Bacterial Growth Monitoring and RNA Isolation

Bacterial cultures were grown in the 1.0x and 0.5x Tryptic Soy Broth (Merck Millipore, Darmstadt, Germany). For Arthrobacter sp., Bacillus sp., Pseudomonas sp., and Rhodococcus sp., inoculation (1% vol/vol) was performed using fresh bacterial cultures grown on Tryptic Soy Agar plates at 30°C. Inocula (OD₆₀₀ = 2) were prepared in the respective sterile growth medium. Bacterial cultures were grown in an orbital shaker Multitron Standard (Infors AG, Bottmingen-Basel, Switzerland) at 30°C, 180 rpm. Growth of the culture was monitored by measuring optical density at 600 nm. For Streptomyces sp., the growth curve was constructed according to Manteca et al. (2005) (link) using a diphenylamine colorimetric method (Zhao et al., 2013 (link)). Sampling of all the strains was performed in the middle of the exponential growth phase, at the transition phase, and at the beginning of the stationary growth phase. RNA isolation was done using the GeneJET RNA Purification Kit (Thermo Fisher Scientific) according to the manufacturer’s instructions. The integrity of RNA samples was analyzed using 1% agarose gel. RNA samples were stored at –20°C until use.