Microbial Marvels: Meet the New Microbes Found in Exotic Plants and Equine Athletes

Posted on October 3, 2023   by Clare Baker

Each month, the Microbiology Society publishes the International Journal of Systematic and Evolutionary Microbiology, which details newly discovered species of bacteria, fungi and protists. Here are some of the new species that have been discovered and the places they've been found.

We can’t believe that it’s October already! Not only are the months flying by, so are the new microbial discoveries. Luckily, it’s time for another edition of ‘New to Science’ that will keep you up to date.

Our first new microbe comes from the gut of a thoroughbred racehorse. Peptoniphilus equinus, a Gram-Stain-positive bacteria, was discovered by researchers who were investigating the gut microbiota of healthy equine athletes. As you may know, the gut microbiota can directly or indirectly shape the health of the host, whether that is through digestion related processes or their role in maintaining general homeostasis. Due to the increased interest in animal welfare, previous studies on horse gut microbiota have been conducted from various perspectives, including diet, drug intake, aging and stress. However, the dynamics of the composition of gut microbiota in healthy equine athletes remains unclear. It was while researchers were trying to bridge that gap at a ranch in Jeju Island, Republic of Korea, that they discovered our new microbe.  

Next up is a microbe that has shown the ability to degrade benzo(a)pyrene. Pseudomonas benzopyrenica (I’m sure you can guess where it got its name from) is a yellow-pigmented aerobic, rod-shaped bacterium isolated from soil in Huangshi, Hubei Province, PR China. P. benzopyrenica joins the genus Psudomonus, a large and diverse genus which is broadly distributed in nature. Pseudomonas is known for its production of secondary metabolites and metabolic capacity. They are known to degrade compounds called polycyclic aromatic hydrocarbons (PAHs), a large class of chemicals that are often formed during incomplete combustion. Benzo(a)pyrene is a PAH that is known to cause cancer in humans. To date, chemical oxidation, photolysis and volatilization are the most widely used degradation methods, even though they cannot remove the pollutants completely and often lead to secondary pollution. Biodegradation is a popular alternative method and P. benzopyrenica could be part of a new approach to the treatment of PAH pollution.

Let’s stay in China for our next microbe. Streptomyces fuscus is a brown pigment producing actinomycete which was isolated from dry mudflat sand near Beibu Bay in southern Guangxi, PR China. The novel streptomyces species can produce enzymes (chitinases) related to the degradation of chitin, the second largest natural polysaccharide found in exoskeletons and the cell walls of fungi. The utilisation of chitin is currently limited because it is insoluble in common solvents and the current methods of degradation have high energy usage, pollution or extensive use of strong acids or bases. Greener and more efficient biodegradation is a new option for exploiting chitin and our new microbes could play a part in that future.

The discovery of two new microbes isolated from tree barks was published in the International Journal of Systematic and Evolutionary Microbiology this month. Hufsiella ginkgonis and Hufsiella arboris are two aerobic, rod-shaped bacteria that form pale-pinkish colonies. The new species, under a new genus, joined the family Sphingobacteriaceae, a family which has been isolated from a variety of environments such as soil and water but also from glacier ice, compost, sludge and plants. H. ginkgonis was isolated from the bark of a Ginkgo (Ginkgo biloba) located in Yongin, South Korea and H. arboris was isolated from the bark of a Korean cornel dogwood (Cornus offcinalis) located in Seoul, South Korea.

And finally we come to our last two new microbes, Microbacterium plantarum and Microbacterium thalli. They were isolated from the inner tissues (leaf and stem) of Sphaeralcea angustifolia and roots of Prosopis laevigata. S. angustifolia is a native plant of Mexico that grows in arid areas and is known to thrive in soils with considerable concentrations of metals and metalloids such as mining tailings, byproducts of mining activity. P. laevigata is another plant endemic to Mexico that manages to develop under heavy metal stress. One of the reasons why these plants can survive in these environments is their association with helpful bacteria. It comes as no surprise then, that our two new bacteria are metal resistant and can grow in environments alongside a variety of metals.