28 August 2025

It’s been almost 100 years since penicillin was discovered and 70-80 years since it’s been widely used but penicillin’s effectiveness waned as bacteria evolved resistance to it. This has happened to many antibiotics so researchers are looking for new sources to kill bacteria. They recently found some in an unlikely place.

Archaea are microbes that thrive just about everywhere, including in our guts and in extremely harsh environments such as hot springs, pictured above. They were initially thought to be bacteria until scientists looked more closely.

Archaeal cells have unique properties separating them from Bacteria and Eukaryota, including: cell membranes made of ether-linked lipids; metabolisms such as methanogenesis; and a unique motility structure known as an archaellum.

— Wikipedia: Archaea account

At the microscopic level, some of them look like this. Click here to see more examples.

Archaea include both single-celled and multi-celled species and have been a separate kingdom since 1977.

In their search for antibiotics two recent studies looked for hardy organisms that co-exist with bacteria and have chemical defenses that may potentially kill bacteria. Archaea in hot springs are one such group.

The first study used an AI algorithm to scan the complete amino acid sequence of each organism, searching for fragments called encrypted peptides that often have antimicrobial properties. Scanning 233 archaea species revealed more than 12,600 likely encrypted peptides. They tested 80 of the most promising, 93% of which showed antibacterial activity in vitro against dangerous human pathogens such as Staphylococcus aureus(1) and Klebsiella pneumoniae(2).

The second study looked for enzymes that could break down the bacterial cell wall peptide shield called peptidoglycan. The group found these enzymes in 5% of the more than 3700 archaea species they surveyed. When exposed to bacteria in the lab, some of the enzymes shredded the bacterias’ peptidoglycan and killed them.”

Paraphrased from Science Magazine: Hot springs’ hardy microbes offer new source of antibiotics

Though the studies have not created new antibiotics, they point to new sources of investigation and potential antibiotic silver bullets.

Read more at Science Magazine: Hot springs’ hardy microbes offer new source of antibiotics.

p.s.

1. Staphylococcus aureus causes skin infections, food poisoning, pneumonia, septicemia, osteomyelitis and infection of the heart valves (endocarditis)
2. Klebsiella pneumoniae causes pneumonia, urinary tract infections, sepsis and meningitis.