Acholeplasma vituli sp nov., from bovine serum and cell cultures

Organisms isolated from commercial foetal bovine serum and from cell cultur e lines containing such serum supplements were found to consist of non-heli cal, non-motile, pleomorphic coccoid forms. One strain (FC 097-2(T)) cultiv ated directly from foetal bovine serum was selected for characterization. I n ultrastructural examination, individual round cells lacked cell wall stru ctures and cells varied in sire, with a mean diameter of about 700 nm. Howe ver, variable numbers of cells were filterable through membranes of 300 nm. Optimum growth occurred between 30 and 37 degrees C. The organism fermente d glucose, fructose and mannose, but did not hydrolyse arginine. The strain was insensitive to 500 U penicillin ml(-1) and was capable of growing in t he absence of serum or cholesterol. The organism was serologically distinct from all 13 currently described species in the genus Acholeplasma and from other sterol-requiring species in the genus Mycoplasma, using growth inhib ition, immunoperoxidase and immunofluorescence tests. Strain FC 097-2(T) wa s found to have a DNA G+C composition between 37.6+/-1 mol% and 38.3+/-1 mo l%. The genome size was determined to be 2095 kbp. The 16S rDNA sequence of strain FC 097-2(T) was compared to 16S rDNA sequences of other mollicutes in nucleotide databases. No deposited sequence was found to be identical; t he closest relatives were several members of the genus Acholeplasma. On the basis of these findings and other similarities to acholeplasmas in morphol ogy and growth, the! absence of a sterol requirement for growth, and simila r genomic characteristics, the organism was assigned to the genus Acholepla sma. Strain FC 097-2(T) is designated the type strain (ATCC 700667(T)) of a new species, Acholeplasma vituli.