Surface colour: An overlooked aspect in the study of cyanobacterial biofilm formation.

Cyanobacteria can grow as biofilms, communities that colonize surfaces and that play a fundamental role in the ecology of many diverse habitats and in the conversion of industrial production to green platforms. Although biofilm growth is known to be significantly affected by several characteristics, the effect of colour surface is an overlooked aspect that has not yet been investigated. In this study, we describe the effect of colour hues (white, red, blue and black) on the growth of cyanobacterial biofilms on air-exposed substrates. We measured growth, architecture, pigment production and levels of ATP and reactive oxygen species in cyanobacterial biofilms formed on different coloured substrates. The study findings demonstrate, for the first time, that the colour of a surface affects biofilm formation at the air-solid interface (with more biomass accumulating on white and red substrates than on blue and black substrates) and also alters the biofilm architecture. In addition, the roles of chromatic adaptation, phototrophic cells and reactive oxygen species as intermediates between colour sensing and biofilm response are discussed. Our results support the importance of colour as a new factor that favours surface colonization by cyanobacteria and its contribution to biofilm formation.

Effects of a vinegar-based multi-micronutrient supplement in rats: a multi-pronged assessment of dietary impact.

We determined the effects of continuous access to drinking of water with a vinegar-based multi-micronutrient (VMm) supplement containing rice and fruit vinegars, vitamins, organic acids and sugars during gestation, lactation, and early adulthood in rats. Pregnant rats were provided with reverse-osmosis water or VMm water from the start of pregnancy through the time of weaning. Weaned pups consumed the same drinking water for 3-12 additional weeks. We examined fecal metabolite and microbial profiles, and other physiological parameters. Body weights were less in rats that drank VMm water. Thirty fecal metabolites involved in amino acid and dipeptide metabolism were significantly altered in VMm-supplemented rats. Analysis of microbial 16S rRNA showed enrichment of bacteria in the family S24-7 in VMm-supplemented rats, and one in Ruminococcaceae in controls. Our data show that a VMm-containing beverage can alter growth, and gut metabolism and microbial community. Future work to correlate these parameters is warranted.

Steady-State Oxygen Isotope Effects of N2O Production in Paracoccus denitrificans.

Knowledge of isotopic discrimination, or fractionation, by denitrifying bacteria can benefit agricultural fertilizer management, wastewater treatment, and other applications. However, the complexity of N transformation pathways in the environment and the sensitivity of denitrification to environmental conditions warrant better isotopic distinction between denitrification and other processes, especially for oxygen isotopes. Here, we present a dataset of δ18O measurements in continuous culture of Paracoccus denitrificans. The authors hope that it will be useful in further studies of N2O in the environment.

Primary care knowledge and beliefs about physical activity and health: a survey of primary healthcare team members.

BACKGROUND: Physical activity has numerous health benefits and the primary healthcare team are ideally suited to promote activity. The Royal College of General Practitioners (RCGP) has announced physical activity to be a clinical priority in the next few years. However little attention is given to this in medical training, with unclear levels of knowledge and confidence. AIM: To explore the primary healthcare team knowledge of the benefits of physical activity in preventing and treating ill health. DESIGN & SETTING: Questionnaire-based study, from six East Midlands sites in the UK. METHOD: Self-completed anonymised questionnaire. RESULTS: Three hundred and two results were obtained in total, from 166 GPs, 65 GP registrars, and 71 practice nurses. There was a mean age of 44.8 years (range 22-71), with 62% female responders. Fifty-five per cent of responders underestimated UK recommended activity guidance. Responders considered activity promotion as part of their professional role, but this was discussed about one-third as often as other health promotion behaviours, such as weight or smoking. Barriers reported were lack of time (91.2%) and resources (36.8%). CONCLUSION: This study has shown reasonable knowledge of recommended levels of activity and accrued health, but most underestimated UK guidance, suggest inadequate levels of activity for optimal health may be being recommended. Confidence in this area is lower in GP registrars than GPs which may mirror other health problems. There was a poor recognition of simple tools to assess the level of physical activity, and low levels of onward signposting or recommendations. If physical activity is to be a clinical priority area of the RCGP, then further opportunities for professional development may be required.

Inactivation of foodborne microorganisms using engineered water nanostructures (EWNS).

