Bivariable model for determining the optimal growth conditions of plant growth-promoting bacteria

The bacterial growth curve graphically represents the development of a bacterial population over time. This analysis is essential to optimize efficiency in research with microorganisms. The research aimed to identify the temperature and time at which bacterial growth reaches the stationary phase and obtain the point of maximum performance. Four species of growth-promoting bacteria were evaluated: Pseudomonas fluorescens, Bacillus aryabhattai, Bacillus subtilis and Azospirillum brasilense, subjected to temperatures of 25 °C, 30 °C and 35 °C. The bacteria were inoculated in a nutrient solution and incubated in a water bath. Samples were taken at four-hour intervals for serial dilution and plating. The colony-forming units (CFUs) were counted every 12 hours. Pseudomonas fluorescens showed maximum growth at 29.9 °C and 52.3 hours. Bacillus aryabhattai reached maximum growth at 25 °C in 48 hours. Bacillus subtilis had maximum growth at 24.1 °C and 47.2 hours. Azospirillum brasilense reached maximum growth at 25.9 °C and 42.5 hours. The results indicate that temperature variations significantly influence the growth of the bacteria analyzed. Based on this research, it is possible to adjust laboratory methodologies to improve the efficiency of microorganism production processes.