<i>Streptomyces</i> sp. BI87 from human gut: potent anticancer activities and divergence from known <i>Streptomyces</i> lineages
Bibliographic record
Abstract
ABSTRACT Cancer is among the deadliest diseases with few truly curative therapies. Recent studies have shown that the human intestinal microbiota contains bacteria that exhibit potent suppressive effects on cancer or coordinate anticancer functions with the immune system. However, whether the peculiar anticancer trait was acquired stochastically by a strain of a non-anticancer bacterial species or an intrinsic property of a phylogenetic lineage of bacteria remained unclear. In this study, we compared a human gut isolate Streptomyces sp. BI87, which had highly effective anticancer activities, with the type strain of Streptomyces albidoflavus , DSM 40455 T , which was most closely related to BI87 among 30 type strains of the genus Streptomyces but did not show any detectable anticancer activities. We found that, although BI87 and DSM 40455 T had >99% 16S rDNA sequence similarity, they are phylogenetically separated by a genetic boundary into distinct natural species as evaluated by the 3Cs definition of bacterial species based on the ratio of common genes with zero sequence degeneracy. In addition to the anticancer activities, BI87 encodes several biological characteristics different from DSM 40455 T , including those of antibacterial and antiviral spectra, secondary metabolites, structural composition in the cell wall, and major cellular fatty acids. Based on the genomic and phenotypic distinctions of BI87 from closely related Streptomyces strains, we propose that the anticancer bacterial strain BI87 represents a new lineage at the natural species level within the genus Streptomyces . IMPORTANCE The characterization of the anticancer bacterial strain, Streptomyces sp . BI87, isolated from a healthy human, suggests the prevalent existence of anticancer microbes in the gut microbiome of humans, which may be nurtured and harnessed for cancer prevention or treatment without the need for the introduction of engineered and non-indigenous microbes to a person or the use of radio- or chemo-therapies. Also important is the finding that a close relative of BI87, Streptomyces albidoflavus DSM40455 T , does not express appreciable anticancer properties in the same in vitro and in vivo experiments, demonstrating that Streptomyces sp. BI87 represents a novel bacterial lineage with selective suppressive activities on cancer, at the phylogenetic level of natural species. Genomic comparisons between BI87 and DSM40455 T demonstrate that phylogenetic delineation of closely related bacteria needs to be conducted at the level of natural species rather than OTUs, as an OTU may contain phenotypically or even phylogenetically radically distinct bacteria.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".