Variations in the microbial community of biofilms under different near-wall hydraulic shear stresses in agricultural irrigation systems

Abstract

The hydraulic characteristics along agricultural irrigation pipelines directly affect the local near-wall hydraulic shear stress and biofilm accumulation. However, the variations in the microbial community during the process remain unknown. Based on the Couette-Taylor reactor, a device was developed to accurately control the hydraulic shear stress. The results indicated that the near-wall hydraulic shear stresses showed quadratic correlations with microbial contents (represented by phospholipid fatty acids r > 0.77, p < 0.05), and the maximum values were obtained under the shear stresses of 0.20-0.35 Pa. For two types of treated wastewater, the mutual operational taxonomic units among different shear stress treatments showed good consistency (>185). Their corresponding response in the microbial community was represented by the quantitative correlations between the near-wall hydraulic shear stresses and the polymorphism indices (r > 0.82, p < 0.05). Among the microorganisms, Firmicutes at the phylum level were significantly affected by the shear stress and significantly influenced the biofilm accumulation process.

Keywords:

• Hydraulic shear stress
• biofilm accumulation
• microbial community
• high-throughput sequencing

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are grateful for financial support from the National Key Research Project (2017YFD0201504), the National Natural Science Fund of China (51621061), and the Key Laboratory of Technologies and Models for Cyclic Utilization from Agricultural Resources, Ministry of Agriculture, China (KLTMCUAR2017-2).