Skip to Content
MilliporeSigma
  • A novel thermometric biosensor for fast surveillance of β-lactamase activity in milk.

A novel thermometric biosensor for fast surveillance of β-lactamase activity in milk.

Biosensors & bioelectronics (2013-06-01)
Shuang Zhou, Yunfeng Zhao, Michael Mecklenburg, Dajin Yang, Bin Xie
ABSTRACT

Regulatory restrictions on antibiotic residues in dairy products have resulted in the illegal addition of β-lactamase to lower antibiotic levels in milk in China. Here we demonstrate a fast, sensitive and convenient method based on enzyme thermistor (ET) for the surveillance of β-lactamase in milk. A fixed amount of penicillin G, which is a specific substrate of β-lactamase, was incubated with the milk sample, and an aliquot of the mixture was directly injected into the ET system to give a temperature change corresponding to the remained penicillin G. The amount of β-lactamase present in sample was deduced by the penicillin G consumed during incubation. This method was successfully applied to quantify β-lactamase in milk with the linear range of 1.1-20 UmL(-1) and the detection limit of 1.1 UmL(-1). The recoveries ranged from 93% to 105%, with relative standard deviations (RSDs) below 8%. The stability of the column equipped in ET was also studied, and only 5% decrease of activity was observed after 60 days of use. Compared with the conventional culture-based assay, the advantages of high throughput, timesaving and accurate quantification have made this method an ideal alternative for routine use.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Penicillin G sodium salt, ~1650 U/mg
Sigma-Aldrich
Penicillin G sodium salt, 96.0-102.0%
Sigma-Aldrich
Penicillin G sodium salt, powder, BioReagent, suitable for cell culture
Supelco
Penicillin G potassium salt, VETRANAL®, analytical standard
Sigma-Aldrich
Penicillin G potassium salt, 95.0 - 102.0%
Sigma-Aldrich
Penicillin G potassium salt
Sigma-Aldrich
Penicillin G potassium salt, powder, BioReagent, suitable for cell culture