Chapter 30, Problem 1CHI

The unicellular cyanobacterium Prochlorococcus sp. is the most abundant photosynthetic microbe in tropical and subtropical oceans. At least two ecotypes exist: one is adapted to high light and the other to lower light intensities. How does the presence of these two ecotypes contribute to their physiological success and their numerical success? How would you determine the amount of fixed carbon they contribute to these open-ocean ecosystems?

Summary Introduction

To determine: The way in which presence of two ecotypes (one adapted to high light and other to lower light) contribute to the physiological and numerical success of cyanobacterium Prochlorococcus sp.

Introduction: Prochlorococcus are green, small, and unicellular bacteria having chlorophyll a and chlorophyll b pigments. The species of this bacterium exist in two ecotypes: one which is adapted to the high intensity of light while the other adapted to low light intensity.

Explanation of Solution

The existence of cyanobacterium Prochlorococcus sp. in two different ecotypes, help them in their survival in different conditions. Because of this adaptation, these bacteria are the most abundant microbe in the oceans of tropical and subtropical those are capable of carrying out photosynthesis.

The presence of two ecotypes in this bacterial species, have given them an advantage over oxygenic phototrophic microbes. By having access to high as well as low light intensities, these bacteria are able to establish two different types of niche for themselves. The strains adapted to high light intensity can inhabit shallow water while those adapted to low light intensity can inhabit deep waters. In such a way, they both would not compete for similar resources with the same bacterial species.

Summary Introduction

To determine: The way in which the amount of fixed carbon contributed by cyanobacterium Prochlorococcus to an open-ocean ecosystem can be determined.

Introduction: Prochlorococcus are green, small, and unicellular bacteria having chlorophyll a and chlorophyll b pigments. The species of this bacterium exist in two ecotypes: one which is adapted to the high intensity of light while the other adapted to low light intensity.

Explanation of Solution

The development of micro-ecosystem in the laboratory would be required to determine the amount of fixed carbon contributed by cyanobacterium Prochlorococcus to the open-ocean ecosystem. By setting up micro-ecosystem similar to the open-ocean ecosystem, would help in manipulating the amount of carbon fixed by the bacterium. The addition, as well as the removal of these microbes from the micro-ecosystem, will help in measuring the amount of fixed carbon by using various electrodes to test the level of carbon dioxide in the system.