Chemicals of Emerging Concern in Treated Wastewater Impact Microbial Growth

Abstract

Agriculture production in California is negatively impacted by soilborne fungi, such as Verticillium dahliae, and limited water availability for irrigation. Some regions have adapted the use of recycling wastewater, i.e., reclaimed water, to supplement the potable water supply. Wastewater purification is not fully efficient at removing all contaminants and small amounts of pharmaceutical products, known as chemicals of emerging concern (CECs), remain. Acetaminophen, trimethoprim, sulfamethoxazole and gemfibrozil are some of the most common CECs found in treated wastewater and were therefore used in this study. These CECs were evaluated for their potential to interact with microorganisms directly, or for their ability to alter the development of Verticillium wilt disease in eggplants. The microorganisms Verticillium dahliae, Fusarium oxysporum f. sp. lycopersici, Piriformospora indica, Phytopthora capsici, and Bradyrhizobium japonicum were used for in vitro growth assays in the presence of CECs. CECs induced varying responses in strains of the same fungi by promoting growth of one strain while inhibiting growth of the other. CECs influenced spore germination of V. dahliae and F. oxysporum. Greenhouse experiments in which Solanum melongena (eggplants) were inoculated with V. dahliae and irrigated with CECs were used to evaluate the impacts of these chemicals on disease development. Overall our results found that most of the organisms we tested were sensitive to the CECs. P. capsici was found to be the most sensitive microorganism, while B. japonicum growth was unaffected by the CECs at the concentrations used. The greenhouse assays results indicated that plant disease severity may be influenced by given CECs at certain stages of plant growth. Overall the results of this study indicate that the concentrations of CECs found in reclaimed water are occurring at biologically relevant concentrations.

Acetaminophen Concentrations Found in Recycled Wastewater alter Soil Microbial Community Structure and Functional Diversity

“…pH, salinity, organic load, heavy metal) 72 to minimize risks to human health and changes in soil properties 3 . The current study and many others [21][22][23][24][25][26] indicate that policies need to address the level of chemical contaminants, such as CECs, that may pose risks to natural and agricultural environments, thus indirectly affecting human health as well. Hopefully these policies will lead to the development of technology that can more effectively clean wastewater for reuse to such a degree that there will be no risk in using the invaluable source of water.…”

“…Therefore, more studies on the impacts of CECs in RWW need to be conducted to ensure that this source of water does not have negative impacts on food and feed production. Our previous study 26 showed that CECs impact plant disease development, which may consequently affect food production.…”

“…The Patio Baby variety of Solanum melongena (eggplants) were cultivated as described in McLain and Gachomo, 2019. This study complies with relevant institutional, national, and international guidelines and legislation for the collection of plant material.…”

“…Processing of wastewater is able to reduce the levels of these compounds, and it was originally believed that the concentrations of these chemicals found in RWW e uent (typically in the ug to mg / L range) were so low that they are biologically irrelevant [18][19][20] . However, more recent evidence suggests that the concentrations of CECs in RWW are able to impact microorganisms, insects, and plants [21][22][23][24][25][26] . These chemicals can end up in natural environments like streams and rivers 13 .…”

Acetaminophen Levels Found in Recycled Wastewater Alter Soil Microbial Community Structure and Functional Diversity

“…It was originally believed that the final CEC concentrations in RWW effluent (typically in the μg to mg/L range) were too low to be biologically relevant [ 18 – 20 ]. However, recent evidence suggests that the concentrations of CECs in RWW can impact microorganisms, insects, and plants [ 21 – 26 ]. CECs accumulate in soils irrigated with RWW [ 14 ], and they are taken up by plants inevitably accumulating in their tissues [ 18 , 19 , 27 ].…”