Final answer:
All light passing through an inoculated test tube during a Turbidity test indicates a low count of bacteria, since greater bacterial density causes more light to be scattered, reducing transmission. It is crucial to compare with a control containing only broth to ensure accurate turbidity attribution to bacterial presence.
Step-by-step explanation:
If all the light passed through the inoculated test tube during the Turbidity test, it suggests that the count of bacteria would be low. This is because the principle behind the turbidity test is that a higher cell density of bacteria in the suspension results in greater turbidity, which in turn scatters more light and allows less to pass through the sample. Thus, more light transmission indicates less scattering by bacteria, pointing to a lower bacterial count.
Measuring the transmission of light through a control tube with only broth is important because it establishes a baseline or reference for zero turbidity. This comparison is crucial to ensure that any absorbance or light blockage is attributed to bacterial growth and not to the medium itself.
A clear thioglycolate medium culture tube, with dense growth only at the bottom, implies that the bacteria present are likely anaerobic or microaerophilic since they are growing where the oxygen concentration is lowest.
Spectrophotometers are instrumental in measuring turbidity. They work by transmitting a light beam through a bacterial suspension and measuring the light that reaches a detector. Calibration curves, developed by correlating measured turbidity with actual viable cell counts, enable estimation of bacterial numbers in samples that fall within the calibration range.