Ensuring microbial safety in large-capacity packaged drinking water is a critical task for food safety authorities and third-party testing labs. Traditional membrane filtration methods—commonly used under national standards like China’s GB 8538-2022—are often labor-intensive, poorly suited for high-volume samples, and vulnerable to cross-contamination and low recovery rates.
A new study out of China highlights a smarter approach.
Researchers at the Zhongshan Institute of Quality Measurement Supervision and Testing evaluated the InnovaPrep CP Select as a novel microbial enrichment system for quantifying viable bacteria in bottled water. The study focused on pathogens of regulatory concern—Pseudomonas aeruginosa, Streptococcus faecalis, and Clostridium perfringens—at concentrations as low as 1 CFU/250 mL.
Traditional Filter/Culture Methods vs. CP Select Enrichment
In side-by-side comparisons, the CP Select's wet foam elution technology outperformed conventional membrane filtration methods:
-
At 10 CFU/250 mL, average recovery rates with CP Select were:
-
P. aeruginosa: 115%
-
S. faecalis: 116%
-
C. perfringens: 111%
In contrast, filtration recoveries were significantly lower:
-
P. aeruginosa: 59%
-
S. faecalis: 55%
-
C. perfringens: 66%
-
-
At 1 CFU/250 mL, the CP Select continued to deliver:
-
P. aeruginosa: 120%
-
S. faecalis: 150%
-
C. perfringens: 130%
Meanwhile, traditional methods often failed to detect the bacteria at all.
-
Using 2-liter samples from 15-liter bottled water containers, researchers achieved a concentration ratio of 2000:1, with eluates processed by magnetic bead-based DNA extraction. This method not only increases the likelihood of detecting low-level pathogens but also avoids the need for cumbersome incubation.
Combined with fluorescence PCR, the CP Select system enabled rapid and highly sensitive detection—offering Ct values below 40 as a clear indicator of target DNA presence.
Practical Impact for the Water Quality Industry
This study underscores several key benefits of the CP Select system for testing agencies and bottled water producers:
-
Higher microbial recovery and quantification accuracy
-
Faster processing time compared to membrane filtration and culture
-
Lower labor burden and contamination risk in the sampling process
-
Compatibility with molecular assays, including qPCR and fluorescence-PCR
-
Reduced biochemical confirmation time for complex samples like P. aeruginosa
Moving Forward: A New Standard in Sample Concentration
The results of this study reflect a growing recognition in China and beyond: modern microbial enrichment tools like the InnovaPrep CP Select can significantly improve compliance with safety standards while reducing operational bottlenecks while delivering speed, sensitivity, and ease-of-use will shape the next generation of water quality monitoring.
Reference: doi:10.16736/j.cnki.cn41-1434/ts.2024.23.041
微生物高效富集系统在大容量包装饮用水采样及测定活菌含量中的应用效果分析
Application Analysis of Microbial Enrichment System in Sampling and Viable Bacteria Quantification of Large-Capacity Packaged Water
◎ 吉宇恒（广东省中山市质量计量监督检测所 食品化工室，广东 中山 528400）
JI Yuheng, et al. (Food Chemical Office, Zhongshan Institute of Quality Measurement Supervision and Testing, Zhongshan 528400, China)
