Detection of 16S rDNA of CandidatusLiberibacter asiaticus in Orange Juice by Quantitative Real-time PCR

Orange juice processed from Huanglongbing (HLB) affected fruit is often associated with bitter taste and/or off-flavor. HLB disease in Florida is associated with CandidatusLiberibacter asiaticus (CLas), a phloem limited bacterium. The current standard to confirm CLas for citrus trees is to take samples from midribs of leaves, which are rich in phloem tissues, and use quantitative real-time polymerase chain reaction (qPCR) test to detect 16S rDNA gene of CLas. It is extremely difficult to detect CLas in orange juice because of the low CLas population, high sugar and pectin concentration, low pH and possible existence of an inhibitor to DNA amplification. The objective of this research was to improve extraction of DNA from orange juice, and detection of CLas by qPCR.