Which method can be used to estimate the density of bacteria in a culture aside from dilution plating?

Using microscopy with a haemocytometer is a reliable method for estimating the density of bacteria in a culture. This approach involves counting the number of bacteria present in a specific volume of the culture by placing a small sample onto a specially designed slide (haemocytometer) that has a grid etched onto it. Each square of the grid represents a known volume, allowing for accurate calculations to determine the concentration of bacteria.

This method offers precision, especially when used carefully, as it enables direct visual observation and counting of bacterial cells. Additionally, it is a quicker method compared to dilution plating, which requires multiple steps and time for colonies to develop, making microscopy a practical alternative for real-time density estimation.

The other options presented do not serve as effective alternative methods for estimating bacterial density. Visual inspection under natural light lacks the precision and quantification needed for density measurements. Freezing and thawing the culture may disrupt the bacteria and introduce variability, and measuring the temperature of the culture does not provide any information about the bacterial density itself.