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Ultrasmall Bacteria

Determining how bacteria interact and influence one another’s behavior is a fundamental goal of microbiology. However, these processes remain poorly understood even in the simplest arrangement of microbial communities. Saccharibacteria (TM7) is a symbiotic bacterium that grow and persist on its host-bacteria, a relationship that is rarely studied due to lack of known examples. However, lack of examples does not translate to lack of such interaction in the environment. Recent sequencing studies discovered a large lineage of bacteria termed the Candidate Phyla Radiation (>73 phyla). Taxonomically this major lineage included Saccharibacteria phylum, and they all shared ultra-small cell size and reduced genome, suggesting bacteria/bacteria symbiosis is more common than expected. Currently, Saccharibacteria is the only phylum in Candidate Phyla Radiation that has cultivated members and our lab is studying many aspects of the Saccharibacteria and its cell physiology.  

Saccharibacteria and its bacterial hosts are readily detected in the human microbiome, especially in the oral cavity. Its relative abundance is increased in multiple diseases such as inflammatory bowel disease and periodontitis. It is therefore crucial to understand how this intimate relationship between two bacteria may shape their role in human health and diseases. To gain new insights, we combine microbial physiology and genetic with tissue culture and animal models across a range of Saccharibacteria strains to determine key biological pathways and mechanisms.

Batbileg Bor, PhD

Assistant Member of Staff

Batbileg Bor was trained as a molecular biologist at UCLA where he studied the regulation of mammalian actin cytoskeleton and its impact on cell polarity. Upon graduation, inspired by his […]

Otari Chipashvili

Research Associate

I am interested in understanding episymbiotic nature of different TM7 with same host bacteria, and how one may or may not protect from the other.

Jett Liu

Research Assistant

My research is focused on designing a rapid, point-of-care diagnostic for oral microbial pathogens and human papilloma virus using CRISPR-Cas based technology.

Deepak Chouhan, PhD

Postdoctoral Research Fellow

My primary focus is to understand the impact of TM7 and its host bacteria on innate immunity, both at the cellular and organism level.

Christian Schuttert, PhD

Postdoctoral Research Fellow

My research focuses on the specific mechanisms involved in the association between Actinomyces/TM7, and how this may influence their interaction.


Publication PDF can be provided upon request. 


Chipashvili, O., Utter, D. R., Bedree, J. K., Ma, Y., Schulte, F., Mascarin, Y. A., Chouhan, D., Hardt, M., Bidlack, F., Hasturk, H., He, X., McLean, J. S., Bor, B., (2021) Episymbiotic Saccharibacteria suppresses gingival inflammation and bone loss in mice through host bacterial modulation. Cell Host & Microbe. Link

Lamont, E. I., Gadkari, A., Kerns, K.A., To, T.T., Daubert, D., Kotsakis, G., Bor, B., He. X., McLean. J. S. (2021) Modified SHI-medium supports growth of a disease-state subgingival polymicrobial community in vitro. Mol Oral Microbiol. PMID: 33174294. Link


Utter, D.R., He, X., Cavanaugh, C.M., McLean, J.S., Bor, B. (2020) The saccharibacterium TM7x elicitis differential responses across its host range. ISME J. PMID: 32839546. PDF

Lamont, E. I., Hendrickson, E. L., McLean, J. S., He, X., Bor, B. (2020) Complete genome sequencing of Strain BB001, a novel epibiont bacterium from the Candidate Phylum Saccharibacteria (TM7). Microbiol Resour Annouc. PMID: 32816985. PDF

McLean, J. S., Bor, B., Kerns, K. A., Liu, Q., To, T. T., Solden, L., Hendrickson, E. L., Wrighton, K., Shi, W., He, X. (2020) Acquisition and Adaptation of Ultra-small Parasitic Reduced Genome Bacteria to Mammalian Hosts. Cell Reports. PMID: 32698001. Link

Bor, B., Collins, A. J., Murugkar, P. P., Balasubramanian, S., To, T. T., Hendrickson, E. L., Bedree, J. K., Bidlack, F. B., Johnston, C. D., Shi, W., McLean, J. S., He, X., Dewhirst, F. E. (2020) Insights obtained by culturing Saccharibacteria with their bacterial hosts. Journal of Dental Research. PMID: 32075512. Link


Bor, B., Bedree, J. K., Shi, W., McLean, J. S. and He, X. (2019) Saccharibacteria (TM7) in the human oral microbiome. Journal of Dental Research. PMID: 30894042. Link


Bor, B., McLean, J. S., Foster, R. F., Cen, L., To, T. T., Serrato-Guillen, A., Dewhirst, F. E., Shi, W., and He, X. (2018) Rapid evolution of host resistance drives the symbiotic lifestyle of the ultra-small bacterium TM7x. Proc Natl Acad Sci. 115:48:12277-12282. PMID 30442671. PDF

Bedree, J. K., Bor, B., Cen, L., Edlund, A., Lux, R., McLean, J. S., Shi, W., and He, X. (2018) Quorum sensing modulates the epibiotic-parasitic relationship between Actinomyces odontolyticus subspecies actinosynbacteri strain (XH001) and its epibiont, a TM7 phylotype (TM7x). Frontiers Microbiology 9. doi:10.3389/fmicb.2018.02049. PDF

He, X., Li, F., Bor, B., Koyano, K., Cen, L., Xiao, X., Shi, W., and Wong., D. (2018) Human tRNA-derived small RNAs modulate host-microbial interactions. Journal of Dental Research. 002203451877060. PMID 29702004. Link


