Effect of Biofilm Formation by Pseudoalteromonas spongiae on Induction of Larval Settlement of the Polychaete Hydroides elegans

Abstract

The effects of culture conditions and chloramphenicol treatment on the induction of the marine bacterium Pseudoalteromonas spongiae to larval settlement of Hydroides elegans were investigated. The results showed that P. spongiae cells grown in the medium containing both yeast extract and peptone (YP-grown P. spongiae) was highly inductive to larval settlement, whereas P. spongiae cells grown in the medium containing only peptone (P-grown P. spongiae) or YP-grown P. spongiae cells treated with chloramphenicol at the onset of biofilm development (YPC-grown P. spongiae) did not induce larval settlement. Analysis of biofilm formation, biofilm structure, and the surface protein profile indicated that only the induction-capable YP-grown P. spongiae formed a well-developed biofilm, while the P-grown P. spongiae and the YPC-grown P. spongiae did not. We report here for the first time that bacterial biofilm formation was associated with its induction of larval settlement.In the marine environment, natural and artificial substrata are readily colonized by micro-and macroorganisms in a process known as "biofouling" (4, 8, 52). The dioecious, freespawning, tube-building polychaete Hydroides elegans (Haswell 1883) is one of the most troublesome fouling organisms, occurring widely in tropical and subtropical seawaters (41, 51). Larval settlement of H. elegans marks the turning point from a planktonic life stage to a sessile life stage and represents a crucial step in biofouling. Factors affecting larval settlement are therefore the focus of biofouling studies and antifouling control.Competent larvae of H. elegans settled rapidly after induction by marine natural biofilms or certain monospecies bacterial films in the laboratory (26, 51). Larvae of H. elegans settle only in the presence of a metabolically active biofilm, however, not on a clean surface (21,27,51). Previous studies suggested that the bacterium-derived settlement cues were produced after bacteria attached to a surface and the cues were biofilm surface associated (11,13,19,25). However, little attention was paid as to whether the bacterial biofilm formation was involved in bacterial induction of larval settlement. Bacteria undergo profound changes in physiological features during biofilm formation, a dynamic process wherein bacteria transform from planktonic (free-swimming) organisms to cells that are part of a complex, surface-attached community (5,9,15,35,36,42,47). Recent research revealed that many kinds of bacterial activity, such as infection or symbioses and production of bioactive compounds, were associated with biofilm formation (2, 12, 32, 53). Microbiologists have turned to biofilm formation for explanations of interesting microbial behaviors/ bioactivities (37, 38).In this study, employing the newly described marine bacterium Pseudoalteromonas spongiae (24, 28), we investigated the possible relevance of biofilm formation for its ability to induce larval settlement of H. elegans.Effect of culture condition on bacterial induction of larval settlement. In...

Indole derivatives inhibited the formation of bacterial biofilm and modulated Ca2+ efflux in diatom

“…The formation of biofilm is very important for the adhesion of subsequent fouling organisms. The studies had proved that bacterial biofilm of Pseudoalteromonas spongiae was associated with its induction of larval settlement of the polychaete Hydroides elegans and the settlement was correlated with bacterial density (Lau et al, 2005;Huang et al, 2007), and the reports suggested that the extracellular polymers of benthic diatoms induced larval settlement in the polychaete Hydroides elegans (Lam et al, 2003(Lam et al, , 2005. Similarly, bacterial biofilm promoted the settlement of Ulva spores and Balanus improvisus cyprid (Joint et al, 2002;Tait and Havenhand, 2013).…”

Evidence for the dynamics of Acyl homoserine lactone and AHL-producing bacteria during subtidal biofilm formation

“…As a global regulation signals for bacterial activities, AHLs may affect not only the biofilm composition, but also the consequence of biofilm activities in environment such as biofouling development, nitrogen fixation, sulfate reduction, the degradation of organic matter and, moreover, provide shelter for certain bacteria (Costerton et al, 1995;Qian, 1999;Decho, 2000;Valle et al, 2004;Queck et al, 2006;Huang et al, 2007b;Case et al, 2008). For examples, the cross-domain communication by AHLs between bacteria in biofilms and spores of green alga Ulva indicated a direct function of AHLs in biofouling development (Joint et al, 2002).…”

“…The assemblage of these attached microorganisms on a surface is referred to as a marine biofilm (Cooksey and Wigglesworth-Cooksey, 1995;Costerton et al, 1995). Marine biofilms play important roles in various biological processes, such as the biofouling development, nitrogen fixation, sulfate reduction and so on, therefore are important topics in marine ecological study (Costerton et al, 1995;Qian, 1999;Decho, 2000;Huang et al, 2007b).…”

Seasonal variations in fouling diatom communities on the Yantai coast

“…Diatoms were the earliest eukaryotic colonizer during biofouling formation. The attached diatoms played a signifi cant role in the development of the subsequent macrofouling community (Joint et al, 2002;Huang et al, 2007;Qian et al, 2007). Only a few studies have focused on the community of biofi lm diatoms in the marine environment (Molino and Wetherbee, 2008;Sweat and Johnson, 2013).…”