Drip irrigation biofouling with treated wastewater: bacterial selection revealed by high-throughput sequencing

Abstract

Clogging of drippers due to the development of biofilms weakens the advantages and impedes the implementation of drip irrigation technology. The objective of this study was to characterise the bacterial community of biofilms that develop in a drip irrigation system supplied with treated wastewater. High-throughput sequencing of 16S rRNA gene amplicons indicated that the bacterial community composition differed between drippers and pipes, mainly due to changes in the abundance of the genus Aquabacterium. Cyanobacteria were found to be involved in the biological fouling of drippers. Moreover, bacterial genera including opportunistic pathogenic bacteria such as Legionella and Pseudomonas were more abundant in dripper and pipe biofilms than in the incoming water. Some genera such as Pseudomonas were mostly recovered from drippers, while others (ie Bacillus, Brevundimonas) mainly occurred in pipes. Variations in the hydraulic conditions and properties of the materials likely explain the shift in bacterial communities observed between pipes and drippers.

Keywords:

• treated wastewater reuse
• biofilm
• 16S rRNA
• opportunistic pathogenic bacteria
• drip irrigation

Acknowledgements

The authors gratefully acknowledge the financial support of the Rhone-Mediterranean and Corsica Water Agence (France), project ‘Experimental platform for the reuse of treated wastewater in irrigation, Murviel-lès-Montpellier’. They thank Annabelle Mange (IRSTEA, Montpellier, France) and Valérie Bru (LBE-INRA, Narbonne, France) for their assistance in the field and at the laboratory. The authors thank also Kim Milferstedt (LBE-INRA, Narbonne, France) and Jérôme Hamelin (LBE-INRA, Narbonne, France) for their assistance in statistical analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.