this study was to develop an in vitro wound infection model that allows the comparison of the bacterial kill rate of antimicrobial wound dressings over the course of 3 days, with renewed microbial challenges each day, under realistic wound-like conditions. A test bed model of a moderately exuding wound was constructed from a hydrogel containing releasable foetal calf serum (FCS), and cellulose discs dosed with test microbes (Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa) suspended in 50% FCS applied at the interface between the test dressing and the hydrogel test bed. Freshly prepared discs were used to challenge the same dressing over a 23-hour period for a course of 3 days.