Copyright X 1993, American Society for Microbiology Characterization of Intergenic Spacers in Two rm of Enterococcus hirae ATCC 9790

and the intergenic spaces between them in Enterococcus hirae ATCC 9790 were cloned and sequenced. The intergenic space of one of these genes contains a tRNAA'a sequence, whereas the other does not. Nevertheless, the intergenic spaces contain several regions that exhibit high levels of sequence homology and are capable of forming structures with similar base pairs. An analysis of Southern blots of chromosomal DNA cut with one and two restriction enzymes indicated that E. hirae has a total of six ml operons. The study of sequences in the genes for rRNA is a powerful tool in bacterial taxonomy (23). Moreover, since related bacteria exhibit more similarities in their rRNA sequences than unrelated bacteria do, rRNA sequences are useful in studies of bacterial evolution (4, 22, 23). Less is known about homologies in the intergenic spaces between the 16S and 23S rRNA genes. Bott and Hollis found se-quence homology in three rrn operons of Bacillus subtilis that contained no tRNA sequences (3). In Escherichia coli, in which rRNA processing has been studied in some detail