Method for absolute quantification of microbial communities by using both microarrays and competitive PCR

Area of Science:

• Microbiology
• Molecular Biology
• Bioinformatics

Background:

• Accurate quantification of bacterial communities is crucial but remains challenging.
• Existing methods often lack the precision for determining absolute bacterial numbers.
• Development of reliable techniques for bacterial enumeration is an ongoing need.

Purpose of the Study:

• To evaluate a novel method combining competitive PCR (cPCR) and microarray assays.
• To determine the absolute content of total bacteria and individual bacterial species in samples.
• To establish a reliable quantification method for complex bacterial communities.

Main Methods:

• Development of a competitor DNA for cPCR and DNA probes for microarray analysis.
• Generation of a calibration curve using genomic DNA standards for cPCR.
• Calculation of hybridization affinity ratio using regression analysis of probe signals.
• Quantification of 16S rRNA gene copy numbers and bacterial genomes using the combined method.
• Validation of results against quantitative real-time PCR (qPCR).

Main Results:

• The cPCR and microarray method successfully quantified total bacteria and specific species.
• Results showed good agreement with qPCR, with an average ratio of 1.53-fold for values >10^2 copies.
• The method demonstrated its utility in quantifying multiple bacterial types simultaneously.

Conclusions:

• The combined cPCR and microarray assay provides a robust and accurate method for bacterial quantification.
• This technique is valuable for determining the absolute abundance of diverse bacterial populations in various samples.
• The developed method contributes to advancing the field of microbial community analysis.