AUTHOR=Singh Ravindra Pal , Baghel Ravi S. , Reddy C. R. K. , Jha Bhavanath 

TITLE=Effect of quorum sensing signals produced by seaweed-associated bacteria on carpospore liberation from Gracilaria dura

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00117

DOI=10.3389/fpls.2015.00117

ISSN=1664-462X

ABSTRACT=<p>Epiphytic and endophytic bacteria associated with green macroalgae <italic>Ulva</italic> (<italic>U. fasciata</italic> and <italic>U. lactuca</italic>) and red macroalgae <italic>Gracilaria</italic> (<italic>G. corticata</italic> and <italic>G. dura</italic>) have been identified from three different seasons to evaluate the effect of quorum sensing (QS) molecules on carpospores liberation from <italic>Gracilaria dura</italic>. The bacterial isolates belonging to the orders <italic>Bacillales, Pseudomonadales, Alteromonadales</italic>, and <italic>Vibrionales</italic> were present in all seasons, whereas <italic>Actinomycetales</italic> and <italic>Enterobacteriales</italic> were confined to pre-monsoon and post-monsoon seasons, respectively. Among all the Gram-negative bacteria, seven isolates were found to produce different types of <italic>N</italic>-acyl homoserine lactones (AHLs). Interestingly, <italic>Shewanella algae</italic> produced five types of AHL: C<sub>4</sub>-HSL, HC<sub>4</sub>-HSL, C<sub>6</sub>-HSL, 3-<italic>oxo</italic>-C<sub>6</sub>-HSL, and 3-<italic>oxo</italic>-C<sub>12</sub>-HSL. Subsequently, the AHLs producing bacterial isolates were screened for carpospore liberation from <italic>G. dura</italic> and these isolates were found to positively induce carpospore liberation over the control. Also, observed that carpospore liberation increased significantly in C<sub>4</sub>- and C<sub>6</sub>-HSL treated cystocarps. Sodium dodecyl sulfate and native polyacrylamide gel electrophoresis of the total protein of the C<sub>4</sub>- and C<sub>6</sub>-HSL treated cystocarps showed two specific peptide bands of different molecular weights (50 kDa and 60 kDa) as compared to the control, confirming their indirect effect on carpospore liberation.</p>