Protocol optimisation
2.1.1. Samples
AS samples were collected from a nitrifying domestic wastewater
treatment plant (WWTP) in Tudhoe Mill, Durham,
United Kingdom (UK), in March 2013. Samples were collected
in polypropylene containers, stored at ~4 C during transit and
fixed within 2 h, as previously reported by Brussaard et al.
(2010). Briefly 1 mL aliquots of each sample were transferred
to 2 mL cryovials and fixed at a final concentration of 0.5%
Glutaraldehyde for 15e30 min at 4 C in the dark. After fixation
aliquots were flash frozen in liquid nitrogen and stored at
80 C. Samples were thawed at room temperature and mixed
via manual shaking for 10 s prior to pre-treatment. Once
established optimal pre-treatments were used in subsequent
experiments.
2.1.2. Pre-treatments for dislodgment of floc bound viruses
2.1.2.1. Chemical treatment. Four dispersants, the surfactants
e polyoxyethylene-sorbitan monooleate (Tween 80, Sigma)
and Triton X-100 (TX, Sigma), and the ionic dispersants