microbiology

The plague outbreak recorded in the Mallorcan towns of Son Servera and Capdepera in 1820, with an overall case-fatality rate of 78 per cent, has historically been regarded as an episode of bubonic plague, a zoonotic disease normally acquired through the bite of an infected flea carried by animals such as rodents. Now, a study published in the journal PNAS, which has drawn on hundreds of contemporary reports—including daily death tolls—and epidemiological models, suggests that the disease was not transmitted exclusively by infected rodents, but was spread from person to person. Therefore, according to the authors, it may have been the pneumonic or septicaemic forms of the plague.

A team of researchers has designed complete and functional genomes for bacteriophages — viruses that feed on bacteria — from scratch using generative artificial intelligence (AI), and has tested them against bacteria that had developed resistance to this type of virus. The study, published in the journal Science, represents a step forward towards generative systems capable of designing complete biological systems. The authors also state that it raises important questions regarding biosafety and biosecurity.

Sexually transmitted variants of the Shigella sonnei bacterium spread more rapidly than other strains, according to a study published in The Lancet Infectious Diseases. This study of more than 3,500 samples collected in the United Kingdom between 2016 and 2021 also observed that strains resulting from sexual transmission were more resistant to the antibiotic azithromycin in men who have sex with men than in other patient groups. The bacterium S. sonnei causes an acute diarrheal infection called shigellosis; it is known to cause traveler’s diarrhea, and over the past two decades, cases have increased as a sexually transmitted disease among men who have sex with men (MSM).

The team led by scientist Kate Adamala of the University of Minnesota has released the news—under an embargo—to several media outlets regarding the creation of a synthetic cell capable of feeding, growing, and replicating, which they have named Spudcell. Their work, which, according to Science News, was rejected by the journal Cell, is published on the team’s website, pending peer review.

In the treatment of obesity, maintaining weight loss is the most difficult phase. Two independent clinical trials published in Nature Medicine have adopted two different strategies to achieve this. The first is a phase 3b trial involving the GLP-1 drug orforglipron, administered orally on a daily basis for 52 weeks. This trial included 376 adults in the United States who had already completed 72 weeks of injectable treatment with tirzepatide or semaglutide. Almost 75% and 80% respectively of patients on each injectable drug maintained their weight loss. The second trial involved 90 obese adults from the Netherlands who followed a low-calorie diet for eight weeks and then received a daily supplement of the bacterium Akkermansia muciniphila for 24 weeks, alongside a healthy diet. Although those who received the supplement regained more than 13% of the weight initially lost, those who took the placebo regained almost 33%.

Drought is linked to the growth of antibiotic-resistant bacteria in the soil, according to a study published in Nature Microbiology. Using data from hospitals in 116 countries, the study observes a link between local aridity and the prevalence of antibiotic-resistant bacteria, although the research does not prove a causal relationship between the two phenomena.

Two articles published in the journal Scientific Reports explore the survival capacity of microorganisms and plants in imitations of lunar and Martian soils. In the first, the team succeeded in cultivating chickpea plants in a lunar soil simulant — lunar regolith — treated with arbuscular mycorrhizal fungi and worm compost. In the second article, microbial growth was investigated in a Martian soil simulant with different water proportions and under pressure and temperature conditions similar to those on Earth. At a water level comparable to that on Mars, an atmospheric humidity of 34 %, microbial mass increased, although it fell back to zero after 60 days. “These findings extend the known physicochemical limits of life in solid substrates and provide new insight into the potential habitability of hyper-arid extraterrestrial environments,” the authors say.

In the ephemeral pools along the coasts of the Caribbean island of Curaçao lives Choanoeca flexa, a tiny unicellular aquatic organism belonging to the choanoflagellates, important for being close relatives of animals. As the pools evaporate and refill, C. flexa can switch between unicellular and multicellular forms in three different ways: by division, by aggregation, or by combining both, mechanisms that were previously thought to be mutually exclusive. The discovery, published today in Nature, may challenge current understanding of the origins of multicellular life.

Infections caused by the fungus Candidozyma auris—formerly known as Candida auris—continue to rise, warns a report by the European Centre for Disease Prevention and Control (ECDC). Spain reported 1,807 of the 4,012 cases in 36 European countries between 2013 and 2023, the highest number ahead of Greece (852 cases) and Italy (712), according to the survey. This microorganism spreads particularly in hospitals, causing infections that are often resistant to existing drugs.

The cyanobacterium Prochlorococcus, the smallest and most abundant photosynthetic organism on Earth, is an important producer of oxygen and is crucial to marine ecosystems. A team from the United States has collected data from ships sailing the Pacific Ocean over a ten-year period and concluded that these cyanobacteria could experience population declines of between 17% and 51% in tropical oceans by the year 2100, depending on the warming scenario. The results, which are the product of modeling work, are published in the journal Nature Microbiology and indicate that this microorganism is more vulnerable to climate change than previously thought.