Plastics and microplastics are attracting increasing public attention due to their wide occurrence in the environment and accumulation in plants, wildlife and humans. In addition to the vast quantity of packaging plastics discharged into the municipal waste stream, an increasing volume of industrial polymeric materials from the electronics industry, space and aviation is also accumulating in the environment. This latter group of materials has received far less attention than it deserves, including toxicological studies. The goals of engineers and materials scientists are to create materials with high durability and exceptional performance, but these are properties that prevent degradation occurring, at least within the designed life span. The public perception is that production of degradable and biodegradable plastics can reduce the negative environmental impacts from these materials. However, another feasible option is to enhance the non-degradability of these functional polymers and hence extend their life span to reduce wastes from their application. Microbial colonization and deterioration of these materials seriously affects their design properties. The most significant challenge is on the fate of industrially produced, mechanically strong, and chemically inert plastics and polymeric materials after disposal at the end of their service life. Biodegradation is the specific focus of this review, and we will discuss the current knowledge and key research questions that remain to be answered.

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.

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.

Biodeterioration of cultural heritage artifacts due to microbial activity presents a significant challenge to conservators and museums around the World. A collection of Chinchorro mummies recovered from the Atacama Desert (the oldest artificial mummies ever found, dating back to 5050 B.C.E.) has been stored in the Universidad de Tarapacá, northern Chile. Over the past ten years, accelerated deterioration of some mummies has been documented. Blackening and exudation of some areas of their remaining skin is causing disfigurement of the mummies and poses a threat to the collection, also for mummies in situ exposed to the natural environment. This study was designed to provide a broad analysis of the skin microbiota of Chinchorro mummies and, investigate the relationship between the presence of microbes and the recent discoloration and biodegradation of the Chinchorro mummies’ skin. Microorganisms isolated from degraded Chinchorro mummy skin samples were similar, based on ribosomal RNA analysis, to bacteria found in the human skin microbiome (predominantly, Bacillus, Staphylococcus, and Methylococcus spp.) and commonly occurring fungi (predominantly, Penicillium and Aspergillus spp.). Some of these microorganisms were able to utilize collagen and/or keratin as the sole carbon source in vitro. We determined the activity of the collagenase/gelatinase enzymes produced by these microorganisms when grown on pig skin, which was used as a surrogate for human skin. The concentration of hydroxyproline, a measure of collagenous protein degradation by the microorganisms, increased with increasing relative humidity. We demonstrated that keratinolytic and collagenolytic opportunistic microorganisms were likely responsible for the recent degradation phenomenon.

Microorganisms found on graffiti and associated environments are potential candidates for biological removal of undesirable graffiti on cultural heritage structures and materials. A feasibility study involving the isolation of natural strains of microorganisms that are capable of degrading graffiti as possible candidates for use in biocleaning treatments for heritage monuments was carried out. A total of 54 different strains were obtained from various sources, recent and old graffiti, the bodywork of a car in a scrapyard and the soil beneath it, an acrylic wall painting and the interior of spray paint cans. The strains were isolated under aerobic conditions and subjected to preliminary laboratory tests to determine their potential as bioremediation agents; i.e., their ability to remove and degrade samples of paint on glass microscope slides. Only those showing such potential were further characterized by sequencing of 16S rDNA and ITS regions. Sequence results identified the isolated strains as bacteria belonging to the genera Arthrobacter, Bacillus, Gordonia, Microbacterium, Pantoea and Pseudomonas and fungi belonging to the genus Alternaria. These findings suggest that existing graffiti surfaces are a good source for putative biodegradative microbial populations, which may aid in the remediation of damaged surfaces.

Outdoor stoneworks sustain biofilm formation and are constantly at risk of deterioration by micro-organisms. In this study, the biofilm microflora of historic limestone tombstones located in a highly polluted urban environment (Cambridge, MA) and in a less polluted location (Lexington, MA) were compared using comprehensive RNA-based molecular analyses of 16S rRNA gene sequences as well as sequences of genes for different pathways of sulphur metabolism (soxB, apsA, dsrA). The metabolically active micro-organisms detected by denaturing gradient gel electrophoresis analysis of 16S rRNA fragments were predominantly represented by cyanobacteria (belonging to the family Nostocaceae and to the genus Chroococcidiopsis) in both polluted and unpolluted environments. The investigation of soxB, apsA, dsrA transcripts reflected the abundance and the diversity of sulphur-oxidizing and sulphate-reducing bacteria in the Cambridge samples in comparison with the Lexington samples. The investigation revealed that in addition to phototrophic sulphur bacteria belonging to the genera Thiocapsa, Halochromatium, Allochromatium, Thiococcus and Thermochromatium, other sulphate-oxidizing prokaryotes (e.g. the genus Thiobacillus) as well as sequences of Deltaproteobacteria from the genus Desulfovibrio occurred at the polluted urban site. The interactions between the main functional groups retrieved from the limestone tombstones were discussed.Significance and Impact of the StudyThe biofilm microflora inhabiting historic limestones are a multi-component open ecosystem sensitively reacting to all environmental factors including air pollutants. Little is known about specific target groups that are active in the biofilm and their physiological functions. For the first time, transcripts involved in important energy-yielding processes were investigated to reveal the metabolic capabilities of the microflora in response to atmospheric sulphur pollution. This work provides novel and important information about the ecology of limestone tombstone microbiota and its complex interaction with the external environment.

