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Bacteria found to arrange themselves in hidden patterns

June 12, 2013
Courtesy of the University of Cambridge
and World Science staff

Sci­en­tists have dis­cov­ered strange, branch­ing pat­terns in bac­te­ri­al popula­t­ions.

Al­though bac­te­ri­al col­o­nies nor­mally form cir­cu­lar shapes, in­ter­nal­ly, their cells form these asym­met­ri­c structures, re­search­ers say.

Researchers used high resolution microscopes to examine the growth of bacterial populations in detail. They discovered that as bacteria grow the cell populations naturally form branching patterns called fractals. (Credit: Jim Haseloff Lab)


They add that the find­ings—pub­lished in the jour­nal ACS Syn­thet­ic Bi­ol­o­gy—have im­plica­t­ions for syn­thet­ic bi­ol­o­gy, a field in which sci­en­tists try to re­pro­gram liv­ing things us­ing DNA.

In the stu­dy, Uni­vers­ity of Cam­bridge sci­en­tists cre­at­ed a sys­tem for ex­am­in­ing the de­vel­op­ment of bac­te­ri­al popula­t­ions. Af­ter mark­ing bac­te­ria by in­sert­ing genes for dif­fer­ently col­ored pro­teins, the re­search­ers used pow­er­ful mi­cro­scopes to ex­am­ine the popula­t­ion growth. 

They found the grow­ing popula­t­ions nat­u­rally form the strik­ing pat­terns, which could be fur­ther an­a­lyzed us­ing large-scale com­put­er mod­els.

They found that as each bac­te­ri­um grows in a sin­gle di­rec­tion, lines or files of cells are formed, but these buck­le and fold eas­i­ly. This hap­pens re­peat­edly as the cells grow and di­vide, lead­ing to the forma­t­ion of rafts of aligned cells ar­ranged in self-si­m­i­lar branch­ing pat­terns—also called frac­tals.

“Vivid bi­o­log­i­cal pat­terns emerge from even sub­tle in­ter­ac­tions. Si­m­i­lar phe­nom­e­na are seen in the emergence of or­der in eco­nom­ic, so­cial and po­lit­i­cal sys­tems,” said Jim Haseloff of the De­part­ment of Plant Sci­ences at the uni­vers­ity, lead au­thor of the stu­dy. 

“The be­hav­ior of large popula­t­ions can be hard to pre­dict, but the work has re­sulted in the val­ida­t­ion of fast and ac­cu­rate com­put­er mod­els that pro­vide a test bed for re­pro­gramming of mul­ti­cel­lu­lar sys­tems.”

The study “pro­vides a new in­sight in­to the way cell popula­t­ions may in­ter­act dur­ing the early forma­t­ion of med­ic­ally im­por­tant bac­te­ri­al popula­t­ions or biofilm­s”—s­limy, re­sil­ient bac­te­ri­al popula­t­ions that can pose a threat to health, he added. “This could have im­por­tant im­plica­t­ions for un­der­stand­ing the forma­t­ion of these biofilms, and for en­gi­neer­ing new bio­films” with use­ful pro­perties.

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Scientists have discovered strange, branching patterns in bacterial populations. Although bacterial colonies normally form circular shapes as they grow, internally, their cells form that which are highly asymmetrical and branched, researchers say. They add that the findings—published in the journal ACS Synthetic Biology—has implications for the emerging field of synthetic biology, in which scientists try to reprogram living things using DNA. In the study, University of Cambridge scientists created a system for examining the development of bacterial populations. After marking bacteria by inserting genes for differently colored proteins, the researchers used powerful microscopes to examine the population growth. They fund the growing populations naturally form striking and unexpected patterns, which could be further analyzed using large-scale computer models. They found that as each bacterium grows in a single direction, lines or files of cells are formed, but these buckle and fold easily. This happens repeatedly as the cells grow and divide, leading to the formation of rafts of aligned cells arranged in self-similar branching patterns—also called fractals. “Vivid biological patterns emerge from even subtle interactions. Similar phenomena are seen in the emergence of order in economic, social and political systems,” said Jim Haseloff of the Department of Plant Sciences at the university, lead author of the study. “The behaviour of large populations can be hard to predict, but the work has resulted in the validation of fast and accurate computer models that provide a test bed for reprogramming of multicellular systems.” The study “provides a new insight into the way cell populations may interact during the early formation of medically important bacterial populations or biofilms”—slimy, resilient bacterial populations that can pose a threat to health, he added. “This could have important implications for understanding the formation of these biofilms, and for engineering new biofilms.”