1977. Characterization of SPP: a temperate bacteriophage fromBocillrissrrbtilis 168M. Can. J . Microbial. 23: 45-51. Bocillrrs srrbtilis 168M is lysogenic for a temperate bacteriophage called SPP. The virus head is 76 nm wide by 82 nm long and the tail measures 12 by 358 nm. The DNA molecular weight is 62 million. SPP is spontaneously released at low levels in cultures of B. .slrbtilis 168M, and can be induced at higher levels by treatment with mitomycin C or N-methyl-N'-nitro-N-nitrosoguanidine.