Biofilms are complex microbial communities that adhere to a surface and encase themselves in a viscous matrix they produce. This structure protects bacteria from antibiotics and the immune system far more effectively than if they lived in a free-floating state, making biofilms one of the most common causes of hard-to-treat chronic infections—such as respiratory infections in people with cystic fibrosis and chronic obstructive pulmonary disease (COPD), chronic wounds, or infections associated with catheters and prosthetic devices. Added to this is the global rise in antibiotic resistance, which makes it increasingly urgent to have tools capable of predicting which treatment will work in each case.

The ocean's aphotic zone—the dark, high-pressure region below the surface, where sunlight cannot reach—is home to a vast wealth of microbial life. Yet scientists know relatively little about the genetic makeup, growth and function of many of these enigmatic organisms.

The ocean's aphotic zone—the dark, high-pressure region below the surface, where sunlight cannot reach—is home to a vast wealth of microbial life. Yet scientists know relatively little about the genetic makeup, growth and function of many of these enigmatic organisms.

Researchers at Queen Mary University of London are closer to understanding tendinopathy, a common condition that can cause persistent pain and impaired movement in people and many animals.

The winners of this year’s Nikon Small World in Motion competition showcase the wiggly, feathery, undulating beauty of invisible life.

The mammalian gut microbiome teems with a delicate balance of bacteria and the viruses that keep them in check, called bacteriophages, or phages. Each bacterial species usually has its own set of phage partners.

The mammalian gut microbiome teems with a delicate balance of bacteria and the viruses that keep them in check, called bacteriophages, or phages. Each bacterial species usually has its own set of phage partners.

Billions of people still suffer from hunger and food insecurity worldwide. Meanwhile, microbial contamination causes a third of global food waste annually, resulting in major economic losses and illnesses. Although antibiotics and pesticides help control contamination, their excessive use can promote bacterial resistance or leave toxic residues. 

One alternative uses materials that generate highly reactive forms of oxygen when exposed to light, called photocatalysts, to prolong food freshness. These molecules kill bacteria by damaging their cell components in a process called photodynamic inactivation or PDI. However, current PDI systems rely on energy-intensive lasers and long exposure times because the bacteria’s protective cell membranes block reactive oxygen molecules. As a result, the systems don’t kill bacteria effectively and risk overheating food, affecting its freshness and nutritional value.

Scientists at Zhejiang University in China thought that it would be possible to achieve a PDI system using accessible, free sunlight with the right photocatalyst. Moreover, they also wanted to integrate this photocatalyst into food packaging to combat microbes during storage. 

To make the photocatalyst, the researchers mixed water with a glue-like plant fiber that provides structural support, called pectin, and a chemical from plant seeds that supplies phosphorus, called phytic acid. Then they heated the mixture in a sealed reactor at 220ºC (428ºF) for 5 hours to form tiny structures composed of a carbon core surrounded by a phosphorus-rich shell called phosphorus-modified carbonized polymer dots or PCDs.

To incorporate the PCDs into film packaging, the researchers dissolved equal amounts of a plant fiber from konjac, called glucomannan, and another plant-derived molecule, called carboxymethylcellulose, in warm water to form a network of entangled molecular chains. Then, they added 1.5 milligrams of PCD per milliliter to this mixture, which linked the chains together like molecular fasteners. Finally, they added a moisture-binding chemical called glycerin to prevent brittleness. The researchers cast this mixture onto separate Petri dishes and dried them, forming thin, plastic-like PCD films.

To test the films, the researchers placed Escherichia coli bacteria between 2 sterilized film sheets and exposed the samples to either darkness or simulated sunlight for 20 minutes. They then transferred the microbes onto agar plates and incubated them for 15 hours, allowing surviving bacteria to form visible colonies. They compared the number of bacterial colonies with those of untreated samples to calculate the percentage of bacteria the films eliminated in each environment. 

Tests under darkness showed that the films eliminated about 60% of the bacteria. The researchers attributed this result to the positive electrical charge of PCDs, which attracts the bacteria’s negatively charged cell surfaces. The electrical attraction stresses their cell membranes, interfering with essential life processes. This result suggested that the films use a separate charge-based antibacterial mechanism apart from PDI, which requires light to work.

