Ampicillin

Enterococcal strains used in the study were obtained from the Biodefense and Emerging Infections Research Resources Repository (BEI Resources) (Manassas, VA, USA), and the American Type Culture Collection (ATCC) (Manassas, VA, USA). Media and reagents were purchased from commercial vendors: tryptic soy broth (TSB), tryptic soy agar (TSA), enterococcosel agar (Becton, Dickinson and Company, Cockeysville, MD, USA), and phosphate-buffered saline (PBS) (Corning, Manassas, VA, USA). Drugs used in the study were purchased commercially: dorzolamide (TCI America, Portland, OR, USA), linezolid and vancomycin (Chem-Impex International, Wood Dale, IL, USA), and ampicillin (IBI Scientific, Peosta, IA, USA).

For all experiments single colonies were picked from Luria–Bertani (LB) agar plates, inoculated in 5 mL LB media pre-cultures and grown overnight at 37 °C [29 ]. These 5 mL cultures were then used to start larger 50 mL cultures. Larger cultures consisted of a modified M9 minimal media containing: M9 salts (Na₂HPO₄, KH₂PO₄, NaCl, NH₄Cl, Becton, Dickinson and Co, Sparks, MD), supplemented with 1.75 % (w/v) glucose (ACS grade, Acros Organics, Fair Lawn, NJ), 0.2 % (w/v) yeast extract (Becton, Dickinson and Co, Sparks, MD), and 100 µg/ml ampicillin (IBI Scientific, Peosta, IA). The addition of small amounts of yeast extract to the culture has been shown to increase PHB yields [27 (link), 30 (link)]. The 50 mL culture was grown overnight in an orbital shaker table at 37 °C and 220 rpm and was used to seed 1 L fermentors of the same media composition. For PHB production studies using fermentors, 0.1 mM Isopropyl β-d-1-thiogalactopyranoside (IPTG) (Gold Biotechnology, Inc. St. Louis, MO) was added at the start of the fermentation (t = 0 h).