My Menetrez

An Analytical Method for the Measurement of Nonviable Bioaerosols

ABSTRACT Exposures from indoor environments are a major issue for evaluating total long-term personal exposures to the fine fraction (<2.5μm in aerodynamic diameter) of particulate matter (PM). It is widely accepted in the indoor air quality (IAQ) research community that biocontamination is one of the important indoor air pollutants. Major indoor air biocontaminants include mold, bacteria, dust mites, and other antigens. Once the biocontaminants or their metabolites become airborne, IAQ could be significantly deteriorated. The airborne biocontaminants or their metabolites can induce irritational, allergic, infectious, and chemical responses in exposed individuals. Biocontaminants, such as some mold spores or pollen grains, because of their size and mass, settle rapidly within the indoor environment. Over time they may become nonviable and fragmented by the process of desiccation. Desiccated nonviable fragments of organisms are common and can be toxic or allergenic, depending upon the specific organism or organism component. Once these smaller and lighter fragments of biological PM become suspended in air, they have a greater tendency to stay suspended. Although some bioaerosols have been identified, few have been quantitatively studied for their prevalence within the total indoor PM with time, or for their affinity to penetrate indoors. This paper describes a preliminary research effort to develop a methodology for the measurement of nonvi-able biologically based PM, analyzing for mold and ragweed antigens and endotoxins. The research objectives include the development of a set of analytical methods and the comparison of impactor media and sample size, and the quantification of the relationship between outdoor and indoor levels of bioaerosols. Indoor and outdoor air samples were passed through an Andersen nonviable cascade impactor in which particles from 0.2 to 9.0 um were collected and analyzed. The presence of mold, ragweed, and endotoxin was found in all eight size ranges. The presence of respirable particles of mold and pollen found in the fine particle size range from 0.2 to 5.25 um is evidence of fragmentation of larger source particles that are known allergens.

Microbial Volatile Organic Compound Emission Rates and Exposure Model

This paper presents the results from a study that examined microbial volatile organic compound (MVOC) emissions from six fungi and one bacterial species (Streptomyces spp.) commonly found in indoor environments. Data are presented on peak emission rates from inoculated agar plates loaded with surface growth, ranging from 33.5 µg·m–2 per 24 h (Cladosporium sphaerospermum) to 515 µg·m–2 per 24 h (Rhodotorula glutinis). Furthermore, changes in MVOC emission levels during the growth cycle of two of the micro-organisms are examined. This report also includes a calculation of the impact of MVOC emissions on indoor air quality in a typical house and an application of an exposure model used in a typical school environment.

Evaluating the potential efficacy of three antifungal sealants of duct liner and galvanized steel as used in HVAC systems

Current recommendations for remediation of fiberglass duct materials contaminated with fungi specify complete removal, which can be extremely expensive, but in-place duct cleaning may not provide adequate protection from regrowth of fungal contamination. Therefore, a common practice in the duct-cleaning industry is the postcleaning use of antifungal surface coatings with the implication that they may contain or limit regrowth. However, even the proper use of these products has generally been discouraged because little research has been conducted on the effectiveness of most products as used in heating, ventilating, and air-conditioning (HVAC) systems. Three different coatings were evaluated on fiberglass duct liner (FGDL). Two of the three coatings were able to limit growth in the 3-month study; the third did not. One of the coatings that was able to limit growth was further evaluated in a comparison of FGDL or galvanized steel (GS) under conditions that mimicked their use in HVAC systems. The results showed that both moderately soiled and heavily soiled uncoated FGDL and GS duct material can support fungal growth, but that GS duct material was more readily cleaned. The use of an antifungal coating helped limit, but did not fully contain, regrowth on FGDL. No regrowth was detected on the coated GS. Journal of Industrial Microbiology & Biotechnology (2002) 29, 38–43 doi:10.1038/sj.jim.7000261

Emission Exposure Model for the Transport of Toxic Mold

Biocontaminants such as mold spores are capable of being released into the indoor air from the site of growth and being transported in a viable or non-viable form. Exposure to toxic mold and the mycotoxins contained in the spore and vegetative body have been shown to produce adverse health effects following inhalation, ingestion and dermal contact. This paper presents the results of a study of the release of Stachybotrys chartarum spores from contaminated gypsum wallboard and of tests on the effects of environmental conditions on the release of viable and non-viable spores and fragments. The findings of S. chartarum spore emissions with low air velocity flow conditions were found to be directly proportional to airflow and indirectly proportional to relative humidity. These emission findings corroborate previous observations involving Penicillium and Aspergillus. The viability of S. chartarum spore emissions is also discussed with respect to culturable and commonly used field measurement techniques.

Meeting the U.S. renewable fuel standard: a comparison of biofuel pathways

The production of renewable energy is undergoing rapid development. Ethanol primarily derived from corn and biodiesel made from recycled cooking oil and agricultural grains are established sources of renewable transportation fuel. Cellulosic ethanol production is increasing substantially, but at a rate below expectations. If future renewable fuel projections are to be accomplished, additional sources will be needed. Ideally, these sources should be independent of competing feedstock use such as food grains, and require a minimal footprint. Although the uses of algae seem promising, a number of demonstrations have not been economically successful in today‟s market. This paper identifies efforts being conducted on ethanol and biodiesel production and how algae might contribute to the production of biofuel in the United States. Additionally, the feedstock and land requirements of existing biofuel pathways are compared and discussed.