Foodborne diseases caused by the consumption of food contaminated with pathogenic microorganisms or their toxins have very serious economic and public health consequences. Here, we explored the effectiveness of a recently developed intervention method for inactivation of microorganisms on fresh produce, and food production surfaces. This method utilizes Engineered Water Nanostructures (EWNS) produced by electrospraying of water vapor. EWNS possess unique properties; they are 25 nm in diameter, remain airborne in indoor conditions for hours, contain Reactive Oxygen Species (ROS) and have very strong surface charge (on average 10 e/structure). Here, their efficacy in inactivating representative foodborne bacteria such as Escherichia coli, Salmonella enterica, and Listeria innocua, on stainless steel surfaces and on organic tomatoes, was assessed. The inactivation was facilitated using two different exposure approaches in order to optimize the delivery of EWNS to bacteria: (1) EWNS were delivered on the surfaces by diffusion and (2) a "draw through" Electrostatic Precipitator Exposure System (EPES) was developed and characterized for EWNS delivery to surfaces. Using the diffusion approach and an EWNS concentration of 24,000 #/cm3, the bacterial concentrations on the surfaces were reduced, depending on the bacterium and the surface type, by values ranging between 0.7 to 1.8 logs. Using the EPES approach and for an aerosol concentration of 50,000 #/cm3 at 90 min of exposure, results show a 1.4 log reduction for E. coli on organic tomato surfaces, as compared to the control (same conditions in regards to temperature and Relative Humidity). Furthermore, for L. innocua, the dose-response relationship was demonstrated and found to be a 0.7 and 1.2 logs removal at 12,000 and 23,000 #/cm3, respectively. The results presented here indicate that this novel, chemical-free, and environmentally friendly intervention method holds potential for development and application in the food industry, as a "green" alternative to existing disinfection methods.

Pyomelanin production in Penicillium chrysogenum is stimulated by L-tyrosine.

From a tomb in Upper Egypt we isolated a strain of Penicillium chrysogenum that was capable of producing brown pigment in vitro when grown in a minimal salts medium containing tyrosine. We present evidence that this pigment is a pyomelanin, a compound that is known to assist in the survival of some micro-organisms in adverse environments. We tested type strains of Pe. chrysogenum, which were also able to produce this pigment under similar conditions. Inhibitors of the DHN and DOPA melanin pathways were unable to inhibit the formation of the pigment. Fourier transform IR analysis indicated that this brown pigment is similar to pyomelanin. Pyrolysis-GC/MS revealed the presence of phenolic compounds. Using LC/MS, homogentisic acid, the monomeric precursor of pyomelanin, was detected in supernatants of Pe. chrysogenum cultures growing in tyrosine medium but not in cultures lacking tyrosine. Partial regions of the genes encoding two enzymes in the homogentisic acid pathway of tyrosine degradation were amplified. Data from reverse-transcription PCR demonstrated that hmgA transcription was increased in cultures grown in tyrosine medium, suggesting that tyrosine induced the transcription.

Fluorometric detection and estimation of fungal biomass on cultural heritage materials.

A wide variety of cultural heritage materials are susceptible to fungal deterioration. The paper, canvas, and stone constituents of our cultural heritage are subjected to harmful physical and chemical processes as they are slowly consumed by fungi. Remediation of fungal contamination can be costly and risk further damage to cultural artifacts. Early detection of fungal growth would permit the use of relatively noninvasive treatments to remediate fungal contamination before visible or lasting damage to the object has occurred. Current methods used for the detection and measurement of microbial biomass, such as colony counts, microscopic biovolume estimation, and ergosterol analysis are expensive and time consuming, or are inappropriate for use with fungi. Beta-N-acetylhexosaminidase (3.2.1.52) activity provides a reliable estimation of fungal biomass in soil and on building materials. Adapted for use on cultural heritage materials' fluorogenic 4-methylumbelliferyl (MUF) labeled substrate N-acetyl-beta-d-glucosaminide (NAG) was used to detect beta-N-acetylhexosaminidase activity in the fungus Aspergillus niger. Fluorescence increased linearly with fungal biomass and the sensitivity of the assay was comparable to other biochemical techniques. The fluorometric assay was used to monitor fungal biomass on a variety of cultural heritage materials non-destructively, and without the introduction of chemicals or solvents to the surfaces.

Epilithic and endolithic bacterial communities in limestone from a Maya archaeological site.

