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Helical growth and macrofiber formation of Bacillus subtilis 168 autolytic enzyme deficient mutants
Abstract:
Two poorly lytic, chain-forming mutants of Bacillus subtilis 168, strains FJ3 and FJ6, each 90-95% deficient in the production of N-acetylmuramoyl-l-alanine amidase and endo-beta-N-acethyglucosaminidase, grew helically under a variety of cultural condtions. The structures formed ranged in complexity from double-standed helices to complex aggregates of entangled and interwoven single chains and multistransded helical fibres. Factors favoring this type of helical growth were investigated. Occasional tight single-standed corkscrew like forms were detected in the mutant cultrues. Two other poorly lytic mutant strains of Bacillus were also found to have helical growth capacity. These results have been interpreted as support for the recently proposed (1976) tension restricted helical growth model of Mendelson.
Insights
Mutant Bacillus subtilis strains deficient in cell wall degrading enzymes exhibited helical growth. This helical morphology supports the tension-restricted helical growth model.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Bacillus subtilis 168 mutants FJ3 and FJ6 are poorly lytic and form chains.
- These mutants are significantly deficient in N-acetylmuramoyl-l-alanine amidase and endo-beta-N-acethyglucosaminidase production.
- Previous research proposed a tension-restricted helical growth model.
Purpose of the Study:
- To investigate the helical growth capacity of poorly lytic Bacillus subtilis mutants.
- To explore factors influencing this helical growth.
- To assess if these findings support the tension-restricted helical growth model.
Main Methods:
- Culturing of Bacillus subtilis 168 strains FJ3 and FJ6 under various conditions.
- Microscopic observation of cell morphology and growth patterns.
- Analysis of enzyme deficiencies in mutant strains.
Main Results:
- Mutant strains FJ3 and FJ6 displayed significant helical growth, forming structures from double-stranded helices to complex interwoven fibers.
- Occasional corkscrew-like single-stranded helical forms were observed.
- Two additional poorly lytic Bacillus strains also demonstrated helical growth capacity.
Conclusions:
- The observed helical growth in enzyme-deficient Bacillus mutants provides evidence supporting the tension-restricted helical growth model.
- Cell wall lysis deficiency is linked to altered cell shape and helical morphogenesis.
- This study contributes to understanding bacterial cell shape determination and growth mechanisms.