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 10e/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 #/cm(3), 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 #/cm(3) 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 #/cm(3), 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.

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.

Hemp-lime concrete is a sustainable and carbon negative construction material. This paper investigates the effect of binder type on mechanical strength and durability (resistance to freeze–thaw, salt exposure and biodeterioration). It compares hemp-lime concretes made with a hydrated lime and pozzolan binder to those including hydraulic lime and cement. SEM analysis revealed abundant hydrates at the hemp interface of the strongly hydraulic commercial binder while the lime:pozzolan binders were mostly carbonated. Increasing binder hydraulicity enhances early strength development however, all concretes achieved similar compressive strengths at 1 year irrespective of the binder type. The concretes with lime:pozzolan binders are more sensitive to freeze:thaw action than those with more hydraulic binders. Salt exposure resulted in the precipitation of salt layers in the concrete however, this did not have a detrimental impact on the compressive strength of the concrete at 1 year. The results evidenced that hemp concrete is resistant to biodeterioration (7 month exposure). Finally, the addition of water retainer improved the early strength development and freeze:thaw resistance of the concrete with lime–pozzolan binder.

This paper reviews current knowledge and recent advances in methods of graffiti removal. Three approaches were considered: chemical, physical (including laser) and biological. Findings concerning the efficiency and effectiveness of the methods, including any damage to the substrate or other side effects, are described. Emphasis is placed on the limitations of the reported methods. Finally, current trends and improvements in graffiti removal methods towards the use of more efficient and less damaging treatments are addressed.

This paper presents the preliminary findings from our investigation into the possible microbial origin of brown spots on the walls of Tutankhamun's tomb. GC/MS analysis of the brown spots indicated that they contained 16% (by weight) of malic acid, suggesting microbial involvement in their formation. However, no microbial structures associated with the brown spots were detected using scanning electron microscopy. Our observations indicate that the organism that created the spots is not active. We undertook an investigation of the current microbial communities on the walls in Tutankhamun's tomb and two other nearby tombs. There were no significant differences in the numbers or types of culturable microorganisms among the three tombs sampled. Using pyrosequencing, no statistically significant differences in community composition and structure were observed. Fungal communities were composed primarily of Penicillium whereas the abundant bacterial taxa were members of the Firmicutes, Actinobacteria and Bacteroidetes phyla. Penicillium chrysogenum isolated in this study produced malic acid in vitro, suggesting that they or other microorganisms may be responsible for the malic acid detected in the brown spots. Findings from this study were compared to those from previous studies, and a possible scenario for the formation of the brown spots was developed. (C) 2013 Elsevier Ltd. All rights reserved.

Library materials are susceptible to fungal deterioration. The paper constituents of archival materials 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 fragile or previously degraded materials. Early detection of fungal growth would permit the use of relatively noninvasive treatments to remediate fungal contamination of artifacts before visible or lasting damage has occurred. Current methods used for the detection of microbial biomass, such as colony counts, microscopic biovolume estimation, and ergosterol analysis are expensive, time consuming, or are inappropriate for use with fungi. Beta-N-acetylhexosaminidase (EC 3.2.1.52) activity provides a rapid and reliable means of fungal detection on a variety of cultural heritage materials. Adapted for use on archival materials, fluorogenic 4-Methylumbelliferyl (MUF) labeled substrate N-acetyl-Beta-D-glucosamine (NAG) was used to detect fungal beta-N-acetylhexosaminidase activity. The fluorescence generated by minute quantities of fungi was quickly detected at an early stage of growth. The sensitivity of the assay was comparable to other biochemical techniques. The fluorometric assay was well-suited for early detection of fungal biomass on paper and assessment of the effectiveness of common remediation practices.

