ZnPO4 + CL2
The remaining water from each microcosm was aseptically quantified by graduated cylinder and harvested by vacuum filtration onto a 0.22 m Millipore Express PLUS Membrane filter (MilliporeSigma, Burlington, MA). Filters were placed into sterile 2 mL tubes and stored at -20C until DNA was extracted. For DNA extraction, the manufacturers protocol for the FastDNA Spin Kit (MP Biomedicals, Solon, OH) was used except for the initial cell lysis steps. For this process, the plastic tubes were placed in liquid nitrogen and filters were homogenized by grinding with a sterile pipet tip. To break open cells, the CLS-TC lysis buffer (1.0 mL) was added, and the tube was subjected to freeze-thaw cycles (x3) in liquid nitrogen and thawing at room temperature with vortexing between cycles (Harrison et al., 2020; Kappell et al., 2019).