The complete nucleotide sequence (580,070 base pairs) of the Mycoplasma genitalium genome, the smallest known genome of any free-living organism, has been determined by whole-genome random sequencing and assembly. A total of only 470 predicted coding regions were identified that include genes required for DNA replication, transcription and translation, DNA repair, cellular transport, and energy metabolism. Comparison of this genome to that of Haemophilus influenzae suggests that differences in genome content are reflected as profound differences in physiology and metabolic capacity between these two organisms.

We have characterized a family of repetitive DNA elements with homology to the MgPa cellular adhesion operon of Mycoplasma genitalium, a

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Cultures of Bacillus subtilis developed competence for the uptake of deoxyribonucleic acid in a chemically defined medium with a predictable, reproducible pattern. The gross effects of individual amino acids were determined. Seven amino acids, most of which are reported to be major components of the cell wall, were shown to impair the development of maximal levels of competence. When the synthetic growth medium was supplemented with a mixture of the nine amino acids which we found to stimulate the development of competence, the level of transfection was increased to 10 to 15% of the population. The actual level of competence in these populations was assayed by transformation of unlinked bacterial markers and by two different transfection assays. The results indicate that calculations from cotransfer of unlinked markers overestimates the degree of competence in highly competent populations of B. subtilis, whereas the number of plaques obtained in transfection is an underestimate of the actual level of competence. The results are interpreted to indicate that neither method of analysis gives a true estimate of the competent population, but that more than 80% of the cells may be competent.

A total of 508 random clones from five Mycoplasma genitalium genomic libraries were partially sequenced and analyzed. This resulted in the identification of 291 unique contigs. Sequence information from these clones (100,993 nucleotides), representing approximately 17% of this pathogen's genome, was analyzed by comparison to the DNA and protein sequence data bases. The frequency with which clones could be identified, by virtue of possessing homology to another data base entry, was 46%. Sequence analysis indicated the following. (i) The M. genitalium genome contains many genes involved in various metabolic processes. (ii) Repetitive DNA may comprise as much as 4% of this genome. (iii) The MgPa adhesin gene may be the result of horizontal transfer from an unknown origin. (iv) Not all dinucleotide pairs are present in this genome at the expected frequency. (v) This genome potentially encodes approximately 390 proteins and makes very efficient use of its limited amount of DNA. In addition, this study allowed us to estimate the number of genes involved with various cellular functions.