Non-fermenting Gram-negative bacteria are problematic in clinical locations, being one of the most prevalent causes of nosocomial infections. Many of these non-fermenting Gram-negative bacteria are ...opportunistic pathogens that affect patients that are suffering with underlying medical conditions and diseases. Brevundimonas spp., in particular Brevundimonas diminuta and Brevundimonas vesicularis, are a genus of non-fermenting Gram-negative bacteria considered of minor clinical importance. Forty-nine separate instances of infection relating to Brevundimonas spp were found in the scientific literature along with two pseudo-infections. The majority of these instances were infection with Brevundimonas vesicularis (thirty-five cases - 71%). The major condition associated with Brevundimonas spp infection was bacteraemia with seventeen individual cases/outbreaks (35%). This review identified forty-nine examples of Brevundimonas spp. infections have been discussed in the literature. These findings indicate that infection review programs should consider investigation of possible Brevundimonas spp outbreaks if these bacteria are clinically isolated in more than one patient.
A range of optical fibre-based sensors for the measurement of ethanol, primarily in aqueous solution, have been developed and are reviewed here. The sensing approaches can be classified into four ...groups according to the measurement techniques used, namely absorption (or absorbance), external interferometric, internal fibre grating and plasmonic sensing. The sensors within these groupings can be compared in terms of their characteristic performance indicators, which include sensitivity, resolution and measurement range. Here, particular attention is paid to the potential application areas of these sensors as ethanol production is globally viewed as an important industrial activity. Potential industrial applications are highlighted in the context of the emergence of the internet of things (IoT), which is driving widespread utilization of these sensors in the commercially significant industrial and medical sectors. The review concludes with a summary of the current status and future prospects of optical fibre ethanol sensors for industrial use.
The Cation Diffusion Facilitators (CDFs) form a family of membrane-bound proteins capable of transporting zinc and other heavy metal ions. Involved in metal tolerance/resistance by efflux of ions, ...CDF proteins share a two-modular architecture consisting of a transmembrane domain (TMD) and C-terminal domain (CTD) that protrudes into the cytoplasm. Discovery of a Zn2+ and Cd2+ CDF transporter from a marine bacterium Maricaulis maris that does not possess the CTD questions current perceptions regarding this family of proteins. This article describes a new, CTD-lacking subfamily of CDFs and our current knowledge about this family of proteins in the view of these findings.
Ochrobactrum species are non-enteric, Gram-negative organisms that are closely related to the genus Brucella. Since the designation of the genus in 1988, several distinct species have now been ...characterised and implicated as opportunistic pathogens in multiple outbreaks. Here, we examine the genus, its members, diagnostic tools used for identification, data from recent Ochrobactrum whole genome sequencing and the pathogenicity associated with reported Ochrobactrum infections. This review identified 128 instances of Ochrobactrum spp. infections that have been discussed in the literature. These findings indicate that infection review programs should consider investigation of possible Ochrobactrum spp. outbreaks if these bacteria are clinically isolated in more than one patient and that Ochrobactrum spp. are more important pathogens than previously thought.
Integrative Conjugative Elements (ICE's) of the SXT/R391 family have largely been detected in clinical or environmental isolates of Gammaproteobacteria, particularly Vibrio and Proteus species. As ...wastewater treatment plants accumulate a large and diverse number of such species, we examined raw water samples taken from a municipal wastewater treatment plant initially using SXT/R391 family integrase gene-specific PCR probes to detect the presence of such elements in a directed approach. A positive amplification occurred over a full year period and a subsequent Restriction Fragment Length Polymorphism (RFLP) analysis revealed a very limited diversity in the treatment plant examined. Samples demonstrating positive amplification were cultured using Vibrio and Proteus selective media and PCR amplification tracking was utilized to monitor SXT/R391-ICE family containing strains. This screening procedure resulted in the isolation and identification of a Proteus mirabilis strain harbouring an ICE. Whole-genome sequencing of this ICE containing strain using Illumina sequencing technology revealed a novel 81 kb element that contained 75 open reading frames on annotation but contained no antibiotic or metal resistance determinants. Comparative genomics revealed the element contained a conserved ICE core with one of the insertions containing a novel bacteriophage defence mechanism. This directed isolation suggests that ICE elements are present in the environment without apparent selective pressure but may contain adaptive functions allowing survival in particular environments such as municipal wastewater which are reservoirs for large bacterial phage populations.
