Characterization and DNA Stable-Isotope Probing of Methanotrophic Bioaerosols

Microbiology Spectrum · 2022-11-21 · 8 citations

Currently, the cellular activities of bacteria in the airborne state outside of water droplets have not been heavily studied. Evidence suggests that these airborne bacteria produce ribosomes and metabolize gaseous compounds. Despite having a potentially important impact on atmospheric chemistry, the ability of bacteria in the air to metabolize substrates such as methane is not well understood. Demonstrating that bacteria in the air can metabolize and grow on substrates will expand knowledge about the potential activities and functions of the atmospheric microbiome. This study provides evidence for DNA synthesis and, ultimately, growth of airborne methanotrophs.

Degradation of chlorinated solvents with reactive iron minerals in subsurface sediments from redox transition zones

Journal of Hazardous Materials · 2022 · 18 citations

• Chemistry
• Environmental chemistry
• Inorganic chemistry

Assessing Reactive Iron Mineral Coatings in Redox Transition Zones with Sequential Extraction

ACS Earth and Space Chemistry · 2022-01-21 · 2 citations

In reduction–oxidation (redox) transition zones (RTZs), reactive iron minerals play an important role in electron transfer between bacteria and contaminants. To better understand their contributions, this study focuses on characterizing iron mineral speciation using sequential extraction. Sediment samples were collected from an anoxic core where the redox condition was preserved. Based on previous analyses, four RTZs were of focus: the Upper Zone [3.96–4.52 m depth below the surface (DBS)], Zone 1 (6.35–6.91 m DBS), Zone 2 (9.45–10.46 m DBS), and Zone 3 (14.63–15.24 m DBS). A six-step sequential extraction (SE) was applied to discern reduced and oxidized forms of Fe mineral coatings in these four RTZs. Based on extraction results, in the Upper Zone, the amorphous Fe sulfide minerals, mackinawite and greigite, increased with depth, while the crystalline Fe sulfide, pyrite, decreased. Because metastable mackinawite was dominant in the Upper Zone and given historical contamination at the site, the absence of volatile organic compounds in the sediment headspace suggests (a)biotic attenuation may be significant. In the Zone 1, the highest concentrations of crystalline Fe sulfide mineral nano-coatings were observed when compared to other three RTZs; importantly, sulfate-reducing bacteria, Desulfosporosinus, was abundant. Fe concentrations in the sediment dramatically decreased in Zone 2, where the Fe(II/III) mineral magnetite was dominant, suggesting a biogenic pathway as iron-reducing bacteria, Geobacter, was abundant. In the aquifer to aquitard interface Zone 3, Fe mineral coatings revealed significant variability between each subsample, suggesting active Fe cycling with biotic processes based on the abundance ofDesulfosporosinusin the clay lenses. Iron speciation with respect to mineralogy [and therefore Fe(II) and Fe(III) forms] in RTZs further supports evidence of (a)biotic contributions in natural attenuation.

<i>Agromyces</i> and <i>Arthrobacter</i> isolates from surficial sediments of the Passaic River degrade dibenzofuran, dibenzo-<i>p</i>-dioxin and 2-monochlorodibenzo-<i>p</i>-dioxin

