Science
Louis Pasteur’s Relentless Hunt for Germs Floating in the Air
Louis Pasteur was at his most comfortable when working in his Paris laboratory. It was there that he had some of his greatest scientific triumphs, including experiments that helped confirm germs can cause disease. “Everything gets complicated away from the laboratory,” he once complained to a friend.
But in 1860, years before he became famous for developing vaccines and heating milk to kill pathogens, Pasteur ventured to the top of a glacier, on a remarkable quest for invisible life.
He and a guide began at the base of Mont Blanc in the Alps, hiking through dark stands of pines. Behind them, a mule carried baskets of long‑necked glass chambers that sloshed with broth. They ascended a steep trail until they reached Mer de Glace, the sea of ice.
The wind blew briskly over the glacier, and the vale echoed with the sound of frozen boulders crashing down the slopes. Pasteur struggled to make out the path in the glare of sunlight bouncing off the ice.
When the scientist reached an altitude of 2,000 meters, he finally stopped. He removed one of the glass chambers from the mule’s pack and raised it over his head. With his free hand, he grabbed a pair of tongs and used them to snap off the end of the neck. The cold air rushed inside the container.
The sight of Pasteur holding a globe of broth over his head would have baffled other travelers visiting Mer de Glace that day. If they had asked him what he was doing, his answer might have seemed mad. Pasteur was on a hunt, he later wrote, for “the floating germs of the air.”
Now, 165 years later, scientists around the world hunt for floating germs. Some study how coronaviruses wafting through buses and restaurants spread Covid. Spores of fungi can travel thousands of miles, infecting people and plants. Oceans deliver microbes into the air with every crashing wave. Even clouds, scientists now recognize, are alive with microbes.
The sky’s ecosystem is known as the aerobiome. In Pasteur’s day, it had no name. The very idea of living things drifting through the air was too strange to imagine.
But Pasteur began to wonder about the possibility of airborne life when he was a little-known chemist teaching at the University of Lille in France. There, the father of one his students approached him for help. The man owned a distillery where he used yeast to turn beet juice into alcohol. But the juice had inexplicably turned rancid.
Inspecting the liquid under a microscope, Pasteur discovered dark rods — bacteria rather than yeast — in the sour vats. The discovery helped him work out a theory of fermentation: Microorganisms absorbed nutrients and then produced new compounds. Depending on the species, they could turn butter rancid or grape juice into wine.
The discovery won Pasteur a prestigious new post in Paris. In his account of the discovery, Pasteur suggested in passing that the bacteria might have floated through the air and settled into the vats. That notion earned him an angry letter from Félix‑Archimède Pouchet, one of France’s leading naturalists.
Pouchet informed Pasteur that the microorganisms Pasteur discovered had not dropped into the vats from the air. Instead, the beet juice had spontaneously generated them. “Spontaneous generation is the production of a new organized being that lacks parents and all of whose primordial elements have been drawn from ambient matter,” Pouchet had written earlier.
Pasteur coolly replied that Pouchet’s spontaneous generation experiments were fatally flawed. The conflict between Pasteur and Pouchet prompted the French Academy of Sciences to announce a contest for the best study addressing whether spontaneous generation was real or not. What started as a private spat had turned into a public spectacle. Pasteur and Pouchet both signed up to compete for the prize of 2,500 francs.
The public eagerly followed the competition, struggling to imagine either view of life. Spontaneous generation had the whiff of blasphemy: If life could spring into existence, it did not require divine intervention. But Pasteur’s claim that the atmosphere teemed with germs also strained the 19th‑century mind. A French journalist informed Pasteur that he was going to lose the contest. “The world into which you wish to take us is really too fantastic,” he said.
To prove that his world was real, Pasteur set out to pluck germs from the air. Working with glassblowers, he created flasks with narrow openings that stretched for several inches. He filled them with sterile broth and waited to see if anything would grow inside. If the necks were pointed straight up, the broth often turned cloudy with microorganisms. But if he sloped the necks so that the openings pointed down, the broth stayed clear. Pasteur argued that germs in the air could drift down into the flasks, but could not propel themselves up a rising path.
When Pouchet heard about Pasteur’s experiments, he sneered. Did Pasteur really believe that every germ in decaying organic matter came from the air? If that were true, every cubic millimeter of air would have been packed with more germs than all the people on Earth. “The air in which we live would almost have the density of iron,” Pouchet said.
Pasteur responded by changing his hypothesis. Germs were not everywhere, he said. Instead, they drifted in clouds that were more common in some places than others.
To prove his claim, Pasteur took his straight-necked flasks out of his lab and began collecting germs. In the courtyard of the Paris Observatory, all 11 of his flasks turned cloudy with multiplying germs. But when he traveled to the countryside and ran his experiment again, more of his flasks stayed sterile. The farther Pasteur got from human settlements, the sparser airborne life became. To put that idea to an extreme test, Pasteur decided to climb Mer de Glace.