Baker, J. L., Bor, B., Agnello, M., Shi, W., and He, X. (2017) Ecology of the Oral Microbiome: Beyond Bacteria. Trends Microbiol. 1412:1-13. PMID 28089325. PDF


Bor, B., Poweleit, N., Bois, J. S., Cen, L., Bedree, J. K., Zhou, Z. H., Gunsalus, R. P., Lux, R., McLean, J. S., He, X., and Shi. W. (2016). Phenotypic and physiological characterization of the epibiotic interaction between TM7x and its basibiont ActinomycesMicrob Ecol 71: 243-255. PMID 26597961. PDF

Bor, B., Lujia, C., Agnello, M., Shi, W., and He, X. (2016). Morphological and physiological changes induced by contact-dependent interaction between Candida albicans and Fusobacterium nucleatumSci Rep 6: 1-11. PMID 27295972. PDF

Join the Bor Lab

Postdoctoral fellow and lab assistant/technician positions are available for anyone who is interested in the projects described in the “research” section of this website, or ideas complementary to our ongoing research.

We encourage undergraduate and graduate students from neighboring schools who are interested in doing independent projects or other research opportunities.

If your are interested in joining the Bor lab, please contact us. Email:

News and Updates

10.11.21 We published one of our major work in Cell Host & Microbes describing how TM7 may function as a good bacteria by suppressing inflammation and bone loss in mice. 

09.25.21 Bor lab had its first hangout as a big group. We finally have enough people in the lab to say we are a functional lab. It was me and Otto for a long time during pandemic. 

09.09.21 Jett Liu joined the Bor lab to design a rapid, point-of-care diagnostic for oral microbial pathogens and human papilloma virus using CRISPR-Cas based technology.

09.01.21 Dr. Christian Schuttert join the Bor lab from University of Rhode Island. He will be studying the specific mechanisms involved in the association between Actinomyces/TM7, and how this may influence their interaction.

06.03.21 After long and hard struggle, Dr. Deepak Chauhan is finally starting his postdoctoral training today at Forsyth. It was extremely difficult to obtain a visa during the pandemic and travel from India to US. We are excited to have Deepak!  

05.17.21 Our lab started working on interesting new project to develop diagnostic tools for oral pathogens. 

03.09.21 After struggling with COVID pandemic recruiting, the Bor lab finally recruited their first postdoctoral scholar. We cannot wait Dr. Deepak Chouhan from India to join us! His story will soon to follow. 

02.5.21 Dr. Bor submitted his first major grant. Small step for the Bor lab but one large one for Dr. Bor. 

08.24.20 Our lab published its first official research article describing the the differential host response of TM7x bacteria in ISME J. We also wrote an accompanying blog-article on Nature Research Microbiology Community forum (Behind the paper). This is and always will be Dr. Bor’s first last author publication! Congrats to all the coauthors! 

08.21.20 We published a genome announcement on newly isolated BB001 strain (Saccharibacteria). Link 

07.30.20 Our recent publication was discussed in the TWiM podcast and they covered all the important topics. We wish that they had invited one us since we would have clarified many questions that they had. Our publication is also covered at EurekAlert! AAAS news. 

07.16.20 Dr. Bor chaired the BBM2020 session on Phages and gene transfer. The talks were amazing and Dr. Bor had wonderful time participating in the conference in middle of COVID-19 shut downs. 

07.09.20 TM7x is made it to the wikipedia before the researchers did

06.20.20 COVID-19 slowed our research progress but we are up and running. Ultra-small bacteria need to be magnified after all. 

02.20.20 Our collaborative work with Dr. Dewhirst, Johnston, He and McLean lab is published and out for the public to view. We are excited to share the story on cultivating multiple Saccharibacteria and their respective biology. Check it out!

02.10.20 Our work was covered in the Small Things Considered, super cool!

01.01.20 Dr. Bor officially starts his Assistant member position at the Forsyth Institute. We study ultrasmall bacteria, but that is the only small thing about these bacteria. We look to characterize their biological impact and specialization. 

12.09.19 Finally with enough members in the Bor lab to have their first group meeting! Exciting times ahead, and we are looking forward to the future science and fun times in the Bor lab. 

12.02.19 Otari Chipashvili joins the Bor lab as a research associate from the Dana-Farber Cancer Institute and we are very excited to have him. He will be leading the project on Saccharibacteria and their interaction with the eukaryotic hosts. Welcome Otari!! LinkedIn page

11.15.19 We submitted our collaborative work with Dewhirst, Johnston, He and McLean lab to the JDR Special Issue on the Oral Microbiome.

9.23.19 Bor lab started hiring interested individuals for postdoc and research assistant positions. Please apply through the Forsyth website or check out Join the Bor lab page.  

7.24.19 Finally Dr. Bor accepted a tenure-track Assistant Member of the Staff position at the Forsyth Institute, Boston, MA. Lab will officially start on Jan 1st, 2020. Stay tuned for more info. 

11.27.18 Our hard work has been published, where we find that TM7x host bacteria has the capability to rapidly evolve reduced-susceptibility to TM7x killing. It is live on PNAS content/pnas/115/48/12277.full.pdf A blog on this article also can be found on the Forsyth website

5.1.18 Dr. Bor received a NIH K99/R00 Pathway to Independence award. 


Published Resources

Constructing phylogenome tree of select Actinomyces strains using gene clusters by Dan Utter (Utter et al., 2020, ISME). Download HERE.

Narrative workflow for analyzing 16S rRNA profiling by Dan Utter. Download HERE.

Lab Alumni

Jie Nie 

Nadja Tzinis