Growth of Bacillus subtilis NRS-762, Pseudomonas aeruginosa PRD-10, Pseudomonas protegens Pf-5, Escherichia coli DH5α, and Chromobacterium violaceum on LB Lennox agar

LB Lennox medium is commonly used for cultivating various bacterial species to relatively high cell density, and it has helped the elucidation of many interesting facets of bacterial genetics and cell biology. Thus, five common bacteria: Bacillus subtilis NRS-762 (ATCC 8473), Pseudomonas aeruginosa PRD-10 (ATCC 15442), Pseudomonas protegens Pf-5 (ATCC BAA-477), Escherichia coli DH5α (ATCC 53868), and Chromobacterium violaceum (ATCC 12472) were grown on LB Lennox agar for understanding their growth characteristics. Experiment results revealed that all five bacterial species could grow to relatively high cell density on LB Lennox agar. Specifically, B. subtilis NRS-762’s growth on LB Lennox agar at 30 ^oC generated beige round colonies that lacked swarming motility typical of this species, which highlighted that possible genetic mutations in the pathway responsible for swarming motility may be harboured by the bacterium. Similarly, P. aeruginosa PRD-10 did not exhibit swarming motility during growth on LB Lennox agar at 37 ^oC, but the bacterium generated small, round, greenish yellow colonies together with the secretion of significant quantities of greenish yellow pigment into the agar. P. protegens Pf-5 also generated small, round, greenish yellow colonies during growth on LB Lennox agar at 30 ^oC. However, no greenish yellow pigment was secreted into the agar, and swarming motility was not observed in the species. E. coli DH5α, on the other hand, grew well on LB Lennox agar at 37 ^oC with the generation of small, round, beige colonies with no swarming motility. C. violaceum also grew to relatively high cell density on LB Lennox agar at 30 ^oC, where small, round, purple, mucoid colonies were recovered with no swarming motility detected. Violacein purple pigment was secreted in significant quantities, but adhered to the cells strongly without diffusing into the agar. Collectively, B. subtilis NRS-762, P. aeruginosa PRD-10, P. protegens Pf-5, E. coli DH5α, and C. violaceum grew well on LB Lennox agar at appropriate temperatures, and exhibited growth characteristics and motility modes that could yield many interesting findings concerning nutritional stress response, swarming motility, nutrient utilization, and metabolism. Thus, LB Lennox agar may be a suitable medium for the five bacterial species as researchers attempt to unravel their molecular mysteries in responding to nutritional and environmental stressors, antibiotic production, as well as motility mode.