Under simulated sunlight, the films eliminated nearly 100% of the bacteria. The researchers identified 2 principal mechanisms causing this. First, the PCDs acted as tiny heaters that generated localized heat, which stretched holes in the bacterial membranes, allowing contents to leak out of their cells through a process called photoporation. Second, the PCDs generated reactive oxygen molecules that could then penetrate the bacteria. Once inside the cells, these molecules irreversibly damage the bacteria’s internal components and genetic material through PDI. 

The researchers also investigated whether PCD films could serve as food packaging by using them to wrap fresh strawberries. Compared with conventional nonbiodegradable polyethylene packaging where visible rotting occurred, the PCD films kept the strawberries fresh for more than 4 days by suppressing bacterial growth and regulating moisture levels. When the team tested whether the films were toxic, they found that the films are safe for humans and compatible for food applications. They also buried the films in soil for 24 days and found that they degraded by 78%, demonstrating biodegradability suitable for packaging fresh foods.

The team concluded that PCD films could be a biodegradable food packaging that combines plant-based materials with multiple antibacterial strategies. The films retained antibacterial activity in darkness and became more effective under sunlight through the combined effects of photoporation and PDI. These findings demonstrated that by combining multiple mechanisms into a single material, researchers can create multifunctional food packaging that remains effective across different storage conditions.

The post Harnessing sunlight to fight bacteria appeared first on Sciworthy.

New findings raise questions about the role of microbes living in the lungs. More than 35 trillion bacteria live throughout the human body, forming microbiomes in the gut, mouth, lungs, skin, and urogenital tract. Researchers increasingly recognize that these microbial communities are connected to both health and disease, but much about what individual microbes do [...]

Even highly antibiotic-resistant bacteria become more vulnerable when their cell wall transport system is disrupted, according to a new study from Umeå University. The discovery reveals a previously overlooked weakness that could help researchers develop new strategies to combat antibiotic resistance.

Even highly antibiotic-resistant bacteria become more vulnerable when their cell wall transport system is disrupted, according to a new study from Umeå University. The discovery reveals a previously overlooked weakness that could help researchers develop new strategies to combat antibiotic resistance.

Learning is often thought to require a brain. But learning is a broad concept that does not necessarily depend on neurons.

Research underway in the lab of Rebecca Alexander, a professor in Wake Forest University's Department of Chemistry, is shedding light on an unusual human bacterium, Mycoplasma penetrans. Alexander's work to understand how and why this unique pathogen acts as it does could one day lead to new classes of drugs that better target illnesses associated with this particular pathogen, as well as others that act similarly.

During the COVID-19 pandemic, we wore masks and kept 2 meters (6.6 feet) apart in an effort to reduce the spread of the tiny droplets we release into the air with every breath, conversation or cough. The main goal was to reduce the number of virus particles—known as virions—to which we were exposed. For each virus, a person must be exposed to a minimum infectious dose to develop disease, and in many cases, the larger the dose, the more severe the illness.

It can't be heard, but different parts of the human body are in constant conversation, communicating to keep the entire system running efficiently. For biologists, being able to listen in on this discussion is a long-sought-after goal. Over the years, researchers have caught snippets of these exchanges, but the complete dialogue has remained out of reach.

It can't be heard, but different parts of the human body are in constant conversation, communicating to keep the entire system running efficiently. For biologists, being able to listen in on this discussion is a long-sought-after goal. Over the years, researchers have caught snippets of these exchanges, but the complete dialogue has remained out of reach.

New research from Indiana University has uncovered a previously unknown vulnerability in how bacteria build the whip-like tails they use to move. The researchers found that building these tails can put stress on the protective wall surrounding a bacterial cell and uncovered systems bacteria use to keep that stress from becoming destructive.

A new study has demonstrated that regional microbial imprints can remain detectable under commercial winemaking conditions. The research, appearing in Applied and Environmental Microbiology, shows that inoculated fermentations do not "override" native microbial diversity and that vineyard management and environmental conditions affect wine quality. The study helps explain why wines from different regions taste distinct even when made with similar techniques and supports regional flavors and branding.

A bacterial molecule called gladiolin can disarm invasive Candida albicans and strengthen the effects of a major antifungal drug. Candida albicans usually lives harmlessly in the human body, but under the wrong conditions it can transform into an invasive form capable of damaging tissue and causing life-threatening infection. Researchers from Monash University and the University [...]

That’s now just 1 billion years for all the apparatus to hit on the lucky combination randomly, unless we start with design principles.

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