Removal of Antibiotic Resistance Genes, Class 1 Integrase Gene and Escherichia coli Indicator Gene in a Microalgae-Based Wastewater Treatment System

Abdullahi B Inuwa; Qaisar Mahmood; Jamshed Iqbal; Emilie Widemann; Sarfraz Shafiq; Muhammad Irshad; Usman Irshad; Akhtar Iqbal; Farhan Hafeez; Rashid Nazir

doi:10.3390/antibiotics11111531

Removal of Antibiotic Resistance Genes, Class 1 Integrase Gene and Escherichia coli Indicator Gene in a Microalgae-Based Wastewater Treatment System

Antibiotics (Basel). 2022 Nov 2;11(11):1531. doi: 10.3390/antibiotics11111531.

Authors

Abdullahi B Inuwa^{1

2}, Qaisar Mahmood^{1

3}, Jamshed Iqbal^{4

5}, Emilie Widemann⁶, Sarfraz Shafiq⁷, Muhammad Irshad¹, Usman Irshad¹, Akhtar Iqbal¹, Farhan Hafeez¹, Rashid Nazir¹

Affiliations

¹ Department of Environmental Sciences, COMSATS University Islamabad (CUI), Abbottabad Campus, Abbottabad 22060, Pakistan.
² Department of Microbiology, Faculty of Life Sciences, College of Natural and Pharmaceutical Sciences, Bayero University Kano, Kano 700006, Nigeria.
³ Department of Biology, College of Science, University of Bahrain, Sakhir P.O. Box 32038, Bahrain.
⁴ Centre for Advanced Drug Research, COMSATS University Islamabad (CUI), Abbottabad Campus, Abbottabad 22060, Pakistan.
⁵ Department of Pharmacy, COMSATS University Islamabad (CUI), Abbottabad Campus, Abbottabad 22060, Pakistan.
⁶ Institut de Biologie Moléculaire des Plantes, CNRS-Université de Strasbourg, 67084 Strasbourg, France.
⁷ Department of Anatomy and Cell Biology, University of Western Ontario, 1151 Richmond St., London, ON N6A5B8, Canada.

Abstract

Microalgae-based wastewater treatment systems (AWWTS) have recently shown promise in the mitigation of antibiotic resistance genes (ARGs) from municipal wastewater (MWW). However, due to the large number of ARGs that exist in MWW, the use of indirect conventional water quality parameters to monitor ARGs reduction in wastewater would make the process less burdensome and economically affordable. In order to establish a robust relationship between the ARGs and water quality parameters, the current study employed different microalgae strains in monoculture (CM2, KL10) and multi-species combinations (CK and WW) for the MWW treatment under outdoor environmental conditions. The studied genes were quantified in the MWW influents and effluents using real-time PCR. All the cultures substantially improved the physicochemical qualities of the MWW. Out of the 14 genes analyzed in this study, tetO, tetW, tetX and ermB were decreased beyond detection within the first 4 days of treatment in all the cultures. Other genes, including blaCTX, sul1, cmlA, aadA, int1 and uidA were also decreased beyond a 2 log reduction value (LRV). The mobile genetic element, int1, correlated positively with most of the ARGs, especially sul1 (r ≤ 0.99, p < 0.01) and aadA (r ≤ 0.97, p < 0.01). Similarly, the Escherichia coli indicator gene, uidA, correlated positively with the studied genes, especially with aadA, blaCTX, blaTEM and cmlA (r ≤ 0.99 for each, p < 0.01). Some of the studied genes also correlated positively with total dissolved solids (TDS) (r ≤ 0.98, p < 0.01), and/or negatively with total suspended solids (TSS) (r ≤ −0.98, p < 0.01) and pH (r ≤ −0.98, p < 0.01). Among the tested cultures, both monocultures, i.e., KL10 and CM2 were found to be more consistent in gene suppression than their multi-species counterparts. The findings revealed water quality parameters such as TDS, TSS and E. coli as reliable proxies for ARGs mitigation in AWWTS and further highlight the superiority of monocultures over multi-species cultures in terms of gene suppression from the MWW stream.

Keywords: Escherichia coli; antibiotic resistance genes; microalgae; municipal wastewater.

Grants and funding

This work was supported in part by the CUI-TWAS Postgraduate Fellowship Award (FR number: 3240299478) granted to ABI and the TWAS-COMSTECH (18- 363 RG/REN/AS_C –FR3240305796) to RN.