Alise Briege
By Elizabeth Pennisi
Soil bacteria called Streptomyces are the guardian angels of the microbial world: they produce antibiotics on which humans depend and protect plants from harmful microbes. But because neither the bacteria nor their spores can move around themselves, researchers have long wondered how they find the plants that protect them.
Now scientists have discovered that the dormant spores (brown) of the microbes on the whip-like appendages – flagella – of mobile soil microbes (blue) drive on their way to plant roots. The journey is an essential part of Streptomyces life cycle, the researchers reported this month in The ISME Journal: Multidisciplinary Journal of Microbial Ecology.
Microscopic examinations revealed that the spore surface was lined with rows of proteins called rodlins, which can grab a passing flag – like velcro. The researchers saw the lifters transport 10 centimeters – the limit of the size of the dish they were on. They think the tracks in soil could move even further.
It is known that some other types of bacteria and a fungus drive other microbes. But it is the first place for spores, which are known to trap insects and other small animals to travel long distances. The team suspects that hitchhiking is a common mode of transportation for non-mobile bacteria.
Not everyone still gets a free ride. According to the study’s authors, the bacteria being transported are “like a ball and chain around your ankle.”