dictyNews Volume 39 Number 13

Published in

· 10 months ago

dictyNews 
Electronic Edition 
Volume 39, number 13 
May 3, 2013 

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========= 
Abstracts 
========= 

 

Hydrolysis of aromatic beta-glucosides by non-pathogenic bacteria 
confers a chemical weapon against predators 

Robert Sonowal, Krithi Nandimath, Sucheta S. Kulkarni, Sandhya P. Koushika, 
Vidyanand Nanjundiah, and S. Mahadevan* 

(* Corresponding author; Department of Molecular Reproduction, Development 
and Genetics, Indian Institute of Science, Bangalore 560 012, India) 

 
Proceedings of the Royal Society of London Series B., in press 

Bacteria present in natural environments such as soil have evolved 
multiple strategies to escape from predation. We report that natural 
isolates of Enterobacteriaceae that actively hydrolyze plant-derived 
aromatic beta-glucosides such as salicin, arbutin and esculin, are able 
to avoid predation by the bacteriovorous amoeba Dictyostelium discoideum 
and nematodes of multiple genera belonging to the family Rhabditidae. This 
advantage can be observed under laboratory culture conditions as well as 
in the soil environment. The aglycone moiety released by the hydrolysis of 
beta-glucosides is toxic to predators and acts via the dopaminergic 
receptor Dop-1 in the case of C. elegans. While soil isolates of nematodes 
belonging to the family Rhabditidae are repelled by the aglycone, 
laboratory strains and natural isolates of Caenorhabditis sp. are attracted  
to the compound, mediated by receptors that are independent of Dop-1,  
leading to their death. The beta-glucosides-positive (Bgl+) bacteria that are  
otherwise non-pathogenic can obtain additional nutrients from the dead  
predators, thereby switching their role from prey to predator. This study  
also offers an evolutionary explanation for the retention by bacteria of  
'cryptic' or 'silent' genetic systems such as the bgl operon. 

  
Submitted by Vidyanand Nanjundiah [vidya@ces.iisc.ernet.in] 
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[End dictyNews, volume 39, number 13]