Amino acid exposure modulates the bioactivity of biofilms for larval settlement of Hydroides elegans by altering bacterial community components

Abstract

Possible relationships among amino acids, bacterial community structure (in terms of relative abundance of bacterial species) of marine biofilms, and larval settlement of Hydroides elegans were investigated. Two day old biofilms were first exposed to 8 different amino acids for 24 h. The bacterial abundance on the treated biofilms was then determined by epi-fluorescence microscopy, and the bacterial community profile was revealed through T-RFLP (terminal restriction fragment length polymorphism) analysis of the 16S rRNA gene. The larval settlement patterns on the treated biofilms were evaluated using laboratory bioassay. Aspartic acid and glutamic acid significantly increased bacterial abundance, modified the bacterial community structures on the biofilms, and elevated the inductive effect of the biofilms. Alanine and asparagine increased while isoleucine decreased the bioactivities of the biofilms by changing the bacterial species composition (not the bacterial abundance) of the biofilms. The other 3 amino acids (leucine, threonine, and valine) did not alter the bacterial community structures or bioactivities of the biofilms. By correlating the peaks of T-RPLP profiles with clone library results or pure bacterial strains isolated from biofilms, we partially identified the bacterial species on the biofilms that may enhance or inhibit larval settlement of H. elegans.

Characterization of biofilm exudates and their effects on settlement of mussel (Perna canaliculus) larvae

“…For example, naturally occurring polar peptides isolated from crude extracts of adult polychaetes (H. elegans) and bryozoans (B. neritina) were able to induce settlement in corresponding larvae . Also, amino acids of natural and synthetic origin have been analyzed for their ability to induce settlement of larvae of oysters (Zimmer-Faust and Tamburri, 1994), polychaetes (Beckmann et al, 1999;Jin and Qian, 2005;Zimmer-Faust and Tamburri, 1994) and barnacles (Mishra and Kitamura, 2000). Moreover, protein molecules of natural origin containing carbohydrate moieties also have been known to induce settlement of marine larvae (Dreanno et al, 2006;Larman et al, 1982).…”

Conditioning film and initial biofilm formation on ceramics tiles in the marine environment

“…For example, Lau et al (2003) demonstrated that settlement of larval Polychaetes was shown to be affected by extracellular polymers (EPS) from bacteria from the Rhodobacteraceae. Understanding the dynamics of primary bacterial settlers is particularly important because these changes may play a role in the succession and settlement of some invertebrate species onto artificial surfaces (Kirchman et al, 1982;Lau et al, 2002Lau et al, , 2005Lee & Qian, 2003;Qian et al, 2003;Webster et al, 2004;Jin & Qian, 2005). The same bacteria on different substrates and in different combinations may have different effects on larva settlement (Kavouras & Maki, 2004).…”

“…Studies have shown that in the marine environment, seasonal changes affect the chemical composition of the conditioning film, and that these changes affect the initial adhering community composition (Bakker et al, 2003;Bhosle et al, 2005). Indeed invertebrate larval settlement has been suggested to be a function of the biofilm community's bacterial species composition (Kirchman et al, 1982;Lau et al, 2002Lau et al, , 2005Lee & Qian, 2003;Webster et al, 2004;Jin & Qian, 2005). Indeed invertebrate larval settlement has been suggested to be a function of the biofilm community's bacterial species composition (Kirchman et al, 1982;Lau et al, 2002Lau et al, , 2005Lee & Qian, 2003;Webster et al, 2004;Jin & Qian, 2005).…”

High bacterial diversity in nearshore and oceanic biofilms and their influence on larval settlement by Hydroides elegans (Polychaeta)

“…To date, the isolated bacterial strains that induce settlement of H. elegans , as well as the environmental biofilms that have been the subject of settlement assays, have come from bays and harbours where the tubeworm resides (e.g. Hawai‘i, Unabia and Hadfield, ; Hong Kong, Jin and Qian, ; India, Arumugam, ; California, Shikuma et al ., ). This leaves the significant question: are the bacteria that induce settlement uniquely present in these harbour biofilms compared to biofilms from locations not known to harbour dense populations of H. elegans ?…”