Biofilm Development and Cell Death in the Marine Bacterium Pseudoalteromonas tunicata

Abstract

The newly described green-pigmented bacterium Pseudoalteromonas tunicata (D2) produces target-specific inhibitory compounds against bacteria, algae, fungi, and invertebrate larvae and is frequently found in association with living surfaces in the marine environment. As part of our studies on the ecology of P. tunicata and its interaction with marine surfaces, we examined the ability of P. tunicata to form biofilms under continuous culture conditions within the laboratory. P. tunicata biofilms exhibited a characteristic architecture consisting of differentiated microcolonies surrounded by water channels. Remarkably, we observed a repeatable pattern of cell death during biofilm development of P. tunicata, similar to that recently reported for biofilms of Pseudomonas aeruginosa (J. S. Webb et al., J. Bacteriol. 185:4585-4595, 2003). Killing and lysis occurred inside microcolonies, apparently resulting in the formation of voids within these structures. A subpopulation of viable cells was always observed within the regions of killing in the biofilm. Moreover, extensive killing in mature biofilms appeared to result in detachment of the biofilm from the substratum. A novel 190-kDa autotoxic protein produced by P. tunicata, designated AlpP, was found to be involved in this biofilm killing and detachment. A ⌬alpP mutant derivative of P. tunicata was generated, and this mutant did not show cell death during biofilm development. We propose that AlpP-mediated cell death plays an important role in the multicellular biofilm development of P. tunicata and subsequent dispersal of surviving cells within the marine environment.

The cidA murein hydrolase regulator contributes to DNA release and biofilm development in Staphylococcus aureus

“…Given that cell death and lysis are important during biofilm development in other organisms (38)(39)(40), we compared the in vitro biofilm-forming ability of UAMS-1 and KB1050 when grown for 24 h in a static biofilm assay (Fig. 2).…”

Biofilm Dispersal: Mechanisms, Clinical Implications, and Potential Therapeutic Uses

“…2). These cavities have been observed in biofilms produced by the human pathogens A. actinomycetemcomitans, P. aeruginosa, Serratia marcescens, and S. aureus (Kaplan et al, 2003a;Yarwood et al, 2004;Koh et al, 2007;Ma et al, 2009); by the plant-associated bacteria P. putida and Chromobacterium violacium (Tolker-Nielsen et al, 2000;Mai-Prochnow et al, 2008); and by the aquatic bacteria Caulobacter crescentus, Pseudoalteromonas tunicate, and Marinomonas mediterranea (Mai-Prochnow et al, 2004, 2008. Increasing evidence suggests that these hollow cavities play a role in biofilm cell detachment through a process termed 'seeding dispersal'.…”

“…The Cid/Lrg proteins are structurally and functionally related to bacteriophage-encoded holins, which regulate host cell lysis during the lytic cycle of infection by modulating the expression of murein hydrolase (Bayles, 2007). An orthologous Cid/Lrg system was shown to be responsible for Seeding dispersal also occurs in biofilms produced by the marine bacterium Pseudoalteromonas tunicata (Mai-Prochnow et al, 2004). Dispersal involves the formation of central voids within the biofilm colony, extensive cell killing, and detachment of the biofilm from the substratum.…”

Variability and abundance of the epiphytic bacterial community associated with a green marine Ulvacean alga

“…There are several recent examples in the literature that address macro-algal bacterial interactions in this context. For example, microbial community interactions have been investigated using bacterial isolates from the green alga Ulva australis in experiments addressing competition in dual species biofilms and biofilm development (Mai-Prochnow et al, 2004;Rao et al, 2005). At the microbe-host level, it has been shown that for normal morphological growth of many green foliaceous macroalgae the presence of certain bacterial strains is essential (Nakanishi et al, 1999;Matsuo et al, 2005;Marshall et al, 2006).…”