title: Staggered mock community from the Santa Barbara Channel
design: For cell lysis, 6 ml of sucrose lysis buffer, 600 l of sodium dodecyl sulfate (10% w/v) and 60 l of 20 mg ml-1 proteinase K to each polyethylene bag.  Bags were then resealed and incubated at 55C for 60 min. DNA was extracted following the phenol and chloroform protocol of Giovannoni et al 1990. Amplification of the V4 region of the 16S rRNA gene was performed using the 515F-Y (5-GTGYCAGCMGCCGCGGTAA-3) and 806RB (5-GGACTACNVGGGTWTCTAAT-3) primers with custom adapters