•Heterogenous crosslinking reaction of HA and HA-CNF films using di-isocyanate.•Bacteriostatic properties of HA depend on molecular weight.•In vitro antimicrobial activity of high molecular weight ...HA.
Biofilm-related infections and contamination of biomaterials are major problems in the clinic. These contaminations are frequently caused by Staphylococcus aureus and are a pressing issue for implantable devices, catheters, contact lenses, prostheses, and wound dressings. Strategies to decrease contamination and biofilm related infections are vital for the success of implantable biomaterials. In this context, hyaluronic acid (HA), a naturally derived carbohydrate polymer, known to be biocompatible, degradable, and immunomodulatory, has shown some antimicrobial activity effects. Due to its poor structural stability, crosslinking strategies, and the incorporation of reinforcing fibres in HA gels is required to produce tailored gels for varying applications. Whilst carbon-based reinforcing materials, such as carbon nanofibers (CNF), present some intrinsic antimicrobial activity related to their high surface area, herein, a crosslinking strategy to enhance the mechanical properties and regulate the rate of degradation of HA is presented. We utilise bis-(β-isocyanatoethyl) disulphide (BIED) as the crosslinker with the gel reinforced using 0.25 wt% CNF. The effects of CNF and BIED on the structural, mechanical, thermal, and swelling behaviour are examined. These new HA derivatives exhibit excellent mechanical properties and are capable of withstanding physiological stresses in vivo. Antimicrobial activity of the HA derivatives were tested against Staphylococcus aureus and the results reveal antibacterial effect. These carbohydrate based materials have potential application on surfaces within clinical settings where staphylococcal contamination is currently an issue.
The bacterial community associated with a full scale autothermal thermophilic aerobic digester (ATAD) treating sludge, originating from domestic wastewater and destined for land spread, was analysed ...using a number of molecular approaches optimised specifically for this high temperature environment. 16S rDNA genes were amplified directly from sludge with universally conserved and Bacteria-specific rDNA gene primers and a clone library constructed that corresponded to the late thermophilic stage (t = 23 h) of the ATAD process. Sequence analyses revealed various 16S rDNA gene sequence types reflective of high bacterial community diversity. Members of the bacterial community included α- and β-Proteobacteria, Actinobacteria with High G + C content and Gram-Positive bacteria with a prevalence of the Firmicutes (Low G + C) division (class Clostridia and Bacillus). Most of the ATAD clones showed affiliation with bacterial species previously isolated or detected in other elevated temperature environments, at alkaline pH, or in cellulose rich environments. Several phylotypes associated with Fe(III)- and Mn(IV)-reducing anaerobes were also detected. The presence of anaerobes was of interest in such large scale systems where sub-optimal aeration and mixing is often the norm while the presence of large amounts of capnophiles suggest the possibility of limited convection and entrapment of CO2 within the sludge matrix during digestion. Comparative analysis with organism identified in other ATAD systems revealed significant differences based on optimised techniques. The abundance of thermophilic, alkalophilic and cellulose-degrading phylotypes suggests that these organisms are responsible for maintaining the elevated temperature at the later stages of the ATAD process.
► Phylogeny presented based on optimised niche specific molecular tools. ► ATAD contains large numbers symbionts, capnophiles and anaerobes. ► Alkalophilic cellulolytic phylotypes are keys to stability of elevated temperature. ► Dataset may have utility in bioaugmentation for improvement of ATAD sludge settling. ► Great dissimilarity in microorganisms between worldwide ATAD systems.
