[Proline-dependent wild strains and proline-dependent mutants of the plague microbe]

Area of Science:

• Microbiology
• Bacteriology
• Molecular Biology

Background:

• Yersinia pestis is a significant bacterial pathogen.
• Understanding Y. pestis nutritional requirements is crucial for controlling plague.
• Previous studies have explored various growth factors for Y. pestis.

Purpose of the Study:

• To investigate the specific nutritional requirements of Yersinia pestis wild strains.
• To determine if proline is essential for Y. pestis growth and if it can be substituted.
• To characterize proline-requiring mutants of Y. pestis.

Main Methods:

• Isolation of Yersinia pestis wild strains from Citellus musicus.
• Culturing Y. pestis in media with and without proline, and with potential substitutes like glutamic acid, other amino acids, and vitamins.
• Selection and characterization of 28 proline-requiring Y. pestis mutants.
• Comparison of mutant groups to Escherichia coli proline auxotrophs.
• Assessment of virulence, pigment formation, and calcium dependence in proline-requiring mutants.

Main Results:

• Yersinia pestis wild strains require proline for growth.
• Proline cannot be substituted by glutamic acid, other amino acids, or vitamins.
• 28 proline-requiring mutants were successfully isolated from Y. pestis marmot strain 20b.
• Three distinct groups of proline-requiring Y. pestis mutants were identified, analogous to Escherichia coli.
• Proline requirement did not affect the virulence, pigment formation, or calcium dependence of the Y. pestis mutants.

Conclusions:

• Proline is an essential growth factor for Yersinia pestis.
• The identified proline auxotrophy in Y. pestis is a stable genetic trait.
• The genetic basis for proline requirement in Y. pestis appears conserved, similar to Escherichia coli.
• The study provides insights into Y. pestis metabolism and potential targets for antimicrobial strategies.