The seemingly mysterious multiplication of the bacteria in the growth rate curve. Bacteria is easy to culture in the lab it takes little time to divide. It grows by process called binary fission by dividing itself after replicating its genetic material. Bacteria growth rate curve is a hyperbolic parabola and it is divided in four phases.
The first phase is the log phase where the bacteria grows slowly mostly in size as it consumes nutrient for biochemical and physiological functions. Growth is slow and it explains while it took time for the bacteria to fill the bottle at first.
The second phase is the log phase. It is also referred to as the exponential phase as the bacteria grows rapidly in a geometric progression. It explains while it took lesser time to fill the bottles compared to the initial stage. The last two stages of bacteria is the stationary and decline phases.