压电体声波传感器快速检测米粉中菌落总数

Rapid Determination of Bacteria Counts in Rice Noodles using Piezoelectric Bulk Acoustic Wave Biosensors

采用压电体声波传感器实时快速检测米粉中的菌落总数。该传感器包括压电石英晶体、检测池、振荡器、频率计和显示器,其检测原理是基于压电体声波传感器对微生物存在的培养体系的电参数变化有灵敏的频移响应,而自制软件能以频移-时间的形式将此变化过程实时记录下来。本研究中将频移显著变化的点所对应的时间定义为微生物检出时间(MDT),将基于MDT检出微生物的方法称为频移检测法。将不同污染程度的米粉样品用频移检测法获得的MDT与平板计数法获得的初始菌落数建立标定方程。当微生物初始菌落数在103～108cfu/g之间时获得标定方程logC=7.7923-0.0071MDT(r=0.985)。通过标定方程得到的不合格样品(参照国家和地方标准)的测定时间仅需7.8h,远小于国标方法的48h。利用建立的压电传感法检测13个米粉样品的菌落总数,并与平板计数法比较,结果表明,压电体声波传感器法具有准确、快速、操作简便等特点,有望在米粉制品的菌落总数检测中得到推广应用。

A piezoelectric bulk acoustic wave biosensor was developed for determination of bacteria counts in rice noodles in real time.The system consists of piezoelectric quartz crystal,detection cell,oscillator,frequency counter and monitor.The determination was based on the sensitive response of the piezoelectric bulk acoustic wave biosensor to the change of culture media during bacteria growth.The frequency shift versus time response curves were recorded by self-developed software.Microbiology detection time（MDT） corresponding to the significant change of frequency shift value was used as a parameter to quantitatively determine bacteria.The calibration curve of detection time against the logarithm of bacteria initial concentration showed a linear correlation coefficient（r=0.985） over the range of 103~108 cfu/mL.The biosensor could acquire sufficient data rapidly（within 7.8 h） and enabled real-time monitoring of bacteria growth.Comparing tests were also carried out using pour plate counts.The results showed that the biosensor has potential application in the detection of bacteria concentration in food at management of quality sampling.