Strains MP1T and 12 grew in the relatively narrow pH range of 5.5–7.3, with the optimum at pH 6.6–7.2. The temperature range for growth of these methanotrophs was 8–45 °C, with the optimum at 35 °C (Fig. 2). No growth occurred at 4 and 48 °C. Low concentrations of NaCl (0.5 %, w/v) stimulated growth of strains MP1T and 12, while the presence of NaCl in a cultivation medium at the concentration of ≥ 1 % (w/v) inhibited growth of these methanotrophs.