Silicate-rich, ordinary ocean beach sand was found to concentrate dissolved DNA from seawater over 10,000-fold, providing a rich, renewable, and easily accessible genetic library that is easy to harvest and inexpensive to process. We found an average of 29 microg/ml of cell-free DNA adsorbed to silicate-rich, wave-washed sand from 14 beaches bordering 9 seas around the world. The physical length of this DNA was 5 to 300 kb. The modal size was 30 kb. The apparent complexity exceeded 1.4 x 1011 nucleotides. The DNA adsorbed to wet sand from a reference site at Pacific Beach in San Diego, California, was shotgun cloned, colonies were randomly selected, and 3,107,399 nucleotides of anonymous, non-redundant sequence were analyzed. The modal GC content of the cloned sequences was 61%, with a range of 21%-84%. Open reading frames were found in all sequences, and ranged in size from 21% to 100% of the clone length. 2562 of the 2571 genes found were new, and 2218 encoded proteins that were similar to known proteins. Of these, approximately 90% of the amino acid sequences were similar to gene products from prokaryotic sources, 9% eukaryotic, and 1% viral. Genes from all kingdoms of life were represented. No significant contigs were found.
Pacific Beach Sand Metagenome
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