DNA extracted from 1 gram of soil: 1000 ng
Normal size of a bacterial chromosome: 4.6 Mbp
Average mass of nucleic acids: 660 Da/bp=1.096×10^(-12) ng/bp
Molecular weight of a bacterial chromosome: 5.039×10^(-6) ng
Assume the copy number of a target gene with a desired function: 1 per chromosome
Assume the percentage of that class of genes among all: 1%
Copy number of one such gene in 1 gram of soil: 1.984×10^(6) copies
Clones need to build a genomic library for soil bacteria: ~1984000 clones
If we could get 1000 successful clones from each experiment, this means we need at least ~1984 experiments. Sequencing such a library is LABORIOUS!!!
pUC18 size: 2.6kb=2.8496×10(-12) ug
Transformation efficiency: 1×10^(9) CFU/1 ug of plasmid=1 CFU/350 copy of plasmid
Because of this hit rate, the actual work would be much more!!!
