This lecture dives into the nutritional needs, growth behaviors, and chemical defenses against microorganisms. It explores how bacteria acquire vital elements such as nitrogen and carbon, sorting them into autotrophs, phototrophs, or chemotrophs based on their energy and food sources. The material unpacks the process of binary fission and reveals how biofilms form as resilient microbial communities that defy standard cleaning methods. It also highlights how environmental factors, such as temperature, shape bacterial growth and affect food safety. Lastly, the effectiveness of disinfectants such as halogens, alcohols, and heavy metals is tested using the disc diffusion meth ...