Daniel Lim

Distinguished University Professor Emeritus





Pathogenic/Molecular/Applied Microbiology

Virulence mechanisms of pathogenic bacteria; rapid identification of pathogens; sample processing; biosensors; public health relevance of bacterial pathogens
My research focused on the characterization of virulence mechanisms in pathogenic bacteria and development of innovative technology to rapidly sample, detect and identify microbial pathogens in food, water, air, surfaces, and infectious diseases.

Conventional procedures to detect and identify pathogens from complex matrices can take days to perform and may provide inconclusive information.   Our research included development of LIM Broth, a selective enrichment broth to rapidly and selectively grow Streptococcus agalactiae (group B streptococci) – a major pathogen of newborn infants – for subsequent detection and identification by commercial immunoassays, PCR, and other detection assays.  LIM Broth is routinely used in the United States and other countries for diagnosis of group B streptococci in pregnant women and infants, and is available through various companies. Additional research in my laboratory involved development of sample processing procedures and detection assays for rapid, accurate, and reproducible identification of pathogenic microorganisms.

We developed rapid processing methods and concentration protocols for complex matrix samples such as ground beef, apple juice, produce, potable water, recreational water, human blood, and saliva, enabling such samples to be directly tested by biosensors and other detection platforms for target analytes.  Assays developed for agents such as Bacillus anthracis,E. coli O157:H7, Vibrio cholerae, Vaccinia virus, and ricin were optimized for reproducibility, sensitivity, and specificity, and tested on various detection platforms.  Assay protocols included orthogonal testing to improve detection specificity and automated concentration procedures to improve detection sensitivity. We studied problems associated with target analyte capture efficiency and developed methods to improve capture efficiency and assay sensitivity using antibodies and other capture molecules.

A Portable Multi-Use Automated Concentration System (PMACS) that uses dead-end ultrafiltration to rapidly (up to 4 liters per minute) concentrate low levels of microbial pathogens and other particulates from large volumes (10 to >100 liters) of water and produce wash was developed by my research staff.  The PMACS has been extensively field tested and validated at water utilities, recreational and other water sites (beach water, river water, source water, Florida deep well aquifer water), cooling towers, and with leafy green produce wash, and continues to be used by researchers.
This research, which was performed in close collaboration with federal and local public health agencies, food processors, and water utilities, was supported by the Department of Defense, NIH, NSF, EPA, USDA, and other agencies.