The practice of enriching nutrient-poor soils with large quantities of chemical fertilizer has contributed significantly to the boost in agricultural productivity witnessed over the last century. Plants also require minute quantities of micronutrients, such as iron (Fe), manganese (Mn), and zinc (Zn). Inadequate micronutrient concentrations in the soil are a crucial problem for crop production that can severely reduce yield and nutritional quality of crops. Modern agriculture can further promote micronutrient deficiency through excessive irrigation and imbalanced application of chemical fertilizers. Anecdotal evidence suggested that irrigation of crops with FFC H2O, a commercial product currently utilized by the agriculture, fishery, and food industries in Japan, improved crop yields. Our study quantified the biomass of radish and shirona plants watered with FFC H2O. These plants developed larger leaves, greater dry weight, and longer stems than plants watered with deionized H2O. Inductively coupled plasma mass spectroscopy revealed the presence of several biologically relevant micronutrients in FFC H2O. Radish plants watered with an FFC H2O solution that lacked micronutrients, or nutrient solutions that lacked either iron or zinc failed to increase plant size relative to controls. These results provide quantitative evidence that FFC H2O operates via micronutrient supplementation, and may alleviate micronutrient deficiencies through the addition of critical elements such as Fe and Zn. FFC H2O offers agriculturalists a simple and effective tool for the fortification of irrigation waters with micronutrients.

Cultural heritage materials are particularly susceptible to biodeterioration by fungi. Improper care and storage of artifacts contaminated with fungal material can promote the growth of these microscopic organisms and the inevitable deterioration that follows. Technology capable of detecting vegetative fungi and their reproductive structures could facilitate the struggle against fungal biodeterioration. Archivists and conservators could be notified of fungal contamination within a collection and apply pre-emptive measures, such as modification of environmental conditions, to prevent biodeterioration. The aim of this study was to improve and simplify a fluorometric assay used for the early detection of minute quantities of fungal biomass on cultural heritage materials. To this end we have successfully developed a non-fluidic assay in which fluid transfers, centrifugation steps, and much of the specialized equipment formerly needed to perform the assay are eliminated. The time required for completion of the assay was reduced to 30 min. Use of the assay was also expanded to include the early detection of viable fungal conidia from several species of fungi. These refinements will expedite implementation of this technology by archivists and conservators as they monitor and combat the fungal deterioration of cultural heritage materials.

Daguerreotypes were a popular method of photography since their introduction in 1839 until their eventual demise ca. 1860. A silver mercury amalgam deposited on a polished silver surface captured many unique images of individuals, landscapes, and the natural world. Daguerreotypes that have survived to the present day exhibit many unique patterns of deterioration and are susceptible to damage. The appearance of fibril accretions on improperly stored daguerreotypes is a common symptom of deterioration. Initial investigations based on morphologic observations of these fibrils concluded that the structures were fungi encrusted with silicon and smaller amounts of other chemicals. Later work proposed that these accretions were strictly chemical in nature. Gross microscopic observation of the fibrous accretions present on several daguerreotypes examined at Harvard University suggested that these structures were fungal in origin. This study used traditional culture techniques and nonculture molecular methods to isolate viable fungal organisms from the face of a daguerreotype and detect fungal nucleic acids. Additional microscopic and energy-dispersive x-ray spectroscopy analyses were performed to further characterize the fibrous accretions. The data demonstrates that some fibril accretions are due to fungal contamination of the daguerreotype surface.

A variety of commercial products are available for use in cleaning stone surfaces contaminated with microbiological growth. The effectiveness of many of these products is questionable, however, and direct comparison of some commonly used products would be of significant interest to conservators. Therefore, a study was carried out to compare commercially available cleaners for the removal of soiling and biological growth from federally issued headstones. Specific goals were to test cleaning products for effectiveness to recommend those products and methods best suited to clean and preserve headstones.The study focused on five national cemeteries: Alexandria National Cemetery in Pineville, Louisiana; Bath National Cemetery in Bath, New York; Jefferson Barracks National Cemetery in St. Louis, Missouri; San Francisco National Cemetery in San Francisco, California; and Santa Fe National Cemetery in Santa Fe, New Mexico. These cemeteries were chosen to represent the various regions of the National Cemetery Administration (NCA) as well as different climatic zones, including subtropical, temperate, continental, semiarid, and oceanic climates. Stones that were tested in the cemeteries were carved from the Colorado Yule marble and georgia White Cherokee marble used for the majority of both modern and historic federally issued headstones. Prior to cleaning, baseline biological activity was documented on test areas in the fall of 2005. Headstones were then evaluated 6 and 12 months after cleaning. Tap water from the site and five commercially available cleaners were selected for application to test areas on 48 headstones at each …