HORIZONTAL GENE TRANSFER. “The transduction frequency varied over orders of magnitude from 10(-8) to 10(-5) per virus…there might be up to 100 transductants l(-1) day(-1) or up to 1.3 × 10(14) transductants per year in Tampa Bay.”
http://onlinelibrary.wiley.com/doi/10.1046/j.1462-2920.2003.00539.x/full