Final answer:
Julia's objective is to investigate the relationship between temperature and bacterial growth, which includes observing effects, determining optimal growth temperature, and comparing the growth of B. subtilis at different temperatures.
Step-by-step explanation:
Julia's objective in this experiment is multifaceted; however, it is most accurately described as aiming to investigate the relationship between temperature and bacterial growth. This encompasses observing the effect of varying temperatures on the growth of Bacillus subtilis (B. subtilis) bacteria, determining the optimal temperature for their growth, and comparing their growth at different temperatures. By measuring and recording the bacteria's growth in each Petri dish over a two-week period set at different temperatures, Julia is conducting an experiment that is a classic example of how environmental factors, such as temperature, can affect the growth rate and sustainability of bacterial cultures.
The experiment takes into consideration mesophilic bacteria, which prefer the temperature range of 20-40°C, with some growing best at body temperature (approximately 37°C) and others at room temperature (approximately 25°C). The methodical approach includes maintaining cultures in an incubator, monitoring bacterial growth indicated by cloudiness in broths, and ensuring that these cultures are not compromised by dehydration or condensation during incubation. The goal is to provide the bacteria with a constant and suitable growth temperature, as part of the conditions necessary for optimal microbial proliferation in a laboratory setting.