3 16pk centrifuge

The cell density was followed by measuring the optical density of the culture at 620 nm (OD_620nm) using UV–Vis spectrophotometer (Ultrospec 1000 (Pharmacia Biotech, Sweden). The cell dry weight (CDW) was determined by centrifugation (Sigma 3-16PK centrifuge) of 5 mL fermentation broth at 4000 g for 20 min in a dried preweighed tube and drying the cell pellet for 12 h at 100 °C in an oven before weighing again and correlating with the volume.
Glycerol, propionic acid, acetic acid, succinic acid, and other minor metabolites were analyzed by HPLC (Jasco) equipped with Aminex HPX-87H organic acid analysis column (Bio-rad, Hercules, California, USA), CTO-6A oven (Shimadzu, Kyoto, Japan), Jasco AS 950–10 intelligent pump, PU 980 automatic intelligent injector (Jasco), and ERC 7515A refractive index detector (ERC, Saitama, Japan). Samples were diluted in MilliQ quality water, acidified with 20% (v/v) H₂SO₄ (20 μL per 1 mL of the sample), and then filtered through a 0.45 μm syringe filter prior to analysis. Chromatography was performed using 5 mM H₂SO₄ as mobile phase flowing at a rate of 0.6 mL/min, column temperature was maintained at 55 °C, and RI detector temperature at 30 °C.

Cells (1–4 × 10⁵) were centrifuged at 300 × g_av for 6 min at RT, supernatant removed, resuspended in 200 μl of medium and centrifuged onto poly‐lysine coated microscope slides (Sigma 3‐16 PK centrifuge with a cytology rotor) at 60 × g_av for 4 min at RT. Slides were left to air dry overnight, stained using Leishman's stain (VWR International, Radnor, PA, USA) and mounted with mounting medium and a glass coverslip. Slides were examined by bright field microscopy using an Eclipse Ti (Nikon, Tokyo, Japan) at 40× magnification.

A pure phage stock was prepared using double-layer agar cultures. Briefly, a phage lysate with a titer of about 1×10¹⁰ PFU/ml to cause a nearly confluent lysis was mixed with 1 ml of the overnight bacterial culture, molten pre-cooled soft agar (TSB broth with 0.6% agarose, 500 ml portioned into 10 ml batches) and spread on the surface of TSA (Tryptone Soy Agar) plates. After an overnight incubation in 30°C, the upper layer was scraped from the plates and resuspended in 1 l of SM buffer. The mixture was vigorously shaken (700 rpm/1 h/30°C/Corning® LSE™ Shaking Incubator), treated with DNase I (0.5 U/ml; 2 h/37°C), centrifuged (3,076 × g/15 min/4°C/Sigma 3-16PK centrifuge) and the collected supernatant was titered.