Genetics of Streptococci, Lactococci, and Enterococci: Review of the Sixth International Conference (2002)

The Sixth International Conference on Streptococcal, Lactococcal, and Enterococcal Genetics, sponsored by the American Society for Microbiology, convened 14 to 17 April, 2002, in Asheville, N.C. From its inception in 1981, this conference has highlighted the best science in the field and has provided a forum for young investigators to present their work, often for the first time, to an international audience. This year's conference continued both traditions, with 39 outstanding presentations from established and young investigators alike, along with 150 poster presentations from among the more than 250 attendees of the meeting. Many of the contributions to the meeting are highlighted in this review, and a number of related articles appear in this issue of the Journal of Bacteriology (1, 5, 10, 13, 16-18, 24, 25).

The streptococci have played a central role in the development of bacterial genetics, beginning with experiments described by Griffith in 1928, in which he provided the first demonstration of bacterial gene transfer (12). Those experiments, involving Streptococcus pneumoniae, were the first description of genetic transformation in bacteria and led to the discovery in 1944 by Avery, MacLeod, and McCarty that DNA was the “transforming principle” of Griffith's experiments and hence the genetic material (2). Since the first streptococcal-genetics meeting, the lactococci and enterococci have been designated as separate genera; antibiotic resistance has increased from an emerging observation to a worldwide health issue; historic observations such as Griffith's capsule transformation have been described at the molecular genetic level; and the gene transfer systems, plasmids, phage, and transposons that first brought streptococcal researchers together now provide the tools for dissecting metabolic and virulence pathways, while still maintaining their own allure. The present time represents another significant era in the history of the streptococci, as we witness the completion of the genome sequences of many streptococcal, lactococcal, and enterococcal species (3, 4, 8, 11a, 14, 26, 27a, 28) and begin the transcriptional and proteomic analyses that will lead us to an unprecedented understanding of the regulatory events that take place within the cell.

The opening lecture by Claire Fraser (The Institute for Genomic Research, Rockville, Md.) provided an overview of the genomic revolution and set the scene for a number of presentations on genomes of Streptococcus, Enterococcus, and Lactococcus species. The next frontiers, made possible by newly developed technologies, will be the discovery and analyses of genomes of yet-to-be-cultured microbes and the genomic analyses of microbes colonizing the oral cavity, respiratory tract, and intestinal system of the human body. Moreover, with the increasing number of known genome sequences and the exploding number to come, comparative genomic analysis will be a powerful tool with which to monitor microbial evolution and will provide insights into the multiple processes that shape microbial diversity. A special case that may become a paradigm in this area is the comparative sequence analysis of seven strains of Bacillus anthracis. The chromosomal sequence comparison of two related strains revealed the presence of only two short inserted or deleted sequences (indels) and two single-nucleotide polymorphisms (SNPs) in their 5.2-Mb chromosomes, while a few dozen more SNPs were found on each of the two plasmids (23). This detailed genomic analysis allowed for an unprecedented distinction at the strain level, revealing a powerful tool for investigating infectious-disease outbreaks. Other medical applications relevant for the pathogenic streptococci involve the discovery of new drug targets and the identification of candidates for vaccine production. However, the challenges ahead deal with all areas of microbiology and include analysis of gene expression under natural conditions, identification of regulatory networks, and expansion and continuous curating of microbial databases, for which there is an urgent need.