64. A Bacillus culture growing in a rich medium was shifted to a sporulation medium. Which of the following is
expected to occur?
1. Genome and transcriptome will change
2. Genome will not change, but transcriptome will change
3. Transcriptome will not change, but proteome will change
4. Genome, transcriptome and proteome will not change

Introduction

In microbiology, shifting bacterial cultures between different types of media can lead to significant changes in their physiological and molecular states. One of the key examples of this process is when a Bacillus culture is transferred from a rich medium to a sporulation medium. The shift to sporulation conditions triggers various cellular processes that prepare the bacteria for survival in adverse conditions. This includes changes in gene expression, protein synthesis, and overall cellular metabolism.

Key Changes in Bacillus Upon Medium Shift

1. Genome Changes:

   • The genome of Bacillus itself is largely stable in response to medium shifts. The DNA sequence does not change as a result of the medium change, but the expression of different genes is altered in response to environmental conditions.

2. Transcriptome Changes:

   • The transcriptome, which represents the entire set of RNA transcripts in the cell, will undergo significant changes upon shifting to a sporulation medium. Many genes involved in sporulation will be activated, while genes associated with vegetative growth may be downregulated. Therefore, the transcriptome will indeed change to reflect the new environmental conditions.

3. Proteome Changes:

   • The proteome, which refers to the complete set of proteins expressed by the cell, will also change as the cell adapts to sporulation conditions. Different proteins, including those involved in sporulation and stress responses, will be synthesized while other proteins associated with regular growth may be reduced or eliminated.

Conclusion

When a Bacillus culture is transferred from a rich medium to a sporulation medium, the transcriptome and proteome are expected to change as the cell shifts its focus from active growth to preparing for spore formation. The genome itself remains unchanged, but the expression of genes and the proteins they encode are adapted to the new environmental conditions.

Final Answer:

1. Genome and transcriptome will change