His first foray to the glacier ended in failure. After holding up a flask, he tried using the flame from a lamp to seal its neck shut, but the glare of the sun made the flame invisible. As Pasteur fumbled with the lamp, he worried that he might be contaminating the broth with germs he carried on his skin or his tools. He gave up and trudged to a tiny mountain lodge for the night.
He left his flasks open as he slept. In the morning they were rife with microorganisms. Pasteur concluded that the lodge was packed with airborne germs that travelers had brought from around the world.
Later that day, Pasteur modified his lamp so that the flame would burn bright enough for him to see it under the glacier-reflected sun. When he climbed back up Mer de Glace, the experiment worked flawlessly. Only one of the flasks turned cloudy with germs. The other 19 remained sterile.
In November 1860, Pasteur arrived at the Academy of Sciences in Paris with the 73 flasks he had used on his travels. He entered the domed auditorium, walked up to the table where the prize committee sat, and laid out the flasks. The judges peered at the broth as Pasteur described his evidence, saying it gave “indubitable proof” of floating germs in inhabited places.
Pouchet refused to accept the evidence, but nevertheless withdrew from the contest. Pasteur was awarded the prize.
Still, the two continued to spar. The rivalry remained so intense that the Academy set up a new commission to evaluate their latest experiments. Pouchet dragged out the proceedings, demanding more time for his research.
Pasteur decided to seize public opinion and put on a spectacle. On the evening of April 7, 1864, in an amphitheater filled with Parisian elites, Pasteur stood surrounded by lab equipment and a lamp to project images on a screen. He told the audience it would not leave the soiree without recognizing that the air was rife with invisible germs. “We can’t see them now, for the same reason that, in broad daylight, we can’t see the stars,” he said.
At Pasteur’s command, the lights went out, save for a cone of light that revealed floating motes of dust. Pasteur asked the audience to picture a rain of dust falling on every surface in the amphitheater. That dust, he said, was alive.
Pasteur then used a pump to drive air through a sterile piece of cotton. After soaking the cotton in water, he put a drop under a microscope. He projected its image on a screen for the audience to see. Alongside soot and bits of plaster, they could make out squirming corpuscles. “These, gentlemen, are the germs of microscopic beings,” Pasteur said.
Germs were everywhere in the air, he said — kicked up in dust, taking flights of unknown distances and then settling back to the ground, where they worked their magic of fermentation. Germs broke down “everything on the surface of this globe which once had life, in the general economy of creation,” Pasteur said.
“This role is immense, marvelous, positively moving,” he added.
The lecture ended with a standing ovation. Pasteur’s hunt for floating germs elevated him to the highest ranks of French science.
By the time he died 31 years later, Pasteur had made so many world-changing discoveries that his many eulogies and obituaries did not mention his trip to Mer de Glace.
But scientists today recognize that Pasteur got the first glimpse of a world that they are only starting to understand. They now know that life infuses the atmosphere far more than he had imagined, all the way to the stratosphere. Our thriving aerobiome has led some scientists to argue that alien aerobiomes may float in the clouds of other planets. Ours is not the only world that seems too fantastic to believe.
NEW YORK — Scientists have unearthed communities of marine life — including jellyfish, tubeworms and brittle stars — thriving on a whale graveyard that is millions of years old.
These graveyards form when whale carcasses fall to the sea floor, becoming a sustaining snack for nearby critters. This one, located up to 23,000 feet below the surface of the southeastern Indian Ocean, spans the largest area and is so far the deepest and oldest found.
A whale’s sheer size and the unique chemistry of its bones are the keys to forming these unique underwater neighborhoods, said Xikun Song, a biologist with the Chinese Academy of Sciences’ Institute of Deep-sea Science and Engineering.
“At the same time, the very nature of the deep ocean makes these sites exceptionally difficult for scientists to locate,” Song, who was involved with the latest find, wrote in an email.
Researchers explored the remains during multiple deep-sea submersible trips in 2023, collecting samples and mapping the extent of the necropolis. They found five carcass sites and fossils, including skulls belonging to beaked and baleen whales. The oldest bones date back 5.3 million years.
Feeding and living on the carcasses were myriad creatures, large and small, including sea cucumbers, squat lobsters and saltwater clams. Many of them are likely species that have never been documented, according to findings published Wednesday in the journal Nature.
“The potential number of specimens is just astounding,” said paleontologist Stephen Godfrey with the Calvert Marine Museum in Maryland, who wasn’t involved in the research.
Many factors likely conspired to preserve the bones for millions of years, according to the study authors. They’re dense enough to outlast attacks from bone-eating worms, and located deep enough in the ocean to avoid getting buried by dust and loose particles. The bones also were coated with a light layer of minerals from the surrounding seawater, which may have prevented them from degrading.
