I have sequenced several metagenomes of complex communities from AD. The assembly of reads was done with Megahit, mapping of reads was done with Bowtie2 and produced coverage.txt file (col 1= contig, col 2 = coverage, col 3 = contig length) e.g.

1 0.901 1005

2 5.89 1323

3 0.905 1168

4 2.435 301

Next, I have pulled out 16S rRNA reads using blastn and gg_13_8 database. How can I use the coverage.txt file to calculate abundance of 16S rRNA reads in my metagenome?