Recent developments in microbiology, curated for educators to engage students and spark exciting classroom conversations
About 12% of cancer cases worldwide, or one in eight, are likely caused by infections, according to a recent study. An estimated 2.3 million new cancer cases worldwide in 2024 were attributable to infections by pathogens such as Helicobacter pylori (predominantly gastric cancer), human papillomavirus (cervical cancer), hepatitis B (liver cancer), Epstein–Barr virus (nasopharyngeal cancer, gastric cancer and Hodgkin lymphoma) and hepatitis C viruses (liver cancer).
These findings highlight the importance of infection control to achieve cancer prevention. Vaccination, testing and treating infections, prophylactic measures to prevent infections and screening of precancerous lesions will go a long way in preventing cancer from developing, particularly in low- and middle-income countries where the burden of infection-related cancers is highest.
Read The Lancet Oncology paper here: https://doi.org/10.1016/S1470-2045(26)00307-4 (open access)
Phage-inducible chromosomal islands (cf-PICIs) are small (∼10–15 kb), chromosomally integrated mobile genetic elements that can spread across bacterial species. These elements can spread virulence and resistance genes that can convert non-pathogenic strains into pathogens.
Capsid-forming PICIs (cf-PICIs) are widespread in nature and are present in multiple host species. Cf-PICIs produce tailless capsids containing their genome. As tails are important for attaching to a host cell, how these elements spread was a mystery until recently. Researchers have now found that these tailless capsids, when released from the host bacterial cell, can interact with phage tails produced in excess by other lytic phages to form chimeric infective particles that inject DNA into different bacterial species depending on the tail they have hijacked. The researchers call this phenomenon tail piracy.
Read the Cell paper here: https://doi.org/10.1016/j.cell.2025.08.019 (open access)
Bacteria use clustered regularly interspaced short palindromic repeats (CRISPR)–Cas systems as an adaptive immune response against viral infections. These systems maintain a genetic record of previous viral infections, which is transcribed into guide RNAs that lead Cas enzymes to complementary viral nucleic acids for cleavage.
Researchers have now identified viral counterparts of CRISPR, which they call Viral Interference Programmable Repeat (VIPR) systems, that play an important role in the naturally occuring "warfare" between competing phages. Unlike the contiguous base-pairing used by canonical CRISPR guides, VIPR systems employ a "noncontiguous code" to recognize double-stranded DNA. The system utilizes VIPR RNAs (vrRNAs) composed of alternating GGY and NN motifs; while the GGY segments are sequestered by the Vipr protein, the NN segments pair with the target, skipping every third nucleotide.
Structurally, Vipr proteins assemble into a right-handed helical filament along the vrRNA. This architecture allows the complex to encircle the nontarget DNA strand, forming a geometric triplex that facilitates target-strand recognition and transcriptional silencing.
Read the two Science papers here: https://doi.org/10.1126/science.aei0498 and https://doi.org/10.1126/science.aei3472 (subscription required)
While it is known that bacteria can be isolated from the atmosphere, it is not clear whether these microbes are active or simply being transported in a dormant state. Contributing to this debate, researchers have found that fog water microbiomes differ significantly from the dry aerosols surrounding them. These fog populations are strongly enriched with photoheterotrophic Methylobacterium species, which appear to metabolize volatile C1 compounds in situ. Notably, these bacteria can degrade atmospheric formaldehyde at remarkably high rates, likely as a form of detoxification.
Evidence suggesting that fog droplets function as active aquatic microhabitats includes an increase in bacterial counts during fog events, a correlation between microbial concentration and temperature, and an increase in cell size and division rates compared to dry aerosols. These findings indicate that bacteria are not just passing through the atmosphere but are actively growing and influencing atmospheric chemistry, which has important implications for the safety and quality of fog-harvested freshwater.
Read the mBio paper here: https://doi.org/10.1128/mbio.00463-26 (open access)