Why did so many whales die here? Maybe they were already living in the area and died of natural causes. A few could have perished from exhaustion or illness caused by deep-sea diving. The area’s shape, akin to the letter V, could also have funneled the remains to their resting spot, the authors wrote.
Such discoveries are important because they clue scientists into the vibrant communities that find a way to live even in remote, hard-to-reach environments.
Studying the whale graveyards “is important for understanding how life can adapt to such extreme conditions, not only due to the lack of light and oxygen but also to the incredibly high pressure,” said study co-author and paleontologist Giovanni Bianucci with the University of Pisa in Italy in an email.
Ramakrishnan writes for The Associated Press.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation.
Science
El Niño turns crumbling California pier into climate battleground over what to save — and who pays
As a historic El Niño supercharges the Pacific Ocean and San Francisco experiences record high seasonal sea levels, the latest structural casualty of intense wave action is prompting Bay Area politicians to call for help from the state and federal governments.
They want to rebuild a concrete pier shut down this month after officials deemed it unsafe because of cracking from decades of pounding surf and storms.
As waves crashed against the derelict structure Monday morning, U.S. Rep. Sam Liccardo (D-San José) held a news conference and asked the federal government to follow through on $50 million in climate resilience funding promised by the Biden administration but terminated by the Trump administration in 2025.
The city of Pacifica had been on the shortlist for the Building Resilient Infrastructure and Communities program, managed through FEMA. California and 22 other states successfully sued to reinstate the program, but the funding has yet to be allocated.
Liccardo also asked for nearly $1 million in promised funds from the National Oceanic and Atmospheric Administration for a handrail project on the pier and an additional $9 million to protect coastal bluffs.
Coastlines are already being buffeted and inundated by rising seas. With the closed-off Pacifica Municipal Pier in the background, local politicians and community members said they’re on the front lines and want to rebuild.
“Pacifica is ground zero for coastal resilience,” said state Sen. Josh Becker (D-Menlo Park), as he asked Gov. Gavin Newsom to declare a state of emergency and “help us fix this pier and help this community recover again.”
“This is very much a reminder that an ounce of prevention is worth a pound of cure,” he said, noting that previous attempts for funding went unheeded. “We cannot wait until infrastructure fails before we invest in protecting it.”
As climate change starts to become expensive, it prompts questions about what to protect and what to abandon.
Chad Nelson, chief executive of the Surfrider Foundation, a coastal environmental advocacy organization, said city piers provide coastal access to people who can’t swim or walk on the beach; they are often popular fishing spots and tend to serve a broad swath of their communities.
On the flip side, he said, they keep getting beat up by the ocean and costing taxpayers millions of dollars to repair or replace.
In Santa Cruz, a public wharf damaged by storms in 2024 recently reopened after $1.3 million in repairs. In Capitola, a storm-damaged wharf reopened earlier this year after $10 million had been sunk into repairs. The city is now considering building an open-air restaurant, public bathrooms, a bait shop and a boat launch.
“I think the larger question is: Are we subsidizing bad responses to problems that we know are going to persist?” he said, responding to a question about infrastructure that won’t last.
Charles Lester, director of the Ocean and Coastal Policy Center at UC Santa Barbara, agreed with Nelson that it’s important to distinguish public from private benefits.
“There’s a bit of a difference between a public recreational pier, for example, and your private development that’s going to impact the beach,” he said.
And at some point, he said, we have to acknowledge things are only going to get worse.
In a white paper authored by Lester and Nelson, the two described the coming El Niño as a “reckoning” for the California coast.
El Niños result in larger waves, elevated sea levels and powerful storms — “predictable signature(s) of a climate pattern that returns every two to seven years and is expected, as the planet warms, to intensify,” they wrote.
Wave energy along the shore can run 50% above average during an El Niño, while sea levels can climb 6 to 12 inches — flooding coastal homes, roads and infrastructure. Coastal erosion increases by more than 69% during extreme El Niño events, according to the U.S. Geological Survey.
During the 1997-98 El Niño, seven Pacifica seaside houses were condemned after powerful waves and storms made them unsafe and irreparable. Seventeen people in the state died as a result of the historic flooding and storms.
The funding requests for the pier also come as San Francisco sees its highest summer water levels ever. On Saturday, the National Weather Service recorded levels 1.83 feet above normal high tide. Early Monday morning, the popular Pier 14 along the city’s Embarcadero waterfront was submerged.
High surf along the coast killed a young girl in Laguna Beach, and hundreds of people have been rescued at Newport Beach. Water stranded a hiker along the cliffs of San Francisco’s Presidio — requiring a seven-hour rescue mission that ultimately left the hiker and a rescuer injured as the waves crashed them into the rocks.
