Two Streptococcus gordonii strains, identical except for the site of single insertion of a reporter gene in ribosomal RNA (rrn) operons, exhibit different growth kinetics and phenotypes when grown under agitated conditions in bioreactors. Under such conditions, viability and membrane integrity of S. gordonii derivative MSP818 were found to be lower than those of MSP812. Flow cytometric protocols were adapted and optimized for Gram-positive streptococci to study these effects at the population level. Unit genome content of S. gordonii was estimated as 1.97 Mb by comparing integral modes observed in DNA content distributions with those of E. coli standards, and this corresponded very well with the estimate obtained using pulsed-field gel electrophoresis (2.13 Mb). Analysis of single chain light scattering intensity, protein, and DNA content distributions of the two strains during batch growth suggests that shear sensitivity of MSP818 and differences in chain length between the two strains significantly affect their growth kinetics. Copyright (C) 1999 Elsevier Science B.V.
Bibliographical noteFunding Information:
The authors would like to thank Dr. William F. Liljemark and Cynthia G. Bloomquist, Department of Diagnostic and Surgical Sciences, University of Minnesota, for their technical advice. This work was supported by the 3M Dental Materials Center at the University of Minnesota.
- Cell enumeration
- Chain formation
- DNA staining
- Flow Cytometry
- Protein staining