Biodeterioration of archaeological sites and historic buildings is a major concern for conservators, archaeologists, and scientists involved in preservation of the world's cultural heritage. The Maya archaeological sites in southern Mexico, some of the most important cultural artifacts in the Western Hemisphere, are constructed of limestone. High temperature and humidity have resulted in substantial microbial growth on stone surfaces at many of the sites. Despite the porous nature of limestone and the common occurrence of endolithic microorganisms in many habitats, little is known about the microbial flora living inside the stone. We found a large endolithic bacterial community in limestone from the interior of the Maya archaeological site Ek' Balam. Analysis of 16S rDNA clones demonstrated disparate communities (endolithic: >80% Actinobacteria, Acidobacteria, and Low GC Firmicutes; epilithic: >50% Proteobacteria). The presence of differing epilithic and endolithic bacterial communities may be a significant factor for conservation of stone cultural heritage materials and quantitative prediction of carbonate weathering.

Binding of harvested bacterial exopolymers to the surface of calcite.

Biologically produced exopolysaccharides (EPS) affect calcite dissolution and precipitation. In this study, natural alkaliphilic microbial isolates were collected from biofilms on historic limestone. The isolates were screened for their ability to produce significant quantities of EPS in cultures. The most productive isolates were identified by 16S rRNA sequence analysis as a close relative of Bacillus cereus. EPS with different chemical structures were harvested from the isolates. Isothermal titration calorimetry (ITC) was used to quantify the thermodynamics of binding by the harvested EPS to calcite. The binding was described by a Langmuir adsorption isotherm. Characterization of the EPS showed that binding strength to calcite depended on the chemical nature of the polymer.

Chelating ligand alters the microscopic mechanism of mineral dissolution.

Ethylenediamine tetraacetate (EDTA)-mediated calcite dissolution occurs via a different process than water-promoted dissolution. Near-atomic-scale observations in EDTA solutions demonstrate that, after penetration through a critical pit depth barrier, step velocity increases linearly with pit depth for EDTA-promoted dissolution. The parallel processes of water-dominated dissolution at point defects and ligand-dominated dissolution at linear defects are clearly observable in real-time atomic force micrographs. EDTA and water initiate and propagate dissolution steps with pit-depth-dependent and -independent step velocities, respectively. The linear defects are susceptible to continuously increasing step velocities, but the point defects are not. The findings update the conceptual framework of the microscopic mechanism of mineral dissolution.

Corrosion of aluminum alloy 2024 by microorganisms isolated from aircraft fuel tanks.

Microorganisms frequently contaminate jet fuel and cause corrosion of fuel tank metals. In the past, jet fuel contaminants included a diverse group of bacteria and fungi. The most common contaminant was the fungus Hormoconis resinae. However, the jet fuel community has been altered by changes in the composition of the fuel and is now dominated by bacterial contaminants. The purpose of this research was to determine the composition of the microbial community found in fuel tanks containing jet propellant-8 (JP-8) and to determine the potential of this community to cause corrosion of aluminum alloy 2024 (AA2024). Isolates cultured from fuel tanks containing JP-8 were closely related to the genus Bacillus and the fungi Aureobasidium and Penicillium. Biocidal activity of the fuel system icing inhibitor diethylene glycol monomethyl ether is the most likely cause of the prevalence of endospore forming bacteria. Electrochemical impedance spectroscopy and metallographic analysis of AA2024 exposed to the fuel tank environment indicated that the isolates caused corrosion of AA2024. Despite the limited taxonomic diversity of microorganisms recovered from jet fuel, the community has the potential to corrode fuel tanks.

Effects of the biologically produced polymer alginic acid on macroscopic and microscopic calcite dissolution rates.

Dissolution of carbonate minerals has significant environmental effects. Microorganisms affect carbonate dissolution rates by producing extracellular metabolites, including complex polysaccharides such as alginic acid. Using a combined atomic force microscopy (AFM)/flowthrough reactor apparatus, we investigated the effects of alginic acid on calcite dissolution. Macroscopic dissolution rates, derived from the aqueous metal ion concentrations, are 10(-5.5) mol m(-2) s(-1) for 5 < pH < 12 in the absence of alginic acid compared to 10(-4.8) mol m(-2) s(-1) in its presence. The AFM images demonstrate that alginic acid preferentially attacks the obtuse steps of dissolution pits on the calcite surface. In pure water, the obtuse and acute steps retreat at similar rates, and the pits are nearly isotropic except under highly acidic conditions. In alginic acid, the acute step retreat rate is nearly unchanged in comparison to water, whereas the obtuse step retreat rate increases with decreasing pH values. As a result, the pits remain rhombohedral but propagate faster in the obtuse direction. To explain these observations, we propose that alginic acid preferentially forms dissolution active surface complexes with calcium atoms on the obtuse step, which results in anisotropic ligand-promoted dissolution.