Bioremediation Journal · 2021-03-10 · 4 citations

The Passaic River in New Jersey, USA is heavily polluted by chlorodibenzo-p-dioxins (CDDs). Highly chlorinated CDDs are dechlorinated by anaerobic bacteria from these sediments, producing lightly chlorinated or even non-chlorinated dibenzo-p-dioxin (DD) daughter products. Surficial Passaic River sediments were enriched under aerobic conditions and three bacterial strains (PR1, PR2 and PR3) were isolated using dibenzofuran (DF) as a model substrate. PR1 is closely related to Janibacter terrae (99.4%), a known CDD and DD degrader. PR2 and PR3 are closely related to Agromyces mediolanus (99.2%) and Arthrobacter oryzae (99.5%), respectively, which are genera not known to degrade CDDs. Janibacter PR1 grew more rapidly on DF than PR2 and PR3. The less well characterized PR2 and PR3 both degraded DD and 2-monochlorodibenzo-p-dioxin (2MCDD), at similar rates. Neither PR2 nor PR3 transformed 2,7-dichlodibenzo-p-dioxin (2,7DCDD). An angular dioxygenase 99.7% identical to that in Terrabacter sp. DBF63 was detected by PCR in Janibacter PR1 and Agromyces PR2. PCR did not detect an angular dioxygenase in Arthrobacter PR3. In this work, novel aerobic bacterial strains that can aerobically degrade the products of dechlorination were identified in surficial Passaic River sediments. The presence of these bacteria could enable an in situ treatment process that completely removes all CDDs from the sediment.

Roles of reactive iron mineral coatings in natural attenuation in redox transition zones preserved from a site with historical contamination

Journal of Hazardous Materials · 2021-07-07 · 8 citations

Diversity In Environmental Engineering: The Good And Bad

2020 · 1 citations

• Political Science
• Sociology
• Engineering

Engineering diversity remains a problem in the USA despite ongoing efforts by government, academia, and the private sector. A committee of the Association of Environmental Engineering and Science Professors (AEESP) is characterizing diversity within the environmental engineering field to determine if there are unique issues associated with this profession that need to be addressed. For this effort, diversity includes gender and ethnic diversity in terms of African Americans, Hispanic Americans, and Native Americans. The committee looked at populations of environmental engineering students (based on degrees granted), faculty, and practitioners using available data from the Engineering Workforce Commission, American Society of Engineering Education, U.S. Department of Labor, and the National Science Foundation. As expected, the study shows that contrary to engineering as a whole, the environmental engineering student population is very diverse in terms of gender. There is some gender diversity in terms of environmental engineering faculty, though numbers of female faculty are still below those for the general population. Also, there is a lower percentage of female environmental engineering faculty than the percentage of females graduating with doctorate degrees in that field. However, women are well represented among environmental engineering practitioners with a growing population trend related to the amount of degrees granted. Unfortunately, environmental engineering is not diverse in terms of ethnicity for students, faculty, and practitioners. At the aggregate level, ethnic diversity for environmental engineering is similar to engineering as a whole and well below the general population. Based on the aggregate results, the committee evaluated programs at ABET-accredited undergraduate environmental engineering programs and noted the subset of those colleges that are reportedly implementing best practices to enhance diversity and/or have a particular advantage in terms of attracting diverse students due to location, etc. This evaluation shows that those colleges that are somewhat successful at increasing ethnic diversity in engineering at the undergraduate level have similar success with environmental engineering programs. However, the remaining schools were less successful with achieving ethnic diversity in environmental engineering than within the overall engineering program. The results for ethnic diversity are limited because the populations are small. Additional study is also needed to determine the reasons why ethnically diverse students may choose engineering disciplines other than environmental engineering at a higher rate.

Cyanobacteria and Algae in Clouds and Rain in the Area of puy de Dôme, Central France

Applied and Environmental Microbiology · 2020 · 33 citations

• Ecology
• Biology

Information regarding the diversity and abundance of oxygenic photoautotrophs in the atmosphere is limited. More information from diverse locations is needed. These airborne organisms could have important impacts upon atmospheric processes and on the ecosystems they enter after deposition. Oxygenic photoautotrophic microbes are integral to ecosystem functioning, and some have the potential to affect human health. A better understanding of the diversity and the movements of these aeolian dispersed organisms is needed to understand their ecology, as well as how they could affect ecosystems and human health.

Sources of polychlorinated biphenyls to Upper Hudson River sediment post-dredging

Chemosphere · 2020 · 14 citations

• Environmental chemistry
• Environmental science
• Environmental engineering