New to science: September 2015

Posted on September 29, 2015   by Anand Jagatia

Each month, the Society for General Microbiology publishes the International Journal of Systematic and Evolutionary Microbiology, which details newly discovered species of bacteria, fungi and protists. Here are a few of the new species that have been discovered and the places they’ve been found. The full papers are available to journal subscribers, but the abstracts are free to read.

This month’s post contains some microbes that have struck up an interesting relationship (or symbiosis) with animals and plants. We also have some micro-organisms capable of producing and degrading unusual chemical substances, including ingredients found in sweeteners and mothballs.

Let’s start with plant–bacteria symbioses. The genus Rhizobium contains bacteria that live within nodules on the roots of some plants, where they ‘fix’ atmospheric nitrogen, converting it into molecules like ammonium. This is a much more useful for the plant – while atmospheric nitrogen is fairly inert and can’t be easily used, fixed nitrogen can be readily incorporated into things like protein and DNA. Nitrogen fixation is therefore essential for life.

Rhizobia were first discovered in the root nodules of legumes (a plant family including peas and beans), and two new such species are described in this month’s issue. R. ecuadorense is a symbiont of the Ecuadorian common bean that has been discovered by researchers in Brazil and Mexico, while R. anhuiense is a new species isolated from the roots of fava beans by Chinese researchers. Outside of the legume family, rhizobia have also been found in the roots of certain cereals. Rhizobium oryzicola is a new species of growth-promoting bacteria that forms a symbiosis with rice plants, discovered by researchers in China and Pakistan.

In the animal world, a team from Spain has identified a novel species of the genus Streptococcus from the respiratory tract of wild rabbits. Four strains of S. pharyngis were isolated from healthy wild rabbits that were hunted on the same day at the same location. Elsewhere, the intestinal tract of the humble egg cockle was the source of Bizionia fulviae, a new bacterial species discovered by scientists in Korea. And a group from Spain and the Czech Republic has described the novel species Pseudomonas coleopterorum – found in the gut of a bark beetle. The bacterium produces enzymes which digest cellulose, and may help in the insect’s development and fitness.

Elsewhere, Cyberlindnera xylosilytica is a new species of yeast which is able to produce xylitol – a sugar alcohol which is as sweet as sugar, but with fewer calories. Xylitol is widely used in foods and pharmaceuticals, so yeast species that can bioproduce it may be useful as greener and more efficient options for its manufacture. Scientists from Korea have also isolated the bacterium Celeribacter naphthalenivorans, from tidal flats. The species is named for its ability to degrade naphthalene, a compound which used to be the main ingredient in mothballs. However, naphthalene destroys red blood cells and can cause a form of anaemia if ingested, so its use in mothballs was banned in 2008.