Question

(a) An estimate for the number of phages on Earth can be obtained using data from Bergh et al. \((1989) .\) By taking water samples from lakes and oceans and counting the various phages, one arrives at counts of the order of \(10^{6}-10^{7}\) phages/mL. Using reasonable assumptions about the amount of water on Earth, make an estimate of the number of phages. (b) Work out the mass of all of the phage particles on the Earth using your result from (a). (Problem suggested by Sherwood Casjens.)

Short answer

The estimated number of phages on Earth is between \(1.332 \times 10^{24}\) and \(1.332 \times 10^{25}\), with a corresponding mass of between \(1.332 \times 10^{6}\) and \(1.332 \times 10^{7}\) grams.

Step-by-step solution

Estimate the number of phages

Bergh's data suggests there are between \(10^{6}\) and \(10^{7}\) phages per milliliter of water. To estimate the total number of phages on Earth, the volume of the Earth's water needs to be estimated. A commonly used estimation is approximately \(1.332 \times 10^{18}\) liters of water on Earth. Note that 1 liter is equivalent to 1000 milliliters. Multiply the range of phages/mL (\(10^{6}-10^{7}\)) with the volume of water on Earth, expressed in milliliters. So, the estimated total number of phages on Earth would be between \(1.332 \times 10^{24}\) and \(1.332 \times 10^{25}\).

Estimate the mass of all phages

After estimating the number of phages, calculate their total mass. The mass of a single phage is approximately \(10^{-18}\) grams. Multiply the estimated number of phages on Earth by the mass of a single phage. The total mass of all the phages on Earth would therefore be between \(1.332 \times 10^{6}\) and \(1.332 \times 10^{7}\) grams.

Key concepts

Phage Estimation

Phages, or bacteriophages, are a type of virus that infects bacteria. They are extremely tiny but immensely numerous, especially in aquatic environments like lakes and oceans. To estimate the total number of phages on Earth, we rely on previous microbial analyses, such as the study by Bergh et al. This study reveals that there are between \(10^{6}\) and \(10^{7}\) phages in each milliliter of water. To make calculations more manageable, we must know the Earth's total water volume. It is estimated that Earth has \(1.332 \times 10^{18}\) liters of water. Since 1 liter equals 1,000 milliliters, this conversion is essential for find the total number of milliliters.Once we have these figures, calculate the total number of phages by multiplying the phage concentration per milliliter by Earth's total water volume in milliliters. The estimates reveal an astonishing range of \(1.332 \times 10^{24}\) to \(1.332 \times 10^{25}\) phages across the globe. Understanding the sheer number of these tiny organisms highlights the incredible magnitude of microbial life and its important role in ecosystems.

Microbiology Calculations

Biological calculations often involve dealing with extremely small entities like phages or bacteria. Precision is crucial when estimating counts or sizes, serving as a cornerstone of microbiological analysis. The calculations begin by identifying the concentration of the target organism in a manageable sample size (e.g., milliliters). Next, you multiply this concentration by the total available space or volume (like Earth's water volume) to estimate the overall count. This extrapolation requires careful conversions of units for accuracy. For example: - Use initial values, such as phage concentration from a sample. - Convert necessary units, like liters to milliliters. - Multiply to expand the estimate to larger scales. These steps provide indispensable insights important for microbiology research, shedding light on the dynamics of life at microscopic scales.

Earth's Water Volume

Understanding the Earth's water volume is critical for various scientific calculations, such as estimating global phage numbers. Earth consists predominantly of water, distributed in oceans, lakes, rivers, and ice caps.The commonly used estimation for Earth's water volume is about \(1.332 \times 10^{18}\) liters. When performing calculations involving microorganisms per mL, knowing the total water in milliliters (or converting from liters) is key. Since 1,000 milliliters equal 1 liter, converting \(1.332 \times 10^{18}\) liters to milliliters results in \(1.332 \times 10^{21}\) milliliters.This volume represents the combined capacity of our planet's bodies of water to host microbial life, making it vital for accurate biosphere estimations.

Mass Calculation in Biology

Calculating mass in biology, particularly for tiny entities like phages, involves using estimated counts of these microorganisms and their individual mass. The individual mass of a phage is estimated at approximately \(10^{-18}\) grams. To find the total mass of all phages on Earth, multiply their estimated number by the mass of a single phage. This calculation is as follows:- Estimate phages: e.g., between \(1.332 \times 10^{24}\) and \(1.332 \times 10^{25}\).- Multiply these figures by \(10^{-18}\) grams.This results in a total mass ranging from \(1.332 \times 10^{6}\) to \(1.332 \times 10^{7}\) grams. Though their combined weight is substantial, it illustrates the enormous number yet tiny scale of individual phages. Understanding these mass calculations is key to appreciating the physical presence of minute biological agents worldwide.