Source Tracking Aerosols Released from Land-Applied Class B Biosolids during High-Wind Events

Abstract

DNA-based microbial source tracking (MST) methods were developed and used to specifically and sensitively track the unintended aerosolization of land-applied, anaerobically digested sewage sludge (biosolids) during high-wind events. Culture and phylogenetic analyses of bulk biosolids provided a basis for the development of three different MST methods. They included (i) culture-and 16S rRNA gene-based identification of Clostridium bifermentans, (ii) direct PCR amplification and sequencing of the 16S rRNA gene for an uncultured bacterium of the class Chloroflexi that is commonly present in anaerobically digested biosolids, and (iii) direct PCR amplification of a 16S rRNA gene of the phylum Euryarchaeota coupled with terminal restriction fragment length polymorphism to distinguish terminal fragments that are unique to biosolid-specific microorganisms. Each method was first validated with a broad group of bulk biosolids and soil samples to confirm the target's exclusive presence in biosolids and absence in soils. Positive responses were observed in 100% of bulk biosolid samples and in less than 11% of the bulk soils tested. Next, a sampling campaign was conducted in which all three methods were applied to aerosol samples taken upwind and downwind of fields that had recently been land applied with biosolids. When average wind speeds were greater than 5 m/s, source tracking results confirmed the presence of biosolids in 56% of the downwind samples versus 3% of the upwind samples. During these high-wind events, the biosolid concentration in downwind aerosols was between 0.1 and 2 g/m 3 . The application of DNA-based source tracking to aerosol samples has confirmed that wind is a possible mechanism for the aerosolization and off-site transport of land-applied biosolids.

Potentially Pathogenic Bacteria in Shower Water and Air of a Stem Cell Transplant Unit

“…Our work verified the work of other gene surveys of air, which found Proteobacteria to be the most common phylum. Specifically, three out of the seven published outdoor air surveys showed Proteobacteria to be exceeding 60% of the bacterial composition (8,32,44). In addition, the indoor air of a shopping mall showed similar percentages of Proteobacteria (Ͼ60%) (66), while the indoor air in modern Finnish houses consisted of 44 to 50% Proteobacteria (55).…”

Influence of long‐term land application of Class B biosolids on soil bacterial diversity

“…The phylum Chloroflexi was reported to be found exclusively in aerosols derived from biosolids land Acidobacteria Acidobacterium Gram-negative, aerobic, some are obligate anaerobes and halophiles, comprise 10-50% of the total bacterial 16S rRNA gene sequences in clone libraries (Barns et al 2007) Little known about their physiology or ecology but able to withstand extreme environments (Barns et al 2007) Bacteroidetes Flavobacterium Gram-negative, rod-shaped, motile, aerobic, widely distributed in soil and freshwater habitats (Bernardet et al 1996) Chemoorganotrophic bacteria that decompose several polysaccharides but not cellulose (Bernardet et al 1996) application because they are one of the most abundant groups in bulk biosolids (Baertsch et al 2007;Brooks et al 2007). On the contrary, members of phyla Chloroflexi were less abundant in biosolid-amended soil than the unamended soil (Table 2).…”

Molecular Source Tracking of Bioaerosols in the Quarantined Katrina Flood Zone

“…Indeed, microbial physiology and water quality factors can influence the potential for microbes (and chemicals) to transfer from water sources into aerosols (Angenent et al 2005;Paez-Rubio et al 2005;Baertsch et al 2007). In the samples analyzed however, any contribution to atmospheric biocomplexity from artificially generated aerosols appears minor, regardless of the tremendous energy inputs from mechanical aerators and pump-induced turbulence.…”

“…The concept of an ubiquitous aerosol community was explored through additional SONs and Unifrac analyses using additional atmospheric sequence data available in GenBank (Hughes et al 2004;Maron et al 2005;Paez-Rubio et al 2005;Baertsch et al 2007;Brodie et al 2007;Fierer et al 2008). When scrutinized at species level (97% sequence ID), SONS analysis indicated few examples of shared diversity.…”