An automated bacterial concentration and recovery system for pre-enrichment required in rapid Escherichia coli detection

Abstract

One of the biggest challenges in rapid low concentration bacterial detection is the pre-concentration or pre-enrichment, which aims to increase bacteria concentration and reduce sample volume for easy bacterial detection. In practical bacterial detection, large-volume water samples with a pathogenic bacterial concentration of less than 1 CFU/mL have to be tested rapidly. The reported biosensors either have insufficient detection limit or have limited capability of handling a sufficiently large water sample. Therefore, a high-performance automated pre-enrichment process is strongly demanded in rapid practical bacterial detection. In this paper, a practical high performance automated bacterial concentration and recovery system (ABCRS) based on the combination of a ceramic membrane and tangential flow filtration technique was presented with short processing time (less than one hour), low pre-enrichment limit (≤0.005 CFU/mL), high concentration ratio (≥ 500), high recovery efficiency (~ 90%), and small final retentate volume (≤ 5 mL).

Figure 1

Measured E. coli recovery efficiencies of the ABCRS at various back-flushing frequencies.

Figure 2

Schematic diagrams of an automated bacterial concentration and recovery system (ABCRS) with the tangential flow filtration technique used in the pre-enrichment process for (a) forward, and (b) backward flow procedure.