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

Abstract

Epiphytic and endophytic bacteria associated with green macroalgae Ulva (U. fasciata and U. lactuca) and red macroalgae Gracilaria (G. corticata and G. dura) have been identified from three different seasons to evaluate the effect of quorum sensing (QS) molecules on carpospores liberation from Gracilaria dura. The bacterial isolates belonging to the orders Bacillales, Pseudomonadales, Alteromonadales, and Vibrionales were present in all seasons, whereas Actinomycetales and Enterobacteriales 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 N-acyl homoserine lactones (AHLs). Interestingly, Shewanella algae produced five types of AHL: C 4 -HSL, HC 4 -HSL, C 6 -HSL, 3-oxo-C 6 -HSL, and 3-oxo-C 12 -HSL. Subsequently, the AHLs producing bacterial isolates were screened for carpospore liberation from G. dura and these isolates were found to positively induce carpospore liberation over the control. Also, observed that carpospore liberation increased significantly in C 4 -and C 6 -HSL treated cystocarps. Sodium dodecyl sulfate and native polyacrylamide gel electrophoresis of the total protein of the C 4 -and C 6 -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.

The cultivation of Pyropia haitanensis has important impacts on the seawater microbial community

“…The advantages of microbes for P. haitanensis growth and development One topic in the macroalgal holobiont is the advantages of the presence of microbes on macroalgae. For example, the microbes produce plant growth regulators (e.g., indole-3-acetic acid and cytokinins) (Maruyama et al 1990;Singh et al 2011), quorum sensing molecules (Twigg et al 2014;Singh et al 2015), and bioactive compounds (e.g., vitamin B 12 ) (Singh et al 2011;Singh and Reddy 2014). Here, Bacillaceae were enriched in the seawater with Pyropia cultivation (Fig.…”

Marine biofilms: diversity of communities and of chemical cues

“…Liberation of carpospores from the algae Gracilaria dura was also found to be associated with the prodution of QS signals by bacteria, specifically N ‐butanoyl‐ l ‐homoserine lactone (Fig. ‐7) (Singh et al ., ). According to Tait and colleagues (), these compounds are required for the attraction of Ulva zoospores to biofilms, which are the preferred sites for their attachment.…”

Large-scale seaweed cultivation diverges water and sediment microbial communities in the coast of Nan'ao Island, South China Sea

“…Many of host-associated bacteria play important roles in anti-fouling, anti-grazing and anti-settlement and protect seaweed from invasion of other organisms including pathogens, fungi and herbivores (Armstrong et al, 2001;Goecke et al, 2010). In addition, seaweed-associated bacterial communities can produce quorum sensing molecules (Singh et al, 2015;Twigg et al, 2014), bioactive compounds (Singh et al, 2011a) and plant growth regulators (e.g. IAA, Cytokinin) (Maruyama et al, 1990;Yokoya et al, 2013) to guarantee normal morphology (Singh et al, 2011b), and development and growth of their host seaweed (Singh and Reddy, 2014).…”