tuberculosis bacteria growth study challenges theories

New Study Challenges Prevailing Theories on Tuberculosis Bacteria Growth

Introduction

Tuberculosis (TB), a rod-shaped bacterium ranked by the World Health Organization as the world's deadliest infectious disease, has been revealed as the first single-celled organism capable of maintaining a constant growth rate throughout its entire life cycle.

Groundbreaking Discovery

Researchers at Tufts University School of Medicine share this groundbreaking discovery in the journal Nature Microbiology on November 15, reshaping long-held views of bacterial cell biology and shedding light on the pathogen's resilience against immune defenses and antibiotics.

New Insights into TB Pathogen Behavior

"The study of bacterial growth and division is one of the simplest areas of research in microbiology, yet our findings show that the TB pathogen operates under an entirely unique set of principles." explained Bree Aldridge, co-senior author and professor at Tufts University School of Medicine and School of Engineering. Ariel Amir of the Weizmann Institute of Science also served as co-senior author.

Implications for Treatment

Tuberculosis (TB) bacteria thrive within humans partly due to their ability to rapidly evolve in certain infection sites, enabling them to evade immune detection and resist treatments. Current TB therapy requires months of antibiotic regimens, yet only achieves an 85% success rate. Aldridge and her team suggest that a deeper understanding of the pathogen's fundamental biology is essential to generate more effective treatment strategies.

Research Process

The research process was labor-intensive and time-consuming. Christin (Eun Seon) Chung, a postdoctoral fellow and one of the paper's first authors, spent three years in a high-containment lab observing individual TB cells.

Innovative Methods for Observation

TB bacteria replicate roughly every 24 hours, far slower than many model bacteria, prompting Aldridge's team to innovate microscopy methods for week-long imaging sessions. Given the bacterium's minuscule size and erratic movement, automated tracking was impractical, requiring Chung to manually analyze the footage and trace the lineage of each cell.

Key Findings

Unique Growth Patterns of TB Bacteria

The experiments revealed that TB bacteria deviate from conventional cell growth patterns. Unlike other bacterial species that exhibit exponential growth—slower in smaller cells and faster in larger ones—TB bacteria maintain consistent growth rates throughout their lifecycle, whether they are newly born and small or nearing division.

"This is the first organism known to exhibit such behavior," states Chung.

Alternative Mechanisms of Growth Control

"TB's growth pattern challenges fundamental assumption in bacterial biology, which traditionally link ribosomes—the protein synthesis machinery—to cell growth rates. Our findings suggest that TB may relay on alternative mechanisms, raising intriguing questions about how its growth is controlled," states Chung.

Novel Growth Characteristic

In addition to identifying significant variability in the growth behaviors of individual bacterial cells, the team uncovered a novel characteristic of TB bacteria: they can initiate growth from either end post-division. This findings was surprising, as related bacteria typically grow exclusively from the end opposite their division site.

The Significance of These Findings

These findings demonstrate that TB microbes employ alternative strategies to enhance variability among their progeny, contradicting assumptions derived from faster-growing, more uniform model organisms. According to Aldridge, the study provides a foundation for her lab and others to further explore and harness these mechanisms to improve treatments.

The Diversity of Microbial Life

"Much of basic microbiology relies on fast-growing model organisms, which are valuable but not necessarily representative of all bacterial types," Aldridge states. "This study underscores the immense diversity of microbial life that remains understudied at a fundamental level, highlighting the importance of investigating pathogens directly."

Conclusion

Prathitha Kar from Harvard University, co-first author of the paper, along with Maliwan Kamkaew, formerly of Tufts University School of Medicine, also played significant roles int he research.

Source

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