“This stretch of coast has been a continuous coastal emergency declaration for almost 10 years due to the repeat damage of storms in recent El Niño years,” the mayor of Pacifica, Christine Boles, said.
Pacifica has been planning for climate change for years, she said. But climate change is outstripping those efforts, and without financial and regulatory support from the federal and state governments, the battle will be all but lost.
Science
Californian is infected with rare tick-borne illness. What to know about the deadly bacteria
A Northern Californian has been confirmed as the fourth-ever person diagnosed with a newly recognized and rare tick-borne disease that causes symptoms similar to Rocky Mountain spotted fever.
The California Department of Public Health confirmed the latest case of Rickettsia lanei bacteria in a patient who was diagnosed in April of this year. Two other California cases were reported in 2004 and 2023.
Public health officials told The Times that the infected person “was seriously ill, hospitalized and has since been discharged and is recovering.”
It is unclear how long the person was in the hospital or what their symptoms were. The state agency said it could not disclose the home county of the person but confirmed the infected person lived and worked in Northern California.
Rickettsia lanei comes from the spotted fever group Rickettsia, bacteria transmitted to humans from the bite of an infected tick.
In California three types of ticks — the American dog tick (Dermacentor similis), the Pacific Coast tick (Dermacentor occidentalis) and the brown dog tick (Rhipicephalus sanguineus) — can transmit the bacteria that cause Rocky Mountain spotted fever in humans and dogs, according to the California Department of Public Health.
Symptoms of Rocky Mountain spotted fever can range from fever and a rash to long-term effects that include damage to internal organs or neurological disorders.
The tick-borne disease has been spreading globally since the early 2000s, most notably in Mexico and Brazil, with reported fatality rates that can exceed 50%, according to a study published by UC Davis.
What is Rickettsia lanei?
Rickettsia lanei bacteria were identified this year in a few Pacific Coast ticks, including a tick in Contra Costa County, according to SFGate, where the latest case was first reported in April.
The new bacterium was added to the list of potentially transmittable pathogens in 2024 by the state public health department after its severe symptoms were studied in two cases of infected men nearly 20 years apart, according to a report published in the Centers for Disease Control and Prevention Emerging and Infectious Diseases journal.
“Sustained investment in public health has enabled development of the advanced molecular tools that detected these infections,” the California Department of Public Health said in a statement to The Times.
According to the report, both men fell ill after spending time outdoors, one playing golf at five courses in Alameda and Contra Costa counties within 14 days of the onset of his symptoms. This first patient had fever, headaches, muscle pain, malaise, loss of appetite, diarrhea and abdominal pain, among other symptoms. His condition worsened on his third day in the hospital, according to the report. The man was ultimately in the hospital for 22 days, including 11 in the intensive care unit with a primary diagnosis of rocky mountain spotted fever and a secondary diagnosis of acute kidney injury.
The other infected person had visited and camped at a county park and state beach in San Mateo and Marin counties. The second man reported a five-day history of headaches, vomiting, light sensitivity, neck pain and confusion, according to the report. On the third day of hospitalization, the man became comatose and was intubated, the report stated. After 13 days, he was discharged with a primary diagnosis of severe Rickettsia.
Researchers have known about Rickettsia lanei since 2018 when it was detected in rabbit ticks in Sonoma County, but they didn’t know its potential harm to humans because the rabbit tick rarely bites people.
“The Pacific Coast tick, which bites humans more frequently, may occasionally acquire the organism from an infected rabbit, which is the most likely route for the rare human infections that have been identified,” the state health agency said.
Should I be worried about contracting Rickettsia lanei?
Human infections are rare but could be underreported because Rickettsia lanei symptoms are very similar to those of rocky mountain spotted fever, said Janet Foley, veterinarian and disease ecologist at UC Davis.
“I think it’s so new that I don’t know if anybody’s really gotten a grant to study it or put it under a microscope,” Foley said.
Rickettsia lanei bacteria cases could also have gone undetected for so long because some cases were not severe, she said.
Foley said Californians should be aware of Rickettsia lanei and take precautions against tick bites.
How to keep disease-carrying ticks at bay
The best way to avoid ticks and tick bites is to be vigilant in your surroundings, Foley said, noting that ticks can transmit other diseases such as Lyme disease.
To keep a disease-carrying tick at bay, Foley recommends:
- Covering up your arms and legs when outdoors by wearing pants and long-sleeved shirts.
- Staying out of the grass where a tick can latch onto your clothing. Instead stay on a cleared path.
- Wearing light-colored clothing so it’s easier to spot a tick if one jumps on you.
- After an outdoor activity, take off your clothes, toss them in the wash and take a shower.
- If your dog goes with you for outdoor activities, give it a bath and then apply tick medication.
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