| Description | Berberine, an alkaloid originally extracted from the plant Coptis chinensis and other herb
plants, has been used as a pharmacological substance for many years. The therapeutic
effect of berberine has been attributed to its interaction with nucleic acids and blocking cell
division. However, levels of berberine entering individual microbial cells minimal for growth
inhibition and its effects on bacterial spores have not been determined. In this work the
kinetics and levels of berberine accumulation by individual dormant and germinated spores
were measured by laser tweezers Raman spectroscopy and differential interference and
fluorescence microscopy, and effects of berberine on spore germination and outgrowth and
spore and growing cell viability were determined. The major conclusions from this work are
that: (1) colony formation from B. subtilis spores was blocked ~ 99% by 25 μg/mL berberine
plus 20 μg/mL INF55 (a multidrug resistance pump inhibitor); (2) 200 μg/mL berberine had
no effect on B. subtilis spore germination with L-valine, but spore outgrowth was completely
blocked; (3) berberine levels accumulated in single spores germinating with 25 μg/mL
berberine were > 10 mg/mL; (4) fluorescence microscopy showed that germinated spores
accumulated high-levels of berberine primarily in the spore core, while dormant spores
accumulated very low berberine levels primarily in spore coats; and (5) during germination,
uptake of berberine began at the time of commitment (T1) and reached a maximum after the
completion of CaDPA release (Trelease) and spore cortex lysis (Tlysis). | en_US |