A novel long period grating (LPG) inscribed balloon-shaped heterocore-structured plastic optical fibre (POF) sensor is described and experimentally demonstrated for real-time measurement of the ...ultra-low concentrations of ethanol in microalgal bioethanol production applications. The heterocore structure is established by coupling a 250 μm core diameter POF between two 1000 μm diameter POFs, thus representing a large core-small core-large core configuration. Before coupling as a heterocore structure, the sensing region or small core fibre (SCF; i.e., 250 μm POF) is modified by polishing, LPG inscription, and macro bending into a balloon shape to enhance the sensitivity of the sensor. The sensor was characterized for ethanol-water solutions in the ethanol concentration ranges of 20 to 80
, 1 to 10
, 0.1 to 1
, and 0.00633 to 0.0633
demonstrating a maximum sensitivity of 3 × 10
%/RIU, a resolution of 7.9 × 10
RIU, and a limit of detection (LOD) of 9.7 × 10
RIU. The experimental results are included for the intended application of bioethanol production using microalgae. The characterization was performed in the ultra-low-level ethanol concentration range, i.e., 0.00633 to 0.03165
, that is present in real culturing and production conditions, e.g., ethanol-producing blue-green microalgae mixtures. The sensor demonstrated a maximum sensitivity of 210,632.8 %T/
(or 5 × 10
%/RIU as referenced from the RI values of ethanol-water solutions), resolution of 2 × 10
(or 9.4 × 10
RIU), and LOD of 4.9 × 10
(or 2.3 × 10
RIU). Additionally, the response and recovery times of the sensor were investigated in the case of measurement in the air and the ethanol-microalgae mixtures. The experimentally verified, extremely high sensitivity and resolution and very low LOD corresponding to the initial rate of bioethanol production using microalgae of this sensor design, combined with ease of fabrication, low cost, and wide measurement range, makes it a promising candidate to be incorporated into the bioethanol production industry as a real-time sensing solution as well as in other ethanol sensing and/or RI sensing applications.
Integrative Conjugative Elements (ICEs) are mosaics containing functional modules allowing maintenance by site-specific integration and excision into and from the host genome and conjugative transfer ...to a specific host range. Many ICEs encode a range of adaptive functions that aid bacterial survival and evolution in a range of niches. ICEs from the SXT/R391 family are found in γ-Proteobacteria. Over 100 members have undergone epidemiological and molecular characterization allowing insight into their diversity and function. Comparative analysis of SXT/R391 elements from a wide geographic distribution has revealed conservation of key functions, and the accumulation and evolution of adaptive genes. This evolution is associated with gene acquisition in conserved hotspots and variable regions within the SXT/R391 ICEs catalysed via element-encoded recombinases. The elements can carry IS elements and transposons, and a mutagenic DNA polymerase, PolV, which are associated with their evolution. SXT/R391 ICEs isolated from different niches appear to have retained adaptive functions related to that specific niche; phage resistance determinants in ICEs carried by wastewater bacteria, antibiotic resistance determinants in clinical isolates and metal resistance determinants in bacteria recovered from polluted environments/ocean sediments. Many genes found in the element hotspots are undetermined and have few homologs in the nucleotide databases.
We report a U-bend plastic optical fiber (POF) sensor for measuring ultralow concentration of ethanol corresponding to the initial bioethanol production rate by cyanobacteria, i.e., 0.1-0.5 ...gL<inline-formula> <tex-math notation="LaTeX">^{\mathrm {\mathbf {-1}}} </tex-math></inline-formula> day<inline-formula> <tex-math notation="LaTeX">^{\mathrm {\mathbf {-1}}} </tex-math></inline-formula>. This production rate corresponds to 0.00499-0.0499 %wt of ethanol in total solution in terms of weight percent concentration. Refractive indices for these minute ethanol concentration values are not available in the literature hence mathematical estimation of the refractive indices for the ethanol-water solutions in this concentration range is demonstrated. The sensing principle is based on optical fiber-based evanescent wave absorption. Parameters affecting the response of an evanescent wave absorption sensor are analyzed for the intended concentration range of ethanol. Experimental results using the U-bend evanescent wave POF sensor are also presented for ethanol-water solutions having refractive indices corresponding to the bioethanol production rate. The excellent repeatability of the measurement is established and these real-time measurements show that sensor has a sensitivity of 817.76 O.D/RIU (O.D refers to optical density, unit of absorbance) with a 99.76% linearity. The limit of detection of the sensor is <inline-formula> <tex-math notation="LaTeX">9.2\times 10^{\mathrm {\mathbf {-7}}} </tex-math></inline-formula> RIU. It is also proved using refractive index calculations of ethanol-water solutions that the sensor exhibits a resolution of <inline-formula> <tex-math notation="LaTeX">10^{\mathrm {\mathbf {-7}}} </tex-math></inline-formula> RIU. The sensor of this investigation, therefore, represents a potential solution for online and real-time monitoring of the production of biofuels even at the very low-level initial concentration of product.
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