Chapter 10, Problem 1R

Which of the following organisms are most closely related? Are any two the same species? On what did you base your answer?

Summary Introduction

To review:

Which of the given organisms are closely related. Any two of the following organisms are same species.

Introduction:

Bacterial species that show similar morphological and biochemical characteristics are generally grouped into a single genus. Characterization of organism using their genomic content denotes that the ratio of guanine and cytosine are similar in related species.

Explanation of Solution

The morphology, Gram reaction, GC percentage, glucose utilization, and presence or absence of cytochrome oxidase of four organisms are provided. The organism A (48-52%) and D (49-53%) possess almost similar amount of guanine and cytosine which is depicted in their GC percentage. However, cytochrome oxidase is present for aerobic respiration is present in organism A and it is absent in organism D. The morphology of both A and D organisms is rod-shaped and they both are gram-positive in nature. Both the organism undergoes fermentation process and utilize glucose. Thus, characteristics of organisms A and D organisms are much closely related compared to other organisms.   

Conclusion

By comparing the characteristics of different organisms given, it is clear that organism A and D are most closely related compared to other organisms.