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Salt-induced filamentous growth of a Salmonella strain isolated from blood
Abstract:
A strain of Salmonella choleraesuis subsp. choleraesuis serovar paratyphi-A isolated from the blood of a febrile patient grew into filaments on a nutrient agar containing various salts, such as NaCl, KCl, MgCl2, NH4Cl, (NH4)2SO4, or (NH4)2HPO4, at concentrations of 50 to 400 mM. The filamentous cells were nonseptate and multinucleate, and they had colony-forming ability. This mutant strain, however, did not show filamentous growth in liquid media which contained the same salts. On nutrient agar containing 20% sucrose but no salts, some of the cells formed large spheroplasts. Both ampicillin treatment and in vivo environment may in part be responsible for the induction of the mutant strain.
Insights
A Salmonella paratyphi-A strain developed filamentous growth on nutrient agar with high salt concentrations. This unique mutant strain showed altered morphology and colony-forming ability under specific laboratory conditions.
Area of Science:
- Microbiology
- Bacterial Genetics
- Cell Biology
Background:
- Salmonella choleraesuis subsp. choleraesuis serovar paratyphi-A is a significant human pathogen.
- Bacterial morphology can be influenced by environmental factors and genetic mutations.
Purpose of the Study:
- To investigate the morphological changes of Salmonella paratyphi-A under specific laboratory conditions.
- To characterize a filamentous mutant strain of Salmonella paratyphi-A.
Main Methods:
- Isolation of Salmonella paratyphi-A from a febrile patient's blood.
- Cultivation on nutrient agar with varying concentrations of salts (NaCl, KCl, MgCl2, NH4Cl, (NH4)2SO4, (NH4)2HPO4).
- Observation of cell morphology (filamentous, nonseptate, multinucleate) and colony-forming ability.
- Testing growth in liquid media and on agar with sucrose.
Main Results:
- Salmonella paratyphi-A exhibited filamentous growth on nutrient agar containing 50-400 mM of various salts.
- The filamentous cells were nonseptate, multinucleate, and retained colony-forming ability.
- Filamentous growth was not observed in liquid media with the same salts; however, spheroplast formation occurred on 20% sucrose agar.
Conclusions:
- High salt concentrations on nutrient agar can induce filamentous growth in a Salmonella paratyphi-A mutant strain.
- The in vivo environment or ampicillin treatment may have contributed to the induction of this mutant.
- This study highlights the adaptability of Salmonella to environmental stressors, potentially impacting its pathogenicity.