Included in the July 10, 2025, biweekly update

This week's articles by MSU faculty, specialists and students making a difference feature sewage-tracked antibiotic resistance, phosphorus recovery from waste, and COVID detection in campus HVAC filters.
 

Global diversity and distribution of antibiotic resistance genes in human wastewater treatment systems

Zhu et al. (2025) analyzed samples from 226 wastewater treatment plants across six continents to study the global spread of antibiotic resistance genes (ARGs), or DNA sequences that allow bacteria to survive exposure to antibiotics. Using standardized sampling and sequencing methods, the researchers identified a core group of 20 ARGs present in every plant. Most of these genes were associated with resistance to commonly used antibiotics, including penicillins and tetracyclines.

Although the total amount of antibiotic resistance genes (ARGs) was similar across all sites, their composition varied by region, with Asia showing the greatest diversity. The researchers identified certain bacterial groups, like Chloroflexi and Acidobacteria, as major ARG carriers. Notably, over half of the microbial genomes recovered contained mobile ARGs, or genes that can move between different bacterial species, highlighting the risk of resistance spreading through microbial communities.

Local environmental factors, like pH, temperature, and city size, help shape these resistance patterns, but random variation also plays a role. These findings show that wastewater treatment plants are key locations where antibiotic resistance can develop and spread. Tracking the bacteria in these systems alongside environmental factors could help to better understand how resistance evolves.

Zhu, C., Wu, L., Ning, D., et al. (2025). “Global diversity and distribution of antibiotic resistance genes in human wastewater treatment systems.” Nature Communications, 16, 4006. https://doi.org/10.1038/s41467-025-59019-3

Corresponding author: Jizhong Zhou jzhou@ou.edu.

Phosphorus adsorption and recovery from waste streams using biochar: review of mechanisms, modifications, and agricultural applications

Kumari et al. (2025) reviewed the potential of biochar, a charcoal-like material made by heating organic waste in low-oxygen conditions, to remove and recover phosphorus from wastewater and agricultural runoff. They focused on how different types of biochar, particularly those enhanced with metals like magnesium, calcium, or iron, adsorbed phosphate through processes like ion exchange, surface precipitation, and electrostatic attraction. In controlled lab conditions, some modified biochars achieved high phosphorus removal rates.

The review also examined challenges to real-world application. In actual wastewater, competing ions reduced the efficiency of phosphate binding. Questions remained about the long-term use of phosphorus-saturated biochar, including concerns about regeneration, stability, and the potential leaching of metals.

Despite these questions, the researchers saw potential for biochar to be part of a circular system—one where phosphorus removed from wastewater could be reused as fertilizer. They emphasized the need for more testing in real-world settings, especially in systems that handle flowing water and changing wastewater conditions.

Kumari, S., Dong, Y., & Safferman, S. I. (2025). “Phosphorus Adsorption and Recovery from Waste Streams Using Biochar: Review of Mechanisms, Modifications, and Agricultural Applications.” Applied Water Science, 15, Article 162. https://doi.org/10.1007/s13201-025-02523-0

Corresponding author: Soni Kumari kumariso@msu.edu.

SARS-CoV‑2 Detection in Heating, Ventilation, and Air Conditioning Filters of University Lecture Rooms

Wang et al. (2025) investigated whether HVAC systems could be used to monitor airborne viruses by testing filters from university lecture halls for SARS-CoV-2 RNA. The team collected used HVAC filters from six lecture rooms at Michigan State University and analyzed them using RT-qPCR to detect traces of the virus’s genetic material. SARS-CoV-2 RNA was found in filters from four of the six rooms, with positive results being more likely in larger, more frequently used spaces.

Unlike clinical testing or surface swabbing, HVAC filter sampling provides a passive, building-wide snapshot of airborne virus exposure over time. Because filters collect air over days or weeks, they capture signals from multiple people, making this approach especially valuable in shared environments like classrooms, offices, or college dorms.

Although this method can’t determine if the virus is still infectious, it can help flag spaces with elevated viral activity. The researchers argue that routine HVAC filter monitoring could aid in early detection and response, especially in places where regular testing isn’t feasible. The study also suggests that HVAC systems could play a larger role in tracking viruses and improving public health surveillance.

Wang, Z., Peidro Guzman, H., Zou, Y., Xagoraraki, I., & Lin, K. (2025). “SARS-CoV-2 Detection in Heating, Ventilation, and Air Conditioning Filters of University Lecture Rooms.” Environmental Science & Technology Air. https://doi.org/10.1021/acsestair.5c00056

Corresponding author: Kaisen Lin kaislin@msu.edu.