Scientists Discover Genes Essential for Mysterious Lifestyle of Tiny Bacteria
Scientists have made a remarkable discovery about a group of minuscule bacteria known as Patescibacteria. These elusive microbes have perplexed researchers due to their unusual survival methods. While only a few types of Patescibacteria can be cultivated in the lab, they are part of a diverse family found in various environments.
Interestingly, the few Patescibacteria that can be grown in the lab reside on the surfaces of larger host-microbes. This unique group of bacteria lacks the genes necessary for producing crucial molecules for life, such as amino acids, fatty acids, and nucleotides. This has led scientists to speculate that these bacteria rely on other bacteria to grow.
In a recent breakthrough study published in Cell, researchers shed light on the molecular mechanisms behind the intriguing lifestyle of Patescibacteria. This advancement was made possible by the ability to genetically manipulate these bacteria, opening up new avenues for research.
Nitin S. Baliga, from the Institute for System Biology in Seattle, noted, “While metagenomics can tell us which microbes live on and within our bodies, the DNA sequences alone do not give us insight into their beneficial or detrimental activities, especially for organisms that have never been characterized before.” The ability to genetically alter Patescibacteria provides a powerful tool for studying their unique biology.
The study, led by Joseph Mougous’ lab at the University of Washington School of Medicine and the Howard Hughes Medical Institute, focused on Patescibacteria for several reasons. These bacteria are part of the “microbial dark matter,” a collection of poorly understood genetic material found within species-rich microbial communities. Exploring this dark matter could offer valuable information about potential biotechnological applications and the overall dynamics of microbial ecosystems.
The specific group of Patescibacteria examined in this study belongs to the Saccharibacteria family, known for inhabiting the human mouth. Saccharibacteria rely on Actinobacteria as their hosts in the oral microbiome. By genetically manipulating Saccharibacteria, researchers were able to identify the genes essential for their growth.
Mougous, professor of microbiology, said, “We are tremendously excited to have this initial glimpse into the functions of the unusual genes these bacteria harbor. By focusing our future studies on these genes, we hope to unravel the mystery of how Saccharibacteria exploit host bacteria for their growth.”
The researchers also discovered potential factors involved in the interaction between Saccharibacteria and their hosts. These include cell surface structures that help Saccharibacteria attach to host cells and a specialized secretion system used for nutrient transport.
Furthermore, the researchers generated Saccharibacteria cells that express fluorescent proteins, allowing them to observe the bacteria’s growth alongside host bacteria using time-lapse fluorescent imaging. S. Brook Peterson, a senior scientist in the Mougous lab, noted, “Time-lapse imaging of Saccharibacteria-host cell cultures revealed surprising complexity in the lifecycle of these unusual bacteria.”
By delving into the genetic manipulation of Patescibacteria, scientists hope to gain a deeper understanding of the vast molecular landscape hidden within these organisms and unveil novel biological mechanisms.
This groundbreaking study was made possible through collaboration between the University of Washington School of Medicine, the Howard Hughes Medical Institute, and the newly established Microbial Interactions & Microbiome Center (mim_c). The study received support from various organizations, including the National Institutes of Health, the National Science Foundation, and the Bill & Melinda Gates Foundation, among others.