IMPROVED DESIGN OF AUTOMATIC LUMINOMETER FOR TOTAL BACTERIA NUMBER DETECTION BASED ON ATP BIOLUMINESCENCE

摘要

An improved design of automatic luminometer for rapid detection of total bacterial number by adenosine 5'-triphosphate (ATP) bioluminescence was developed. To reduce the impact of bioluminescence absorption and scattering, an automatic optical calibration unit was embedded into the luminometer. An automatic injection unit was integrated to add reaction reagents automatically for accuracy of quantitative reagents and reaction time. The original data of bioluminescence intensity were fitted to improvethe detection range of the improved luminometer. After calibration using bacterial suspension containing known quantity of Escherichia coli and Staphylococcus aureus, the improved luminometer was used to measure more than 500 food samples. The results showed a satisfactory linear response (R = 0.858) when comparing with the results of conventional plate count method in the bacterial concentration range from 10 to 10~8 cfu/mL. The reproducibility of the luminometer was tested by 12 tests of standard E. coli and S. aureus suspension and the coefficient variation was 8.1%.