There are various parameters to assess microbial growth. What are some microbial growth curve characteristics? Can you explain how microbiologists measure specifically bacteria growth?

What is the difference between a bactericidal antibiotic and an antibiotic that is bacteriostatic? Examine the zone of inhibition around each disk for the presence of micro colonies within the zone. What do these micro colonies represent? Why didn't plants evolve anti-microbial agents against all the microbes in their environment?

1. Plate count data are used to calculate microbial population density as colony forming units (CFUs) per milliliter of culture. Culture density (CFU/mL) = number of colonies (dilution factor) x (volume plated, in mL) Use these data below to calculate the CFU/mL in this sample of bacteria after 1 hr of growth. **Important to know for these types of questions - only use colony counts that fall between 10 and 300. TNTC = too numerous to count, so many colonies that you can't distinguish them to count. Use the plates with numbers of colonies that can be counted, calculate the CFU on each one, and then calculate the average between all of them. Looking for more assistance? Read section 7.3 in the textbook. Time 1h Dilution (before plating) Volume spread on plate 0.1 mL 0.1 mL 0.1 mL 0.1 mL none 1:10 (1 x 10-¹) 1:100 (1 x 10-²) 1:1,000 (1 x 10-³) Number of colonies observed (replicate plates) TNTC 499 83 10 TNTC 518 87 8 TNTC indicates too numerous to count. *Cell density could not be…

Please discuss the different environmental factors that influence microbial growth. What would be the basic profile of a microbe pathogenic to humans?

Compare and contrast bacteriocidal, bacteriostatic and bacteriolytic agents. What are their effects on the optical density (OD) and viable count of a bacterial culture, respectively?

What is the difference between selective and differential media? Give one example of each.

Why do soil microbes naturally produce antibiotics?

What is the major difference between an enrichment culture and a selective culture? Why are microbial doubling times in nature typically longer than those obtained in the lab? Briefly describe the following mechanisms of measuring bacterial growth: Direct microscopic cell count Plate count Most probable number

Is nutrient agar (NA)  a complex or defined medium? Explained based on its composition. Is NA a differential, selective, neither differential nor selective media? Explaining based on what kind of Organism it allows to grow?

Describe methods used to grow microbes anaerobically and under high CO2 conditions