The Potential Environmental Impact of Waste from Cellulosic Ethanol Production

Abstract The increasing production of ethanol has been established as an important contributor to future energy independence. Although ethanol demand is increasing, a growing economic trend in decreased profitability and resource conflicts have called into question the future of grain-based ethanol production. Growing emphasis is being placed on utilizing cellulosic feedstocks to produce ethanol, and the need for renewable resources has made the development of cellulosic ethanol a national priority. Cellulosic ethanol production plants are being built in many areas of the United States to evaluate various feed-stocks and processes. The waste streams from many varying processes that are being developed contain a variety of components. Differences in ethanol generation processes and feedstocks are producing waste streams unique to biofuel production, which could be potentially harmful to the environment if adequate care is not taken to manage those risks. Waste stream management and utilization of the cellulosic ethanol process are equally important components of the development of this industry.

A simple polymerase chain reaction-sequencing analysis capable of identifying multiple medically relevant filamentous fungal species

Due to the accumulating evidence that suggests that numerous unhealthy conditions in the indoor environment are the result of abnormal growth of the filamentous fungi (mold) in and on building surfaces it is necessary to accurately determine the organisms responsible for these maladies and to identify them in an accurate and timely manner. Historically, identification of filamentous fungal (mold) species has been based on morphological characteristics, both macroscopic and microscopic. These methods may often be time consuming and inaccurate, necessitating the development of identification protocols that are rapid, sensitive, and precise. To this end, we have devised a simple PAN-PCR approach which when coupled to cloning and sequencing of the clones allows for the unambiguous identification of multiple fungal organisms. Universal primers are used to amplify ribosomal DNA sequences which are then cloned and transformed into Escherichia coli. Individual clones are then sequenced and individual sequences analyzed and organisms identified. Using this method we were capable of identifying Stachybotrys chartarum, Penicillium purpurogenum, Aspergillus sydowii, and Cladosporium cladosporioides from a mixed culture. This method was found to be rapid, highly specific, easy to perform, and cost effective.

Testing Antimicrobial Efficacy on Porous Materials

The efficacy of antimicrobial treatments to eliminate or control biological growth in the indoor environment can easily be tested on non-porous surfaces. However, the testing of antimicrobial efficacy on porous surfaces, such as those found in the indoor environment (i.e., gypsum board, heating, ventilating and air-conditioning duct-lin er insulation, and wood products) can be more compli cated and prone to incorrect conclusions regarding re sidual organisms and non-viable allergens. Research to control biological growth using three separate antimicro bial encapsulants on contaminated duct-liner insulation has been performed in both field and laboratory testing. The results indicate differences in antimicrobial efficacy for the period of testing.

Detection of Stachybotrys chartarum using rRNA, tri5, and β-tubulin primers and determining their relative copy number by real-time PCR

Highly conserved regions are attractive targets for detection and quantitation by PCR, but designing species-specific primer sets can be difficult. Ultimately, almost all primer sets are designed based upon literature searches in public domain databases, such as the National Center for Biotechnology Information (NCBI). Prudence suggests that the researcher needs to evaluate as many sequences as available for designing species-specific PCR primers. In this report, we aligned 11, 9, and 16 DNA sequences entered for Stachybotrys spp. rRNA, tri5, and beta-tubulin regions, respectively. Although we were able to align and determine consensus primer sets for the 9 tri5 and the 16 beta-tubulin sequences, there was no consensus sequence that could be derived from alignment of the 11 rRNA sequences. However, by judicious clustering of the sequences that aligned well, we were able to design three sets of primers for the rRNA region of S. chartarum. The two primer sets for tri5 and beta-tubulin produced satisfactory PCR results for all four strains of S. chartarum used in this study whereas only one rRNA primer set of three produced similar satisfactory results. Ultimately, we were able to show that rRNA copy number is approximately 2-log greater than for tri5 and beta-tubulin in the four strains of S. chartarum tested.

Research and Development of Prevention and Control Measures for Mold Contamination

The U.S. Environmental Protection Agency, Air Pollution Prevention and Control Division, Indoor Environment Management Branch has, since 1995, conducted research into controlling biological contamination in the indoor environment. In this paper four areas of research are discussed: (1) research and development of prevention and control measures for mitigation of indoor air pollutants by biocontaminants; (2) duct cleaning effectiveness for prevention and control of microbial growth on duct materials; (3) investigation and evaluation of antimicrobial treatments as control technologies to reduce ambient exposure; and (4) field testing of sealants and encapsulents used in air duct systems. The conclusions resulting from this body of research are listed to summarise the accomplishments and put into perspective the interrelationships of these areas of investigation in reducing human exposure to biological contamination in the indoor environment.